The Experts below are selected from a list of 174 Experts worldwide ranked by ideXlab platform
Barbara A Block - One of the best experts on this subject based on the ideXlab platform.
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oceanographic drivers of the vertical distribution of a highly migratory endothermic shark
Scientific Reports, 2017Co-Authors: Daniel M. Coffey, Aaron B Carlisle, Elliott L. Hazen, Barbara A BlockAbstract:Salmon sharks Lamna ditropis are highly migratory, upper trophic level predators in North Pacific ecosystems. We analysed a multi-year satellite tag dataset to investigate the habitat use of female salmon sharks across their broad range in the eastern North Pacific (NEP) and identified key environmental factors that influence vertical distribution. Salmon sharks displayed remarkable plasticity in habitat use across disparate oceanographic regions in the NEP and increased utilization of deeper waters in offshore habitats. Diel shifts in vertical distribution and behaviour were consistently observed across their range and likely reflect shifts in their foraging ecology. Salmon sharks utilized a broad thermal niche and exhibited submergence behaviour, possibly for thermal refuge, when encountering sea surface temperatures outside their preferred temperature distribution. Moreover, the vertical distribution of salmon sharks indicates they were able to exploit low dissolved oxygen environments (<1–3 ml l−1), occasionally for extended periods of time in offshore habitats. However, salmon sharks generally reduced their use of deeper waters when encountering the combination of cold temperatures (<6 °C) and low dissolved oxygen concentrations (<1–3 ml l−1). Combining vertical distribution with high-resolution horizontal movements furthers our understanding of the ecological and environmental drivers of movement across short (diel) and long-term (migratory) scales.
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Oceanographic drivers of the vertical distribution of a highly migratory, endothermic shark
Nature Publishing Group, 2017Co-Authors: Daniel M. Coffey, Aaron B Carlisle, Elliott L. Hazen, Barbara A BlockAbstract:Abstract Salmon sharks Lamna ditropis are highly migratory, upper trophic level predators in North Pacific ecosystems. We analysed a multi-year satellite tag dataset to investigate the habitat use of female salmon sharks across their broad range in the eastern North Pacific (NEP) and identified key environmental factors that influence vertical distribution. Salmon sharks displayed remarkable plasticity in habitat use across disparate oceanographic regions in the NEP and increased utilization of deeper waters in offshore habitats. Diel shifts in vertical distribution and behaviour were consistently observed across their range and likely reflect shifts in their foraging ecology. Salmon sharks utilized a broad thermal niche and exhibited submergence behaviour, possibly for thermal refuge, when encountering sea surface temperatures outside their preferred temperature distribution. Moreover, the vertical distribution of salmon sharks indicates they were able to exploit low dissolved oxygen environments (
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Reconstructing habitat use by juvenile salmon sharks links upwelling to strandings in the California Current
Marine Ecology Progress Series, 2015Co-Authors: Aaron B Carlisle, Kenneth J. Goldman, Elliott L. Hazen, Steven Y Litvin, Daniel J Madigan, Robert N. Lea, Barbara A BlockAbstract:The use of nursery areas by elasmobranchs is an important life history strategy that is thought to reduce juvenile mortality and increase population growth rates. The endothermic salmon shark Lamna ditropis uses the California Current System (CCS) as a nursery area, though little is known about how juveniles use this ecosystem. Juvenile salmon sharks consistently strand along the west coast of North America. Strandings in the southern CCS occurred throughout the year, while those in the northern CCS were limited to summer and autumn, when mean sea sur- face temperatures were warmest. Strandings primarily occurred when water temperature was between 12 and 16°C, suggesting that juveniles occupy a relatively narrow thermal niche. Stable isotope analysis (SIA) indicated that juveniles primarily feed on offshore meso- and epipelagic prey from the outer shelf, slope, and oceanic habitats as opposed to inshore and coastal habitats, although sharks appeared to move closer to shore prior to stranding. Generalized additive models indicate that the probability of stranding was greatest when mean water temperatures were rela- tively high (~14°C) and sharks were exposed to acute cold-water events (~9°C) during coastal upwelling. This suggests that juveniles are thermally limited and stressed by upwelling events, resulting in bacterial infections that are the proximate cause of the strandings.
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stable isotope analysis of vertebrae reveals ontogenetic changes in habitat in an endothermic pelagic shark
Proceedings of The Royal Society B: Biological Sciences, 2015Co-Authors: Aaron B Carlisle, Kenneth J. Goldman, Steven Y Litvin, Daniel J Madigan, Jennifer S Bigman, Alan M Swithenbank, Thomas C Kline, Barbara A BlockAbstract: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.
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R EPORTS Satellite Tagging and Cardiac Physiology Reveal Niche Expansion in Salmon Sharks
2013Co-Authors: Kevin C Weng, Kenneth J. Goldman, Pedro C Castilho, Jeffery M Morrissette, David B Holts, Robert J Schallert, Ana M. L, Barbara A BlockAbstract:Shark populations are declining globally, yet the movements and habitats of most species are unknown. We used a satellite tag attached to the dorsal fin to track salmon sharks (Lamna ditropis) for up to 3.2 years. Here we show that salmon sharks have a subarctic-to-subtropical niche, ranging from 2- to 24-C, and they spendwinterperiodsinwatersascoldas2- to 8-C. Functional assays and protein gels reveal that the expression of excitation-contraction coupling proteins is enhanced in salmon shark hearts, which may underlie the shark’s ability to maintain heart function at cold temperatures and their niche expansion into subarctic seas. Many sharks are threatened by fishing around the world (1), and biological knowledge is urgently needed to design management strategies. Sharks have been tracked using shortterm acoustic telemetry (2) and towed satellite tags, which are attached to large, slow-moving basking and whale sharks (3, 4). Pop-up satellit
Jeffrey B. Graham - One of the best experts on this subject based on the ideXlab platform.
