The use of muscle lipids and fatty acids to assess shark diet and condition

Meyer, Lauren; Chambers, Sherrie; Gervais, Connor R.; Beckmann, Crystal; Bruce, Barry D.; Huveneers, Charlie

doi:10.1111/jfb.14602

Cited by 8 publications

(2 citation statements)

References 30 publications

(63 reference statements)

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“…Studies exploring dietary preference and broader trophic ecology of sharks have traditionally relied on assessments of stomach contents, which requires major intervention (e.g., gastric lavage) and/or lethal dissection (Barnett et al, 2010;Cortés, 1999). The impetus to consider highly vulnerable or protected species (Heupel & Simpfendorfer, 2010), however, has prompted greater adoption of minimally invasive techniques, such as stable isotope analysis (Hussey et al, 2012), fatty acid analysis (Meyer et al, 2021), and DNA analysis of fecal material (fDNA; Poulakis et al, 2017), to characterize species' resource use. Like stomach content data, DNA sequencing (e.g., high-throughput and metabarcoding techniques) of consumer fecal samples can provide short-term insights into prey consumption on a variety of taxonomic scales (Brown et al, 2012;Poulakis et al, 2017).…”

Section: Introductionmentioning

confidence: 99%

DNA metabarcoding of cloacal swabs provides insight into diets of highly migratory sharks in the Mid‐Atlantic Bight

Olin,

Urakawa,

Frisk

et al. 2023

Journal of Fish Biology

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The abundances of migratory shark species observed throughout the Mid‐Atlantic Bight (MAB) during productive summer months suggest that this region provides critical habitat and prey resources to these taxa. However, the principal prey assemblages sustaining migratory shark biomass in this region are poorly defined. We applied high‐throughput DNA metabarcoding to shark feces derived from cloacal swabs across nine species of Carcharhinid and Lamnid sharks to (1) quantify the contribution of broad taxa (e.g., invertebrates, fishes) supporting shark biomass during seasonal residency in the MAB and (2) determine whether the species displayed distinct dietary preference indicative of resource partitioning. DNA metabarcoding resulted in high taxonomic (species‐level) resolution of shark diets with actinopterygian and elasmobranch fishes as the dominant prey categories across the species. DNA metabarcoding identified several key prey groups consistent across shark taxa that are likely integral for sustaining their biomass in this region, including Atlantic menhaden (Brevoortia tyrannus), Atlantic mackerel (Scomber scombrus), and benthic elasmobranchs, including skates. Our results are consistent with previously published stomach content data for the shark species of similar size range in the Northwest Atlantic Ocean, supporting the efficacy of cloacal swab DNA metabarcoding as a minimally invasive diet reconstruction technique. The high reliance of several shark species on Atlantic menhaden could imply wasp‐waist food‐web conditions during the summer months, whereby high abundances of forage fishes sustain a diverse suite of migratory sharks within a complex, seasonal food web.

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Section: Introductionmentioning

confidence: 99%

DNA metabarcoding of cloacal swabs provides insight into diets of highly migratory sharks in the Mid‐Atlantic Bight

Olin,

Urakawa,

Frisk

et al. 2023

Journal of Fish Biology

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“…Anthropogenic threats to sea turtles are widely studied and clearly defined [1], but to adequately protect these endangered species, it is important to understand how natural environmental variability influences their behavior and physiology. Animal behavior and physiology are reflected in plasma metabolites, such as lipid profiles, which also contain information about an organism's diet, environment, and health [2][3][4][5][6][7][8]. Generally, lipids can be divided into structural lipids, storage lipids, and signaling lipids.…”

