Stomach Content Samples Research Articles

Seasonal trophic niche width and overlap of mottled sculpin and brown trout in a regulated high‐elevation river

AbstractIn temperate ecosystems, resource availability fluctuates seasonally due to changes in environmental conditions and productivity. Intra‐ and inter‐specific trophic niche overlap under resource limitation is a measure of competitive interactions and influences species coexistence and community dynamics, but patterns of this overlap are influenced by anthropogenic activities. To investigate seasonal trophic niche dynamics of coexisting fish species in a flow‐altered river, we analysed prey resources, stomach content samples and stable isotope signatures of mottled sculpin Cottus bairdii and juvenile brown trout Salmo trutta in the Blue River, Colorado, USA, a high‐elevation oligotrophic river. Prey biomass (i.e. benthic macroinvertebrates) peaked in spring and declined through summer and autumn. Stomach content and stable isotope analysis results showed that diet composition of mottled sculpin and brown trout varied seasonally in response to changes in prey availability. Stomach content analysis results revealed that in autumn, both species exhibited the highest frequency of empty stomachs and expanded population trophic niches due to increased inter‐individual diet variation despite decreased individual trophic niche breadth. Inter‐specific trophic niche overlap was relatively high across all seasons, but the lowest degree of overlap occurred in autumn of both years when prey availability was lowest. Isotopic analysis revealed similar trends to stomach content analysis, of wider isotopic niches and reduced overlap in autumn compared to spring. Our data indicated that seasonal variation affected individual‐ and population‐level trophic niche dynamics and inter‐specific niche overlap between mottled sculpin and brown trout. This trophic segregation under resource limitation may serve as a mechanism that facilitates species coexistence in a flow‐regulated, oligotrophic river.

TROPHIC SPECTRUM AND FORAGING MODE OF LISSOTRITON VULGARIS IN A TEMPORARY POND OF THE CITY OF RIVNE, UKRAINE

The article summarizes the state of research on the trophic spectrum and foraging mode of the common newt in Europe in general and in Ukraine in particular. It is concluded that the level and diversity of such studies abroad is high compared to Ukraine. The relevance of such studies in temporary ponds is determined. The article analyzes the trophic spectrum and feeding mode of the common newt in temporary pond in Rivne. The stomach contents samples of 46 individuals of L. vulgaris were obtained, in which 2309 trophic objects were found. Food of animal origin prevails in the trophic spectrum of L. vulgaris and makes up 97%. Food objects of plant origin make up only 1% and mineral partic les – 2%. It was found that the most abundant food items are the larvae of the lake flies (Chironomidae) – 53% and crustaceans (Cladocera: Daphniidae; Chydoridae; Copepoda: Cyclopidae; Ostracoda) – 46%. The diet of L. vulgaris is significantly dominated by objects originating from the aquatic environment – 98.2% of the total number. Individuals of this species will capture prey of quite different sizes. The smallest food objects of the studied newts are planktonic crustaceans Chydoridae: 0.3–0.5 mm, the largest are earthworms Lumbricidae: 150–200 mm. It was found that the food spectrum of the newt changes during the season and depends on the life cycles of prey. In spring, when the trophic resources of the temporary pond are limited, crustaceans, in particular daphnia (Daphnіidae) and shell crustaceans (Ostracoda), dominate in the diet of the newt. During this period, the consumption of shed skin fragments, plant fragments, grains of sand is higher and larvae of the lake flies (Chironomidae) are absent, but in the second decade of May they dominate (more than 70%) in the diet. It was found that L. vulgaris uses different foraging mode in different periods. The predominance of crustaceans (daphnia, cyclopes) in the diet at the beginning of the season indicates that newts use active foraging tactics. In late April-May, we observed a significant predominance of larvae of the lake flies, which indicates that L. vulgaris uses sit-and-wait foraging. It was found that the foraging behavior of the newt in temporary ponds in Rivne is labile and varies depending on environmental conditions and its trophic offer.

Ants (Hymenoptera: Formicidae) and termites (Blattodea: Termitoidae) in the diet of wild white-bellied pangolin (Phataginus tricuspis) in forest-savanna habitats of Cameroon.

