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Olin JA, Urakawa H, Frisk MG, Newton AL, Manz M, Fogg M, McMullen C, Crawford L, Shipley ON. DNA metabarcoding of cloacal swabs provides insight into diets of highly migratory sharks in the Mid-Atlantic Bight. JOURNAL OF FISH BIOLOGY 2023; 103:1409-1418. [PMID: 37640692 DOI: 10.1111/jfb.15543] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2023] [Revised: 07/27/2023] [Accepted: 08/26/2023] [Indexed: 08/31/2023]
Abstract
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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Affiliation(s)
- Jill A Olin
- Department of Biological Sciences, Great Lakes Research Center, Michigan Technological University, Houghton, Michigan, USA
| | - Hidetoshi Urakawa
- Department of Marine and Ecological Sciences, Florida Gulf Coast University, Fort Myers, Florida, USA
| | - Michael G Frisk
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, USA
| | - Alisa L Newton
- New York Aquarium, Wildlife Conservation Society, Bronx, New York, USA
| | - Maria Manz
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, USA
| | - Michael Fogg
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, USA
| | - Colin McMullen
- Department of Marine and Ecological Sciences, Florida Gulf Coast University, Fort Myers, Florida, USA
| | - Lisa Crawford
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, USA
| | - Oliver N Shipley
- School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, New York, USA
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Conditional alternative movement tactics in male crocodiles. Behav Ecol Sociobiol 2023. [DOI: 10.1007/s00265-023-03303-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/07/2023]
Abstract
Abstract
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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Chandelier G, Kiszka JJ, Dulau-Drouot V, Jean C, Poirout T, Estrade V, Barret M, Fayan J, Jaquemet S. Isotopic niche partitioning of co-occurring large marine vertebrates around an Indian ocean tropical oceanic island. MARINE ENVIRONMENTAL RESEARCH 2023; 183:105835. [PMID: 36527765 DOI: 10.1016/j.marenvres.2022.105835] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/21/2022] [Revised: 11/23/2022] [Accepted: 11/25/2022] [Indexed: 06/17/2023]
Abstract
Tropical oceans host a high diversity of species, including large marine consumers. In these oligotrophic ecosystems, oceanic islands often favour the aggregation of species and biomass as they provide feeding opportunities related to the mechanisms of island mass effect. As such, the waters surrounding La Reunion (Southwest Indian Ocean) host seabirds, large pelagic teleosts, elasmobranchs, delphinids and sea turtles. Isotopic niche partitioning and comparison of trophic levels among these species (n = 21) were investigated using stable carbon (δ13C) and nitrogen (δ15N) isotope analysis. Overall, δ13C values were highly variable among taxa, indicating that the species exploit multiple foraging habitats along a coast-open ocean gradient. Overlap in δ15N values was limited, except for teleost species, the two species of sea turtles and two species of delphinids, the Indo-pacific bottlenose dolphin (Tursiops aduncus) and the Spinner dolphin (Stellena longirostris). Stable isotope analyses of samples collected over a 9-years period on different tissues with different integration times provide a consistent picture of the structure of the community of large marine vertebrates species around La Reunion and highlight the underlying mechanisms to limit the competition between species. The wide range of isotopic values confirms that large marine vertebrates have different trophic roles in coastal marine food webs around this oceanic island, which limits their potential of competitive interactions for resources.
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Affiliation(s)
- Guillaume Chandelier
- UMR Entropie, Université de la Réunion, 15 avenue René Cassin, 97744, Saint Denis Cédex 9, Ile de La Réunion, France
| | - Jeremy J Kiszka
- Department of Biological Sciences, Florida International University, 3000 NE 151th Street, North Miami, FL, 33181, USA
| | - Violaine Dulau-Drouot
- Groupe Local d'Observation et d'Identification des Cétacés (GLOBICE), 97432, Ravine des Cabris, Ile de La Réunion, France
| | - Claire Jean
- Kelonia, l'observatoire des tortues marines, 46 rue du Général de Gaulle, 97436, Saint Leu, Ile de La Réunion, France
| | - Thomas Poirout
- UMR Entropie, Université de la Réunion, 15 avenue René Cassin, 97744, Saint Denis Cédex 9, Ile de La Réunion, France
| | - Vanessa Estrade
- Groupe Local d'Observation et d'Identification des Cétacés (GLOBICE), 97432, Ravine des Cabris, Ile de La Réunion, France
| | - Mathieu Barret
- Kelonia, l'observatoire des tortues marines, 46 rue du Général de Gaulle, 97436, Saint Leu, Ile de La Réunion, France
| | - Jacques Fayan
- Brigade Nature Océan Indien (BNOI), 12 All de la forêt parc de la providence, 97400, Saint-Denis, Ile de La Réunion, France
| | - Sébastien Jaquemet
- UMR Entropie, Université de la Réunion, 15 avenue René Cassin, 97744, Saint Denis Cédex 9, Ile de La Réunion, France.
