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Diet is one of the most important aspects of an animal's ecology, as it reflects direct interactions with other organisms and shapes morphology, behavior, and other life history traits. Modern birds (Neornithes) have a highly efficient and phenotypically plastic digestive system, allowing them to utilize diverse trophic resources, and digestive function has been put forth as a factor in the selectivity of the end-Cretaceous mass extinction, in which only neornithine dinosaurs survived. 1 Although diet is directly documented in several early-diverging avian lineages, 2 only a single specimen preserves evidence of diet in Enantiornithes, the dominant group of terrestrial Cretaceous birds. 3 Morphology-based predictions suggest enantiornithines were faunivores, 4,5,6 although the absence of evidence contrasts with the high preservation potential and relatively longer gut-retention times of these diets. Longipteryx is an unusual Early Cretaceous enantiornithine with an elongate rostrum; distally restricted dentition 7 ; large, recurved, and crenulated teeth 8 ; and tooth enamel much thicker than other paravians. 9 Statistical analysis of rostral length, body size, and tooth morphology predicts Longipteryx was primarily insectivorous. 4,5 Contrasting with these results, two new specimens of Longipteryx preserve gymnosperm seeds within the abdominal cavity interpreted as ingesta. Like Jeholornis , their unmacerated preservation and the absence of gastroliths indicate frugivory. 10 As in Neornithes, 11 complex diets driven by the elevated energetic demands imposed by flight, secondary rostral functions, and phylogenetic influence impede the use of morphological proxies to predict diet in early-diverging avian lineages. • Unusual enantiornithine Longipteryx with an elongate rostrum predicted to be a faunivore • Direct evidence indicates Longipteryx was a frugivore, eating gymnosperm "fruits" • Like crown birds, morphological proxies fail to predict diet in early birds Evidence of diet is rare, so morphological proxies are used to predict diet in fossils. These suggest the unusual enantiornithine bird, Longipteryx , was an insectivore. O'Connor et al. describe direct evidence it was a frugivore, indicating that, as in modern birds, the morphology of the rostrum cannot be used alone to predict diet in Mesozoic birds. [ABSTRACT FROM AUTHOR]

The Rosy Litter Frog (Leptobrachella eos) is known from Thailand, Laos, and Vietnam. Knowledge about the natural history of this species is virtually lacking. As a result of our field work in Son La, Nghe An, and Ha Tinh provinces of Vietnam, we provide data on the food composition of L. eos for the first time. Using the stomach-flushing method, we analyzed stomach contents of 34 individuals (23 males and 11 females) from a total of 42 frogs, with stomachs of five males and three females (19%) being empty. A total of 13 prey categories were observed in the stomachs of L. eos , with 232 items, comprising 230 items of invertebrates and two unidentified items. The most important (IRI) groups among the prey of L. eos were Blattodea (26.31%), Araneae (17.26%), Orthoptera (13.21%), Coleoptera (12.39%), and Opiliones (10.09%). There was an overlap of 51.11 % in the diet between males and females, The trophic spectrum of males comprising 11 prey categories revealed to be wider than that of females comprising nine prey categories. Despite differences in diets between the sexes, Blattodea, Orthoptera, Araneae, Coleoptera, and Opiliones represented the most important prey category for all of them. In addition, we also report a new find of Leptobrachella eos , with a new subpopulation from Ha Tinh Province, Vietnam. [ABSTRACT FROM AUTHOR]

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Human–wildlife conflict is often a driver of species declines, and understanding the material basis of this conflict is the first step in addressing it. The Titicaca Grebe Rollandia microptera is an endangered endemic species found solely in the Lake Titicaca watershed of Peru and Bolivia, and has experienced population declines due to fisheries bycatch. Human fishers often have negative opinions of the Titicaca Grebe, because they consider it as a competitor for declining fish stocks. We tested that assumption by an analysis of the bird's diet and found that the Titicaca Grebe does not compete with fishers for more lucrative fish species such as trout Oncorhynchus sp. and Pejerrey Odontesthes bonariensis, but does compete for the less desirable (to human fishers) native Orestias sp. [ABSTRACT FROM AUTHOR]

The Wadden Sea is an important habitat for a large number of fish species, supporting functions such as reproduction, breeding and feeding. The hooknose (Agonus cataphractus, Linnaeus, 1758) is a resident demersal fish species of the Wadden Sea, but due to its non-commercial importance it is rarely studied. In the present study, the feeding strategy and prey selection of the hooknose related to the benthic in- and epifauna in the field were investigated in six different habitat types (circalittoral sand, circalittoral mud, circalittoral mixed sediments, circalittoral coarse and gravel sediments, sublittoral sandbanks and reefs) in coastal waters of the German Wadden sea between 2020 and 2021. The stomach contents of A. cataphractus were dominated in most of the habitat types by very mobile epibenthic prey species, mainly the brown shrimp (Crangon crangon, Linnaeus, 1758), amphipods (Ampelisca spp., Microprotopus maculatus, Norman 1867) and cumaceans (Diastylis bradyi, Norman 1879, Pseudocuma longicorne, Bate 1858), similar to the benthic communities in the field. Infauna species such as the tube-building polychaete Lanice conchilega (Pallas 1766) were rarely consumed and potentially avoided due to their ability to withdraw below the feeding depths. Our results further showed habitat-specific differences in the hooknose diet, especially in reefs, where skeleton shrimps (caprellids) dominated the diet. The habitat type also influences the condition of A. cataphractus being highest in reefs but lowest on sandbanks. Our results highlight the importance of knowledge functional relationships between smaller-sized Wadden Sea fish species and its typical habitats, which in turn is essential for applicable management measures of the whole Wadden Sea area. [ABSTRACT FROM AUTHOR]

I examined 107 shining cuckoos that died accidentally in the northern North Island, New Zealand, during 39 years. Birds arriving on migration in spring were all in adult plumage. Juveniles occurred mainly from January to March. The sex-ratio of adults was 1:1. In several measurements, females were slightly larger than males on average, and adults slightly larger than juveniles. Gonad size suggested readiness for breeding from September to January (inclusive). Ninety-one gizzards held a total of 3754 arthropod food items. Insects (10 orders) made up around 94% of items and just two orders accounted for 79% of food items: caterpillars (larval Lepidoptera, 55%) and beetles (Coleoptera, 24%). 'Spiny' caterpillars made up roughly 8% of total caterpillars. Ladybirds (Coccinellidae) made up 21% of beetles. Shining cuckoos ate small prey, mostly 1–10 mm long (44%) and 11–20 mm long (43%). By eating hairy caterpillars and ladybirds, shining cuckoos exert predatory control on insects that other birds avoid. By gorging (up to 258 insects per stomach) the cuckoo might dampen the impact of herbivorous insects (e.g. caterpillar infestations) on plants. [ABSTRACT FROM AUTHOR]