The white-bellied pangolin Phataginus tricuspis (Rafinesque 1821) is a semiarboreal species occurring in tropical sub-Saharan Africa. It is the world's most trafficked African pangolin species based on volumes recorded in seizures. Reintroduction of confiscated live pangolins and ex-situ rearing are being explored worldwide as a conservation action. However, the husbandry of seized animals is challenging as the diet of the white-bellied pangolin is poorly known and little studied. We analyzed the stomach contents of dead white-bellied pangolins from two forest-savanna protected areas. Stomach content samples from 13 white-bellied pangolin specimens contained ~165,000 Arthropoda, mostly Hymenoptera (60.34%) and Blattodea (39.66%). Overall, we identified 39 termite and 105 ant species consumed as prey by pangolins. Individual pangolins examined had fed on a maximum of 31 ant species and 13 termite species. The termite and ant species richness varied significantly across the pangolins'last consumed meal. We recorded 24 ant genera dominated by Crematogaster (relative importance [RI] = 17.28). Out of 18 termite genera recorded, the genus Pseudacanthotermes (RI = 17.21) was the most important prey. Ten ant species were preferentially eaten by white-bellied pangolin, with Crematogaster acis being the most common prey species. Four species of termite were most frequently eaten with Pseudacanthotermes militaris being the most abundant. The mean abundance of ants and termites varied among pangolin individuals. The season did not influence the mean abundance of termites eaten by pangolin individuals. However, ant abundance in stomach contents was significantly higher in the dry season. An improved understanding of pangolin feeding behavior and prey selection may help inform conservation husbandry efforts. For example, nutritional analysis of the food eaten by wild pangolins can guide the development of nutritional diets for captive pangolins.

Molecular detection of bacterial zoonotic abortive agents from ruminants in Turkey.

Abortions in cattle and sheep are one of the major causes of economic losses worldwide. Brucella spp. are the most common infectious agent associated with these abortions. However, abortions caused by bacteria such as Listeria spp., Leptospira spp., Campylobacter spp. and Mycoplasma spp. are usually overlooked due to their sporadic nature and their status as non-priority abortion agents. In our study, we investigated the bacteria associated with abortion cases in cattle and sheep using PCR. For this purpose, we collected vaginal swab samples (n: 110) of aborted cattle and sheep, as well as stomach content samples (n: 69) of aborted calves and lambs from various cities in Turkey. The samples were analysed by bacteria-specific PCR to detect Campylobacter fetus, Leptospira spp., Listeria spp., Mycoplasma spp., and Yersinia spp. PCR analyses revealed that the investigated bacterial agents were present in 18.85% and 19.3% of the cattle and sheep samples, respectively, with an overall percentage of 18.99%. While the overall positivity rate for C. fetus, Leptospira spp., and Mycoplasma spp. was 2.79%, 10.06%, and 4.47%, respectively, the positivity rate for co-infection with Leptospira spp. and C. fetus was 1.68%. All samples were found to be negative for Yersinia spp. and Listeria spp. The high C. fetus positivity rate detected in sheep and in the stomach contents was statistically significant (p < 0.05). However, the difference in positivity rates between the cities, hosts, co-infections and causative agents was statistically insignificant (p > 0.05). This study provides preliminary data on the significant involvement of C. fetus, Leptospira spp. and Mycoplasma spp. in cattle and sheep abortions in Turkey indicating that they should not be overlooked in diagnosis. In addition, further research is needed to investigate the zoonotic potential of these pathogens for public health in Turkey.

Evidence for dopamine production and distribution of dopamine D2 receptors in the equine gastrointestinal mucosa and pancreas.

