Photos found here main photo, and small photo.

Fig. S24 shows predicted maps salinity (psu) across seasons in Holyrood Bay, from July 2020-April 2021.  

Seasonal combination of benthic species observed
A total of 61 morphotaxa were recorded in Holyrood Bay, with seasonal species‑accumulation curves reaching asymptote. Species richness peaked in spring (50 morphotaxa) and was lowest in summer (43), while overall species density was highest in summer and lowest in winter. The fuzzy sea cucumber Psolus cf. phantapus was the most frequently observed taxon, though at reduced densities in fall and winter. Anthropogenic debris was also common, averaging 14 ± 18.96 items per season, including bottles, cans, rope, a tire, and a plastic bag.
 
Further results can be read in the article published in Marine Ecology Progress Series.

Photo of fuzzy cucumber.

Reduced daytime activity with reference strain 

An important methodological element of the experiment was the use of DST micro-ACT data loggers from Star-Oddi, which were implanted subcutaneously in the baboons. These miniature loggers continuously record body temperature and activity throughout the infection period every 10 minutes, allowing researchers to quantify behavioral and physiological changes associated with disease progression. Using this approach, the team observed that animals infected with the reference strain exhibited significant reductions in daytime activity from pre infection (d(-5) to d(-1)) and disruptions in normal diurnal body temperature rhythms during peak infection (d6, d8, d9, d11 and d12). These objective measurements provided a valuable physiological readout of illness severity that complemented traditional indicators such as bacterial load and immune responses. 

Figure 1: Activity following the challenge tracked by DST micro-ACT.a)  Pre challenge data white  and peak challenge data (gray) are showned for AvgEA (average activity over one minute) b) the change in AvgEA between pre and peak-challenge ofr individual animals. 

Altered Circadian Temperature Patterns During Infection 

One of the most striking physiological signals observed during infection was a shift in nighttime temperature patterns. Baboons infected with the reference Bordetella pertussis strain exhibited a noticeable increase in nighttime body temperature compared with their normal circadian rhythm. This elevation occurred during the period of peak disease and coincided with other signs of infection, including reduced activity and increased leukocyte counts. Because of the continuous temperature measurements, the researchers were able to capture these subtle changes in daily body temperature patterns that would likely be missed with intermittent measurements. 

Figure 2: Body temperature patterns observed over 24-h at pre- and peak infection. 

Continuous Monitoring Reveals Subtle Differences in Disease Severity 

Interestingly, baboons infected with some PRN-negative strains showed much smaller changes in activity and temperature patterns, consistent with other signs of reduced virulence such as lower leukocytosis and less coughing. The study highlights how implantable biologging tools can strengthen infectious disease models by capturing continuous physiological data that would otherwise be difficult to quantify. By combining microbiology, immunology, and high-resolution animal monitoring, the research demonstrates the growing role of advanced data loggers in modern biomedical studies, providing deeper insight into how pathogens affect host physiology in real time. 

You can read more about their findings in the paper.

The survey confirmed that the capelin migration remained partly north of its typical winter distribution, reflecting the species’ natural variability. Acoustic measurements and biological sampling were used to estimate stock size and distribution. 

Based on the survey results, the capelin quota for the current season has been set at 197,000 tons. While this allows for a limited fishery, the quota is small compared with historical levels. In previous periods of high abundance, capelin quotas have on several occasions exceeded one million tons, highlighting the large natural fluctuations in the stock. 

Layout of Iceland’s Annual Winter Capelin Search 

Every winter, Iceland sets out on a familiar - but never predictable - mission: finding the capelin. This small fish plays a big role in the North Atlantic ecosystem, and each year its whereabouts keep scientists and fishermen equally alert. 

The vessels' mission sounds simple - track the capelin's location, abundance and stock health - but in practice it's anything but. The figure above shows the survey track lines of the five participating vessels, displayed in different colors for the period 19–25 January 2026, along with capelin density based on acoustic (echo-sounder) measurements (lines perpendicular to the survey tracks)/ fig. from Icelandic Marine and Freshwater Research Institute

As often happens, the capelin chose its own path. Instead of appearing exactly where expected, it has lingered north of Iceland longer than usual - reminding everyone that nature follows no schedule but its own. Using echo sounders and sampling equipment, the vessels sweep large areas of ocean, gradually piecing together the story hidden beneath the surface. 

The findings from the survey form the scientific basis for fisheries management decisions and provide guidance for the capelin fishery in the season ahead. 

Fig. 1 shows the mean circadian body temperature pattern for the selected 72h, a) 23°C and b) 4°C used in the study.
 
H-BMR mice show higher T_MEAN at 23°C and during night-time at 4°C
Mice with H-BMR maintained higher mean body temperatures at ambient temperature of 23°C compared to L-BMR mice, but this difference disappeared at ambient temperature of 4 °C due to a greater temperature drop in the H-BMR line during nighttime (active period). Both lines showed significant decreases in body temperature under cold acclimation, highlighting the interaction between metabolic rate and thermal flexibility.
The impact of BMR selection on body temperature was more pronounced at night in cold-acclimated mice. While both lines showed similar daytime responses at 23°C, nighttime (active) temperature dropped significantly in H-BMR mice at 4°C but not in L-BMR mice, while L-BMR mice reduced the body temperature by more than a degree during daytime at 4°CThis indicates a line-specific differences in thermoregulation under cold stress.

Account for BMR differences when studying body temperature
Artificial selection of BMR causes a 60% higher BMR in H-BMR male mice over their L-BMR counterpart. This resulted in a 0.32 °C body temperature difference at 23 °C, which disappeared at 4 °C and was lower than expected. This suggests that while BMR variation can influence body temperature and fat content, their relationship is flexible and context-dependent. Therefore, the authors’ conclusion is in a few words: BMR should always be considered in studies of body temperature and other physiological and metabolic traits like obesity.

Photo borrowed from here.

Fig. 5 from the paper showing heart rate (HR), acceleration (ACC), and amplitude of QRS wave (AMP) during the crowding stress challenge test.

A matrix of four welfare state described
Based on the swim tunnel trial and the crowding test, the authors defined four behavioural states for the European seabass based on a combination of low or high heart rate and acceleration: Reactive response, Proactive response, Resting state and Regular activity.

Fig. 7 from the paper. Behavioural states of European seabass based on data obtained by implanted biologgers on captive individuals.

This study demonstrates that biologgers are an effective method for detecting changes in behavioural patterns that indicate fish welfare in aquaculture. It further highlights heart rate as a reliable proxy for predicting stress in European seabass

The paper was published in Scientific Reports and can be accessed here

Photo: Nausicca

Fig. 7 from the article, with average temperature measurements.

Temperature as dominant driver
The analysis shows that temperature is the main factor determining polar cod presence. In the spring when adults approach their spawning season, occurrence plummeted at bottom temperatures above 2°C. None were found in waters warmer than 7-9°C. Using random forest models, the team showed that warm years consistently shrank the species’ suitable habitat, especially across Iceland’s northern shelf. Autumn patterns were less dramatic, likely because young cod are still descending from surface waters and haven’t yet settled into long-term habitat.

Continued withdrawal likely
The pattern seen around Iceland mirrors declines in the Bering and Barents Seas. With record heat in the North Atlantic during 2023–2024, the authors warn that the species may withdraw even further north if ocean warming continues. 

The paper was recently published in the Journal of Fish Biology and can be found here

• Automatic updates – You’ll need to download and reinstall this version to enable them.
• Improved performance and smaller program size – The software has been rewritten for faster operation and easier expansion.
• Support for raw acceleration data (*.ACT) – You can now import ACT files for manual annotation, enabling calculation of respiratory rate and tail beat frequency.
• Zoom functionality – You can now zoom in on data for detailed inspection.
• Interval measurement – You can get a measurement between two points in milliseconds (ms) to estimate the duration of various intervals RR, QT, PQ and so forth within a record.
• Record search – Quickly locate specific ECG records in the Record ID dropdown list.
• Record comments – Add predefined or custom comments to individual records.
• Improved filter interface – Default and custom filters are now more intuitive to use.

The HRT Analyzer software is free and lets you process ECG data from *.HAT files, validate on-board algorithms and QI grading, calculate HRV (SDNN/RMSSD) automatically or manually, and measure QRS waveform amplitudes. It’s a powerful tool for both new and existing datasets. Some of these methods are manual, while others are automatic, and we continue to work on improvements.

You find free download and tutorial here

Antigenic cartography used to choose antigens for vaccine design 

Hot off the press in Nature, a group of scientist in the Netherlands (Erasmus University and Utrecht University) and the UK (University of Cambridge) have mapped the global antigenic evolution of avian influenza A(H5) by constructing a high-resolution antigenic map of 127 HA antigens. They found out that the antigenic behaviour of the virus does not show the typical directional drift like H1 and H3 viruses but a non-directional structure. Using this map, they designed a centrally located antigen called AC-Anhui and tried it in a challenge experiment in ferrets using two types of strain from different clades: H5N1 Giza and H5N6 Sichuan, with homologous vaccines for those strains. Their central-antigen vaccine triggered antibodies that recognized a much broader range of H5 strains then conventional vaccines. It provided protection for both strains even if they were from different clades and the protection was comparable or superior to the strain-matched vaccines.

Star-Oddi loggers used in the challenge study 

The group implanted 6 ferrets in each group with Star-Oddi DST micro-T temperature loggers 14 days after the prime vaccination. The loggers measured core body temperature every 10 minutes, which allowed for close monitoring of temperature changes throughout the challenge study as shown in figure 4 from the article. Temperature data from the loggers revealed reduced febrile responses in vaccinated groups, correlating with lower viral loads and milder clinical signs. 

Bleaching survivors 
The results showed that gall crab populations plummeted on nearshore reefs where coral death was extensive, while offshore reefs, with healthier corals, maintained stable and even reproductively active populations. At one nearshore site, a combination of bleaching and crown-of-thorns starfish predation caused a complete local collapse. Yet elsewhere, the species showed remarkable resilience and able to persist on bleached but living corals, quickly recolonize available hosts once conditions improved.

Tiny crabs with big ecological impact
The study also revealed that gall crabs quietly contribute to the reef’s energy flow. By feeding on coral mucus, they recycle nutrients and may help transfer energy to higher levels of the food web, much like tiny reef fish. Their high reproductive output and persistence on stressed corals make them important, if understated, players in reef recovery.

The study was recently published in Ecology and Evolution and can be found here 

Photo: Shawn Miller 

A recent study published in Aquaculture by researchers from Chonnam National University and the National Institute of Fisheries Science in South Korea aimed to move beyond traditional stress indicators such as cortisol. The team instead measured heart rate (HR) and heart rate variability (HRV), a key indicator of the autonomic nervous system activity, to better understand how fish respond to crowding stress. 

Monitoring flounders under different densities 
After a 14-day acclimation and a 5-day recovery period following tag implantation, 16 olive flounders were equipped with Star-Oddi's implantable bio-loggers DST milli-HRT. Fish were distributed across four tanks, two maintained at normal density and two at high density, following national stocking guidelines of 12-32 individuals for normal and 18-48 individual for high based on average weight of 600g. Heart rate data were recorded every 20 minutes, and electrocardiogram (ECG) signals were sampled at 100 Hz every 3 hours over a 25-day monitoring period. HR data were processed with Mercury software, and ECG signals analysed using HRT Analyzer freeware. 

Crowding increases heart rate and reduces HRV 
Results showed that fish in high-density tanks had significantly higher average heart rates (47.6 ± 3.0 bpm) than those in normal-density tanks (39.3 ± 3.7 bpm). This elevation closely mirrored plasma cortisol levels, which were also higher under crowded conditions. In contrast, heart rate variability (HRV), measured as the coefficient of variation (CV), was significantly lower in the high-density group, indicating reduced autonomic flexibility and higher physiological stress.

Implications for aquaculture 

The study highlights that high-density rearing induces measurable stress in olive flounder, evident in both cardiac and hormonal responses. These findings emphasize the need for density management in land-based aquaculture systems to support fish welfare and production efficiency. 
The use of real-time cardiac bio-logging provides a powerful tool for continuous monitoring of fish stress, offering new insights that go beyond traditional cortisol-based assessments. 
 
The paper was published in Aquaculture, and can be found here 

The article was published in Aquaculture Reports and can be found here 

Photo: Lebanese Aquaculture

Fig. 1 from the article. Map of stereo-BRUVs sampling locations with mean salinity (PSU) and mean water temperature (°C) per site

Some fish thrive in high salinity
As hypothesised, many of the fish species’ richness and abundance decreased with increasing salinity, particularly across the Faure Sill and  into Hamelin Pool. Over 20,000 fish from 90 different species, most of them carnivores, were recorded. Despite these hypersaline conditions (reaching <91.5 PSU) in Hamelin Pool, once thought too harsh for most fish, several species were still present. Two species stood out — Western Striped Grunter (Helotes octolineatus) and Western butterfish (Pentapodus vitta) — making up half of all fish observed. Seagrass habitats were hotspots for fish life, though the mix of species varied depending on the location.

Increased salinity levels due to climate change
With climate change expected to increase salinity in shallow coastal areas worldwide, the study raises concerns about future biodiversity. Fewer species are able to cope with high salinity, and even the resilient fish of Shark Bay may be at risk.

Further results can be found in the article published recently in Marine Environmental Research

Photo: https://www.sharkbay.org/place/hamelin-pool/

Fig. 1. J showing Cth^-/- mice fed control diet (black), or alternatively 75% cysteine (green line) with cysteine free diet (green line with red dots).

Increased body temperature with cysteine depletion
The researchers found that cysteine deprivation led to an increase in body temperature, indicating enhanced thermogenesis. This rise in temperature was linked to the activation of the sympathetic nervous system and the browning of white adipose tissue. Remarkably, even when fed a high-fat diet, cysteine-deficient mice exhibited substantial weight loss, improved metabolic profiles, and reduced inflammation. These findings position cysteine as a key dietary regulator of adipose tissue function and systemic metabolism.

This and further results can be read in the article published in Nature Metabolism.

Photo borrowed here

The session aims to bring together providers and field practitioners to explore the current state of wildlife monitoring tools, share real-world experiences and challenges, and discuss what innovation are needed next and the future.