Invasive American Bullfrogs (Lithobates catesbeianus) are a threat to native species in riparian ecosystems worldwide. They are indiscriminate predators consuming both vertebrate and invertebrate prey, negatively affecting biodiversity. Documenting the diet and feeding ecology of invasive L. catesbeianus can help management agencies identify affected species and facilitate eradication efforts. We present a dietary analysis of two invasive L. catesbeianus populations over multiple breeding seasons (2016–2020), elucidating ontogenetic changes in diet and dietary differences between sexes and habitats. This is the first study to analyze dietary variation from contemporary populations of invasive L. catesbeianus occupying different watersheds in Southern California, an area where their invasion presents acute conservation challenges. Our analysis of 667 gut contents shows that adult females had more prey in their guts than adult males, even though male and female body size was not significantly different. Adults were more likely than juveniles to consume vertebrate prey, and juveniles were more likely than adults to have empty stomachs. We also found that invasive Red Swamp Crayfish (Procambarus clarkii), made up a substantial portion of the diet of adult L. catesbeianus at the site where they were present. These results provide an important ecological context for designing mitigation actions that ameliorate the impacts of invasive L. catesbeianus. [ABSTRACT FROM AUTHOR]

Juvenile North Pacific Albacore tuna (Thunnus alalunga) support commercial and recreational fisheries in the California Current Large Marine Ecosystem (CCLME), where they forage during summer and fall. The distributions of the commercial and recreational fisheries and estimates of forage availability have varied substantially over the past century. Time-series quantifying Albacore diet can help link forage composition to variability in Albacore abundance and distribution and, consequently, their availability to fishers. Previous diet studies in the CCLME are of relatively short duration, and long-term variability in Albacore diet remains poorly understood. We describe the diets of juvenile Albacore from three regions in the CCLME from 2007 to 2019 and use classification and regression tree analysis to explore environmental drivers of variability. Important prey include Northern Anchovy (Engraulis mordax), rockfishes (Sebastes spp.), Boreal Clubhook Squid (Onychoteuthis borealijaponica), euphausiids (Order: Euphausiidae), and amphipods (Order: Amphipoda), each contributing >5% mean proportional abundance. Most prey items were short lived species or young-of-the-year smaller than 10 cm. Diet variability was related to environmental conditions over the first 6 months of the year (PDO, sea surface temperature, and NPGO) and conditions concurrent with Albacore capture (region and surface nitrate flux). We describe foraging flexibility over regional and annual scales associated with these environmental influences. Continuous, long-term studies offer the opportunity to identify flexibility in Albacore foraging behavior and begin to make a predictive link between environmental conditions early in the year and Albacore foraging during summer and fall.

The Banna fanged frog (Limnonectes bannaensis) is known from China, Laos, and Vietnam; however knowledge about the natural history and dietary requirements of this species is virtually lacking. In this study, we provide data on the variation in dietary composition of L. bannaensis based on stomach-flushing of 117 individuals (41 males and 76 females) captured and subsequently released during our recent field work in Son La Province, northwestern Vietnam. A total of 19 prey categories with 513 items, comprising 502 items of invertebrates, seven items of vertebrates, and four unidentified items were found in the stomachs of L. bannaensis. The most important groups among the prey of L. bannaensis were Coleoptera (38.04%), followed by Hymenoptera (9.31%), Araneae (7.93%), Polydesmida (7.07%), Orthoptera (6.37%), Hemiptera (5.23%), and Lepidoptera (5.01%). Adult males (16 prey categories) consumed preys with slightly lower diversity than adult females (17 prey categories). There was 88.25% overlap in the diet between males and females and in both sexes the trophic spectrum was similar, predominantly consisting of Coleoptera, Polydesmida, Araneae, Hymenoptera, Orthoptera, Lepidoptera, and Hemiptera. [ABSTRACT FROM AUTHOR]

Study of the diet of squid is hampered by the fact that these animals masticate their prey prior to ingestion and do not necessarily ingest the hard parts that allow the identification of prey remains present in the stomach. The result is a large percentage of prey in stomach contents that can be identified only according to broad categories (e.g., "teleost fish"). This is widely described in the literature and has also been found in samples from the English Channel of the two loliginid squid fished in this area (Loligo forbesii and Loligo vulgaris). New biological samples of both species were collected at the Port-en-Bessin fish market during the 2019–2020 fishing season. Stomach contents were studied through DNA metabarcoding targeting a small fragment of the COI mitochondrial gene selected by PCR and sequenced using high-throughput next generation sequencing. The DNA metabarcoding results were compared with databases available online. These preliminary results validated a protocol based on commercial samples kept frozen (−20 °C) before analysis. Sequences allowed 34 different types of prey to be identified to the species level, including 17 teleost fish species. Results revealed the high occurrence of cuttlefish eaten by both species of squid. Food composition was analysed in order to make comparisons between species, between seasons (in L. vulgaris) and according to the size of the predator. Differences in diet of L. vulgaris between November and March samples were greater than the difference between L. vulgaris and L. forbesii, which is consistent with opportunistic behaviour in these squids. Differences in diet related to predator size do not suggest a change in trophic level during the growth of recruited stages. [ABSTRACT FROM AUTHOR]

Due to their relationship with prey availability, elasmobranchs with an opportunistic diet can serve as indicators of changes in the marine community, thereby enhancing our understanding of the health of marine ecosystems. In this study, the Zearaja brevicaudata's trophic ecology was studied, by analysing its stomach contents, aiming to provide evidence of long-term changes in diet resulting from shifts in the structure of the Argentine Patagonian marine community in response to fishing pressure. Changes were evaluated according to catch area, predator size, sex, maturity over time. Moreover, the relationship between Zearaja brevicaudata's dietary shifts and the fishing effort of Merluccius hubbsi was investigated. Our results suggest a gradual replacement of the main prey species with lower trophic level species. Although no correlation was found with fishing effort, the diet of Z. brevicaudata over time reflected changes similar to those associated to the fishing exploitation of M. hubbsi in the Patagonian system. In this context, the Z. brevicaudata's diet emerges as a valuable tool for monitoring and assessing changes in the marine community. By serving as an indicator, Z. brevicaudata's diet provides crucial insights into the conservation status of the marine ecosystem, enabling informed management and conservation efforts. [ABSTRACT FROM AUTHOR]

We describe and analyze the mimetic behavior in juvenile Maracaibo leatherjack, Oligoplites palometa, establishing correlations with feeding diet composition during daytime. The relationships between behavioral patterns and the feeding diet of O. palometa were analyzed during daylight hours, considering seasonal and lunar cycle variations within a tidal channel in the estuary of the Caeté River, Northeastern Pará, Brazil. The two relatively well-defined seasons associated with the study area—rainy and dry seasons—have influenced the behavioral patterns and feeding diet of the fish. During the dry season, higher foraging frequencies were observed, consistently related to mimetic swimming behavior, and correlated with the abundance of food items found in the stomach contents. In contrast, during the rainy season, both behavioral and food item frequencies were lower, although the food items presented greater diversity. The fish have exhibited zooplanktivorous feeding habits, preferring copepods over other prey types. The lunar cycle may be associated with the temporal distribution of prey, whereas Brachyura, Clupeid larvae, and unidentified Crustacea are more related to the full, waning, and new moon phases, respectively. Our results clarify the dynamics between the environment and prey types, behavioral tactics, and feeding diets adopted by mimetic juvenile O. palometa. [ABSTRACT FROM AUTHOR]