Insulin dysregulation in horses is characterised by hyperinsulinaemia and/or tissue insulin resistance and is associated with increased risk of laminitis. There is growing evidence in other species that dopamine attenuates insulin release from the pancreas; however, this has yet to be examined in horses. The present study aimed to identify whether there are cells capable of producing or responding to dopamine within the equine gastrointestinal mucosa and pancreas. Tissue samples were collected from the stomach, small and large intestines, and pancreas of six mature horses following euthanasia. Samples of stomach contents and faeces were also collected. Immunohistochemistry was performed to identify tyrosine hydroxylase (TH), the rate-limiting enzyme for dopamine production, and dopamine D2 receptors in tissue sections. Additional immunostaining for glucagon, insulin and chromogranin A was performed to identify α cells, β cells and enteroendocrine cells, respectively. Gastric parietal cells expressed both TH and D2 receptors, indicating that they are capable of both producing and responding to dopamine. Dopamine was quantified in stomach contents and faeces by high-performance liquid chromatography with electrochemical detection, with similar concentrations found at both sites. Dopamine D2 receptors were expressed in duodenal epithelial cells but not more distally. A subset of enteroendocrine cells, located sporadically along the gastrointestinal tract, were found to be immunopositive for the D2 receptor. In pancreatic islets, TH was present in α cells, while D2 receptors were strongly expressed in β cells and variably expressed in α cells. These findings are consistent with studies of other species; however, dynamic studies are required to further elucidate the role of dopamine in the modulation of insulin and glucagon secretion in horses. This descriptive study provides preliminary evidence for a potential role of dopamine to act as a paracrine messenger in the gastrointestinal mucosa and endocrine pancreas of horses.

Metals and arsenic distribution in stray dogs' tissues around a lead-zinc mine in Kabwe, Zambia.

Metal contamination poses a threat to human, animal, and environmental health. The purpose of the current study was to assess the accumulation of toxic and trace metal concentrations in tissues of stray dogs in Kabwe, a town known for lead pollution due to a long history of lead and zinc mining. Brain, spleen, heart, stomach, stomach content, small intestine, kidney, liver, and bone samples were collected from 29 stray dogs (14 from locations within 3km of the mine and 15 from sites 7km away from the mine) after necropsy. Inductively coupled plasma mass spectrometry was used to analyze toxic metals, arsenic (As), cadmium (Cd), and lead (Pb), and trace elements, copper (Cu) and zinc (Zn). The lungs (0.117 ± 0.114mg/kg dry weight), kidney (7.515 ± 8.830mg/kg dry weight), and bone (41.68 ± 66.83mg/kg dry weight) were found to have the highest concentrations of As, Cd, and Pb, respectively. In contrast, higher Cu and Zn concentrations were measured in the liver than in other tissues. In all tissues analyzed, tissues sampled from dogs near the mine had significantly higher mean concentrations of Cd and Pb than dogs far away. Neither sex nor age-related differences were observed in the distribution of metals in most tissues. There were significant associations among toxic (Pb and Cd) and trace metals (Cu and Zn). In the kidney, Cd positively correlated with Pb (ρ = 0.534) and Zn (ρ = 0.600), whereas in the liver, Cu correlated with Zn (ρ = 0.565). The current study's findings suggest that environmental pollution is still a problem in Kabwe, and environmental remediation is needed to address the pollution.

Invasive European green crab (Carcinus maenas) predation in a Washington State estuary revealed with DNA metabarcoding.

Predation by invasive species can threaten local ecosystems and economies. The European green crab (Carcinus maenas), one of the most widespread marine invasive species, is an effective predator associated with clam and crab population declines outside of its native range. In the U.S. Pacific Northwest, green crab has recently increased in abundance and expanded its distribution, generating concern for estuarine ecosystems and associated aquaculture production. However, regionally-specific information on the trophic impacts of invasive green crab is very limited. We compared the stomach contents of green crabs collected on clam aquaculture beds versus intertidal sloughs in Willapa Bay, Washington, to provide the first in-depth description of European green crab diet at a particularly crucial time for regional management. We first identified putative prey items using DNA metabarcoding of stomach content samples. We compared diet composition across sites using prey presence/absence and an index of species-specific relative abundance. For eight prey species, we also calibrated metabarcoding data to quantitatively compare DNA abundance between prey taxa, and to describe an 'average' green crab diet at an intertidal slough versus a clam aquaculture bed. From the stomach contents of 61 green crabs, we identified 54 unique taxa belonging to nine phyla. The stomach contents of crabs collected from clam aquaculture beds were significantly different from the stomach contents of crabs collected at intertidal sloughs. Across all sites, arthropods were the most frequently detected prey, with the native hairy shore crab (Hemigrapsus oregonensis) the single most common prey item. Of the eight species calibrated with a quantitative model, two ecologically-important native species-the sand shrimp (Crangon franciscorum) and the Pacific staghorn sculpin (Leptocottus armatus)-had the highest average DNA abundance when detected in a stomach content sample. In addition to providing timely information on green crab diet, our research demonstrates the novel application of a recently developed model for more quantitative DNA metabarcoding. This represents another step in the ongoing evolution of DNA-based diet analysis towards producing the quantitative data necessary for modeling invasive species impacts.