Your organisation should therefore expect to be charged 15% on top of the price of the products from Star-Oddi by the US government. Authorities in the US may also charge local taxes upon import, expenses incurred by the buyer.

If your organisation is tax-exempt it may be tariff-exempt but we cannot confirm that as of yet.

You can learn how our physio-loggers help improve fish welfare and aid in reducing mortality through analysing response to stress and behaviour in aquaculture.

Get an insight into the functionality and applications of the implantable heart rate and activity loggers by analysing cage distribution, crowding effects and swimming performance.

Watch it here: Webinar: Advancing Fish Welfare in Aquaculture by Using Physio-Loggers

Session organisers

• Prof. Andrea Fuller, University of the Witwatersrand, South Africa
• Emily Bennitt, University of Botswana

Session Description
The topic will cover research undertaken using biologging approaches in freshwater, marine and terrestrial ecosystems, aimed at providing insights on animal physiology for conservation and management. It also will feature new technological developments in biologging technology.

Invited Speakers

• Kim Birnie-Gauvin, Technical University of Denmark
• Ágeir Bjarnason, Star-Oddi
• Jessica Kendall-Bar, Scripps Institution of Oceanography, UC San Diego
• Maria Thaker, Centre for Ecological Sciences, Indian Institute of Science (IISc)
• Emily Choy, Department of Biology, McMaster University

In summary, reduced body temperature and heart rate in ewes post-weaning likely resulted from common management practices. Increased heart rate variability signaled stress recovery and improved welfare. HRV data from physio-loggers offered key insights to support more welfare-friendly weaning strategies.

Further results can be found in the article that was published in Smart Agricultural Technology and can be found here.

Photo borrowed here

Further results can be read in the article published in Hormones and Behaviour.

Picture: reddit.com

Photo Credit: Captain Andy Bliss

Picture: earth.com 

If you are attending you are welcome for a chat with our expert in ocean and marine applications, Baldur. We will be there June 16-19, 2025.

Date: May 21st, 2025
Time: 1.30-2pm EST

Get an insight into the functionality and applications of the implantable heart rate and activity loggers and the importance of monitoring aquatic environments for sustainability. Don’t miss this chance to learn from one of the leading experts in the field Ásgeir Bjarnason, biomedical engineer, and discover how technology is shaping the future of aquaculture.

Sign up for a zoom-link for the webinar and ask your questions directly to our expert  >>

You will also be able to watch a recording of the webinar afterwards.

We will then continue to APS 2025, American Physiology Summit, in Baltimore, MD, where we will exhibit during April 24-27, 2025.

If you are attending, we hope to meet you at our booth to discuss how the loggers can add value to your current and future studies. Whether it is mammals, birds, fish or invertebrates, in the lab or in extreme environment, our loggers work with almost all animal models and conditions.

As you may know, our loggers are suitable for vaccine studies, cardiovascular screening and to detect changes in activity. The logging only solution can be used in high biosafety levels, and in animals down to 20g. You can read more about virology research using our loggers here, and much more in our scientific articles section on our website.

Star-Oddi at SEB
If you are at SEB Annual Conference in Antwerp in July, do not miss Session A16 which Star-Oddi is sponsoring: "Insights and tools from biologging for conservation physiology". Session organisers are Prof. Andrea Fuller, University of the Witwatersrand, South Africa, and Emily Bennitt, University of Botswana.

Hope to see you there!

Your organisation should therefore expect to be charged 10% on top of the invoice from Star-Oddi from the US government. Authorities in the US may also charge local taxes upon import, expenses incurred by the buyer. 

If your organisation is tax-exempt it may be tariff-exempt but we cannot confirm that as of yet.

Connection of ODBA and heart rate studied in free-ranging cows
In a recent study, cattle in Norway were studied while grazing free-ranging in the woods of the mountains with the aim to see if ODBA could be used this way. Free-range grazing in the woods is practiced in many places in Norway due to low rugged landscapes, maximizing the utilization of fields to grow winter feed. Under these grazing circumstances, the cattle face similar environmental pressures as wildlife does, through changing weather conditions, predators, and injuries. Using ODBA could be more feasible as non-invasive welfare monitoring on a large scale, especially in remote places where capture and handling of wild species is difficult.

One minute resolution used to compare heart rate and ODBA
In the spring of 2022, a group of scientists from the University of Inland, Norway, implanted 14 cows with Star-Oddi DST centi-HRT. Three farms participated in the study where 4-5 cows from each farm were implanted with a heart rate logger and fitted with an external activity collar. The cows were all adults and were accompanied by their calves. The loggers measured the heart rate every 15 minutes throughout summer for three-week period (maintenance period) followed 48h where temperature and heart rate were sampled every minute, called the intensive period. During the intensive period, ECGs were stored during the first 12 hours (6 am - 6 pm). This raw ECG data was verified by using the free Star-Oddi HRT Analyzer software and used for ODBA comparison, where 12495 1-min averaged observations were compared.

Low OBDA and heart rate can be associated with static behaviours
Behaviours as resting lying, resting standing, suckling of calves, ruminating standing or lying and vigilance showed a correlation to low ODBA values and heart rate. As expected, high ODBA values were in correlation with more active behaviour like foraging, walking, and other activities like running. However, scratching with teeth also showed high ODBA values due to rigorous head movements. The linear relationship between ODBA and heart rate is solid when the ODBA values are low, this gets more challenging with high ODBA values and heart rate and the risk of under or overestimating energy expenditure increases. It interested the scientists that heart rate prediction revealed a circadian pattern seen in low-intensity grazing conditions.

The article was published in Conservation Physiology and can be found here.

Photo at top borrowed from the Fjords in Western Norway

Our product expert, Asgeir Bjarnason, will then head straight to the IEEE MeAVeAS Workshop in Pisa, Italy, held April 28-30. He will together with José Alfonso Abecia, Universidad de Zaragoza, organize Special Session #1: Biologging in Veterinary and Animal Sciences: Measuring Physiology, Behaviour and Movement. 

If you are attending any of those meetings, we hope to meet you to discuss how the loggers can add value to your current and future studies. Whether it is mammals, birds, fish or invertebrates, in the lab or in extreme environment, our loggers work with almost all animal models and conditions.

Feel free to contact us if you want to make an appointment

Core body temperature measured during viral challenges
Scientists from the University of Texas Medical Branch (UTMB), Experimental Pathology Laboratories, University of Missouri, and SUNY Upstate Medical University, all in the USA, implanted all cynomolgus macaques in the study intra-abdominally with Star-Oddi’s DST micro-T temperature loggers. The loggers were programmed to take temperature measurements every 15 minutes throughout the study. The implantation was done 20 days prior to the first viral challenge in the first study, and at the time of vaccination and 14 days prior to the viral challenge in the second study. In the graph below from Fig. 1, the temperature variations during the first study challenge period are shown, and Fig. 4 from the second study.

Single dose of EILV/CHIKV vaccine induces superior T-cell response
Vaccination of cynomolgus macaques with a single dose of EILV/CHIKV vaccine gave protection for up to a year. Various analyzes show adaptive immunity including T-cells and B-cells, as well as antibody response. This provides a long term and specific response against viral infection. The CHIKV 181/25 also induced powerful protection against a viral infection, however, through different T and B cell responses. The EILV/CHIKV response was shown to be superior T cell immunity that was sustained after one year. Compared to the CHIKV 181/25 memory B-cell response, which declined after one year. 

Further results can be viewed in the article published in NPJ Vaccines and can be accessed here.

Heart rate measured in 18 fish during husbandry procedures
The researchers implanted 18 fish (785 ± 76 g) with Star-Oddi’s DST milli-HRT physio-loggers and separated them into six tanks - three with EE and three without EE. Seven untagged fish were added to each tank. After a five-day recovery period, the fish underwent a series of husbandry procedures: feeding, chasing, and cleaning on days six, seven, and eight. On day nine, an anti-parasite treatment was conducted, where the fish were bathed in formaldehyde. For this procedure, the water level was lowered to one-third of the tank, 150 ppm formalin was added, and the fish were left undisturbed for one hour - a common practice in Portuguese aquaculture.

ECG data processed using Star-Oddi's HRT Analyzer software
Following the four days of husbandry procedures, the fish remained undisturbed in the tank for eight days while recordings continued or until the loggers' memory was full, at which point the devices turned off. The fish were then kept in the tanks for six months before being euthanized and the loggers retrieved. Finally, the Star-Oddi HRT Analyzer software was used to verify heart rate based on 50,148 ECG records and to calculate the amplitude of the QRS waveform.

Environmental enrichment affected the heart rate
Environmental enrichment had a significant impact on lowering heart rate and led to a sharper reduction in heart rate to baseline after husbandry procedures. However, EE did not affect heart rate during post-surgical recovery. The study also reported an increase in QRS amplitude associated with increased heart rate during husbandry procedures but not during surgical recovery. 

Further investigations are needed to determine whether these responses have a causal relationship, but the authors theorize that this might be due to increases in stroke volume.

The paper was published in Aquaculture Reports and can be found here

Photo: © Canal Mar Menor

Satellite measured temperature available 
Sea surface temperature (SST) measured from a satellite is essential for describing marine environments. Such measurement data is widely used today but has a relatively low spatial resolution. However, the NASA ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station (ECOSTRESS) instrument aboard the International Space Station has a much higher spatial resolution but is not validated for thermo measurements over reef environments.

Correlation study on data from space and in-situ
Temperature data from ECOSTRESS would be a great resource for the coral reef research community and would support adaptive management, especially so for the design of marine protected areas. Researchers from King Abdullah University of Science and Technology, Saudi Arabia, Coral Reef Alliance, University of Miami, and University of South Florida, USA, recently published a study evaluating the correlation between the different water temperature data sources - both from space and the field.

Water temperature measured at two reef sites in the Red Sea
21 Star-Oddi DST CTD loggers were deployed at two reef sites in the Saudi Red Sea to measure temperature for three years (see Fig 1.). Six loggers were distributed between 4.3 m and 9.7 m water depth and measured data from June 2021 to March 2023 at a 30-min recording interval. At the second site, 15 loggers were distributed between 4.0 m and 7.9 m water depth and provided data from July 2022 to August 2023 at 10-min intervals. GPS fixed the positions of the loggers to within 5 m, thereby allowing for a straightforward comparison of the in-situ and remote sensing data. 

Compared data shows the advantage of new space temperature measurements
Data from all 21 loggers were combined into one master dataset and compared with temperature datasets from space (low resolution SST and high resolution ECOSTRESS). Both orbital platforms correlated strongly with the CTD logger recordings, but only ECOSTRESS data was detailed enough to construct thermal microclimate maps with the dynamic temperature fluctuations in the reefs.

In the ECOSTRESS data there was a systematic bias to cooler temperatures by 1.02°C-1.03°C as compared to the in-situ loggers, which is consistent with prior studies using ECOSTRESS over water. Regardless, the researchers conclude that ECOSTRESS represents a significant advancement in the capability to monitor heat stress on reefs from space.  

The paper was published in the journal Coral Reefs in February 2025, and can be found here 

Picture: Red Sea Development company

You find it on our YouTube channel

It's available online: "Physio-loggers: Advancing Fish Welfare Research" 

Enjoy!

Fig: 5c QT intervals from wild lions at matched heart rates compared to anesthetized zoo lions.

Impact of physical fitness
The significance of the shorter QT intervals shows the plasticity of cardiac electrophysiology of lions and suggests functional differences of the heart in zoo-kept and wild lions. This may be significant when reintroducing captured lions to the wild and can impact veterinary treatments in zoo-kept lions, taking into consideration a shorter QT interval could suggest that zoo lions face a higher risk of sudden cardiac death.
 
Further results can be read in the article published in Experimental Physiology.

In the session they will give an insight into the use of biologgers in farmed animals, both implanted and externally attached. They will present cases in large mammals, birds, and aquatic species and give the attendees an insight into how biologging can be helpful in improving animal welfare, behaviour and disease control.

Further results can be found in the article published in the MDPI Special Issue Antiviral Immune Responses of Bat.

During the holiday season, our offices will be closed on December 24th-26th, 31st and January 1st. 

Salinity, temperature and depth measured during towing
During the summer period when the air temperature and sea salinity were high, experiments were conducted from a commercial fishing vessel in the Western Baltic Sea. Three deployments were sampled from a Danish seine and Star-Oddi’s DST CTD loggers measuring salinity, temperature and depth were attached to the codend, the closed end of the trawl net. Deck temperature was also measured using Star-Oddi loggers. Other parameters as tow speed, tow time, gear configuration, and video footage were collected.  

Injuries and survival observed 
A total of 98 plaice were collected, individually tagged and housed in live wells for ten days to observe their survival and injures. Reflex impairments and external injuries were assessed after capture and at the end of the observation periods using reflex action mortality predictor (RAMP) and catch-damage index (CDI) methodologies. External injuries were primarily minor bruises, fin fraying, and net marks and they changed little from after capturing to the end of the observation period.

Higher survival rate than expected
Survival was expected to be negatively affected by high temperatures, high salinity gradients and time on deck. Average seabed and surface temperatures were 7.2°C and 14.3°C, average seabed and surface salinities 27.0 PSU and 9.2 PSU, and average deck temperature was 16.5°C. The air temperature reached about 30°C during mid-day. The experiment showed that 87 % of the studied fish survived after 10 days of observation. The survival rate was significantly higher for the fish that had remained on deck for 30 min or less, compared to those that remained on deck for more than 30 minutes. 

The researchers suggest that more studies involving other vessels fishing in other periods of the year are essential to obtain average estimates for this fishery. 

The study was recently published in the journal Fisheries Research and can be found here

Photo: LeDrezen

Dual tagging fish with physio and TD loggers
The study, conducted over two consecutive years in commercial sea-cages in Newfoundland by researchers from Memorial University of Newfoundland, Cooke Aquaculture, and Carleton University, provides valuable insights into the behaviour and physiology of salmon during winter. Researchers employed externally attached tags DST milli-TD and surgically implanted tags: DST milli-HRT ACT in the fish, which recorded critical parameters such as depth, temperature, heart rate, and 3D acceleration (swimming activity). These tags offered a window into the environmental and biological conditions faced by salmon during the coldest months.