The Atlantic blue crab Callinectes sapidus (Decapoda, Portunidae) Rathbun, 1896 is native to the east coasts of North and South America and has recently expanded its distribution in the non-native range into the Gulf of Cadiz (SW Iberian Peninsula, Europe). Considering the impacts caused by this invasive species in numerous estuarine ecosystems and its generalist feeding behavior, this study aims to provide the first account of the Atlantic blue crab diet on the East Atlantic coast. We studied the species' feeding habits using stomach content analyses to predict food web interactions and putative impacts. Samples were obtained in the Guadalquivir estuary (SW Spain, Europe), which was colonized in 2017. The main food items identified on their stomach were, fish (49.9%), mollusks (44.4%) and crabs (32.3%). They also consumed plant material (27.2%), and the sediment (32.3%) in their digestive tract was likely the result of secondary ingestion. The Atlantic blue crab exhibited the same omnivorous behavior as in the native area. There was no sexual variation in diet composition or feeding activity in general, but there was a seasonal variation in the diet composition of females. The decrease of the caramote prawn Penaeus kerathurus (Forskål 1775) observed in the Guadalquivir estuary since 2021 is likely not due to the Atlantic blue crab because they seldomly eat this prey. Overall, our study provides clear baseline information to expand the knowledge about the ecological roles of the Atlantic blue crab in non-native ecosystems. [ABSTRACT FROM AUTHOR]

The northern Gulf of Mexico (nGOM) is a taxonomically rich ecosystem. Previous work based on a meta-analysis of stomach contents data has shown the trophic connectivity of predators and prey to be substantial. However, the trophic dynamics of many economically and ecologically important species are still not well understood. Sportfish, such as Spotted Seatrout (Cynoscion nebulosus), Red Drum (Sciaenops ocellatus), and Southern Flounder (Paralichthys lethostigma), support recreational fisheries throughout the region. Gulf Menhaden (Brevoortia patronus), a high biomass forage fish with the region's largest commercial fishery, is considered an important forage species. In this study, we use information from meta-analysis of stomach contents and stable isotope analysis to investigate the importance of prey taxa, including Gulf Menhaden, for nGOM nearshore predators. Stomach contents and stable isotope analyses are generally evaluated independently, with stomach contents used to directly identify trophic interactions, while stable isotopes of carbon (δ13C) and nitrogen (δ15N) provide insight into a consumer's long-term feeding habits. We used a multispecies trophic model, EcoDiet, developed by Hernvann et al. (2022), that integrates information of both stomach contents and stable isotopes into a single framework to estimate trophic link probabilities and diet proportions. Data in the model include n = 41 predators, n = 173 prey, and n = 497 unique predator and prey interactions. The results indicate that nGOM nearshore predators are generalists using the diverse prey base, and in concordance with previous findings, there is no single Menhaden-dependent predator. Our findings better quantify the trophic interactions of the highly diverse nGOM region and have important implications regarding future ecosystem modeling and management considerations for the Gulf Menhaden stock.

Wildlife roadkill surveys in Brazil often focus on birds, as they are one of the main groups affected by road accidents. In addition roadkill, anthropogenic litter also contributes to a significant number of bird fatalities every year. The present study aimed to investigate the stomach contents and possible contamination by inorganic material of birds killed on a federal highway that crosses the Serra de Itabaiana National Park in the state of Sergipe, Brazil. Monitoring and data collection were carried out from January to June 2022, with a motorcycle at an average speed of 60 km/h. The collected animals were transported to the Institute of Technology and Research, located at the Tiradentes University, Sergipe, Brazil, and a plastic material was identified. The plastic material found was subjected to Fourier Transform Infrared Spectroscopy (FTIR), which showed a similar wavenumber to a polymer in the polypropylene chain, very common in plastic packaging. The presence of plastics and metals in the intestinal contents of Caracara plancus and Crotophaga ani is noteworthy, as they have a greater tendency to ingest plastics due to their generalist diet. Plastic contamination in Progne chalybea and Nyctidromus albicollis probably occurred through bioaccumulation, from the consumption of insects contaminated by microplastics. [ABSTRACT FROM AUTHOR]

The stomach of a spotted wolffish (Anarhichas minor) caught in Icelandic waters was found to contain ~727 greater eelpout larvae (Lycodes esmarkii). All the larvae were of similar size and at a similar state of digestion, indicating they were all consumed together. The likely explanation for this observation is that greater eelpout lay their eggs in a nest, with the larvae remaining in the nest for a short period after hatching. The larvae were then predated upon by the spotted wolffish while still in the nest. This study sheds new light on greater eelpout in Icelandic waters, with recently hatched larvae being present in March, breeding at a depth of ~200–250 m, and likely exhibiting nesting behavior, which has not previously been documented. [ABSTRACT FROM AUTHOR]

Microplastics (MPs) contamination is a well-established impact in oceans, but integrated approaches combining simultaneous analyzes of biotic and abiotic components are scarce. This study addresses this gap, demonstrating Atherinella brasiliensis (fish species) ingestion of MPs and comparing with the contaminant presence in water and sediment. Three Ubatuba beaches (exposed, calm and sheltered estuary) were surveyed for fish, water, and sediment components in summer and winter. Environmental data evidenced spatial and seasonal differences (PCA/ANOVA). Presence of synthetic particles (SPs) in fish was high (~38%). Maximum concentrations occurred in the estuary, for water (490 SPs/m³), and in the exposed beach, for sediment (62 SPs/50g). Fibers format predominated in all components. Fish preference for blue color seems to occur. Significant statistical relationships were determined for fish length and SPs size and between SPs concentrations in water and fish. The chemical identities (µ-FTIR spectra) polypropylene, polyethylene, polyamide, polyester, and cardboard/cellulose predominated. Influences of local hydrodynamics (e.g., SPs sizes) and reduction in tourism during Covid-19 epidemic (e.g., less SPs in summer) are discussed. This study confirms environmental contamination by SPs (mostly MPs) in Ubatuba beaches, affecting fish through direct water column ingestion. Urgent actions from authorities and changes in local user's habits are crucial. [ABSTRACT FROM AUTHOR]

The Arctic and Antarctica represent two of the most inhospitable and poorly investigated biomes in the world. Although polar regions are still perceived as some of the most pristine places still in existence, these remote places are no longer immune to anthropogenic pollution, in particular, micro- and nanoplastics. Seabirds, avian species feeding mainly at sea, are indicators of change in the environment and represent an early study group of ecological indicators for plastic pollution. The goal of this bibliometric overview is to evaluate international research trends on the impacts of microplastics (MPs) and nanoplastics (NPs) on seabirds inhabiting polar regions. A total of at least 13 seabird species were reported to have ingested MPs from 1983-2023. Overall, 1130 samples were investigated, including stomach content, pouch content, guano, and pellets. Pellets were the most investigated substrate (699), followed by stomach contents (309), guano (101), and pouch contents (21). A median of 31.5 MPs per sample was found in the Arctic, with an average of 7.2 MPs per sample. A median of 35 MPs per sample was found in Antarctica, with an average of 1.1 MPs per sample. Overall, MPs were most frequently found in fragment form. A total of 3526 MPs were retrieved from stomachs (3013), pellets (398), guano (75), and pouch contents (40). Polyethylene was the dominant plastic polymer found, followed by polypropylene and polystyrene. The monitoring of MP ingestion is crucial to mitigating the impacts on marine and terrestrial organisms. Standardized protocols could boost the safeguarding of seabirds and reduce the impacts of MPs on polar regions. [ABSTRACT FROM AUTHOR]