Development of habitat suitability criteria for macroinvertebrate community metrics for use in habitat restoration projects

Community-based macroinvertebrate habitat suitability criteria are needed for two reasons: (1) community-based criteria, such as with macroinvertebrates, are a better measure of ecosystem health than single-species habitat suitability criteria (HSC); and (2) if food rather than physical habitat is the limiting factor for juvenile salmonids, it is better to evaluate habitat restoration projects based on macroinvertebrate habitat than juvenile habitat. The goal of this study was to generate habitat suitability criteria for macroinvertebrates in the Sacramento River. Habitat suitability criteria were derived for three macroinvertebrate community metrics. One of the metrics (biomass of baetids, chironomids and hydropsychids) was selected to represent food supply for juvenile salmonids, while the other two metrics (total biomass and diversity) were selected as measures of ecosystem health. Baetidae, Chironomidae and Hydropsychidae were chosen because they are the dominant taxa present in stomach contents samples of Sacramento River juvenile Chinook Salmon Oncorhynchus tschawytscha. Habitat suitability criteria were developed using data from 75 macroinvertebrate samples stratified by season, mesohabitat type, depth, velocity, and substrate. The criteria for depth, velocity and substrate were developed taking into account several potential confounding variables, and using a polynomial regression for depth and velocity, and analysis of variance for substrate (a categorical variable). The criteria showed no effect of substrate on baetid/chironomid/hydropsychid biomass or diversity. Criteria for total biomass showed a higher suitability for larger cobbles, versus other substrates, for total biomass. The optimum depths for baetid/chironomid/hydropsychid biomass, total biomass and diversity were, respectively, 0.82–0.85 m, 0.61–0.67 m and 1.16–1.19 m. The optimum velocities for baetid/chironomid/hydropsychid biomass, total biomass and diversity were, respectively, 0.73–0.79 m/sec, 0.61–0.67 m/sec, and 0.61–0.73 m/s. Suggestions for development of future macroinvertebrate HSC include: (1) stratifying sampling by depth, velocity and substrate; (2) measuring the amount of organic matter in samples for use as an additional potential confounding factor; and (3) sampling a large area (0.84 m2) with a sampler with a rubber foam lining on the bottom of the sampler.

Seven-Month Vitamin D Deficiency Inhibits Gastric Epithelial Cell Proliferation, Stimulates Acid Secretion, and Differentially Alters Cell Lineages in the Gastric Glands.

Vitamin D (VD) deficiency can result from insufficiency of either light exposure or VD intake. We investigated the biological effects of VD deficiency for 7 months on the mouse gastric glands. Varying degrees of VD deficiency were induced in C57BL/6 mice by keeping them on standard diet with constant-dark conditions (SDD) or VD deficient diet with constant-dark conditions (VDD). Samples of serum, glandular stomach, and gastric contents were collected for LCMS/MS, RT-PCR, immunohistochemistry, and acid content measurements. Both SDD and VDD mice had a significant decline in 25OHVD metabolite, gastric epithelial cell proliferation, and mucin 6 gene expression. These effects were enhanced with the severity of VD deficiency from SDD to VDD. Besides and compared to the control group, SDD mice only displayed a significant increase in the number of zymogenic cells (p ≤ 0.0001) and high expression of the adiponectin (p ≤ 0.05), gastrin (p ≤ 0.0001), mucin 5AC (*** p ≤ 0.001) and the Cyclin-dependent kinase inhibitor 1A (**** p ≤ 0.0001). These phenotypes were unique to SDD gastric samples and not seen in the VDD or control groups. This study suggests that the body reacts differently to diverse VD deficiency sources, light or diet.