Heart rate measured down to 1.1°C
The heart rate of salmon decreased progressively with falling temperatures, indicating metabolic adjustments to conserve energy during colder periods. Water temperatures steadily declined from 8-10°C in late October/early November and heart rate about 50bpm to a weekly average low of 1.10°C in early March with heart rate in the range of 20-25bpm. Temperatures remained below 5°C for approximately five months and dipped below 2°C for around 1.5 months. Despite temperature homogeneity with depth, salmon largely occupied the upper 5 meters of the cages. During the coldest months, vertical migrations to deeper depths were observed, particularly at night, suggesting a response to environmental or physiological factors.

Implications for Industry Sustainability
The authors highlight that continued collection and analysis of data from sea-cage environments during winter will help the aquaculture industry in Atlantic Canada to develop strategies to mitigate the impacts of prolonged cold stress on salmon health and welfare. Furthermore, it can help the industry to create technologies and husbandry practices that reduce winter mortality.

The paper was recently published in Aquaculture, and can be found here

Photograph by Paul Nicklen

We will be exhibiting our small, implantable physio-loggers, measuring heart rate, activity, and temperature.

Hope to see you there! 

From fig. 2 in the article, show the lowering of body temperature and heart rate prior to migration.

Energy expenditure not downregulated in the time before spring migration
In contrast to fall, little evidence was found of pre-migratory metabolic changes in the time leading up to spring migration. Specifically nocturnal thermoregulatory downregulation was not observed as was so clear in the time leading up to the fall migration.

Further results can be found in the paper published in Nature Ecology & Evolution and can be found here.

Photo credit: © Christian Ziegler / Max Planck Institute of Animal Behavior

Decreased locomotor activity measured in infected hamsters
By day two post-infection the average externa acceleration was noted, and it lasted until seven days post-infection. This correlated with lower body temperature of the infected hamsters seen by day two post-infection and remaining low throughout the experiment. This in turn correlates with lower daily energy expenditure and lower water intake compared to the control group. Fig. 4 from the article shows changes in average external acceleration of in blue (non-infected) and red (infected).

Pre-hibernation stage suspected in COVID-19 infected hamsters
Hamsters can go into hibernation, however, hypothermia and hibernation have distinct causal features. In this case it could be concluded that the hamsters go into pre-hibernation state with lowering of body temperature and body mass without adverse effect due to their hibernation ability.
 
Further results can be found in the paper published in Nature Scientific Reports and can be found here.

Featured Image: iStock.com/4kodiak

If you are attending, we hope to meet you at our booth to discuss how the loggers can add value to your current and future studies.

Invaluable insight into migrant and resident bird lifestyles
The research provides unprecedented insight into the lifestyle of migrant and resident birds and their strategies to preserve energy prior to migration. This gives an invaluable insight into which birds species may respond to climate change.

The findings have been covered extensively in the New York Times, and Newsweek.

Research paper: Linek N, Yanco SW, Volkmer T, Zúñiga D, Wikelski M, Partecke J. 2024 Migratory lifestyle carries no added overall energy cost in a partial migratory songbird. Nature Ecology & Evolution

You can read more about the scientific article with the findings, a press release from Max Planck, and get further information.

Photo credit: © Christian Ziegler / Max Planck Institute of Animal Behavior

Available sensors are conductivity-salinity, depth, temperature, 3D tilt angle, acceleration, and compass heading for ocean research, and heart rate and activity for fish physiology.

Come by our booth for a chat on how our loggers may suit your study, or to take part in our Raffle for a chance to win a CTD pilot package for your next study!

Heart rate was also found to be diurnal
Variations in heart rate could only be explained by the time of day and showed a diurnal pattern. The heart rate variation could not be explained by activity level nor the water temperature. Furthermore, a sinus arrythmia was detected as well as bradycardia during dives. 

To the best of the researcher’s knowledge this study is the first report of weeks of continuous temperature measurements and well as of heart rate for several consecutive days. 

Further results can be read in the article published in the journal of Animal Biotelemetry and can be accessed here.

Photo: Joe Platko

The northern shrimp (Pandalus borealis) is a crustacean sensitive to environmental changes and temperature is a critical factor for its survival. Researchers from Greenland Institute of Natural Resources, Niras, and Royal Netherlands Institute for Sea Research have in a recent study generated a unique high-resolution spatial model (i.e._>50 meters) to map the distribution of the northern shrimp in the Arctic. 

Oceanographic data collected with robust loggers on trawls
The study focused on Disko Bay (Qeqertarsuup tunua) in West Greenland which is a complex area with several geological differences and various seabed topography. The researchers used factors from several disciplines such as geophysics, oceanography, biology, and fishery to create the model. Physical factors included, i.e. seafloor depth, sediment samples, bottom water temperature, salinity, and bottom current velocity. In addition, shrimp fishery catch per unit effort (CPUE) and biological factors were gathered. Oceanographic data was collected with Star-Oddi’s robust Starmon mini subsea temperature loggers in titanium housing attached to trawl. Bottom water temperature (°C) measurements were taken at 145 stations during 2010-2019.   

Medium-deep waters at 1-6°C preferred by the shrimp 
The ultimate habitat for northern shrimp is distinguished by medium-deep waters (approx. 150-350m), turbulent conditions, and mixed sediments, which is primarily located in the northern and southern regions of the Disko Bay. The shrimp was found in waters ranging from 1 to 6°C.

More understanding of the allocation of northern shrimp
The one-of-a-kind high-resolution model developed by the researchers in this study considerably enhances the understanding of the physical factors and detailed spatial patterns influencing the allocation of northern shrimp in the Arctic. 

Further results can be found in the paper published in Science of the Total Environment, and can be found here 

Photo: Maxima, www.goodfon.com

Vaginal temperature measured every minute
Scientist from University of Wisconsin-Madison looked at six facilities which were naturally ventilated and six which were mechanically cross-ventilated. All were high-producing herds with 300-3000 milking cows, of which body temperature and activity of 360 cows were measured, 180 per facility type. Star-Oddi’s DST centi-T temperature loggers were attached to a blank CIDR and placed intra-vaginally on day one and removed on day 5, programmed to measure body temperature every minute. Concurrently an activity device was attached to the left hind leg to record lying and standing posture.

Air speed does not have influence on vaginal temperature
In the current study, the cows spent overall at least 12 hours per day lying down regardless of ventilation type. It was recorded that with greater wind speed the cows had fewer lying bouts. The researchers found that with the minimum cooling airspeed (MCAS) greater than 1m/s cows had fewer lying bouts per day but greater total lying time, compared to when fans were turned off. The average vaginal temperature vas 39.4°C regardless of farming facilities. Average air speed had no influence on vaginal temperature.  They did however find that for every 10 units of temperature humidity increase, the daily maximum vaginal temperature increased by 0.4°C 

These finding show the importance of providing sufficiently high air speed in and across the resting area to keep the cows comfortable.

Further results can be found in the article published in Frontiers in Animal Science and can be found here. 

Studies in wild and captive animals applicable include: baseline measurements, measuring immune response to infection, testing vaccine efficacy and safety pharmacology, and measuring physiological changes and circadian rhythm. The logger is designed for simple implantation and retrieval.

For studies in water, the logger is also ideal for smolt tagging, in i.e. physiological studies, recording migration behaviour such as thermal preference observation, marine habitat-use, and ocean entry timing. 

Cynomolgus macaques and squirrel monkeys implanted with temperature loggers
Scientist from New Mexico State University, Houston Methodist Hospital, University of Washington and UTMB used two species of non-human primates of both sexes, or a cynomolgus macaques (Macaca fasciculatis) and squirrel monkeys (Saimiri bolivensis boliviensis) of both sexes. All animals were implanted with Star-Oddi’s DST micro-T temperature loggers that were set to measure body temperature every 15 minutes throughout the study. The cynomolgus represented the Old World sylvatic or Asian host species, whereas the squirrel monkeys represented the Americas or Neotropical sylvatic mosquito species.  
 
Temperature data show circadian rhythm
The temperature data showed circadian temperature rhythm in both species. The same control animals were used for both viral infections, and are shown in grey in the figure below. The cynomolgus macaques are shown in A and C and squirrel monkeys in B and D. Blue line is the Zika viral infection and the green is the Dengue viral infection. Normal temperature ranges were established to be 36-39.5°C for cynomolgus macaques, and 33.3-41°C for the squirrel monkeys. Two animals were euthanized due to sickness and deterioration and the drop in temperature to 34°C is seen clearly in D.

Further results can be found in the article published in Nature communications and can be found here.

Male flying squirrel implanted with tiny temperature loggers
Scientists from the University of Maine and Pennsylvania State University implanted 7 males with Star-Oddi DST nano-T temperature loggers. The females were either pregnant or nursing during the study time and therefore excluded. The loggers were programmed to measure every 5 minutes for the duration of the deployment. All measurements were matched with ambient temperature and categorized as daytime or nighttime. Additionally, a squirrel-defined date running from dusk to dusk was assigned to each record. This allowed the researchers to examine the activity period as one instead of two.

Flying squirrels showed high thermal tolerance
Free ranging squirrels showed a distinct pattern of temperature fluctuations during their activity cycle, during which the body temperature rose during the nighttime and lowered during the resting phase in daytime. This heterothermy ranged from 1.9°C – 2.2°C on average. Torpor was not observed. It was found that the Southern flying squirrels do not increase their metabolic rate significantly with increasing ambient temperature, as anticipated. The Southern flying squirrels showed a high thermal tolerance and did not show increased evaporative heat loss until above 36°C. The lab tests mirrored the results from the wild squirrels.

Further results can be found in the article published in Journal of Mammalogy and can be found here.

Photo by MDC Staff, courtesy Missouri Department of Conservation

Unusually low serum concentrations
It has been shown in previous studies that the Ansell’s mole-rat (Fukomys anselli), as well as the African mole-rats (Heterocephalus glaber), have unusually low serum concentrations of the thyroid hormone T4, so much that it is more in line with poikilothermic reptiles rather than mammals. In a recent study, researchers looked at what effect raising the serum thyroid hormones had on resting metabolic rate and body temperature in Ansell’s mole-rats.

Core body temperature measured with DST nano-T
Scientists from the University of Duisburg, Charité – Universitätsmedizin Berlin, and German Centre for the Protection of Laboratory Animals implanted 15 non-reproductive Ansell’s mole-rats with Star-Oddi DST nano-T temperature loggers in the abdominal cavity, 5 females and 10 males. The loggers were set to measure core body temperature every 20 minutes throughout the whole treatment period to investigate the effects of increasing thyroid hormone on body temperature.

Higher body temperature seen with T4 treatment
The research team worked from the hypothesis that T4 treatment would result in higher resting metabolic rate, increased core body temperature and heat dissipation. Surprisingly the effects of the treatment were not as pronounced in the female mole-rats as in the males. Different statistical tests showed significantly higher body temperature in the T4 treated animals. It was however significantly more effective in the male rats compared to the females. Also, the trend of heat dissipation from the ventral or abdominal was also higher in the male rats compared to the females.

Further tests were performed, all results can be found in the article published in Frontiers in Endocrinology and can be found here.

Photo: iNaturalist

One example is this research: here

You can now calculate Heart Rate Variability (HRV), min/max/average amplitude of QRS waveforms and the number of QRS waveforms within each record, in addition to heart rate and Quality Index (QI) validation.

You are welcome to book a virtual meeting with our heart rate and activity product experts to find out more.

You can download HRT Analyzer for free here.

High condition factor in tagged fish
The cage had a low stocking density of 8,000 conspecifics. The tagging was conducted on July 30^th, 2021, and the fish were harvested on July 26^th, 2022. Fourteen fish were implanted, and all survived until the experimental period ended on March 31^st, 2022, when the acoustic tags and HRT-ACT loggers ceased recording. Seven fish were retrieved at the production line. Their average weight was 4 kg at tagging and 7.46 kg at harvest. Six out of seven fish had an excellent condition factor (K > 1.6) at harvest, while one fish had a poor condition factor (1.0 > K > 1.2).

Optimal temperature threshold determined with two methods
The optimal temperature threshold (T_Opt), the temperature at which aerobic scope is maximized, was determined using two methods. The first method used the difference between daily maximum and daily average heart rates, resulting in a T_Opt of 12.7°C. The second method employed Arrhenius breakpoint calculations, which also indicated a T_Opt of 12.7 °C.

Seasonal variations and thermal stress detected
Throughout the study, temperatures above 19°C and below 2°C were recorded. The highest daily fish body temperature was 18.5°C on September 26^th, while the lowest daily average fish body temperature was 1.9°C on February 1^st. The average daily heart rate showed more variation than the temperature but followed a similar pattern. The maximum daily heart rate was 71 bpm on August 29^th, and the minimum daily heart rate was 19 bpm on February 1^st. The highest hourly average heart rate was 80.78 bpm at 17.9°C, and the lowest was 14.89 bpm at 4°C. Seasonal periodograms revealed 24-hour cycles of heart rate and external acceleration in summer, and 24-hour cycles of heart rate in winter. In winter, acceleration exhibited a dominant frequency of 3.9 days.

Implications for aquaculture
The authors suggested that using cardiac scope as a metric of thermal stress is effective for temperatures above 19°C and below 2°C, where the scope was significantly reduced. Identifying these thermal stress limits can help farmers select suitable farming locations to minimize climate change risks and make informed husbandry decisions, such as when to withhold feed.

The paper Influence of temperature on the behaviour and physiology of Atlantic Salmon (Salmo salar) on a commercial farm was published in the journal Aquaculture and can be accessed here.

Photo: Salmon Evolution

Conductivity, temperature and depth measured
Little is known about diel patterns of the sand lance species in the Northwest Atlantic and hence scientist from University of Manitoba, Canada, conducted a study on this at the northeast Newfoundland coast. Star-Oddi’s DST CTD loggers were attached together with cameras to metal frames to measure the salinity, temperature and depth. It was set to measure every 5 seconds near the seabed in the seven inshore areas where the population of Ammodytes was being investigated. Samples of sediment were also collected to measure the grain size in which the sand lace prefers to bury itself in. 