Black ruff (Centrolophus niger) is a rare and poorly studied species found in both the Atlantic and Pacific Oceans and also in the Mediterranean Sea. It is sporadically caught south of Iceland during the annual International Ecosystem Summer Survey of the Nordic Seas. In total, 43 specimens were caught from 2009 to 2021, of which 41 specimens were caught during 2017–2021. All specimens, except one, were caught using a pelagic trawl (cod‐end mesh‐size: 50 mm) close to the surface (trawl depth: 0–35 m) with in situ temperature ranging from 9 to 13°C. The area south of Iceland is characterized by having warmer temperatures than other areas around the island, which might be indicative of a northern limit for the distribution of black ruff. The fish were primarily in the range of 29–46 cm with a few larger individuals up to 71 cm. Fourteen fish, caught in 2017 and 2021, were dissected to gather biological information on this species. These fish were all juveniles with no obvious sign of gonad development. Correlations between total length, fork length, and standard length are presented. Otoliths were thin and delicate with a length of ~13–16 mm, and otolith size (length, width, and area) was correlated with fish size. Much of the stomach content was at an advanced stage of digestion, but some contents could be identified and consisted of invertebrates, primarily of the orders Amphipoda and Calanoida with some unidentified fish also present. [ABSTRACT FROM AUTHOR]

This study reveals early prey eating by a short‐finned pilot whale (Globicephala macrorhynchus Gray, 1846, Cetacea: Delphinidae) in the Canary Islands. Stomach contents, trophic markers, skin isotopic ratios of nitrogen (δ15N:15N/14N) and carbon (δ13C:13C/12C), and fatty acid profiles of the blubber of a short‐finned pilot whale of 213 cm size euthanized in free‐ranging conditions were analyzed. A total of 15 species of oegopsid squids, mostly diel vertical mesopelagic migrant species of the families Enoploteuthidae, Ommastrephidae, and Histioteuthidae, as well as mother's milk, were identified in the stomach contents. Asperoteuthis acanthoderma (Lu, 1977, Cephalopoda: Chiroteuthidae) was found as first time in this area, suggesting the possibility of its presence on both sides of the subtropical Atlantic, extending its current known distribution. The δ15N value (11.55‰) was higher than expected based on the size range of squid ingested, but lower than that of adult pilot whales, suggesting that mother's milk intake has a significant effect on these values in calves. Similarly, the δ13C values (−17.99‰) were shifted to those of adult pilot whales rather than the ingested squids, also due to the ingestion of high‐fat breast milk. The fatty acid (FA) composition of blubber showed a clear stratification. Long‐chain polyunsaturated fatty acids (LC‐PUFA) were mainly present in the inner layer, while most relevant ≤C20 monounsaturated fatty acids (MUFA) were more abundant in the outer layer. [ABSTRACT FROM AUTHOR]

The purpose of this study is to analyze the characteristics of wild birds fell victim to pesticides poisoning in South Korea. The main outbreak of pesticide poisoning intensively occurred in winter, when food is rapidly reduced, and hungry birds easily fell victim to food contaminated with pesticides, resulting in ecologically fatal mass mortality. From 2017 to 2018 in South Korea, 1379 wild birds fell victim to pesticide poisoning. In detail, 832 (60.33%) waterfowls such as Baikal teals, and 547 (39.67%) forest birds such as brown-eared bulbuls died. The major pesticides identified in wild birds died of acute pesticide poisoning were carbofuran, monocrotophos and phosphamidon. Taken together, it is pesticide poisoning caused by artificially spraying rice seeds contaminated with pesticides that gives rise to mass death of wild birds in winter in South Korea, and continuous public education and dedicated institutions are needed to prevent this accident. [ABSTRACT FROM AUTHOR]

Abstract Microplastics (MPs) contamination is a well-established impact in oceans, but integrated approaches combining simultaneous analyzes of biotic and abiotic components are scarce. This study addresses this gap, demonstrating Atherinella brasiliensis (fish species) ingestion of MPs and comparing with the contaminant presence in water and sediment. Three Ubatuba beaches (exposed, calm and sheltered estuary) were surveyed for fish, water, and sediment components in summer and winter. Environmental data evidenced spatial and seasonal differences (PCA/ANOVA). Presence of synthetic particles (SPs) in fish was high (~38%). Maximum concentrations occurred in the estuary, for water (490 SPs/m³), and in the exposed beach, for sediment (62 SPs/50g). Fibers format predominated in all components. Fish preference for blue color seems to occur. Significant statistical relationships were determined for fish length and SPs size and between SPs concentrations in water and fish. The chemical identities (μ-FTIR spectra) polypropylene, polyethylene, polyamide, polyester, and cardboard/cellulose predominated. Influences of local hydrodynamics (e.g., SPs sizes) and reduction in tourism during Covid-19 epidemic (e.g.,less SPs in summer) are discussed. This study confirms environmental contamination by SPs (mostly MPs) in Ubatuba beaches, affecting fish through direct water column ingestion. Urgent actions from authorities and changes in local user’s habits are crucial.

Knowledge of post-larval swordfish (Xiphias gladius) ecology in the world's oceans is incomplete as they are rarely found in ichthyoplankton samplings or commercial catches and individuals are difficult to observe in the marine ecosystem. Analyses of stomach contents of apex predators can provide otherwise unobtainable ecological insights. Two well-preserved bills of post-larval swordfish were identified among the partially digested stomach contents of an adult male dolphinfish (Coryphaena hippurus) caught in the northern Tyrrhenian Sea. The lower jaw to fork lengths of the two predated swordfish were estimated at, respectively, 18 and 22 cm, corresponding to 81- and 99-day-old swordfish hatched in the 2022 spawning season. This analysis and recent information on the reproductive dynamics of swordfish in the same area reported in the literature shed light not only on the early stages of swordfish growth but also on dolphinfish ecology in the Tyrrhenian Sea. The two species share the same habitat and are both caught with commercial pelagic surface longlines. Environmental shifts associated with climate change could unpredictably modify the reproduction dynamics, growth, recruitment and distribution of both species. This knowledge is important for the sustainable management of regional fisheries. [ABSTRACT FROM AUTHOR]

We investigated the food composition of the Southeast Asian Rhacophorid frog species Polypedates leucomystax, an invasive species introduced to Okinawajima in the Ryukyu Archipelago, during their breeding activities and the month immediately after that. We examined the stomach contents of 190 males and 54 females, uncovering 215 prey items (including at least 56 species) from 113 males and 21 females. The rate of empty stomachs was relatively high, 45.1% for all frogs (40.5% for males and 61.1% for females). Most prey were arboreal, with a minority being obligately terrestrial or aquatic. Insects constituted the majority of the diet (61.4%), followed by other arthropods, gastropods, and a vertebrate (an agamid lizard neonate). Orthopterans were the dominant prey group in terms of number (29.8%), frequency of occurrence (43.3%), and volume (51.6%). This species is considered an opportunistic feeder, a conclusion corroborated by comparisons with locally varied dietary data from populations of conspecific or closely related species in Southeast Asia. The average prey length was approximately one-third of the body length, but instances of the consumption of larger prey were observed. Similarly, males are able to swallow prey up to two-thirds of their gape width and females up to one-third. The data obtained in this study cover most of the active season of this species on the island, and thus provide a basis for elucidating the ecological impact of this species. [ABSTRACT FROM AUTHOR]