Validation and Uncertainty Calculation of Rodenticide Analysis Methods in a Simulated Gastric Content Matrix – Uncertainty of Rodenticide Analysis Methods

Warfarin (WAR), brodifacoum (BDF) and bromadiolone (BDL) are compounds present in rodenticides, highly toxic to rats, humans and other animals. These compounds can be detected in complex matrices, such as stomach contents, by liquid chromatography techniques (HPLC) with mass spectrometry (MS) or fluorescence detection (FLD). However, no validated method showed determination of uncertainty in the quantification of these compounds. In this study, we compare the validation parameters of two analytical methods, HPLC FLD and ultra high performance liquid chromatography (UHPLC – MS), with uncertainty estimation for the three cited compounds. The results showed that UHPLC-MS outperformed HPLC FLD, however both methods were considered adequate for detection of WAR, BDF or BDL in samples of simulated human stomach contents, especially in cases of suspected contamination.

Feeding strategy and prey selectivity in common minke whales (Balaenoptera acutorostrata) foraging in the southern Barents Sea during early summer

Stomach content samples from 33 minke whales (Balaenoptera acutorostrata), caught during Norwegian commercial whaling between May-June 1998, were collected in four sub-areas in the southern Barents Sea. Simultaneously, a comprehensive resource survey was conducted in order to identify and estimate the abundance of potential prey items for the whales in the four sub-areas. Krill (Thysanoessa sp. and Meganyctphanes norvegica) dominated the diet in all but one sub-area although pelagic fish such as capelin and herring also contributed significantly. The minke whales displayed monophagus feeding in all sub-areas investigated, including the medium-scale area resulting from pooling of all sub-areas. The small-scale resource surveys revealed significant variations in absolute and relative prey abundance between sub-areas, while the temporal (1-7 days) variations in relative prey biomass within sub-areas appeared to be less significant for all prey items, except herring (Clupea harengus) and perhaps capelin (Mallotus villosus). Krill was by far the most important prey item available in all areas, followed by either herring, cod (Gadus morhua) or saithe (Pollachius virens), depending on sub-area and survey. Although minke whale prey preference appeared to vary greatly in space, some new features of minke whale foraging behaviour were evident. Minke whales showed a strong preference for capelin, whereas gadoids (cod, haddock (Melanogrammus aeglefinus) and saithe) appeared to be avoided by the whales. Krill appeared to have been either avoided, fed upon randomly or were the preferred prey depending on sub-area and analyses level.

Macrofauna parasitária de Podocnemis unifilis dos rios Tocantins e Javaés, Amazônia Oriental, Brasil

ABSTRACT: The parasitic fauna of Podocnemididae species is of great relevance to understanding the ecological relationships of the organisms in this genus. The parasites can have a symbiotic relationship with their hosts; however, environmental imbalances may change this relationship. Therefore, these parasites may become agents that generate zoonoses, especially in animals used by parasites as a food source. The aim of this study was to investigate the gastrointestinal parasitic fauna of specimens of Podocnemis unifilis. The animals were collected from the Tocantins and Javaés Rivers, both of which flow in the State of Tocantins, predominantly in the Cerrado territory. Samples of stomach and intestinal contents were fixed in 10% formalin buffered with sodium phosphate, transferred to 70% alcohol for analysis, and separated after 72 hours. Parasites were isolated and identified according to morphology and identification key. Four species of parasites were observed in 100% of specimens of P. unifilis, namely Nematophila grandis (Trematoda) and Paratractis hystrix, Paraorientatractis semiannulata, and Orientatractis leiperi (Nematoda). N. grandis was the only parasite that was not observed in the intestine; it appeared to adhere to the inner wall of the stomach. All nematodes were observed both in the stomach and intestine. These data expand the knowledge related to the P. unifilis parasitic fauna and the geographic distribution of these parasites in P. unifilis from the Tocantins and Javaés Rivers.