Preferred depth down to 41 meters
The preferred sediment grain size was recorded as in the range of 0.25-2 mm, and preferred temperatures were shown to be 1-11°C, typically ~2°C. Study sites were down to 41 meters. This is also shown in the figure below (fig. 3 from the article). The salinity measurements showed unexpectedly very little variation in the salinity between the investigated areas and was ultimately excluded from the analysis.

Similar diel patters as in other regions
Findings from this study suggest that sand lance tend to feed during day-time and bury in the sediment later in the day when stomachs are non-empty. These results correlate with diel patterns previously shown for sand lance in the Pacific and Northeast Atlantic regions.

Further results can be found in the article, published in Environmental Biology of Fishes here.

Photo: Ground Truth Trekking

Gestation period hypothermia detected
The pregnant females became increasingly hypothermic during the gestational period but returned to normal shortly after birth. Gestating females consistently had lower 24-h body temperature compared to non-pregnant females, however, during drought periods the non-pregnant females had lower body temperature compared to the pregnant ones. Gestating females had consistently narrower 24-h temperature amplitudes compared to the non-pregnant females.

Lactation period - higher mean and minima temperature
Lactating female monkeys had higher 24-h mean and minima temperatures, but lower 24-h maximal and narrower temperature amplitudes in comparison with the non-pregnant females. As lactation progressed, the females had higher max 24-h temperatures but no change in means, minima, or amplitudes. The effect of drought periods had lowering effects on maxima, minima, and wider temperature amplitudes. Lactating females showed lower minima during drought periods.


Predicted pattern of gestational hypothermia observed.
The predicted hypothermia pattern was observed, reinforcing the hypothesis that maternal thermoregulation supports and provides optimal temperature for development and protection of the foetus from potential heat-induced teratogenic effects.



Fig 1. From the article showing the average (a) 24-h mean (black), minimum (blue) and maximum (red), and (b) amplitude (green) of body temperature rhythm during preproduction (solid lines, N=23 births from 14 monkeys) and time-matched non-reproductive (dotted lines, N=30 monkeys) periods, coinciding with the 164 days of gestation and 155 days of lactation, centred on Day 0, the day of parturition. Grey lines demarcate trimester.

The article was published in Functional Ecology and can be accessed here.

Photo: Stuart Mackay

Deep-sea landers equipped with temperature and depth loggers
Researcher at Beneath The Waves and University of Rhode Island, USA, used customized deep-sea landers to study pelagic sharks in The Bahamas. The surveys were conducted using several free-falling, deep-rated baited remote underwater video systems, called dBRUV. The system included a camera, LED lights, bait-cage, and an acoustic weight-release system mounted on a frame, together with a Star-Oddi Starmon TD temperature and depth logger. At the end of deployment, the dBRUV systems were released on command and all were located and retrieved at the surface.

Sharks observed at novel depths 
The surveys targeted a depth range of 300-1000m along the reef wall approximately 10 km east of Chub Cay, Bahamas. One of the dBRUV systems was during a deployment at a depth of 470 m, recording a total of 487.95 minutes when a female subadult silky shark (Carcharhinus falciformis) was monitored making three quick passes. The bottom temperature measured by the Starmon TD was 15.79°C. During another deployment of a dBRUV system, an adult male dusky shark (Carcharhinus obscurus) was observed making 30 passes during 2.95 min at 767 m depth. The bottom temperature here was 9.22°C. This dusky shark bumped the lander several times causing it to slide down the slope about 30 meters to a deeper silt platform. This sliding movement was measured and determined by the Starmon TD temperature and depth logger.

Deep dives possibly more common than expected
The novel depth data presented in this study increase the knowledge of marine predatory sharks’ behaviour in mesopelagic ocean, something which is lacking in this ocean region. The previously known depth record for the dusky shark was 573.3 m and thus the 767 m is a new depth record for the species. Both dusky sharks and silky sharks prefer shallow depth of 0-100m and spend 99% of their time there.  However, due to oceanic warming, sharks may be frequenting the deep-sea as a thermal refuge by seeking cooler waters. The scientists of this study recommend further research on this matter.

The paper was recently published in Environmental Biology of Fishes and can be found here 

Photo © Steve Garner Wikicommons

Figure 2:The seasonal and interannual 24-h body temperature patterns of pangolins for the two study years.

Food availability is an indicator of pangolin welfare
The scientists concluded that there is a strong relationship between food availability and body temperature, meaning that pray abundance could be a useful and strong indicator of pangolin welfare. This is shown in the temperature data collected as the body temperature is kept within a narrow range when times are good, but this is more relaxed when food is scarce. From this it is possible to conclude that pangolins prioritize energy conservation over thermoregulation.

Picture: Keith Connelly

The volcanic activity is confined to a small part of the country. The small town of Grindavík has been evacuated as the eruption caused damage on houses and infrastructure in and around the town. The eruption stopped after a few days.

Tail beat frequency (TBF) derived from acceleration
Eight juvenile channel catfish were surgically implanted and allowed to recover for 5 days with several other catfish. Then each fish underwent a critical swimming speed test at 20°C in a Blazka-style swim tunnel respirometer for measurement of metabolic rate. Data loggers were set to record acceleration at 10Hz, storing the raw data. Overall dynamic body acceleration (ODBA) and TBF was calculated from the raw accelerometry measurements and validated with visual observation. This allowed the researchers to determine the relationship between acceleration, metabolism, and water velocity.

All variables increased with water velocity
ODBA and TBF both showed an exponential relationship with increasing water velocity as expected. The overall dynamic body acceleration increased about 3.2 times while TBF increased 1.5 times from water velocities of 30cm/s to 60cm/s. The relationship between ODBA and metabolism was 1:1. In conclusion, the authors highlight the benefits of using fine scale biologging information such as acceleration to increase the understanding of metabolic processes and energy expenditure which will help maximize aquaculture productivity.

The paper titled The relationship among acceleration, metabolism, and tail beat frequency of channel catfish (Ictalurus punctatus) during critical swimming speed tests can be accessed here

Photo: Sam Stukel (USFWS)

Workshop on physio-logging in terrestrial and aquatic animals
On March 3, our physio-logging expert Asgeir Bjarnason will organize a pre-conference workshop with Andreas Fahlman (Linköping University/Global Diving Research) on physio-logging in both terrestrial and aquatic animals.

In this workshop, various experts will present state of the art physio-logging methods with special emphasizes on both short term and long-term heart rate measurements in various species addressing methodological challenges of recording and processing such data. We also include presentations of new technologies and trends as well as development of some new physio-logging tools that will enable both physiological capacity and energy use to be estimated. 

Come by and meet us
If you are attending BLS8, we would love to meet you. Come by our booth for a chat on how our physio-loggers may suit your study, or to take part in our Raffle! Also, make sure to sign up for the workshop due to limited spaces.

Sign up for the conference and workshop today!

Salinity, temperature and pH measured hourly
In a study carried out by University of Moncton, environmental parameters were measured in three bays of Northeastern New Brunswick. The Caraquet Bay, St. Simon Bay, and Tracadie Bay are of interest for the aquaculture of the Eastern oyster (Crassostrea virginica), which is the principal bivalve species grown in this area. Salinity, pH and temperature were hourly measured by several instruments, among others Star-Oddi DST CTD data loggers which measured salinity, temperature and depth. The instruments were retrieved every 1 to 2 weeks during the study period which was between 2-8 months at the three studied sites. In addition, Chlorophyll-a concentration was measured as an indicator for phytoplankton biomass, and two samples of water were collected once a week for total alkalinity analysis.

No present threat to the Eastern oyster farming
The results showed that pH is highly variable in the studied area, not least depending on season with lowest levels in winter when snow and ice covered the bays. Periods of low salinity such as those noted in the spring at St. Simon Bay and during the summer at Tracadie and Caraquet might occasionally impair the impact of acidification on juvenile oysters’ mortality. However, based on the results from this study, the situation for the Eastern oyster is currently not critical. Nonetheless, further acidification might harm the species as the larvae is produced during winter in commercial hatcheries. 

Further results can be found in the paper published in Anthropocene Coasts and can be accessed here

Photo: Ben Stern, Unsplash

During the holiday season, our offices will be closed on December 25th-26th and January 1st.

Fig 5. from the article shows the 24-hour circadian rhythm in temperature and heart rate.

Daily Rhythms Important for Thermoregulation
Wild boars use the predictability of daily cycles, especially in their skin temperature rhythms, to create significant temperature differences within their bodies. The researchers suggest that this ability to thrive in diverse climates stems from the efficient use of low-cost cold thermoregulation and effective heat-countering behavioural strategies. Their main threat being reduced food availability due to more frequent droughts.

The paper was recently published in Journal of Comparative Physiology B and can be found here

Three Experimental Techniques
The first of the three methods employed a "rapid screening protocol," where fish were implanted with Star-Oddi DST micro-HRT heart rate bio-loggers. The fish were then pharmacologically stimulated to reach their maximum heart rate (HR) using atropine sulfate and isoproterenol during a heating rate of 10°C per hour. In the second method, the fish were fitted with a Doppler flow probe, followed by recovery in a respirometer, and determination of CTmax at a rate of 2°C per hour. The third and final method involved the implantation of DST micro-HRT bio-logger in fish, allowing for a recovery period of 4 weeks before determining CTmax with a heating rate of 2°C per hour. Additionally, oxygen levels were reduced from 100% to 30% air saturation to ascertain the oxygen level at which bradycardia occurred.

Highest CTmax for free-swimming fish
Results showed that heart rate increased linearly with temperature, as expected. However, the fish that underwent the rapid screening protocol had a lower Arrhenius breakpoint temperature (ABT) than the other two experiments. ABT, or the point where HR stops predictable scaling with temperature, was determined to be 14.6°C for the first experiment compared to 18°C in the other two. Fish in the third experiment had the highest CTmax (27.7°C), the lowest resting HR (49 bpm), and the highest cardiac scope (104 bpm). However, it did show bradycardia due to oxygen levels at 62%, compared to 53% air saturation in the fish instrumented with the Doppler probe. The authors suggest that this is due to a higher cholinergic tone in the free-swimming fish compared to the fish in the respirometer.

This novel study highlights some of the limitations of lab-based methods to determine thermal tolerance in fishes. It also suggests that cardiac scope may be a more reliable and predictive measure of fish CTmax than their peak HR.

The paper titled The upper temperature and hypoxia limit of Atlantic salmon (Salmo salar) depend greatly on the method utilized can be access here.

Photo by USFWS

Measuring metabolic rate in swim tunnels
The experimental protocol involved measuring the fish during surgical recovery in either a Blazka or Brett Type swim tunnel respirometer. Subsequently, the fish were swum at three different speeds: 0.5, 1, and 1.5 body lengths per second (BL/s). Finally, the fish underwent a stress protocol before euthanasia.

Close Correlation between Acceleration and TBF
Key findings revealed that acceleration serves as a reliable proxy for swimming activity and exhibits a strong correlation with tail beat frequency (TBF). The variation in acceleration significantly accounted for differences in venous partial pressure of oxygen, blood lactate, plasma concentration, as well as pH and mean corpuscular haemoglobin concentration.

Variation in Acceleration as a Swimming Indicator
The study also affirmed earlier research, highlighting that the variance in acceleration is a robust indicator of burst-swimming activity, influencing acid-base imbalance and the release of catecholamines. In conclusion, the authors emphasized that heart rate, acceleration, and variance in acceleration can be employed as predictors of metabolic rate.

The paper titled Under the sea: How can we use heart rate and accelerometers to remotely assess fish welfare in salmon aquaculture can be accessed here

Picture from paper

About 96% of the island is geographically not affected by the turmoil as can be seen in the picture, and with Iceland being somewhat the size of New York state in the US, the area affected is quite small.

The turmoil is still quite damaging for Grindavik, a fishing village in the Reykjanes peninsula close to where the earthquakes and subsidence have taken place. The locals, about 3,500, have already been evacuated. We hope for the best possible outcome for the villagers.

Should any questions arise, we welcome them 

Velferð fiska og sjálfbærni fiskeldis hefur verið mikið í umræðunni undanfarið og mun meiri áhersla er á þessa þætti en áður um heim allan. Star-Oddi býður upp á brautryðandi tækni sem sýnir áhrif umhverfisbreytinga og mannlegs áreitis á eldisfiska og gerir stjórnendum eldisfyrirtækja kleift að nota þær upplýsingar til að minnka hin skaðlegu áhrif á fiskinn, auka velferð hans og þar með gæði afurðanna.

Hvaða tækni er þetta?

Star-Oddi hefur þróað hjarta- og virknismæla sem hafa gagnast vel í rannsóknum á fiski, bæði villtum fiski og eldisfiski. Það hefur sýnt sig að það er beint samhengi á milli hjartsláttartíðni, eða púls, og stress í fiskum. Star-Oddi er í dag eina fyrirtækið í heiminum sem býður upp á þessa mæla til notkunar í fiski, en mælarnir hafa enga utanáliggjandi víra. Þessi einstaka hönnun gerir að verkum að ígræðslan í þá er mjög einföld. Tæknin hefur hlotið mikla viðurkenningu og hafa yfir 100 fræðigreinar verið birtar í virtum vísíndatímaritum, svo sem Aquaculture og Journal of Fish Biology.

Hvernig fara mælingarnar fram?

Mælarnir eru græddir í ákveðinn fjölda fiska og þeim síðan sleppt í kvíina þar sem þeir lifa sínu lífi án nokkurs auka áreitis við mælingu. Hegðun hvers og eins fisks (dýpismælingar) og lífeðlisfræðibreytingar hans (hjartsláttur og virkni) eru mældar. Mælirinn mælir hjartsláttartíðni en getur einnig mælt hve mikið, hve hratt og öfugt hve lítið, fiskurinn er virkur. Þetta gefur til kynna hegðun fisksins undir ákveðnum aðstæðum.

Hvernig hefur þessari aðferðafræði verið tekið?