Context: Strandings are an important source of information for estimating marine mammal biodiversity, particularly in data-sparse ocean basins such as Oceania. Aims: Here, we report on knowledge acquired from 218 stranding events recorded in the waters of New Caledonia (1877–2022). Methods: We investigated spatio-temporal distribution, stable isotope signatures, trace element concentrations, biometry measurements, genetic diversity, and diet, for the four most commonly stranded taxa (dugongs, 35% of events; sperm whales, 19%; Delphinidae, 18%; pygmy and dwarf sperm whales, 14%). Key results: Beginning in 1991, reports of stranding events increased (183 events, 322 individuals, 20 species from seven families: Dugongidae, Physeteridae, Delphinidae, Kogiidae, Ziphiidae, Balaenopteridae, Otariidae), with hotspots identified on the west coast (Bourail, Ouano, Nouméa) and in Prony Bay. Causes of death were not determined in 84% of stranding events, but were identified in the majority of expert-led necropsies (24 of 29 individuals from 10 species). Yet, valuable information regarding the impact of anthropogenic activities was gathered for some species of concern, such as the endangered dugong (28% human-caused). Since 2016, training and outreach have been provided to rangers, veterinarians, and various public safety officers to support their engagement in the scientific monitoring of marine mammal strandings. A website (www.rescue.ird.nc) was developed to facilitate standardised data collection and storage, and to provide public access to stranding records. Conclusion: Although the number of individuals reported here remains modest, this study provides new information on poorly documented species in New Caledonia. Implications: Long-term monitoring of strandings can help design effective conservation measures. RESUME: Contexte: Les échouages constituent une source d'informations importante pour estimer la biodiversité des mammifères marins, en particulier dans les bassins océaniques pour lesquels les données sont rares, comme l'Océanie Objectif: Nous présentons ici les connaissances acquises à partir de 218 échouages enregistrés dans les eaux de Nouvelle-Calédonie (1877–2022). Méthodes: Nous avons étudié la distribution spatio-temporelle, les signatures isotopiques, les éléments traces, les mesures biométriques, la diversité génétique et le régime alimentaire des quatre taxons les plus fréquemment échoués (dugongs, 35% des échouages; cachalots, 19%; Delphinidae, 18% ; cachalots pygmées et nains, 14%). Principaux résultats: À partir de 1991, les signalements d'échouages ont augmenté (183 événements, 322 individus, 20 espèces de sept familles: Dugongidae, Physeteridae, Delphinidae, Kogiidae, Ziphiidae, Balaenopteridae, Otariidae), avec des points chauds identifiés sur la côte ouest de la Grande Terre (Bourail, Ouano, Nouméa) et dans la Baie de Prony. Les causes de décès n'ont pas été déterminées pour 84% des échouages, mais elles ont été identifiées dans la majorité des autopsies réalisées par des vétérinaires (24 des 29 individus de 10 espèces). Des informations précieuses concernant l'impact des activités anthropiques ont été recueillies pour certaines espèces préoccupantes, telles que le dugong, une espèce en voie de disparition (28% des échouages d'origine humaine). Depuis 2016, des formations et des activités de sensibilisation ont été dispensées aux gardes nature, aux vétérinaires et à divers agents publics pour soutenir leur engagement dans la surveillance scientifique des échouages de mammifères marins. Un site Web (www.rescue.ird.nc) a été développé pour faciliter la collecte et le stockage de données standardisées et pour fournir un accès public aux enregistrements d'échouages. Conclusion: Bien que le nombre d'individus signalés échoués ici reste modeste, cette étude apporte de nouvelles informations sur des espèces peu documentées en Nouvelle-Calédonie. Implications: La surveillance à long terme des échouages peut aider à concevoir des mesures de conservation efficaces. Map of strandings in New Caledonia; people gathered around a stranded whale; four commonly stranded species. Conservation of marine mammals in Oceania is limited by a lack of understanding of these relatively rare, yet emblematic species. Here, we report on significant biological and ecological data acquired from several decades of monitoring strandings in New Caledonia. This increased knowledge may help guide management measures locally and regionally. Photograph by Marine Mammal Stranding Center. This article belongs to the Collection Marine Mammals in the Pacific. [ABSTRACT FROM AUTHOR]

The objective of this study was to elucidate the effect of temperature on food intake and time for digestion in larvae of Lophiosilurus alexandri. An experiment was performed with four constant temperatures (23°C, 26°C, 29°C, and 32°C), four ages (8, 13, 18, and 23 days post-hatching (DPH)) and eight sampling times (5, 15, 30, 45, 60, 120, 180, and 300 minutes after feeding). The effect of temperature was more evident at 18 and 23 DPH. Due to the increase in age and temperature, there was a decrease in the time to reach the highest rate of digested nauplii. In addition, the larvae were estimated to ingest up to 0.30 ± 0.10 MJ/larva at 32°C in the first meal of the day. Temperatures of 29°C and 32°C provided the most satisfactory results for intake, digestion rate, and intake as percentage of live weight in one meal. [ABSTRACT FROM AUTHOR]

Short-tailed shearwaters Ardenna tenuirostris are seasonally abundant consumers in the Southern Ocean, but their diet in this region is debated. Among birds found on vessels at high latitudes (n = 11 live birds and 4 carcasses), at least six had recently ingested Antarctic krill Euphausia superba. Accumulated fresh remains with no flesh attached were also found in the gizzard of two birds. Liver isotopic values suggested that STSHs fed primarily on krill in southerly habitats. Clarifying whether this abundant predator commonly feeds on Antarctic krill is important to better understand and manage the Southern Ocean food webs. [ABSTRACT FROM AUTHOR]

Copyright of Marine Mammal Science is the property of Wiley-Blackwell and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Revista U.D.C.A Actualidad & Divulgación Científica is the property of Universidad de Ciencias Aplicadas y Ambientales U.D.C.A and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The leopard seal Hydrurga leptonyx is one of five phocid species with a circumpolar distribution in the Southern Ocean. They do not breed on the Australian coast. We document records of 14 leopard seals (two collected specimens, 12 live sightings) in South Australia (SA) between November 2017 and November 2022, from Fowlers Bay to the mouth of the River Murray. We used records from the SA Museum, reports from coastal officers of SA Department for Environment and Water, and information from the public. All 14 seals were juvenile and most were in fair/thin body condition. Two collected specimens and two sighted animals showed evidence of blunt trauma. Stomachs contained fish remains and feathers, and one contained 21 semi-digested smooth toadfish Tetractenos glaber, a species which contains the toxin tetrodo-toxin. Necropsies on two specimens involved gross, histopathological, and diagnostic assessment of pathogens, organs, and skin lesions. All records were between June and December, similar to the seasonal distribution reported previously in southern Australia. The 14 records over 5 years to 2022 averaged 2.8 per year, higher than during a previous study in SA that ran over three decades to October 2009 at 1.2 per year. [ABSTRACT FROM AUTHOR]