Real Time- Polymerase Chain Reaction (RT-PCR) Test to Diagnose Brucellosis in Sheep in ANBAR Province

The aims of the study were to determine incidence ratio of brucellosis in aborted ewes in Anbar governorate using real time PCR technique and bacterial culture and evaluating the efficiency of bacterial culture. 50 samples of stomach contents of an aborted fetus and vaginal swabs from aborted ewes were collected. The incidence ratio of brucellosis in ewes in Anbar governorate were 72% in PCR test However in bacterial culture were 46%. The positive prediction value and Negative prediction value and Sensitivity and Specificity of bacterial culture were (100%, 51.8 %,63%,100%) respectively when use Real time PCR as an assessment test. Conclusions: Anbar province is endemic with brucellosis, especially in sheep. The Real Time PCR is a fast, easy and accurate test in detecting even small numbers of bacteria in a sample, Significant superiority of polymerase chain reaction technology over bacterial culture.

Confirmation Using Triple Quadrupole and High-Resolution Mass Spectrometry of a Fatal Canine Neurotoxicosis following Exposure to Anatoxins at an Inland Reservoir.

Cyanobacterial blooms are often associated with the presence of harmful natural compounds which can cause adverse health effects in both humans and animals. One family of these compounds, known as anatoxins, have been linked to the rapid deaths of cattle and dogs through neurotoxicological action. Here, we report the findings resulting from the death of a dog at a freshwater reservoir in SW England. Poisoning was rapid following exposure to material at the side of the lake. Clinical signs included neurological distress, diaphragmatic paralysis and asphyxia prior to death after 45 min of exposure. Analysis by HILIC-MS/MS of urine and stomach content samples from the dog revealed the detection of anatoxin-a and dihydroanatoxin-a in both samples with higher concentrations of the latter quantified in both matrices. Detection and quantitative accuracy was further confirmed with use of accurate mass LC-HRMS. Additional anatoxin analogues were also detected by LC-HRMS, including 4-keto anatoxin-a, 4-keto-homo anatoxin-a, expoxy anatoxin-a and epoxy homo anatoxin-a. The conclusion of neurotoxicosis was confirmed with the use of two independent analytical methods showing positive detection and significantly high quantified concentrations of these neurotoxins in clinical samples. Together with the clinical signs observed, we have confirmed that anatoxins were responsible for the rapid death of the dog in this case.

A Study was Under taken to Assess the Effectiveness of Structured Teaching Program on Knowledge Regarding Various Methods to Check the Placement of Nasogastric Tube in Patients among Student Nurses

The normal healthy adult can consumes food orally. Patients who are unconscious, surgery on throat, paralysis of soft palate, requires nasogastric tube feeding. In hospitals, nutrition may refer to the food requirements of patients, including nutritional solutions delivered via an IV (intravenous) or fluid food delivered by Nasogastric tube. It refers to the process of placing a soft plastic Nasogastric through a patient’s nostril, past the pharynx down the esophagus in to the patient stomach. The most common indication for inserting a Nasogastric tube is to deliver tube feeding to patients when they are unable to eat especially, Patient who have undergone neck or facial surgery or patient on mechanical ventilation. It is used to empty the stomach when accidental poisoning or drug overdose has occurred, and it is also used to remove air that accumulate in the stomach during cardio pulmonary Resuscitation. It is used to remove the stomach content after major trauma or surgery to prevent aspiration of the stomach content. Placing Nasogastric tube helps to prevent Nausea and vomiting by removing stomach contents and preventing distension of the stomach other a patient has a bleeding ulcer, bowel obstruction, or other gastrointestinal disease. It helps to be inserted to take samples of stomach contents for laboratory studies and to test for pressure of the gastrointestinal tract. Materials and Methods: A quasi-experimental single group pre-test post-test design to evaluate the effectiveness of structured teaching program on knowledge regarding various methods to check the placement of nasogastric tube in patients. The study conducted on 50student nurses. Data was collected in the month of August - September 2022. Data was collected using structured questionnaire to evaluate the effectiveness of structured teaching program on knowledge regarding various methods to check the placement of nasogastric tube in patients. Results: The data revealed that, the significant level stated as P&lt;0.05. Overall pre-test mean score was 16.92. The overall post-test mean score was 26.32. The comparison was analyzed by using paired ‘t’ test and value was 23.20. This was found statistically significant at &lt; 0.05 level of degree of freedom. Then final findings were associated with demographic variable in educational status was significant and other demographical variable such as age, gender, current residence, previous source of information was not significant. Conclusion: After the detailed analysis of the study it shows that structured teaching program on knowledge regarding various methods to check the placement of nasogastric tube is effective in enhancing knowledge about same among student nurses. A relationship between the students and the teachers helps to empower the knowledge in the students to deal adequately with the patients with nutritional needs.