Star-Oddi er nú þegar með nokkur hundruð viðskiptavina í fiskeldi á alþjóðavísu, bæði á landi og í sjó, en einnig viðskiptavini sem eru að skoða villta fiska. Helstu markaðirnir eru í Svíþjóð, í Noregi og síðan Kanada en yfir 2000 mælar hafa verið seldir nú þegar. Salan fór vel af stað árið 2020 og gert er ráð fyrir góðri aukningu í sölu.

Nytsemi þess að mæla atferli fisksins í kvínni

Þrír þættir sýna fram á nytsemi mælinganna og hvernig má nýta niðurstöður þeirra

1. Bestun á meðhöndlun og fóðurgjöf

Atferli fiska þýðir í raun hvað fiskurinn er að gera í kvínni eða tankinum. Þetta inniheldur sundhegðun t.d. hraða og reglulegt eða óreglulegt sund, staðsetningu í kvínni út frá dýpi og hitastigi og hjartsláttatíðni sem er þá bein mæling á líkamsstarfsemi fisksins. Þessar mælingar geta verið tengdar við fóðurgjöf eða önnur  umhverfisáhrif. Með því að greina þessi gögn er hægt að ná sem bestri fóðurgjöf og meðhöndlun á fisknum til að minnka streitu, sem getur leitt til aukins vaxtahraða.

2. Lágmörkun streituvaldandi þátta sem auka velferð fisksins

Velferð fiska tengist ótrúlega mörgum hlutum en hjartsláttamælingarnar eru sérstaklega notaðar til að skoða streituvaldandi þætti. Með því að fylgja fisknum eftir svo mánuðum skiptir er hægt að sjá frávik frá eðlilegri líkamsstarfsemi og tengja þau við innri þætti svo sem sjúkdóma, sár og áhrif af t.d. laxalús eða ytri þátta eins og hitastig og súrefni í sjókví. Enn eitt dæmið eru áhrif af svokölluðum umhverfisbótum (e. environmental enrichment) þar sem reynt er að auðga umhverfi fisksins og gefa honum þar með tækifæri á að sýna sína náttúrulega hegðun sem hefur þau áhrif að streita minnkar.

3. Áhrif umhverfisþátta, t.d. sjávarhita á fiskinn

Stöðugt er stefnt að kynbótum á eldisfiski og er hitaþol fisksins ein helsta kynbótin sem sóst er eftir. Þar telur til dæmis hvort fiskurinn getur synt betur, þolað betur sjúkdóma eða miklar sveiflur í umhverfishita. Flestir fiskar eru með kalt blóð og því er mjög sterkt samband á áhrifum umhverfishita á hjartsláttartíðni. Á Íslandi er kuldinn oftar meira vandamál en á svæðum eins og Nýfundnalandi þar sem er mikið laxeldi. Þar getur sjávarhitinn við yfirborð verið nálægt frostmarki á veturna en farið upp í allt að 25°C á sumrin. Hitasveiflur geta haft miklar afleiðingar þó nýjustu rannsóknir sýna að hitastigið eitt og sér er yfirleitt ekki nóg til að valda laxadauða. Það er meðal annars það sem Kurt Gamperl og Rebeccah Sandrelli (sjá fyrir neðan) rannsaka einna helst.

Vísindamaður segir frá nytsemi mælanna í eldisfiskum á Lagarlíf

Rebeccah Sandrelli sjávarlíffræðingur og aðstoðamaður Kurts Gamperls, eins fremsta vísindamanns á sviði rannsókna á umhverfisáhrifum á fisk og fiskeldi í heiminum, var með framsögu á ráðstefnunni Lagarlíf um nytsemi þessara hjarta- og virknismæla í eldisfiskum. 

Um Kurt og hans störf

Kurt Gamperl er samanburðarlífeðlisfræðingur sem hefur einbeitt sér að skoða áhrif umhverfis- og lífeðlisfræðilegra þátta á líffræði fiska. Hann hefur lengi rannsakað fisk bæði í sjó og ferskvatnsfisk. Þeir þættir sem hann hefur aðallega skoðað eru súrefnisupptaka, virkni hjartans, og áhrif streitu á fiskinn almennt. Hann vinnur að aukinni sjálfbærni í fiskeldi og áhrifum á vistfræði villtra fiska.

Frekara efni um Kurt

https://www.mun.ca/osc/dr-kurt-gamperl/

https://www.scientia.global/dr-kurt-gamperl-exploring-how-fish-adapt-to-climate-change-sustainable-aquaculture-and-species-conservation/

 Samantekt um notkun mælanna í fiskeldi má finna hér.

Photo: Xaime Beiro

More than seven variables sampled
During the north-east monsoon season between 2020 and 2022, environmental variables including temperature, salinity, dissolved oxygen, turbidity, chlorophyll-a, and macronutrients were gathered. The entire coastal belt of Bangladesh is 710 km long and samplings were performed from the entire coastal ecosystem during high tide using artisanal fishing boats. 

Temperature and salinity measured with CTD
Star-Oddi’s DST CTD logger was attached under the boat for continuous measurement of surface water temperature and salinity. Measurements were taken at a 1-minute interval and in total 2500 measurements were taken. Vertical profile data of temperature, salinity, DO and chlorophyll-a was taken on 210 samplings sites by probe from another manufacturer. Water samples, plankton net, and other equipment were also used in the study. 

Salinity variation main factor
The result showed that spatial variability in environmental conditions were strong and mainly related to salinity variation due to freshwater from the many rivers. The central coast was characterized by low salinity and high turbidity and silicate concentration, while the south-east coast was characterized by high salinity and low nutrient concentrations. On the contrary, the south-west coast was recognized by high nitrate and phosphate concentration, and moderate levels of turbidity and salinity. In addition, the study identified 121 phytoplankton species. Salinity and macronutrients were identified as the major drivers of phytoplankton variability.

Further results can be found in the article that was published in regional Studies in Marine Science and can be accessed here 

Photo credit: European Space Agency

Mynd Kathryn Murdoch

The emergence of the Siberian hamster
Traditionally ferrets have been the "golden standard" animal model in influenza research, owing to the similarity of the disease symptoms they develop to those seen in humans. However, in recent years, the Golden Syrian hamster has emerged as an attractive animal model in influenza research. Despite its potential, the hamster model is not as widely utilized as ferrets or mice.

In a current study, researchers conducted a comparison between the hamster and the ferret animal models, specifically examining their responses following infection with the human H1N1 influenza virus.
 
Body temperature measured with DST nano-T
Scientists from the UK Health Security Agency implanted 27 healthy ferrets (Mustela furo), aged 15-19 weeks, and 24 healthy Syrian hamsters (Mesocricetus auratus), aged 6 weeks or 20-22 weeks, with Star-Oddi’s DST nano-T temperature loggers. The animals were implanted two weeks prior to infection and the loggers were set to record temperature every hour. 
 
Syrian hamsters don’t show different baseline temperatures between sexes as ferrets do
Baseline was calculated for both sexes of the hamsters as well as the ferrets by using measurements taken in the three days before infection until just before infection. The female ferrets had significantly higher baseline temperature in comparison to the male ferrets; no such difference was shown between the sexes of hamsters. However, young hamsters were shown to have lower temperatures than the older hamsters. Following infection, the ferrets developed a fever compared to hamsters that experience a significant drop in body temperature, below baseline. The male hamsters in contrast showed lower temperatures than the females post-infection.


Fig. 1 from the article, showing the drop in temperature post-infection in the hamster groups. 

Hamsters are easier to house in high bio-safety levels
Golden Syrian hamsters are small and easier to house, and handle, compared to ferrets, which is practical and important when it comes to virus strains that require biosafety level 3, like the influenza virus strains H7N9 or H5N1. This is very valuable where space is tight and being able to use more animals under high bio-safety levels could provide greater power for pathogenicity or protection research.

Further results can be found in the article that was published in Pathogens and can be accessed here.

• Journal of Fish Biology (Advances in telemetry approaches and technologies applied to fish ecology and management) Deadline 31. October 2023
• Biology (Sensor Application to Study the Biology of Fish Movement) Deadline 30 September 2023 

 
Heart rate monitored in rapidly changing water temperatures as well as constant high temperatures

 
Heart rate significantly higher at high water temperatures

The results show significantly higher heart rate at high temperatures. In Experiment 1 the heart rate remained unaltered even when the water temperature was raised at daily intervals up to 22°C, indicating that these fish had evolved to certain water temperature ranges. Even so, the heart rate became significantly elevated at 23°C. Moreover, in Experiment 2 it was consistently higher than the control group throughout both trials. It was also noted that, in the dark phase during feeding the heart rate in Experiment 2 was higher than during the light phase. The control group remained stable. Cortisol was also measured, and it was found to be significantly higher at the end of both experiments compared to baseline of the control group.

The findings in this study indicate that heart rate can be utilized to monitor the health of olive flounder in aquaculture settings.




Fig. 2 from the article. Variations in heart rate in Experiment 1. (a) Average values (average of 7 animals in each trial) and (b) variability ranges (variation of 14 animals in trials 1 and 2) (p < 0.05).

Further results can be found in the article published in Aquaculture and can be accessed here.

We will display our rechargeable fast sampling and fast response data loggers in the Starmon series – for analysing movements and orientation of subsea equipment and fishing gear, or long-term environmental monitoring.

Our miniature multi sensor DST data loggers will also be presented measuring salinity (CTD & CT), temperature-depth, 3D tilt angle and compass heading.

Our experts in booth #1 will be happy to meet you in person! Come for a chat and try your luck in our Raffle!

Our data loggers have been shown to be ideal for virology and vaccination studies. The temperature and activity loggers are reliable and simple in use, and are used in all biosafety levels. We have gathered publications in this field that can be accessed here.

The course will be held at Wageningen University & Research (WUR) in the Netherlands on 13-17 November, 2023.

Application is open: Read more

The Star-Oddi HRT Analyzer enables:

• Manual and computer assisted validation of HR and QI from the raw ECG data
• Post process ECG data with different filter options, needed to:
  • Reduce movement artifacts
  • Reduce EMG artifacts
  • Reduce powerline interference
• Calculations of HRV (SDNN/rMSSD) from identified peaks within record

With the the release of this official version, it is possible annotate raw and bandpass filter data and combine computer and user annotated data in a single HRV file.

HRT Analyzer software

Multiple sensors for analysing movements
Both the Starmon Tilt and Compass loggers boast multiple sensors, high accuracy and large memory. They are ideal for analysing movements on subsea gear and robotics. Both vertical and horizontal placement is possible.

Fast sampling and response
The enhanced battery makes the instrument even more suitable for profiling with fast sampling interval in multiple tests or long-term monitoring on moorings. In addition to fast sampling, the temperature probe has a fast response time constant of 2 seconds, especially useful when using on moving gear. Response is immediate on the other sensors. 

Tilt-acceleration and depth measurements at 100 Hz
A new feature in Starmon Tilt allows simultaneous measurements of tilt-acceleration and depth up to 100 measurements per second (100 Hz).

For shallow to deep ocean
Both Starmon Tilt and Starmon Compass have a robust and compact titanium housing with wide selection of pressure sensor ranges, from shallow depth to deep ocean, up to 6000 meters.

See further specifications at the Starmon Compass or Starmon Tilt product page.

You can access the case study here.

Baseline temperature established 5 days before inoculation
A group of scientists from RIVM and UMC in the Netherlands with scientists from USA and Canada, used 63 female ferrets in this study and a subset of those were implanted with Star-Oddi DST micro-T temperature logger intra abdominally. The temperature loggers were configured to measure the core temperature every 30 min. during the study trial. The researchers established baseline temperature by determining the average temperature in the five days prior to infection. The individual temperature variation was shown as deviation from the baseline.

Hypothermia observed in a few ferrets 
Hypothermia was observed in three animals starting at day 2 after infection and were euthanized at day four instead of day five. In general, the prior therapy had no effect on the height and duration of the fever, since all groups showed equivalent rises (fever) in body temperature. The dip at day 0 was caused be anesthesia of the ferrets during inoculation.
 

Figure 4.D from the article showing the temperature in the days after viral inoculation

Result show potential of influenza mRNA-LNP vaccine 
The results from this study showed that the nucleoside-modified mRNA-LNP T cell vaccine is a promising candidate to boost broadly reactive cellular responses and can be used to enhance protection against heterosubtypic influenza viruses. Furthermore these result show that this kind of vaccine could results in decrease of severe influenza disease and deaths, hence decreasing the societal effect of future influenza epidemics and pandemics. 

Core body temperature measured during experiment
Scientists from SIAT (Shenzhen Institute of Advanced Technology) implanted in a group of male cynomolgus monkeys (Macaca fascicularis) with Star-Oddi DST micro-T in the abdominal cavity two weeks before the  trials started. The loggers were attached to the abdominal wall and removed two weeks after all recording sessions finished. The loggers were set to measure the core body temperature every 5 minutes for months. Several other parameters were measured among them locomotion, ECG, EMG, blood samples and fMRI. 

Chemogenetically activation of POA resulted in hypothermia
The researchers used a complex procedure to activate the POA which included injection with a DREADD - encoded virus (DREADD: designer receptors exclusively activated by designer drugs) followed by injection of the DREADD agonist Clozapine N-oxide (CNO). 

The results showed that, the CNO induced hypothermia in both the hM3Dq gene expressing monkeys and the control animal. The same effect were not produced in the same monkeys when injected only with saline. These results were shown both in free moving animals and anesthetized animals. The clinical signs of the cold defense shown by the monkeys mimics strenuous exercise, showing increased movements, increased heart rate, vasoconstriction and shivering.

Further results can be accessed in the article, published in The Innovation in January 2023, and can be accessed here.

The conference will take place 3rd-7th of January. If you are attending, we hope to meet you at our booth to discuss how the loggers can add value to your current and future studies. It does not matter if you study mammals, birds, fish or invertebrates - our loggers work with “almost” all animal models.

We want to highlight the Symposia: Daily torpor across birds and mammals: Recent progress and how do we advance the field? with leading experts in the field, some of who have used our loggers. Star-Oddi loggers have been used in torpor and hibernation studies in numerous animal models for over a decade. We have summarized these studies here.

Also, a newly published article by Abecia et al. may be of interest to you where our loggers were used in intravaginal sponges and implanted subcutaneously in ewes. Check it out.