Rainbow smelt (Osmerus mordax) have been introduced widely but are associated with declines in walleye (Sander vitreus) recruitment. A primary hypothesis for these declines is that O. mordax consume larval S. vitreus. We confirmed overlapping spatial–temporal distributions of larval S. vitreus and O. mordax in our study system and used mtDNA analyses to determine if O. mordax stomach contents contained S. vitreus. Approximately 20% of O. mordax composite stomach samples were considered positive for S. vitreus consumption. These findings support the predation hypothesis and have S. vitreus management/stocking implications. [ABSTRACT FROM AUTHOR]

The Black-spotted Paddy Frog (Micryletta nigromaculata) was recently discovered from northern Vietnam. Due to its restricted distribution in limestone karst forests and habitat degradation, the endemic species has been listed as "Endangered" in the IUCN Red List. However, knowledge about the natural history of this species is scarce, including data on its dietary ecology. Recent field surveys revealed new populations of M. nigromaculata occurring in Son La Province, northwestern Vietnam based on morphological analysis. Using the stomach-flushing method, we analyzed stomach contents of 45 individuals (21 males and 24 females) from a total of 52 captured frogs because stomachs of six males and one female (13.5%) were empty. The food spectrum of M. nigromaculata comprises 12 types with a total of 691 prey items (687 invertebrate items and four unidentified items), belonging to six insect orders, larvae and Araneae. Similar to other species of the family Microhylidae, M. nigromaculata is also identified as an ant (Formicidae) - termite (Rhinotermitidae) eating specialist with distinctly higher percentages of occurrence frequency (F = 65 %), number of prey items (N = 80 %), and importance (Ix = 75 %) than those of remaining types. The Simpson diversity index of 0.939 shows a high abundance of food prey in the wild, and the Evenness index of 0.536 suggests biased consumption of feeding selection for M. nigromaculata. [ABSTRACT FROM AUTHOR]

Abstract This study reveals early prey eating by a short‐finned pilot whale (Globicephala macrorhynchus Gray, 1846, Cetacea: Delphinidae) in the Canary Islands. Stomach contents, trophic markers, skin isotopic ratios of nitrogen (δ15N:15N/14N) and carbon (δ13C:13C/12C), and fatty acid profiles of the blubber of a short‐finned pilot whale of 213 cm size euthanized in free‐ranging conditions were analyzed. A total of 15 species of oegopsid squids, mostly diel vertical mesopelagic migrant species of the families Enoploteuthidae, Ommastrephidae, and Histioteuthidae, as well as mother's milk, were identified in the stomach contents. Asperoteuthis acanthoderma (Lu, 1977, Cephalopoda: Chiroteuthidae) was found as first time in this area, suggesting the possibility of its presence on both sides of the subtropical Atlantic, extending its current known distribution. The δ15N value (11.55‰) was higher than expected based on the size range of squid ingested, but lower than that of adult pilot whales, suggesting that mother's milk intake has a significant effect on these values in calves. Similarly, the δ13C values (−17.99‰) were shifted to those of adult pilot whales rather than the ingested squids, also due to the ingestion of high‐fat breast milk. The fatty acid (FA) composition of blubber showed a clear stratification. Long‐chain polyunsaturated fatty acids (LC‐PUFA) were mainly present in the inner layer, while most relevant ≤C20 monounsaturated fatty acids (MUFA) were more abundant in the outer layer.

The Arctic and Antarctica represent two of the most inhospitable and poorly investigated biomes in the world. Although polar regions are still perceived as some of the most pristine places still in existence, these remote places are no longer immune to anthropogenic pollution, in particular, micro- and nanoplastics. Seabirds, avian species feeding mainly at sea, are indicators of change in the environment and represent an early study group of ecological indicators for plastic pollution. The goal of this bibliometric overview is to evaluate international research trends on the impacts of microplastics (MPs) and nanoplastics (NPs) on seabirds inhabiting polar regions. A total of at least 13 seabird species were reported to have ingested MPs from 1983–2023. Overall, 1130 samples were investigated, including stomach content, pouch content, guano, and pellets. Pellets were the most investigated substrate (699), followed by stomach contents (309), guano (101), and pouch contents (21). A median of 31.5 MPs per sample was found in the Arctic, with an average of 7.2 MPs per sample. A median of 35 MPs per sample was found in Antarctica, with an average of 1.1 MPs per sample. Overall, MPs were most frequently found in fragment form. A total of 3526 MPs were retrieved from stomachs (3013), pellets (398), guano (75), and pouch contents (40). Polyethylene was the dominant plastic polymer found, followed by polypropylene and polystyrene. The monitoring of MP ingestion is crucial to mitigating the impacts on marine and terrestrial organisms. Standardized protocols could boost the safeguarding of seabirds and reduce the impacts of MPs on polar regions.

Stomach contents of three commercially important species, anchovy (Engraulis japonica), small yellow croaker (Larimichthys polyactis) and yellow goosefish (Lophius litulon) were analyzed to investigate difference of prey between Spring and Fall. Trawl surveys for target fishes were conducted at 12 stations by the RV Tamgu-8 in the Yellow Sea-Korean side in Spring and Fall 2008 as a part of the United Nations Development Programme/Global Environment Facility (UNDP/GEF), Yellow Sea Large Marine Ecosystem (YSLME) survey. Stomach contents of 50 individuals of each species were analyzed to species level of prey, if the number of specimens was more than 50 for each species. Fullness and digestion condition of stomach contents were determined by five and six levels, respectively. In anchovy stomachs, 23 species in Spring and 15 species in Fall were identified, respectively. Stomach contents were mostly occupied by copepods and euphausiids, mostly Euphausia spp., calyptopis in Spring while by copepods and amphipods in Fall. In small yellow croaker stomachs, 23 species in Spring and 11 species in Fall were identified. Stomach contents were mostly occupied by copepods and euphausiids in Spring, but by only euphausiids in Fall. Total 368 yellow goosefish (151 in Spring and 217 in Fall) were captured, but stomach contents only in Fall were analyzed. Most of stomach contents were anchovy with small proportion of Hakodate sand shrimp, Tanaka’s snailfish, Pacific cod, and miscellaneous things. The present research unveiled that main food items of plankton feeder were distinctly different by species and seasons in the Yellow Sea-Korean side, as coincided with previous reports.