Trophic Structure and Diet of Predatory Teleost Fishes in a Tropical Demersal Shelf Ecosystem

Predatory fishes are a major component of many tropical fisheries, although little is known about their diet and trophic structure, which can hinder effective management. We used stable isotopes δ15N and δ13C in conjunction with dietary prey items of five fishes (Lutjanus sebae, Lethrinus punctulatus, Epinephelus areolatus, Epinephelus multinotatus, and Plectropomus maculatus) to describe the diet and trophic structure across this assemblage. A total of 153 isotope and 87 stomach content samples were collected at two locations that were ≈30 km apart, over two sampling trips, separated by three months. There was clear separation of species’ mean δ15N and δ13C values in isotopic space; the highest mean δ15N was exhibited by E. multinotatus (13.50 ± 0.11 SE) and the lowest was L. punctulatus (11.05 ± 0.13). These two species had the lowest overlap of isotopic niche space, whereas the highest overlap occurred between L. sebae and P. maculatus. δ15N increased with fish body size for all species. However, body size was not significantly related to δ13C values for any species. There was a notable shift in both δ15N and δ13C between sampling trips, with δ13C being more depleted in the second trip. There was also a difference in δ13C between locations for all species, suggesting localised foraging. A multiple tissue comparison for L. sebae indicated positive relationships for both δ15N and δ13C between dorsal fin and muscle tissue. Mean δ15N values were the same for both fin (12.1 ± 0.10 SE) and muscle tissue (12.1 ± 0.09 SE), although δ13C was more enriched in fin (-15.6 ± 0.14 SE) compared to muscle tissue (-17.3 ± 0.11 SE). The most common dietary items across species were teleosts and crustaceans, which was consistent with isotope data indicating a reliance on a demersal food web (δ13C values ranging from -18 to -15‰). The results from our study indicate a dynamic spatio-temporal trophic structure and diet for commercially important demersal species and highlight the benefits of a multi-facetted sampling approach.

Daytime diet of the lesser sac-winged bat (Saccopteryx leptura) in a Colombian Pacific Island

Insectivorous bats represent more than half of all the Chiropterans of the world. Although they are important stabilizers of insect populations within their habitat due to their feeding habits, just few studies have been focused on the diet of insular bat species. The lesser sac-winged bat, Saccopteryx leptura, is widely distributed in the new world tropics, but little is known about its prey selection. In this study we determined the diet composition of the population of S. leptura from Gorgona Island, Colombia, using stomach and intestinal content samples. We focused our research on their atypical daytime feeding behavior to evaluate differences in prey selection considering two main factors: 1) plant canopy cover and 2) bat sex. We found prey representatives of nine orders of insects, with Hymenoptera, Coleoptera and Hemiptera as the most consumed according to their abundance and volume percentage. We identified two new records at genus level in S. leptura´s diet, Camponotus (Formicidae) and Trigona (Apidae). In general terms, we did not find differences in the diet between canopy covers nor sexes. However, when analyzing the consumed percentage volume by order, there were significant differences in consumption of Psocoptera in both factors. Our results suggest that S. leptura has an opportunistic diet, as they tend to feed on prey of a wide range of sizes, usually the most abundant and available in the environment.