As you may know, our loggers are suitable for vaccine studies, cardiovascular screening and to detect changes in activity. The logging only solution can be used in high biosafety levels, and in animals down to 20g. You can read more about virology research using our loggers here.

Feel free to reach out to us for further information on using Star-Oddi’s loggers in your research: sales@star-oddi.com.

During the holiday season, our offices will be closed on December 26th.

Contact email: sales@star-oddi.com

In a current study it was hypothesized that the tachycardia-bradycardia trend often associated with chemical anesthesia would be visible in chemically anesthetized fish, attaining lower hear rates earlier than fish receiving electroanesthesia or electrostunning.

85 walleyes implanted with heart rate loggers
Scientists from Carleton University and Trent University in Canada, Sandusky Fisheries Research Station in USA, and Michigan State University, USA, implanted 48 (trial 1) and 37 (trial 2) walleyes (Sander vitreus) with Star-Oddi’s DST centi-HRT loggers, in a comparison study of three anesthesia treatments. The three treatments consisted of firstly anesthesia with AQUI-S® 20E (eugeneol), secondly transcutaneous electrical nerve stimulation (TENS), and thirdly electrostunning (PES) with a commercially developed stunning unit.

Heart rate measured every 5 minutes and ECG stored every 2 hours
They were set to collect temperature, heart rate and ECG traces for 7,5s (80 Hz) once every 5 min, with raw ECG data stored every 2 hours. No mortalities were noted and therefore not analyzed. The data was filtered manually and only data with heart rate quality index of 0 and 1 were used, and one fish from each trial had inconsistent data and was removed from the study. In general, 75% of the fish in trial 1 and 96% in trial 2 gave useful data sets. First trial was conducted at 1.5-6.2°C and the second trial between 3.7-8.2°C. 

All three anesthesia treatments showed similar but significant changes in heart rate
No welfare-relevant differences were observed and there was no concern associated with one treatment over another. In trial 1 it was observed that a natural circadian rhythm appeared beneath the recovery trends after 1-2 days post treatment. Also little or no difference of maximum heart rates between treatments was observed. What was interesting though, was that the scope and maximum heart rate decreased considerably during trial 2 treatments, and scopes were consistently higher in PES and TENS treated fish during trial 2, compared to AQUI-S 20E.

In this study the scientists were unable to pin-point welfare-relevant differences or concerns that could be associated with one of the three above treatments. All methods showed 100% short-term survival and fish returning to resting heart rates within 30h to 15-20bpm. Further investigation into cardiac function and other stress markers are necessary to be able to identify best practices for fish handling in fisheries science.

The article was published in Journal of Fish Biology and can be accessed here.

Photo: https://www2.illinois.gov/dnr/education/Pages/WAFWalleye.aspx

Researchers at the Institute of Marine Research and The Norwegian Fisheries Directorate in Norway, have in a study designed a catch limitation system for fishing the blue whiting without risking too large catches, hence the bursting of the codend.

Catch limitation system with three components
The catch limitation system in the study consisted of three key components: a fish release section, a fish lock, and a choking unit. Different designs of these components were tested to find the best option during two cruises between March 9th to April 10^th 2022. Cameras and sensors were installed for observation and measurement. Several Starmon TD temperature and depth loggers from Star-Oddi were mounted on the fish release section of the catch limitation system, and at numerous locations along the codend in order to measure release depth. The loggers were set to measure depth every second, clocks synchronized with all other recording instruments including the cameras.

Effective limitation of the volume of the catch
Results of the study show that there was a clear relationship between the position of the choking rope and the actual catch in tons. Managing catch quantity in the blue whiting pelagic trawl fishery can be done effectively through fairly simple modifications to the codend section. The novel catch limitation system was shown to be able to effectively limit the volume of the catch to the level set by the skipper, contributing to more sustainable and responsible fisheries. Future work is needed to optimize the design to fit other fish sizes.
 
The article was published in Frontiers in Marine Science and can be accessed here

Illustration: from the article.
FIGURE 5 Artistic impression of the depth triggered releaser in operation. (1) catch is retained in the codend ahead of the closed releaser; (2) the trigger depth is reached, and the releaser opens; and (3) the retained catch dissipates into the residual component of the codend.  

We will be exhibiting our physiologgers, measuring heart rate, activity and temperature at SICB 2023! We are looking forward to meeting everybody! Come by our booth for a chat on how they may suit your study, or to take part in our Raffle!

Download here

Clear drops in temperatures but no obvious circadian rhythm seen
At 30°C no obvious temperature drops were observed in any of the animals. When the house musk shrews were kept at 24°C three different temperature patterns were observed. Four animals showed a relative constant temperature throughout the light-dark cycle, while the other animals showed drop in temperature, but no clear circadian rhythms. Temperatures between 24°C and 8°C effectively brought on torpor.

House musk shrews were shown to be a potential animal model for daily torpor studies
It is plausible to believe that ambient temperature affects how quickly body temperature drops, even if deliberate depression of metabolic rate is a typical occurrence regardless of ambient temperature. When the surrounding temperature was cold it attributed to rapid drop in body temperature and the rate was higher when multiple peaks showed in the measurements. In the animals that were submitted to cold acclimation protocol (stepwise reduction of the surrounding temperature), there was a clear evidence of torpor at 24°C ambient temperature.

It was noticeable that House musk shrews go into torpor without fasting procedures or short daylight condition. It seems that it was sufficient to put the House musk shrews into moderately cold environment to induce torpor. This makes the house musk shrew an interesting study animal to study endogenous mechanisms related to circadian rhythm that drives torpor.

The article was published in Biomedical Research (Tokyo) and can be accessed here

Shift work could be a factor in the pathology of T2DM
In short, the results of this study indicate that shift work impairs mitochondrial functioning in muscles on multiple levels. Furthermore, the results show that, by disturbing the circadian system, such as occurs during shift work, could be causal or at least contribute significantly to the pathology of T2DM. 

The article was published in the FASEB Journal and can be accessed here

Photo: My Medical News Today

Photo: A. H. Rikardsen

Our miniature multi sensor data loggers will be presented measuring salinity (CTD & CT), temperature-depth, 3D tilt angle, acceleration and compass heading.

The Star-Oddi loggers apply to both profiling and long-term monitoring, stationary or gear monitoring.

Our experts in booth #C301 will be happy to meet you in person! Come for a chat and try your luck in our Raffle!

The CTD and CT loggers are small and easy to attach to gear. They have a low energy consumption, allowing up to 5 years of monitoring at 10 minute intervals. Depth ranges offered range from 100 meters up to 2400 meters.

A wide salinity, 3 to 68 mS/cm range is available, capturing low to high salinity.

Online CTD and CT versions are also available.

See further specifications at the DST CTD product page.

Photo National Geographic

Baseline core body temperature was established
Scientists from the Departments of Viroscience and Neurology, Erasmus Medical Center and the Division of Pathology, Utrecht University in the Netherlands, implanted 6 ferrets intra-abdominally with Star-Oddi’s DST micro-T temperature loggers two weeks before the second influenza vaccine inoculations. Core body temperature was recorded every 10 min throughout the study. Four different combination of vaccines were used as well as placebo, and at day 56 they were challenged with the H3N2 influenza virus. The body condition was recorded, antigen responses were measured, virus shedding from nose and throat as well as the core body temperature. Temperature baseline was established before and after the virus H3N2 challenge with the average temperature for the 3 days prior to the challenge.

NA can potentially protect ferrets from lower respiratory tract infections
It was discovered that a NA that was antigenically matched might lessen the severity of illness, lessen virus shedding from the nose, and shield ferrets from lower respiratory tract infection. Also, the lack of virus in the lower respiratory tract suggested that vaccination with a matched NA can prevent the infection just as effectively as the homologous HA-containing vaccines.

Despite having a decreased effectiveness, the homologous NA vaccine led to a decrease in disease severity seen through a drop in fever and a considerable reduction in viral shedding from the nose; which may prevent further transmission to others. The conclusion was that, although this was greatly reliant on the enzymatic activity and protein stability, inactivated influenza vaccines have the capacity to produce powerful and protective immune responses to the NA protein.

The article was published in Journal of Virology and can be accessed here

Photo proteste.org.br

Researchers at Skretting Aquaculture Innovation (Skretting AI) in Norway recently conducted a study on Atlantic Salmon (Salmo salar L.) to test if heart rate can be used for fish welfare monitoring during standard farming operations: crowding, grading, and vaccination. 

In depth analysis of surgical healing
Total 60 fish (~1kg) were used in the study and kept in three groups at 12°C. 10 fish in each group were implanted with Star-Oddi’s DST milli-HRT sensor and allowed to recover for up to three weeks before the three handling experiments started. Two post-healing periods of 1 week and 3 weeks were compared both macroscopically and microscopically with biopsies and histology analysis. Concluding that 1 week period was not sufficient time to have a complete skin/peritoneal apposition, but 3 weeks was.

The study also applied an anchoring technique that threated two separate thin sutures (5-0) through the skin muscle wall and then tied them together listing advantages to ensure better fish welfare during the surgery.

Aquaculture practices subject stress in farmed Atlantic Salmon
All handling experiments increased heart rate to ranges of 62-78 bpm compared to pre-stress levels of 44-48bpm. Only during the crowding stress experiment, the fish reduced heart rate to pre-stress levels within 48h, indicating different heart rate response to different stressors which might require more time to stabilize to pre-stress levels. The authors suggest that fish should be given enough time (>48h) to stabilize heart rate levels before starting another test or handling.

The paper was published in the journal Aquaculture and can be accessed here 

Photo: Daily Scandinavian

14th International Congress on the Biology of Fish (ICBF)
First up is the ICBF 2022, taking place in Montpellier, France, on June 28 to July 1. Come and see how you can measure the physiology and the swimming behavior of your fish model.

If you are attending, we hope to meet you at our booth where our heart rate and activity product expert will be able to answer all your questions and show real data examples.

Our expert will also demonstrate a new ECG analytical software called HRT Analyzer, which is available to download from our website and complements our heart rate loggers. With the HRT Analyzer you re-process your data, verify QI index, and a lot more.

Society of Experimental Biology Annual Meeting (SEB)
The SEB annual meeting and exhibition is taking place at the same place, Montpellier, France, the week after on July 5-8. You can discuss with us your study design, implantation surgery and how you can maximize the usage of the loggers for your study.

A research study conducted by NTNU and NINA in Norway investigated if it was possible to measure the physiological status in farmed Atlantic salmon by recording heart rate and swimming activity of individual fish. 

Tagged and untagged fish studied
A total of 60 fish were used in the study distributed in six tanks kept at 4.2°C. Out of those 60 fishes 12 were implanted with a combination of tags including Star-Oddi’s DST milli-HRT, DST centi-HRT and DST centi-HRT ACT and a tag from another manufacturer measuring swimming activity. These 12 fishes were distributed in four tanks with 16 untagged fish as a reference group.

Data was collected for 24 days, including a 14-day recovery period after implantation, a stress challenge where the water levels of the tanks were reduced four times and another 10-day recovery period after challenge. All fish was blood sampled four times and levels of Cortisol, Lactate, Glucose and Osmolarity measured.

Heart rate a sensitive stress indicator for salmon
Response of heart rate and swimming activity were consistent with blood proxies for stress levels in Atlantic Salmon. It was highlighted that heart rate showed an immediate response to stress while in contrast the swimming activity were low until 2.4 hours after water levels were restored and swimming activity reached significantly higher levels then before the stressing period. That contradicted previously published work of the same research group where gradually increased activity levels were measured during stress experiment followed by a drop to lower levels when fish was released. Heart rate remained elevated for 24.5h and activity levels remained elevated for 16.2h. 

The study was published in the journal Aquaculture and can be accessed here.

Photo: www.fao.org

Comparison between sham operated and ligated basses
A team of scientist from University of Gothenburg in Sweden, Carleton University in Canada, Queen’s University in Canada, and Autonomous University of Barcelona in Spain investigated the effects on behavior of smallmouth male bass with ligated second gill arch and sham operated fish. Two groups of bass were implanted with Star-Oddi’s DST milli-HRT loggers and were compared to two groups which did not get implanted with loggers.

Cardiac performance unaffected but lower reproductive fitness observed
Fish are known to regulate their cardiac output predominantly through frequency modulation. Therefore, the scientist’s work based on the hypothesis that, the ligation would lead to elevation of the resting heart rate among other effects on the heart, and also have negative effect on the paternal behavior.

Contrary to the hypothesis, the ligation appeared to have no effect on cardiac performance, nor on paternal care behavior. It did appear though to reduce the reproductive fitness during spawning season, with fewer broods reaching maturity and higher abandonment rate. The explanation behind this remains to be discovered as it was unrelated to the ligation and heart rate performance. This information suggests that efforts should me made to prevent and reduce gill injuries during angling and with that reduce sub-lethal consequences of the angling and release method. 

The paper was published in Journal of Comparative Biochemistry and Physiology and can be accessed here

Photo: hatchmag.com/articles/crow-rock-years/7714819

Fits for both short-term profiling and long-term monitoring
The enhanced memory size makes the instrument further capable for profiling with fast sampling interval or long-term monitoring on moorings. The software allows starting the logger with a single interval or multiple intervals, enabling the user to go from a fast to a slower interval. Number of measurements can be defined for each interval.

Fast sampling and response
Starmon tilt can record acceleration and tilt in burst mode at up to 100 Hz (100 measurements per second).
The temperature probe has a fast response time constant of 2 seconds, especially useful when using on moving gear. Response is immediate on the other sensors.

High pressure survival - shallow to deep ocean
Starmon tilt has a robust and compact titanium housing with wide selection of pressure sensor ranges, from shallow depth to deep ocean.

See further specifications at the Starmon tilt product page.

Our miniature multi sensor data loggers will be presented measuring salinity (CTD & CT), temperature-depth, 3D tilt angle and compass heading.

We will also display our fast sampling and response data loggers in the Starmon series – with long life replaceable battery and large memory for measuring tilt and depth of subsea equipment.

Our experts in booth #C300 will be happy to finally meet you in person! 