To study their feeding habits, Coregonus ussuriensis samples were collected seasonally in the Amur River, China. A total of 574 samples were collected, including 200 individuals with empty stomachs. The stomach contents of the remaining 374 samples were identified, counted, weighed, and analyzed. The results showed that the vacuity rate of Coregonus ussuriensis was 34.84% in total; the rates in summer and autumn were higher than in spring and winter. Prey items could be divided into three categories: fish, benthos, and mammals, with 62 taxonomic units. Of these, fish had the highest relative importance index (IRI), followed by benthos and mammals. Specifically, Exopalaemon modestus was the dominant species among the food species of Coregonus ussuriensis, and unidentified fish, Hydropsyche sp., Hemiculter leucisculus, Abbottina rivularis, and Saurogobio dabryi were important species. The average repletion index (RI, %) of Coregonus ussuriensis was highest in autumn (1.86), followed by winter (1.40), summer (1.26), and spring (1.02). The main food of Coregonus ussuriensis was benthos in spring and autumn, and fish in summer and winter. Cluster analysis showed that, according to the similarity level of the bait biological composition, the fork length group samples of Coregonus ussuriensis could be divided into three groups: 210–330 mm, 330–450 mm, and >450 mm. The highest IRI% of feed organisms in these three groups of samples were fish (73.67%), benthos (75.12%), and benthos (94.46%), respectively. It can be observed that with the growth of the fork length of Coregonus ussuriensis, the importance of benthos in its diet increases. The results of an RDA analysis on the relationship between main bait organisms and various factors indicated that season, river level, river width, and fish size have a significant impact on bait organisms and a positive or negative impact on the quality scores of some bait species. This study filled the gap in biological research on the feeding ecology of Coregonus ussuriensis and laid a research foundation for ecological research on this species and its resource protection and aquaculture.

During summer, native anadromous Arctic char (Salvelinus alpinus) and the alien species pink salmon (Oncorhynchus gorbuscha) now coexist in marine environments in Svalbard, following the introduction of the latter in the Barents Region. To investigate potential dietary competition between these two salmonid species, stomach contents from Arctic char (n = 301) and pink salmon (n = 28) were sampled from different areas within the archipelago. The most important prey in terms of biomass for both salmonid species were amphipods; Themisto libellula (B = 26.0%) for Arctic char and Onisimus litoralis (B = 35.0%) for pink salmon. Pianka's niche overlap revealed that dietary overlap between the two species was moderately high (Oobs = 0.59); both species had strong associations with intertidal invertebrates in areas where direct comparisons were possible (Kongsfjorden/Krossfjorden). However, both salmonid species did also eat some fish, with Arctic char consuming more offshore pelagic fish, while the small number of fish eaten by pink salmon were primarily coastal demersal fish species. Arctic char was a more generalist feeder, while pink salmon was more of a dietary specialist. Furthermore, the diet composition of the Arctic char consisted of 32.9% Atlantic prey while the pink salmon, surprisingly, ate only Arctic species, likely due to their tightly coastal feeding habits. Even though the sample size for pink salmon was low, this study contributes new insights into salmonid diets in Svalbard and the potential for introduced species to compete with native Arctic endemics, particularly in the expected warmer Arctic of the future. [ABSTRACT FROM AUTHOR]

Plastic pollution has become a global environmental problem of major concern. However, the plastic contamination in the marine top predators, particularly in endangered species, is incompletely understood because of the limited amount of data on their presence in the digestive system and prey. This study investigated the stomach contents of an endangered but poorly known shark species, the longfin mako shark (Isurus paucus), found in the tropical western Pacific Ocean. We examined the plastics in this female specimen (1.22-m fork length) and her prey to assess the potential for trophic transfer of microplastics. Polypropylene bottle cap and lollipop packaging, longnose lancetfish (Alepisaurus ferox), and squid were found in the stomach of I. paucus, while no apparent internal injuries were noted. The microplastic fragments and granules, confirmed by laser direct infrared spectroscopy, were found in the digestive system of the intact squid ingested by I. paucus, suggesting that trophic transfer may occur between shark and prey. These results indicate that I. paucus is vulnerable to plastic ingestion and provide evidence of trophic transfer of microplastics in shark species. Our study emphasizes the need to evaluate the potential ecotoxicological consequences of increasing plastic pollution to endangered marine top predators. [ABSTRACT FROM AUTHOR]

The segregation in one trophic niche of n -dimensional niches can allow many species to coexist in the same habitat. In this study, we conducted surveys in Ben En National Park, Thanh Hoa Province, Vietnam to examine stomach contents of two syntopic tree frog species, Hyla simplex and Polypedates megacephalus , using the stomach-flushing method. A total of 21 individuals of H. simplex and 32 individuals of P. megacephalus were sampled revealing 352 food items (H. simplex : 131 invertebrates belonging to 20 prey types of seven orders; P. megacephalus : 215 invertebrates belonging to 22 prey types of 11 orders). Generally, both species consumed slightly diverse and equal prey types. However, ants (Formicidae) and termites (Rhinotermitidae) were identified as the most dominant and important prey for the two tree frog species. With only 38.95% overlap, it is evident that there is tropic segregation between the two syntopic species. [ABSTRACT FROM AUTHOR]

The Egyptian mongoose (Herpestes ichneumon) is considered a generalist and opportunistic predator whose European distribution is restricted to Iberia. However, all the previous studies on the Egyptian mongoose's diet in the Iberian Peninsula have been performed in Portugal and Doñana National Park (southwestern Spain), covering a small region of the species' current distribution. To improve the knowledge on the trophic ecology of the species, we estimated the feeding habits of the Egyptian mongoose in central Spain, its north-eastern range edge. Our study was based on the analysis of (1) scats (n = 251) and (2) stomach contents (n = 32); samples were collected between 2018 and 2022. We calculated the relative frequency of occurrence (%RFO) and the percentage consumed biomass (%CB) for 12 food groups across central Spain and we assessed site-seasonal variations in diet composition in three study areas. We also estimated rabbit densities in the three study areas to assess the effect of rabbit abundance on mongoose diets. Overall, our results showed that European rabbits were the group with highest %CB (30.7%) in the diet of the Egyptian mongoose, followed by reptiles (19.9%) and small mammals (19.9%). In the intensively studied areas, the %CB of rabbits was the highest in the area with the highest abundance of this prey, whereas reptiles had the highest %CB in the area with the lowest availability of rabbits. Diet diversity (Shannon index) varied between 1.73 and 2.47 in those areas and was inversely related to the availability of rabbits. Our results confirm the dietary flexibility of this predator that adapts its diet to the relative availability of different prey species in different habitats. [ABSTRACT FROM AUTHOR]

Sympatric flatfish predators may partition their resources in coastal environments to reduce competition and maximise foraging efficiency. However, the degree of spatial and temporal consistency in their trophic ecology is not well understood because dietary studies tend to overlook the heterogeneity of consumed prey. Increasing the spatial and temporal scale of dietary analyses can thus help to resolve predator resource use. We applied a stomach content and multi‐tissue (liver and muscle) stable isotope (δ13C, δ15N and δ34S) approach to investigate the feeding habits of two co‐occurring flatfish predators, common dab (Limanda limanda) and European plaice (Pleuronectes platessa), across four bays on the Northumberland coast (UK) over short (hours), medium (days) and long (months) temporal scales. Stomach content analyses showed spatial consistencies in predator resource use, whereas stable isotope mixing models revealed considerable inter‐bay diet variability. Stomach contents also indicated high dietary overlap between L. limanda and P. platessa, while the stable isotope data yielded low to moderate levels of overlap, with cases of complete niche separation. Furthermore, individual specialisation metrics indicated consistently low levels of specialisation among conspecifics over time. We document changes in resource partitioning in space and time, reflecting diet switching in response to local and temporal fluctuations of patchily distributed prey. This study highlights how trophic tracers integrated at multiple temporal and spatial scales (within tens of kilometres) provide a more integrative approach for assessing the trophic ecology of sympatric predators in dynamic environments. [ABSTRACT FROM AUTHOR]