Prevalent toxin types of Clostridium botulinum in South Korean cattle farms

Clostridium botulinum produces neurotoxic substrates that can cause fatal flaccid paralysis called botulism. These neurotoxins are classified into types A–G. Several botulism cases were recorded in 2012–2013 in the Gyeonggi province, South Korea. We assessed the distribution of C. botulinum types B, C, and D in several South Korean farms. A total of 184 samples collected in 2012–2013, including feces (n = 72), hay and silage (n = 50), soil (n = 26), water trough (n = 21), and stomach contents (n = 15), were subjected to multiplex polymerase chain reaction (PCR) to screen for types B, C, and D. Twenty-four samples tested PCR-positive as follows: type B (n = 11), type C/D (n = 4), and type D (n = 18). Eight of the 11 type B samples were detected in hay and silage. Sixteen of the 18 type D samples were detected in fecal and stomach content samples. PCR-positivity was observed in fecal (n = 9, 12.5%), hay and silage (n = 10, 20.0%), water trough (n = 2, 9.5%), and stomach content (n = 12, 80.0%) samples. Fourteen (42.4%) C. botulinum-positive samples were isolated from the PCR-positive samples (type B [n = 8], type C/D [n = 1], and type D [n = 5]). Our findings demonstrate that C. botulinum types B, C/D, and D were prevalent in South Korean cattle farms between 2012 and 2013.

Temporal variation in prey selection by adult European sardine (Sardina pilchardus) in the NW Mediterranean Sea

In the North-Western Mediterranean Sea (NWMS), changes in size and taxonomic composition of zooplankton have been hypothesized to underlie observed changes in populations of Sardina pilchardus, one of the main small pelagic fish species. The present study was undertaken to better understand the link between the temporal variability of zooplankton and the diet of adult sardine in the Bay of Marseille over a period of 16 months by comparing the taxonomic and prey size composition of sardine stomach content with net-collected zooplankton samples from a fixed station. A greater similarity was found between sardine stomach content and 80-μm mesh size net samples than with the traditionally used 200-μm net samples. Sardine showed a high diet plasticity over the entire study period, covering a broad diversity of prey species and a wide prey size range (ranging from 400 to 1000 μm in measured total length), including a lot of small copepods (Microsetella/Macrosetella spp., Corycaeidae and Oncaeidae). The most consumed prey groups were not necessarily the most abundant in the zooplankton sampled with nets, suggesting potential prey selection. Sardine showed most often an opportunistic selective predation on larger individuals for most taxonomic prey groups. Results highlighted the diet flexibility of sardine between months and showed seasonal variation in prey size, suggesting a continuous filter-feeding mode on relatively small prey when prey densities were high and more frequent selective particulate-feeding on larger prey when prey densities were low. Sardines were able to feed on a wide diversity of prey and size range and thus to shift their diet between months. This ability probably allows them to adapt to high spatial and temporal variability of the zooplankton community in a context of both human-induced and climatic changes.

Ice seals as sentinels for algal toxin presence in the Pacific Arctic and subarctic marine ecosystems.

Domoic acid (DA) and saxitoxin (STX)‐producing algae are present in Alaskan seas, presenting exposure risks to marine mammals that may be increasing due to climate change. To investigate potential increases in exposure risks to four pagophilic ice seal species (Erignathus barbatus, bearded seals; Pusa hispida, ringed seals; Phoca largha, spotted seals; and Histriophoca fasciata, ribbon seals), this study analyzed samples from 998 seals harvested for subsistence purposes in western and northern Alaska during 2005–2019 for DA and STX. Both toxins were detected in bearded, ringed, and spotted seals, though no clinical signs of acute neurotoxicity were reported in harvested seals. Bearded seals had the highest prevalence of each toxin, followed by ringed seals. Bearded seal stomach content samples from the Bering Sea showed a significant increase in DA prevalence with time (logistic regression, p = .004). These findings are consistent with predicted northward expansion of DA‐producing algae. A comparison of paired samples taken from the stomachs and colons of 15 seals found that colon content consistently had higher concentrations of both toxins. Collectively, these results suggest that ice seals, particularly bearded seals (benthic foraging specialists), are suitable sentinels for monitoring HAB prevalence in the Pacific Arctic and subarctic.