We will be displaying our small, implantable, leadless data loggers that can measure: heart rate, temperature and activity in a wide range of animal models. We will also show our temperature and depth loggers for fish tagging.

Our heart rate expert will be at the booth offering a great opportunity for those who would like to discuss options to measure heart rate and activity in fish.

If you are attending, we welcome you to visit our booth #517 - we are looking forward finally meeting you in person!

Twelve fish implanted with heart rate and activity biologgers  
A team of scientists from Ifremer, CNRS and CHU de Montpellier measured activity and heart rate of gilthead seabream (Sparus aurata) to hypoxia and warming. Twelve 18 months old gilthead seabreams were implanted intraperitoneally with Star-Oddi’s DST milli HRT-ACT loggers. Two experimental procedures were conducted and compared: each fish was either free swimming in a tank or confined individually in a respirometer chamber.

The fish were allowed to recover, and the experiments were conducted over five days. During a two-day period, the fish were exposed to hypoxia and warming twice, with a recovery period of 24 hours in between. 

Hypoxic bradycardia and warming tachycardia were observed 
Wildlife studies of e.g. sockeye salmon have shown that heart rate is significantly affected by the temperature of the water. Unexpectedly, the researchers in this study observed a higher heart rate in the confined seabream than when they were swimming freely, which was contradictory to what they expected. This happened irrespective of handling the day before. The authors suggest that confinement may introduce bias in physiological studies of fish to environmental stressors. 

Activity was in general low under hypoxic condition and increased significantly with warming. Hypoxic bradycardia and warming tachycardia were observed in the fish regardless of if they were free swimming or confined. The data showed novel insight into the drivers of cardiac responses to temperature as well as behavioral responses to warming.

The paper was published in Journal of Experimental Biology and can be accessed here

Picture: https://joseluisalcaide.com/sparua-aurata/

Six cows were selected and implanted subcutaneously on the left thorax with Star-Oddi’s DST centi-HRT ACT logger. The loggers were set-up to collect data every 5 minutes for 5 days in low density grazing, and 5 days in high density grazing environment.

Temperature, heart rate and activity affected by grazing density
Light and dark periods had significant effect on temperature and activity, while heart rate was affected by grazing density as well as light and dark periods. Heart rate was significantly higher in high density surroundings and activity was significantly higher during daytime. Possibly hyperthermia during the night might be related to social stress although it was not supported statistically.

Most likely the cows experienced higher inter-cow competition at high density surroundings compared to low density grazing, and therefore increase in nocturnal temperature, which could be an indicator of stress.

It is suggested in this study that high density animal grazing might increase competition for resources. This results in changes in circadian rhythm of temperature, heart rate and activity of the cows, in either advancing or delaying their acrophases.

The paper was published in Frontiers Physiology and can be accessed here

Photo: Herefordcattle.com

Fever based on baseline
Each animal was implanted with Star-Oddi´s DST micro-T temperature logger to measure core body temperature every 30 minutes 5 days prior to inoculation and until the end of the experiment. Fever was determined as a deviation from the established baseline.

No clinical disease was observed in neither young nor adults regardless of inoculation route
Intranasal inoculation was more effective compared to intratracheal, especially within the young ferrets. Contrary to what was expected, disease and pathology was not increased in the adult ferrets inoculated intratracheally.

In the infected ferrets the viral RNA was high in the nasal turbines and low in the lungs, and intratracheal inoculation did not result in higher viral RNA in the lung tissues or the trachea.

Ferrets a suitable model for COVID-19 research
The general outcome of the study was that the mature ferret model can be helpful in improving our understanding of COVID-19 and improve and aspire development of new treatments and vaccines. Even though no clinical disease was observed in this study, the ferret model can also be helpful in the understanding of long-COVID disease and or the asymptomatic COVID-19.

The paper as published in Frontiers Immunology and can be accessed here

Photo: https://vetmed.tamu.edu/news/pet-talk/ferret-distemper/

In a recent study published in Journal of Experimental Biology, scientists at the University of Ottawa, Carleton University and Aarhus University explored the hypothesis that chronic elevation of circulating cortisol levels reduces thermal tolerance in subordinate trout. This was done in a series of three experiments using Star-Oddi heart rate loggers.

Three experiments
The first experiment investigated the effectors of chronic social stress and elevated cortisol levels on critical thermal maximum (CT_max). The second looked at heart rate during a CT_max trial and aimed to provide more information on differential responses of dominant versus subordinate fish to acute warming. The third and final trial explored weather chronic social stress causes cardiac remodelling in subordinate trout.

In vivo heart rate measured during 5 days of social stress
Three groups (sham, dominant and subordinate) of juvenile rainbow trout weighing an average 143g were implanted with Star-Oddi's leadless DST micro-HRT (2.35% body mass). The loggers were programmed to record temperature, heart rate and electrocardiogram (ECG) traces during 5 days after a 20h recovery period.

Cortisol a major influencing factor
Results from the experiments showed that cortisol is a key driver to the lowered CT_max in rainbow trout experiencing chronic social stress. The authors propose additional research to identify the mechanisms linking changes in CT_max to circulating cortisol levels.

Picture

The CTD and CT loggers are small and easy to attach to gear. They have a low energy consumption, allowing up to 4 years of monitoring at 10 minute intervals. Depth ranges offered range from 100 meters up to 2400 meters.

A low conductivity range CTD and CT logger, capturing from 0.3 to 5 mS/cm will continue to be available. Our previous ranges are available on request.

The CTD online is also available with the wide salinity range.

See further specifications at the DST CTD product page.

(DST CT picture: Ignacio Garrido)

In 2019, record highs in seawater temperature in Newfoundland, Canada, caused mass mortality of salmon at cage-sites in the region. During that time bio-logging data was being collected in several Atlantic salmon (Salmo salar) by researchers at the Memorial University. The results, published in Frontiers in Physiology, shed light on how sea-cage conditions influence the physiology and behaviour of fish.

Temperature, depth, heart rate and behaviour recorded for over 84 days
In July 2019, 12 Atlantic salmon were equipped with Star-Oddi DST milli-TD and DST milli-HRT ACT loggers and sea-caged with 35.000 conspecifics on the south coast of Newfoundland. The DST milli-TD were attached externally and set to measure temperature and depth every 5 minutes, while the DST milli-HRT ACT were implanted and set to record heart rate (based on ECGs recorded at 100 Hz for 15 s), acceleration (at 1Hz for 60 s), and temperature every 2 hours. ECG data was further manually processed to extract HRV data while the acceleration analysis relied on statistical parameters provided by logger.

Increased water temperatures forced fish to go deeper 
Sustained high environmental temperatures forced the fish to swim deeper in the cage. Fish preferred 14-18°C when available, this meant the salmon swam deeper during day-time than night-time (about 2 meter difference between day/night), and near the bottom of the cage over the warmest period. High environmental temperatures were also associated with higher day-time heart rate values (usually around 10bpm difference between day/night), higher day-time activity levels, and higher day-time percentage of non-steady swimming. 

Weekly averages of the before mentioned variables were all highest during the week where reported mortality in neighbouring cages were the highest, although temperature had dropped reaching its peak temperature just over 19°C a week earlier. These results indicate that high temperature coupled with moderate hypoxia (about 70% air saturation) cannot be the primary cause of mortality.

Biotic challenges and high temperatures confirmed as big concerns for aquaculture
The results of this study, as well as those of previous studies by the same group, strongly suggest that a large climate-related challenge facing salmon aquaculture is the combination of high temperatures and biotic challenges.

Photo: Frode Oppedal, Institute of Marine Research, Norway

44 pink salmon tagged in four rivers 
During a study period from July to September in 2011-2015, 44 pink salmon were captured in four river systems in northern Japan. 23 males and 21 females were measured for fork length and externally tagged with Star-Oddi’s DST CTD logger measuring salinity, temperature, and depth. The loggers were set to record water temperature, depth, and salinity at 1-minute intervals.  

Results show abrupt salinity changes
14 out of 44 fish were recaptured 9 hours to 23 days post release. Nine were recaptured near their tagging site, four were recaptured in marine nearshore trap fisheries within 5 km of the tagging sites, and one fish was caught in a different river 20 km away.  

Analysis of the salinity data from the 14 loggers showed that seven tagged fish remained in fresh water during the time between tagging and recapture. However, sudden changes in salinity levels from the other seven tagged fish suggest that these fish made short-term excursions from freshwater to brackish/saltwater environments. The duration of these short-term visits varied from around 1 minute to eight hours. Six of the seven fish that showed the reverse migration from river to brackish/saltwater were males. 

The results of this study show periodic, short-term movements (minutes to hours) made by mature homing pink salmon between fresh and saltwater. According to the author, this would not have been detected using other techniques such as otolith microchemistry.

Photo: Author

• On-board calculation of acceleration statistics from 3-axis accelerometer data
• Programmable sampling frequency of 0.03Hz-10Hz and option to store raw accelerometry data
• Detection of lethargy and estimation of dynamic body acceleration over time
• Battery life of 122 days when measuring every 15 minutes

If you have any questions or would like pricing information for the new logger don’t hesitate to get in touch.

The scientists from the two universities implanted 20 European whitefish (Coregonus lavaretus) with Star-Oddi DST milli-HRT loggers which recorded undisturbed for 21 days. The biologgers measured the body temperature and heart rate of fish in a sea cage prior to slaughter.

Correlation in plasma cortisol and heart rate during harvest procedure
Harvest procedures such as crowding, transportation and brailing were recorded. Blood samples collected from the fish and conspecifics on day 20 revealed an increase in heart rate and plasma cortisol. After these acute stressors the fish was kept undisturbed for 10 hours. During tat time, heart rate and plasma cortisol reduced. Heart rate increased sharply again prior to the final slaughtering procedure, brailing and CO2 narcosis on day 21.

Surprising predator pray interaction
An unforeseen finding in the study was an increase in heart rate of whitefish when a sea cage containing approximately 5000 large rainbow trout was towed and secured within 10 meters of the whitefish's sea cage. This generated a mean heart rate increase of 34% from 32 to 43 bpm on average and heart rate remained elevated. The researchers suggest this is a physiological response to the threat of predation.

The paper was published in the journal Aquaculture and can be accessed here.

These results are a positive first step to improving tamoxifen treatment in humans in the future.

Salinity, temperature and depth measured
Four fish were collected during two research trips, in February and November 2016, with bottom longline surveys and in situ camera observations. Three Star-Oddi DST CTD loggers were attached to the start, mid and end points of the main lines and measured salinity, temperature and depth. A DST CTD logger was also attached to the camera system which was deployed from one of the vessels in a free-fall mode. 

Giant fish of almost 140 cm length
Suruga Bay is the deepest bay in Japan with depths down to <2500 m and is located in the central region of the Pacific coastline of the Japanese Archipelago. The specimens were caught at depths between 2171 and 2572 m. The total length of the individuals caught ranged from 122 to 138 cm, and they weighed around 25 kg. 

This new species differs in several ways from other species in the same family (slickheads), which are usually under 40 centimeters long. Apart from being much larger, the new species also has tiny sharp teeth which indicates that it is a predator. It also has a different looking dorsal fin and more scale rows. 

The new deep-sea fish species was given the Japanese name Yokozuna iwashi after the highest rank for sumo wrestlers. 

The paper was published in Scientific Reports and can be accessed here.

• Double the memory allows for storing more ECG measurements, 349 compared to 178 in the previous version

DST centi-HRT ACT G2
Second generation of our largest heart rate, activity and temperature logger

• Improved sensitivity of the acceleration sensor
• More acceleration sampling frequencies to choose from (0.03Hz-10Hz)
• Fixed recording period of 1 minute for each activity measurement

DST centi-ACT G2
Second generation of our largest activity and temperature logger

• Improved sensitivity of the acceleration sensor.
• More acceleration sampling frequencies to choose from (0.03Hz-10Hz)
• Fixed recording period of 1 minute for each activity measurement

See our full range of implantable loggers here and a comparison of the specifications for generation 1 and 2 below:

DST micro-HRT

DST centi-HRT ACT

DST centi-ACT 

Photo: Stephen Cunliffe

Photo: Hans-Petter Fjeld

Photo: Copyright: the Author(s) 2020.
Published by Oxford University Press and the Society for Experimental Biology

Photo: Thomas Shahan

Photo: B Devine, L Van Guelpen

Photo: Martyn Unsworth/Dreamstime

Photo: Rudolf Svensen/FishFarmingExpert

The paper was published in Scientific Reports, Nature and can be accessed here.

Photo: Terry Maas/Smithsonian Tropical Research Institute

Researchers from the Technical University of Denmark recently presented survival rates of undersized plaice (Pleuronectes platessa), caught by two commercial vessels with different fishing gear in Skagerrak.

Fish examined in on-land tanks for 14 days
The fishing was conducted on two vessels, a bottom otter trawler and a Danish anchor seiner, for eight days distributed between August and October. Operational and environmental conditions, i.e. air and water temperature and weather conditions, were recorded during the hauls.

Two Star-Oddi DST CTD, conductivity, temperature and depth loggers, were attached to the fishing gear, measuring fishing depth and water temperatures.

The caught undersized fish (below 27 cm of length) were examined and monitored in on-land observation tanks for 14 days, instead of being released into the sea.

Air exposure and water temperature critical factors
Biological, environmental, and operational factors that influence survival were determined and survival probabilities were calculated. At large, fish caught by the trawler showed lower survival (44%) than those caught by the seiner (78%). The most important factor in determining survivability of fish discarded from the trawler was air exposure. For the seiner, bottom temperature was identified as an additional important determinant.

The study was published in Marine Policy journal and can be accessed here.

Photo: Dietmar Lill

To shed light on this, a research group consisting of researchers from Carlton University, University of British Columbia and University of California, Santa Barbara explored whether heart rate and dominance relate to each other during spawning of sockeye salmon (Oncorhyncus nerka).

Heart rate loggers used to assess relative energy expenditure
Sockeye salmon were implanted with Star-Oddi’s leadless DST milli-HRT, heart rate and temperature loggers. This was done with the intention of using heart rate to assess relative energy expenditure of the study animals.

