7 results on '"Carlisle, Aaron B."'
Search Results
2. Integrating multiple chemical tracers to elucidate the diet and habitat of Cookiecutter Sharks.
- Author
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Carlisle, Aaron B., Allan, Elizabeth Andruszkiewicz, Kim, Sora L., Meyer, Lauren, Port, Jesse, Scherrer, Stephen, and O'Sullivan, John
- Subjects
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SHARKS , *OSTEICHTHYES , *SPECIES distribution , *STABLE isotope analysis , *GENETIC barcoding - Abstract
The Cookiecutter shark (Isistius brasiliensis) is an ectoparasitic, mesopelagic shark that is known for removing plugs of tissue from larger prey, including teleosts, chondrichthyans, cephalopods, and marine mammals. Although this species is widely distributed throughout the world's tropical and subtropical oceanic waters, like many deep-water species, it remains very poorly understood due to its mesopelagic distribution. We used a suite of biochemical tracers, including stable isotope analysis (SIA), fatty acid analysis (FAA), and environmental DNA (eDNA), to investigate the trophic ecology of this species in the Central Pacific around Hawaii. We found that large epipelagic prey constituted a relatively minor part of the overall diet. Surprisingly, small micronektonic and forage species (meso- and epipelagic) are the most important prey group for Cookiecutter sharks across the studied size range (17–43 cm total length), with larger mesopelagic species or species that exhibit diel vertical migration also being important prey. These results were consistent across all the tracer techniques employed. Our results indicate that Cookiecutter sharks play a unique role in pelagic food webs, feeding on prey ranging from the largest apex predators to small, low trophic level species, in particular those that overlap with the depth distribution of the sharks throughout the diel cycle. We also found evidence of a potential shift in diet and/or habitat with size and season. Environmental DNA metabarcoding revealed new prey items for Cookiecutter sharks while also demonstrating that eDNA can be used to identify recent prey in stomachs frozen for extended periods. Integrating across chemical tracers is a powerful tool for investigating the ecology of elusive and difficult to study species, such as meso- and bathypelagic chondrichthyans, and can increase the amount of information gained from small sample sizes. Better resolving the foraging ecology of these mesopelagic predators is critical for effective conservation and management of these taxa and ecosystems, which are intrinsically vulnerable to overfishing and exploitation. [ABSTRACT FROM AUTHOR]
- Published
- 2021
- Full Text
- View/download PDF
3. Stable isotope analysis reveals ontogenetic feeding shifts in Pacific blue marlin (Makaira nigricans) off eastern Taiwan.
- Author
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Chang, Ching‐Tsun, Chiang, Wei‐Chuan, Chang, Yun‐Chen, Musyl, Michael K., Sun, Chi‐Lu, Madigan, Daniel J., Carlisle, Aaron B., Hsu, Hung‐Hung, Chang, Qi‐Xuan, Su, Nan‐Jay, Ho, Yuan‐Shing, and Tseng, Chen‐Te
- Subjects
STABLE isotope analysis ,TOP predators ,FORAGE fishes ,CARBON isotopes ,STABLE isotopes ,FOOD chains - Abstract
To gain a better understanding of the trophic ecology of Pacific blue marlin Makaira nigricans off eastern Taiwan, nitrogen and carbon stable isotopes (δ15N and δ13C) and Bayesian mixing models were used to explore trophic dynamics and potential ontogenetic feeding shifts across M. nigricans of different size classes. Makaira nigricans samples from east of Taiwan (n = 213) and Palau (n = 37), as well as their prey (n = 70), were collected during 2012 and 2013. Results indicated increases in δ15N with size, with values of larger size classes (> 200 cm eye‐to‐fork length; LEF) significantly higher than those < 200 cm LEF. Values of δ13C were negatively correlated with size. Makaira nigricans > 200 cm LEF had the highest estimated trophic position (4.44) and also exhibited ontogenetic changes in trophic position. Large M. nigricans fed more on dolphinfish Coryphaena hippurus and hairtail Trichiurus lepturus, while smaller M. nigricans consumed smaller forage fish (e.g., moonfish Mene maculata) and cephalopods. These changes may relate to greater swimming speeds and vertical habitat use in larger M. nigricans, allowing capture and consumption of larger prey items at higher trophic positions. The high trophic level of M. nigricans east of Taiwan confirms its important role as an apex predator in marine food webs and how ecological role changes with size. [ABSTRACT FROM AUTHOR]
- Published
- 2019
- Full Text
- View/download PDF
4. Influence of ontogeny and environmental exposure on mercury accumulation in muscle and liver of male Round Stingrays.
- Author
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Lyons, Kady, Carlisle, Aaron B., and Lowe, Christopher G.
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ONTOGENY , *STINGRAYS , *MERCURY , *STABLE isotope analysis , *BIOACCUMULATION - Abstract
Mercury tissue distribution and its dynamics are poorly understood in elasmobranchs. Total mercury was measured in liver and muscle of male Round Stingrays ( Urobatis halleri ) from Seal Beach, California, an anthropogenically impacted site, and from the offshore island of Santa Catalina, a less impacted site. Stable isotope analysis was also performed on the muscle and red blood cells (RBCs) of a subset of rays over a range of age classes to investigate mercury accumulation with respect to trophic ecology. Mercury in both tissues was found to be significantly greater in adults than juveniles in mainland rays; however, liver mercury accumulation drastically increased after maturity and was significantly greater in mainland adult rays than Catalina rays. There were no patterns in δ 15 N or δ 13 C with size in muscle; however, there were indications of seasonal changes in RBC δ 15 N, suggesting short term shifts in diet or behavior is likely linked to reproductive status as is mercury accumulation. [ABSTRACT FROM AUTHOR]
- Published
- 2017
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- View/download PDF
5. Interactive effects of urea and lipid content confound stable isotope analysis in elasmobranch fishes.
- Author
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Carlisle, Aaron B., Litvin, Steven Y., Madigan, Daniel J., Lyons, Kady, Bigman, Jennifer S., Ibarra, Melissa, and Bizzarro, Joseph J.