Section: Introductionmentioning

confidence: 99%

Lipid profiling suggests species specificity and minimal seasonal variation in Pacific Green and Hawksbill Turtle plasma

et al. 2021

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In this study, we applied multiple reaction monitoring (MRM)-profiling to explore the relative ion intensity of lipid classes in plasma samples from sea turtles in order to profile lipids relevant to sea turtle physiology and investigate how dynamic ocean environments affect these profiles. We collected plasma samples from foraging green (Chelonia mydas, n = 28) and hawksbill (Eretmochelys imbricata, n = 16) turtles live captured in North Pacific Costa Rica in 2017. From these samples, we identified 623 MRMs belonging to 10 lipid classes (sphingomyelin, phosphatidylcholine, free fatty acid, cholesteryl ester, phosphatidylserine, phosphatidylinositol, phosphatidylglycerol, phosphatidylethanolamine, ceramide, and triacylglyceride) and one metabolite group (acyl-carnitine) present in sea turtle plasma. The relative ion intensities of most lipids (80%) were consistent between species, across seasons, and were not correlated to body size or estimated sex. Of the differences we observed, the most pronounced was the differences in relative ion intensity between species. We identified 123 lipids that had species-specific relative ion intensities. While some of this variability is likely due to green and hawksbill turtles consuming different food items, we found indications of a phylogenetic component as well. Of these, we identified 47 lipids that varied by season, most belonging to the structural phospholipid classes. Overall, more lipids (n = 39) had higher relative ion intensity in the upwelling (colder) season compared to the non-upwelling season (n = 8). Further, we found more variability in hawksbill turtles than green turtles. Here, we provide the framework in which to apply future lipid profiling in the assessment of health, physiology, and behavior in endangered sea turtles.

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Conditional alternative movement tactics in male crocodiles

Barham

Baker²,

Franklin³

et al. 2023

Behav Ecol Sociobiol

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In species where conflict is costly, individuals adopt alternative movement tactics to minimise the risk of competitive interactions. Dominant males often maintain defined territories, while less competitive males may be forced to adopt alternative tactics to maximise fitness and reduce conflict. However, the extent to which males switch tactics according to current social or physiological status is poorly understood. Using implanted acoustic tags and a fixed array of tracking receivers, we investigated how the behaviour of 78 male estuarine crocodiles (Crocodylus porosus) shifted over an 11-year period in relation to ontogeny, body condition, and the extent of physical injuries. We discovered that male crocodiles sorted into three common movement classes, with 51% of males maintaining the same movement class across consecutive years (max = 9 years). Males > 4 m in total length maintained confined territories both within and across years and had the greatest extent of injuries and the highest condition score, indicative of territory holders. In contrast, smaller males sorted into high movement roamer or low movement site-philopatric tactics, where the tactic an individual adopted was less stable between years and did not correlate with condition or external injuries. Our study reveals the socio-biological mechanisms by which estuarine crocodiles coexist within a restricted habitat. Significance statement Identifying individual-level differences in movement helps us predict which individuals are more likely to be involved in human-wildlife interactions. However, studying long-term shifts in movement is challenging, as large datasets of co-occurring individuals tracked in their natural environment over multiple years are required. We tracked a population of 78 male estuarine crocodiles (1030–4687 mm total length) in a shared environment over 11 years and assessed how eight movement traits were linked to body size and physical condition. At the population level, males sorted into different movement tactics according to ontogeny, with large territorial males having better body condition yet a greater incidence of injury. However, 49% of males showed variability across years, suggesting that tactics were conditional relative to environmental variability and a male’s own status. Our study provides insights into the mechanisms and costs of movement tactics in wild crocodile populations.

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The use of muscle lipids and fatty acids to assess shark diet and condition

Cited by 8 publications

References 30 publications

DNA metabarcoding of cloacal swabs provides insight into diets of highly migratory sharks in the Mid‐Atlantic Bight

DNA metabarcoding of cloacal swabs provides insight into diets of highly migratory sharks in the Mid‐Atlantic Bight

Lipid profiling suggests species specificity and minimal seasonal variation in Pacific Green and Hawksbill Turtle plasma

Conditional alternative movement tactics in male crocodiles

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