The loggers were set to measure heart rate every 5 minutes at 100Hz. In addition, the raw ECG signal was saved every 1.5 hours for additional validation.

During the study individual animal behaviour was monitored daily. This consisted of an approximately two-minute behaviour assessment. Assigned behaviours were: aggregating, dominant and subordinate.

No clear difference
As was to be expected, heart rate increased with temperature, and heart rate was found to be higher during the day compared to night-time heart rate. On the group level, heart rate was not found to differ between sexes or among different reproductive behaviours, nor was it found to differ significantly on the individual level.

The research group concludes that while the study identified a complex relationship between cardiac performance and reproductive behaviours, heart rate does not seem to be related to specific spawning behaviours. They suggest that future studies investigate how physiological performance and reproductive investment relate to each other in wild animals.

The paper was published in the journal Integrative Organismal Biology and can be accessed here.

Photo: Hlodrik/goodfon.com

However, a study published in Science shows that lockdown in India provides a unique opportunity to collect data that would otherwise be impossible to obtain.

Rivers and streams in India are polluted with industrial and human waste, making it impossible to collect baseline data. With the complete shutdown of industrial operations nationwide, the waters are cleaner than ever.

One example is the Yamuna River, which now is much clearer and with enhanced water quality.

Photo: Amal Kshindustan Times/Getty Images

To understand this better a research group consisting of scientists from the University of Amsterdam in The Netherlands looked at the effects of time-restricted feeding, simulating human shift work, on rats in a laboratory setting.

Two groups compared
The study looked at the effects of putting rats through four weeks of time-restricted feeding where rats were fed during the light period. A control group was fed during the dark period, in accordance with rats’ regular feeding patterns.

During the study, various parameters were monitored. This included measuring each animals' core body temperature throughout the study with Star-Oddi's DST nano-T temperature loggers.

Poor health outcomes for light-fed animals
Feeding during the light period was associated with poor health outcomes for the study animals, while feeding during the dark period was associated with good health outcomes.

Light-fed animals displayed the smallest day/night difference in body temperature, food intake, activity, and respiratory exchange ratio. These animals also demonstrated that they had not fully recovered from the change in their regular eating schedule 11 days later. The effects were shown to be both tissue- and gene- dependent.

Implications for human health
These results indicate that similar effects may be observed in human shift workers. Humans working on rotational shifts may, therefore, be at risk of long-lasting disturbed physiological rhythms after shift work periods which may in turn negatively affect their health.

The paper was published in the journal Obesity and can be accessed here.

Bio-loggers provide valuable data
12 female moose were equipped with a GPS collar with an acceleration sensor, as well as a temperature sensor. In addition, a temperature sensor was placed in the animals’ rumen and a Star-Oddi’s DST centi-HRT, leadless heart rate and temperature logger, was implanted subcutaneously.

Clear seasonal differences identified
The researchers identified seasonal differences in both body temperature and heart rate. The moose had lower levels of both body temperature and heart rate during the winter season compared to the summer.

The highest daily recorded mean for body temperature was 38.64°C, measured on July 10, while the highest recorded mean daily heart rate was 71.9 bpm (June 26). The lowest daily mean for body temperature was 38.03 (March 17) and the lowest mean heart rate was 40.5 bpm.

Lower metabolic rate in winter
The results demonstrate that the animals have a lower metabolic rate during winter compared to summer to reduce energy expenditure when the temperature is colder, and resources are not as readily available.

The paper was published in Frontiers in Ecology and Evolution and can be accessed here.

On May 25, Icelandic authorities lifted the state of emergency implemented on February 28, when the first local COVID-19 infection was confirmed.

Iceland is currently in the second stage of relaxing COVID-19 restrictions and now bars, gyms and swimming pools are open again. The country will open its boarders in mid-June.

Almost 60.000 samples have been taken, which is a high percentage of Iceland’s 364.134 inhabitants.

At Star-Oddi business is as usual, and services at Star-Oddi remain the same. As always, you are welcome to contact us with any questions you may have.

After an introduction by our heart expert, three knowledgeable researchers shared their experience of working with heart rate loggers in fish. Finally, questions from the participants were answered by the speakers through a Q&A chat.

Watch the video of the full webinar here

Evaluating the effects of antibiotic treatments
A study performed by researchers at the Swedish University of Agricultural Sciences and the University of Gothenburg set out to evaluate whether the use of enrofloxacin reduced systemic inflammation after implantation of Star-Oddi heart rate loggers in Rainbow trout (Oncorhynchus mykiss).

After implanting Star-Oddi’s leadless DST milli-HRT, heart rate and temperature loggers, intraperitoneally in 36 fish heart rate was recorded for 21 days. Half of the fish received enrofloxacin treatment while the other half received no treatment.

No clear benefit of using antibiotic treatments
Interestingly, and contrary to the group’s hypothesis, the treated trout took longer to recover than the untreated group. The treated group also displayed elevated resting heart rates and prolonged recovery time post-surgery.

Surgical experience shortens recovery times
Although treatment with enrofloxacin did not seem to benefit the fish post-surgery the results indicated that the more experienced the person performing the surgery, the more likely the fish was to have a quick recovery.

The findings highlight the importance of surgical training as well as providing animals implanted with bio-loggers time to recover post-surgery.

The paper was published in Nature’s Scientific Reports journal and can be accessed here.

Photo: USGS

Researchers from Chile, Canada and USA recently reported findings of the first settlement of the Chilean blue mussel (Mytilus cf. platensis) in a shallow subtidal habitat of the South Shetland Islands in the Antarctic. This indicates a potential for coming invasions of the Antarctic ecosystem.

Water temperature measured for two years
Star-Oddi’s miniature DST CT, conductivity and temperature loggers, were used to record seawater temperatures in Fildes Bay, Antarctic, and in two locations (Strait of Magellan and Beagle Channel) in Patagonia, Chile.

Temperature was measured at 30, 60, and 15 minutes intervals respectively between February 2017 and January 2019. The researchers compared these two regions since southern Patagonia is the closest region where indigenous population of the Chilean blue mussel occur.

Mussels can exist at frigid temperatures
Results from the temperature comparison shows that the mussels are able to survive in this new system at the steadily low temperatures that characterize Antarctica. This is the first time an invasive species has made its way to Antarctica and survived, according to the authors.

Future impact uncertain
The 47 juvenile mussels observed were very small, ca 2 mm, and were probably carried by ships coming from South America. The bivalves probably did not drift there, because circulating ocean currents effectively barricade Antarctica.

The key questions are now if the mussels will stay, and in that case, what impact they will have on the isolated ecosystem.

The study was published in Nature’s Scientific Reports journal and can be accessed here.

Photo: BARON REZNIK/FLICKR

The workshop will take place through Zoom at 20:00-21:30 CEST/14:00-15:30 ET and is open to current users as well as anyone interested in heart rate measurements in fish.

Program

Overview of Star-Oddi Heart Rate Loggers
Ásgeir Bjarnason, Star-Oddi, Iceland

How to Make the Most of Studies Using Heart Rate Loggers in Fish
Albin Gräns, Swedish University of Agricultural Sciences, Sweden

Measuring Heart Rate in Nesting Smallmouth Bass and Spawning Sockeye Salmon
Tanya Prystay, Marine Institute, Newfoundland, Canada

Using Heart Rate and Acceleration Tags in Atlantic Salmon and Lumpfish
Zoe Zrini, Memorial University of Newfoundland, Canada

To sign up for the webinar please fill out the registration form here.

Compact with multiple sensors
Starmon compass boasts multiple sensors in a compact titanium housing. In addition to heading, pitch & roll, and 3-D tilt-acceleration, this unique data logger also measures depth and temperature.

Vertical or horizontal placement
When starting the logger the user selects if it is placed horizontally or vertically on the equipment. The user software offers a real-time view of measurements when connected to a computer, which is helpful for doing a short test before deployment.

Fast response and sampling
The temperature probe has a fast response time constant of 2 seconds, beneficial for the measurements of the moving gear underwater. Response is immediate on the other sensors. Sampling intervals are user programmable, down to 1 second fastest.

High accuracy and large memory
Memory capacity is 2.2 million measurements per sensor parameter. The heading accuracy is better than +/-5° and pitch and roll accuracy +/-2°, when within a tilt range of +/-45°. The depth sensor accuracy is +/-0.3% of the selected calibration range and temperature accuracy +/-0.025°C.

See further specifications at the Starmon compass product page

1. Severity of Pneumonia Due to New H1N1 Influenza Virus in Ferrets Is Intermediate between That Due to Seasonal H1N1 Virus and Highly Pathogenic Avian Influenza H5N1 Virus
2. New Class of Monoclonal Antibodies against Severe Influenza: Prophylactic and Therapeutic Efficacy in Ferrets
3. Oseltamivir-Resistant Pandemic A/H1N1 Virus Is as Virulent as Its Wild-Type Counterpart in Mice and Ferrets
4. Recombinant Modified Vaccinia Virus Ankara Expressing the Hemagglutinin Gene Confers Protection against Homologous and Heterologous H5N1 Influenza Virus Infections in Macaques
5. Comparison of Temporal and Spatial Dynamics of Seasonal H3N2, Pandemic H1N1 and Highly Pathogenic Avian Influenza H5N1 Virus Infections in Ferrets

Our miniature multi sensor data loggers will be presented measuring salinity (CTD & CT), temperature-depth, 3D tilt angle and compass heading.

We will also display our fast sampling and response data loggers in the Starmon series – with long life replaceable battery and large memory for measuring tilt and depth of subsea equipment.

If you are planning on going, then please be sure to visit us at stand C750.

• Improved sensitivity and accuracy.
• A higher sampling frequency when recording acceleration/activity. New available frequencies are 2,4,5 and 10Hz, compared to a maximum of 1Hz with the centi-ACT.
• Programming the loggers has been made more user-friendly. You can now choose the sampling frequency for the activity measurements over the course of one minute.
• Six statistical parameters are included to help quantify the activity of the animal. It is also possible to store the raw accelerometer data.

If you have any questions or would like a quote for the new loggers don’t hesitate to contact us.

Clams put in tanks with simulated salinity fluctuations
Clams were collected by hand from shellfish beds at Cambados in Spain. After being measured and marked, 22 clams were placed onto the sediment surface in each monospecific tank with running seawater. The salinity range in the tanks varied from 5 to 30 during a 24h period, and was monitored by the Star-Oddi DST CTD logger.
To simulate low and high tide, the clams were subjected to two low salinity and two higher salinity exposures per day. The experiment lasted for six days and the study was conducted two times, in March and in May.

Three types of activities were observed in the experiment: burrowing activity, siphon activity and fecal deposition as evidence of activity. This was quantified using a combination of pressure sensors and direct observations.

Breakpoint in behaviour at salinities below 15 PSU
In all cases, the overall pattern was expected and the breakpoint in behaviour was at or below salinities of 15 PSU. Below this breakpoint all three clam species significantly reduced their movements, activity and feeding. This indicates that significant variations in salinity, i.e. large difference in high and low tide, affect the species in the eco-region near the bottom of the oceans. In Galicia for instance, around 7100 harvesters are dependent on the number of clams and reductions in growth and reproduction can have enormous negative socioeconomical effects.

This study was part of a larger study on growth and reproductive success of these three clam species under fluctuating salinity ranges. The paper was published in the Journal of Experimental Marine Biology and Ecology in November 2019 and can be accessed in full here.

Picture: www.idscaro.net

High pressure tilt-acceleration logger for all ocean depths
A custom version of Starmon tilt-acceleration logger is available for deep ocean use - down to 11,000 m. The titanium housing is customized to withstand all ocean depths.

This ultra-high-pressure resistant housing cannot include the pressure sensor, thus the logger is only equipped with 3D tilt and temperature sensors. The standard version of Starmon tilt, with pressure/depth sensor included, is available with various ranges up to 2,000 m. The Starmon tilt is ideal for use on subsea equipment or gear.

Heart rate and behavioural footage collected
22 nesting smallmouth bass were implanted with Star-Oddi’s DST milli-HRT, heart rate and temperature loggers. The loggers measured heart rate at 100 Hz as well as temperature every two minutes.

Behavioural footage was collected using a GoPro camera placed 1 m from the nest. In addition, the presence of a predator was simulated on day three to evaluate aggression levels. This was done by placing a pumpkinseed (Lepomis gibbosus) in a glass jar close to the nest for 10 minutes.

Changes in heart rates only related to individual aggression levels
Heart rates were not found to be related to any of the parental care behaviours measured during the study, with the exception of individual aggression level. The researchers corrected for the effect of water temperature on heart rate in their analysis and found that individual fish heart rate differed both between days and nights. The fish also showed evidence of diel variation with higher heart rates during daytime than nighttime.

Further studies in this field are needed to better understand the complicated relationship that exists between physiology, fitness and behaviour in wild animals.

Image: Sportsmen's nation

Image: Joachim S. Müller via Flickr

Our miniature multi-sensor data loggers will be presented measuring temperature-depth, salinity/CTD, 3D tilt angle and compass heading.

We will also display our robust fast sampling and response data loggers in the Starmon series – with long life replaceable battery for measuring movements of subsea equipment, fishing gear and long-term monitoring. The newest feature is the titanium housing which is now standard for Starmon TD and Starmon tilt for ocean research.

If you are going, then please be sure to visit us at booth #715.

Picture: www.carbonbrief.org

Leadless heart rate loggers used in sockeye salmon
Heart rate data used in the study was gathered using varying methods. For sockeye salmon (Oncorhynchus nerka) leadless heart rate and temperature loggersfrom Star-Oddi were used.

During the summer of 2016, data were collected on mature sockeye salmon. The fish were dip-netted from the mouth of the Gates Spawning Channel in British Colombia. They were then instrumented with DST milli-HRT heart rate and temperature loggers, programmed to record heart rate at 100 Hz every 10 minutes, and raw ECG every 1,5 hour.

Different energy expenditure
Based on the data collected for the 16 species in the study the researches found that certain individuals of a species consistently use considerably more energy than others. Yet, all individuals were found to make compromises in how they spent the energy they obtained. 

The paper was published in the journal Functional Ecology and can be accessed here.

Picture: www.wildsalmoncenter.org