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Xu M, Pethybridge HR, Li Y. Trophic niche partitioning of five sympatric shark species in the tropical eastern Pacific Ocean revealed by multi-tissue fatty acid analysis. ENVIRONMENTAL RESEARCH 2022; 214:113828. [PMID: 35817163 DOI: 10.1016/j.envres.2022.113828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 06/30/2022] [Accepted: 07/02/2022] [Indexed: 06/15/2023]
Abstract
Fatty acid (FA) analysis of consumer tissues has recently shown utility in drawing further inferences about trophic niche dynamics of marine predators such as sharks. In this study, we examined liver, plasma, and muscle FAs in five coexisting pelagic sharks (blue (Prionace glauca), silky (Carcharhinus falciformis), bigeye thresher (Alopias superciliosus), pelagic thresher (Alopias pelagicus), and smooth hammerhead (Sphyrna zygaena)) inhabiting the tropical eastern Pacific Ocean. Results showed complex inter- and intra-individual and tissue variation among the five shark species. Based on multivariate analysis of the muscle FAs, P. glauca and C. falciformis have the largest FA niche widths, indicating diverse feeding habits or habitat isolation, whereas A. pelagicus and S. zygaena occupied a narrower niche width, reflecting increased trophic specialization. High percentages of muscle FA niche overlap indicated strong resource competition between S.zygaena and C. falciformis and a degree of dietary isolation by P. glauca. Interpretations of feeding ecology differed based on the analysis of plasma FAs, which could be attributed to higher dietary FA turnover rates. The liver was deemed unsuitable to examine FA niche metrics based on high and unexplained intra-specific variance in liver FAs as well as the unique lipid metabolism in chondrichthyans. Overall, our multi-tissue approach revealed the magnitude of potential competitive interactions among coexisting tropical shark species. It also expanded our understanding of inter-tissue variability and best practices when using FA analysis to estimate trophic niche metrics of sharks.
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Affiliation(s)
- Min Xu
- College of Marine Sciences, Shanghai Ocean University, Shanghai, China
| | - Heidi R Pethybridge
- Oceans and Atmosphere, Commonwealth Scientific and Industrial Research Organization, Hobart, Tasmania, Australia
| | - Yunkai Li
- College of Marine Sciences, Shanghai Ocean University, Shanghai, China; Key Laboratory of Sustainable Exploitation of Oceanic Fisheries Resources, Ministry of Education, Shanghai, China; National Engineering Research Centre for Oceanic Fisheries, Shanghai Ocean University, Shanghai, China; Key Laboratory of Oceanic Fisheries Exploration, Ministry of Agriculture and Rural Affairs, Shanghai, China.
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Clyde-Brockway CE, Ferreira CR, Flaherty EA, Paladino FV. Lipid profiling suggests species specificity and minimal seasonal variation in Pacific Green and Hawksbill Turtle plasma. PLoS One 2021; 16:e0253916. [PMID: 34280208 PMCID: PMC8289036 DOI: 10.1371/journal.pone.0253916] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 06/16/2021] [Indexed: 01/03/2023] Open
Abstract
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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Affiliation(s)
- Chelsea E. Clyde-Brockway
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, United States of America
- * E-mail:
| | - Christina R. Ferreira
- Bindley Bioscience Center, Purdue University, West Lafayette, IN, United States of America
| | - Elizabeth A. Flaherty
- Department of Forestry and Natural Resources, Purdue University, West Lafayette, IN, United States of America
| | - Frank V. Paladino
- Department of Biology, Purdue University-Fort Wayne, Fort Wayne, IN, United States of America
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