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Squaliform sharks are relatively vulnerable bycatch in many deepwater fisheries. The diets of two deep-water sharks, Deania calcea and Deania profundorum, on the continental slope and continental shelf (200-1100 m) of the Moroccan coasts (North-East Atlantic) were subjected to an examination of the stomach content using monthly samples collected between February 2018 and March 2021. For investigation, 683 Deania calcea individuals were collected, ranging in size from 55 to 116cm, with 423 females and 267 males. While, 161 Deania profundorum individuals were sampled, with 117 females and 44 males ranging in size from 49 to 100cm. It was observed that, the diet of both Deania calcea and Deania profundorum consisted of four essential prey groups; cephalopods, bony fish, crustaceans and annelids. The main prey species of the two deep-sea sharks studied were the bony fish, cephalopods and crustaceans. This study would provide comprehensive information for the conservation of the species under study and managing a good exploitation. [ABSTRACT FROM AUTHOR]

Describing the trophic structure and interactions of demersal elasmobranch assemblages is fundamental to understanding food web dynamics and developing ecosystem-based management approaches. Stomach content analysis (SCA) and stable isotope ratios (SIA) of carbon (δ13C) and nitrogen (δ15N) from muscle were used to examine the dietary habits and intra- and interspecific trophic ecology of three sympatric batoid species (Dasyatis pastinaca, Raja clavata, and Raja maderensis) from the Azores, Northeast Atlantic. Data were analyzed with respect to sex and maturity stages. SCA showed that D. pastinaca feeds mostly on crustaceans, whereas R. clavata and R. maderensis prey almost exclusively on teleosts, but not on the same species. Dasyatis pastinaca displayed higher δ13C and lower δ15N values compared to R. clavata and R. maderensis. Trophic niche breadth was variable, D. pastinaca and R. clavata had the broadest and the narrowest trophic breadth, respectively. Relative trophic position categorized D. pastinaca as a mesopredator, while R. clavata and R. maderensis occupied higher trophic positions. With size, R. clavata and R. maderensis shifted from small prey such as crustaceans to larger prey such as teleosts, and they also exhibited significant increases in δ15N with size. Dietary and isotopic overlap was overall low among species, but it was higher between R. clavata and R. maderensis, suggesting more similarity in diet and habitat use between them than with D. pastinaca. This study depicts trophic interactions and functional roles of three co-existing batoid species in the Azorean food webs. In addition to presenting new information on the trophic ecology of D. pastinaca and R. clavata, the present study provides, to our knowledge, the first description of the diet composition and trophic level of the Macaronesian endemic batoid R. maderensis. [ABSTRACT FROM AUTHOR]

The sex ratio, length–weight relationship (LWR) and diets based on stomach contents of whiting (Merlangius merlangus) were investigated in the south-eastern Black Sea, Turkey. A total of 3507 females (7.5–24.0 cm), 1602 males (9.4–20.0 cm), and 78 unidentified sex (5.5–16.5 cm) whiting were caught during monthly sampling from February to December 2017. The sex ratio was dominated by females, and their ratio (♀:♂, 1:0.46) significantly deviated from 1:1. The LWR indicated a negative allometric growth for males, while females had a positive allometric growth pattern. The stomach content analysis based on the relative importance index (IRI%) indicated exclusively piscivorous diets dominant by Sprattus sprattus and Engraulis encrasicolus made up more than 91 IRI% of the total diets of M. merlangus. The modified Costello-Amundsen's graphical analyses evinced the specialized feeding strategy of M. merlangus throughout this study. The contribution of these two preys to the diets of M. merlangus showed considerable seasonal variations that were totally dependent on their abundance. Sprattus sprattus contributed to more than 98% of the total diets during June, July and August, while in the following months, E. encrasicolus appeared to take its position. Based on fish size, a general trend of a rise in prey diversity was found with increasing fish size. Also, the contribution of S. sprattus tended to decrease with increasing predator size, which is replaced by a rise in E. encrasicolus contribution. Hence, larger M. merlangus predominantly fed on E. encrasicolus while smaller size predators preferred to feed on S. sprattus. [ABSTRACT FROM AUTHOR]

Food webs allow us to understand the dynamics of energy flows within an ecosystem through consumption relationships. This research describes the food webs of two seasonal pools (Manaure and Maicao) in the north of the department of La Guajira. The aquatic macroinvertebrates and vertebrates were collected in the littoral and limnetic zones in two samplings per pound (filled with water) between October 2018 and January 2019. To evaluate the trophic relationships, an analysis of stomach contents was performed. These data were grouped by percentages found in stomachs (fine and coarse particulate organic matter, microalgae and animal material). Consumption relationships were analyzed in binary matrices of predator vs. prey. With these matrices and using the Network3D program, the food web models were made. In addition, a principal component analysis was performed. The Manaure pond showed greater richness (25 genera) and greater number of individuals (3121), higher density of links (5.10 L/S) and number of trophic links (171 L), probably evidenced cannibalism that did not occur in Maicao. The resource that predominated in both ecosystems was fine particulate organic matter. From the data obtained, the Manaure pond is observed with a more complex trophic network. These data serve as great contributions to the initial knowledge of the trophic relationships of these seasonal ponds and can be compared with data on food webs in ponds from other parts of the world. [ABSTRACT FROM AUTHOR]

Feeding patterns of sheepshead, Archosargus probatocephalus, in the northwest Gulf of Mexico were examined from samples collected at two locations in Texas, USA; Galveston and Port Aransas. A total of 53 sheepshead stomachs (Galveston, n = 35; Port Aransas, n = 18) had their contents analyzed along with tissue samples from the muscle and liver for a stable isotope analysis (δ13C, δ15N, and δ34S) because they provide a contrast between short-term (liver) and long-term (muscle) measurements. Multiple species of amphipods made up the majority of the prey items in sheepshead from Galveston (%IRI = 61.79), whereas barnacles were the primary diet item for sheepshead collected in Port Aransas (%IRI = 39.53). We observed diet shifts prior to and during the spawning season. MANOVA revealed significant differences in δ13C, δ15N, and δ34S stable isotope values from the muscle and liver tissue of sheepshead based on the location. In both muscle and liver samples, δ13C values were lower in Galveston than Port Aransas, but δ15N and δ34S values were higher in Galveston than Port Aransas. Niche size and overlap also differed between sheepshead from both locations and tissue types. Sheepshead collected in Galveston had a larger niche size in the muscle and liver samples ((mean ± SD) 479.3 ± 131.2, muscle; 433.3 ± 120.3, liver) than Port Aransas (178.8 ± 54.3, muscle; 270.0 ± 80.9, liver). The trophic niche of sheepshead from Galveston overlapped Port Aransas in muscle samples by 16.47% and 18.56% in liver samples. The trophic niche overlap of sheepshead from Port Aransas measured in muscle samples overlapped with sheepshead from Galveston by 18.49% and by 39.17% in liver samples. This study shows that there are subtle but significant differences between the diets of sheepshead along the Texas coast, with the majority of the differences potentially attributable to differences in the prey field along the natural salinity gradient of the Texas coast. This work provides an insight into the widely generalist grazing behavior of sheepshead, which potentially changes during the springtime spawning season. [ABSTRACT FROM AUTHOR]

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