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STABLE isotope analysis , *CHONDRICHTHYES , *UREA , *LIPIDS , *ELASMOBRANCH fisheries - Abstract
Stable isotope analysis (SIA) is becoming a commonly used tool to study the ecology of elasmobranchs. However, the retention of urea by elasmobranchs for osmoregulatory purposes may bias the analysis and interpretation of SIA data. We examined the effects of removing urea and lipid on the stable isotope composition of 14 species of sharks, skates, and rays from the eastern North Pacific Ocean. While effects were variable across taxa, removal of urea generally increased δ15N and C:N. Urea removal had less influence on δ13C, whereas extracting urea and lipid generally increased δ15N, C:N, and δ13C. Because C:N values of nonextracted tissues are often used to infer lipid content and adjust δ13C, shifts in C:N following urea extraction will change the inferred lipid content and bias any mathematical adjustment of δ13C. These results highlight the importance of urea and lipid extraction and demonstrate the confounding effects of these compounds, making it impossible to use C:N of non-urea-extracted samples as a diagnostic tool to estimate and correct for lipid content in elasmobranch tissues. [ABSTRACT FROM AUTHOR]
- Published
- 2017
- Full Text
- View/download PDF
6. Stable isotope analysis of vertebrae reveals ontogenetic changes in habitat in an endothermic pelagic shark.
- Author
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Carlisle, Aaron B., Goldman, Kenneth J., Litvin, Steven Y., Madigan, Daniel J., Bigman, Jennifer S., Swithenbank, Alan M., Kline Jr, Thomas C., and Block, Barbara A.
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STABLE isotopes , *VERTEBRAE , *ONTOGENY , *ENDOTHERMIC reactions , *HABITATS - Abstract
Ontogenetic changes in habitat are driven by shifting life-history requirements and play an important role in population dynamics. However, large portions of the life history of many pelagic species are still poorly understood or unknown. We used a novel combination of stable isotope analysis of vertebral annuli, Bayesian mixing models, isoscapes and electronic tag data to reconstruct ontogenetic patterns of habitat and resource use in a pelagic apex predator, the salmon shark (Lamna ditropis). Results identified the North Pacific Transition Zone as the major nursery area for salmon sharks and revealed an ontogenetic shift around the age of maturity from oceanic to increased use of neritic habitats. The nursery habitat may reflect trade-offs between prey availability, predation pressure and thermal constraints on juvenile endothermic sharks. The ontogenetic shift in habitat coincided with a reduction of isotopic niche, possibly reflecting specialization upon particular prey or habitats. Using tagging data to inform Bayesian isotopic mixing models revealed that adult sharks primarily use neritic habitats of Alaska yet receive a trophic subsidy from oceanic habitats. Integrating the multiple methods used here provides a powerful approach to retrospectively study the ecology and life history of migratory species throughout their ontogeny. [ABSTRACT FROM AUTHOR]
- Published
- 2015
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7. Stable isotope analysis reveals feeding ecology and trophic position of black marlin off eastern Taiwan.
- Author
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Chiang, Wei-Chuan, Chang, Ching-Tsun, Madigan, Daniel J., Carlisle, Aaron B., Musyl, Michael K., Chang, Yun-Chen, Hsu, Hung-Hung, Su, Nan-Jay, Sun, Chi-Lu, Ho, Yuan-Shing, and Tseng, Chen-Te
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STABLE isotope analysis , *TOP predators , *FEED analysis , *ECOLOGY , *FORAGE fishes , *FISH stocking , *BIOACCUMULATION in fishes - Abstract
Black marlin (Istiompax indica) are large, highly mobile, apex pelagic predators of tropical and subtropical oceans with high economic importance in western North Pacific fisheries. To assess the ontogenetic trophic ecology of black marlin in the western North Pacific Ocean, the stable isotopic composition of 177 black marlin muscle samples (87–383 cm, eye-orbit fork length (EFL); 33–447 kg, body weight) were examined for ontogenetic shifts and seasonal variability in trophic position. δ15N and δ13C values for black marlin ranged from 9.7 to 14.5‰ and −18.5 to −15.2‰, respectively, and δ15N values were positively correlated with size. δ15N and δ13C values varied across seasons, with highest δ15N values in autumn. Based on trophic position estimates and Bayesian mixing models, large black marlin (>250 cm EFL) occupied a higher trophic position (4.8) and fed on more mesopelagic prey (e.g. hairtail, Trichiurus lepturus) compared to smaller individuals, which were estimated to feed more on forage fish and squids as well as hairtail. These results suggest that the trophic position of black marlin varies across life-history stages and seasons, possibly reflecting seasonal movements in surrounding pelagic ecosystems. Trophic level estimates highlight the important ecological role of black marlin as a top predator in pelagic ecosystems, and indicate potential regional importance of mesopelagic fishes in diets. [ABSTRACT FROM AUTHOR]
- Published
- 2020
- Full Text
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