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Quantification of red myotomal muscle volume and geometry in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis) using T1‐weighted magnetic resonance imaging
Journal of Morphology, 2007Co-Authors: Cameron N. Perry, Diego Bernal, Jeffrey B. Graham, Chugey A Sepulveda, Daniel P. Cartamil, Rebecca J. Theilmann, Lawrence R. FrankAbstract:T1-weighted magnetic resonance imaging (MRI) in conjunction with image and segmentation anal- ysis (i.e., the process of digitally partitioning tissues based on specified MR image characteristics) was eval- uated as a noninvasive alternative for differentiating muscle fiber types and quantifying the amounts of slow, red aerobic muscle in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis). MRI-determinations of red muscle quantity and position made for the mid-body sections of three mako sharks (73.5-110 cm fork length, FL) are in close agreement (within the 95% confidence intervals) with data obtained for the same sections by the conventional dissection method involving serial cross-sectioning and volumetric analyses, and with previously reported findings for this species. The overall distribution of salmon shark red muscle as a function of body fork length was also found to be consistent with previously acquired serial dissec- tion data for this species; however, MR imaging revealed an anterior shift in peak red muscle cross-sectional area corresponding to an increase in body mass. Moreover, MRI facilitated visualization of the intact and anatomi- cally correct relationship of tendon linking the red mus- cle and the caudal peduncle. This study thus demon- strates that MRI is effective in acquiring high-resolution three-dimensional digital data with high contrast between different fish tissue types. Relative to serial dis- section, MRI allows more precise quantification of the position, volume, and other details about the types of muscle within the fish myotome, while conserving speci- men structural integrity. J. Morphol. 268:284-292, 2007. 2007 Wiley-Liss, Inc.
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Quantification of red myotomal muscle volume and geometry in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis) using T1‐weighted magnetic resonance imaging
Journal of morphology, 2007Co-Authors: Cameron N. Perry, Diego Bernal, Jeffrey B. Graham, Chugey A Sepulveda, Daniel P. Cartamil, Rebecca J. Theilmann, Lawrence R. FrankAbstract:T1-weighted magnetic resonance imaging (MRI) in conjunction with image and segmentation analysis (i.e., the process of digitally partitioning tissues based on specified MR image characteristics) was evaluated as a noninvasive alternative for differentiating muscle fiber types and quantifying the amounts of slow, red aerobic muscle in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis). MRI-determinations of red muscle quantity and position made for the mid-body sections of three mako sharks (73.5-110 cm fork length, FL) are in close agreement (within the 95% confidence intervals) with data obtained for the same sections by the conventional dissection method involving serial cross-sectioning and volumetric analyses, and with previously reported findings for this species. The overall distribution of salmon shark red muscle as a function of body fork length was also found to be consistent with previously acquired serial dissection data for this species; however, MR imaging revealed an anterior shift in peak red muscle cross-sectional area corresponding to an increase in body mass. Moreover, MRI facilitated visualization of the intact and anatomically correct relationship of tendon linking the red muscle and the caudal peduncle. This study thus demonstrates that MRI is effective in acquiring high-resolution three-dimensional digital data with high contrast between different fish tissue types. Relative to serial dissection, MRI allows more precise quantification of the position, volume, and other details about the types of muscle within the fish myotome, while conserving specimen structural integrity.
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Comparative studies of high performance swimming in sharks I. Red muscle morphometrics, vascularization and ultrastructure
The Journal of Experimental Biology, 2003Co-Authors: Diego Bernal, Chugey A Sepulveda, Odile Mathieu-costello, Jeffrey B. GrahamAbstract:SUMMARY Tunas (family Scombridae) and sharks in the family Lamnidae are highly convergent for features commonly related to efficient and high-performance (i.e. sustained, aerobic) swimming. High-performance swimming by fishes requires adaptations augmenting the delivery, transfer and utilization of O 2 by the red myotomal muscle (RM), which powers continuous swimming. Tuna swimming performance is enhanced by a unique anterior and centrally positioned RM (i.e. closer to the vertebral column) and by structural features (relatively small fiber diameter, high capillary density and greater myoglobin concentration) increasing O 2 flux from RM capillaries to the mitochondria. A study of the structural and biochemical features of the mako shark ( Isurus oxyrinchus ) RM was undertaken to enable performance-capacity comparisons of tuna and lamnid RM. Similar to tunas, mako RM is positioned centrally and more anterior in the body. Another lamnid, the salmon shark ( Lamna ditropis ), also has this RM distribution, as does the closely related common thresher shark ( Alopias vulpinus ; family Alopiidae). However, in both the leopard shark ( Triakis semifasciata ) and the blue shark (Prionace glauca ), RM occupies the position where it is typically found in most fishes; more posterior and along the lateral edge of the body. Comparisons among sharks in this study revealed no differences in the total RM quantity (approximately 2–3% of body mass) and, irrespective of position within the body, RM scaling is isometric in all species. Sharks thus have less RM than do tunas (4–13% of body mass). Relative to published data on other shark species, mako RM appears to have a higher capillary density, a greater capillary-to-fiber ratio and a higher myoglobin concentration. However, mako RM fiber size does not differ from that reported for other shark species and the total volume of mitochondria in mako RM is similar to that reported for other sharks and for tunas. Lamnid RM properties thus suggest a higher O 2 flux capacity than in other sharks; however, lamnid RM aerobic capacity appears to be less than that of tuna RM.
Diego Bernal - One of the best experts on this subject based on the ideXlab platform.
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Quantification of red myotomal muscle volume and geometry in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis) using T1‐weighted magnetic resonance imaging
Journal of Morphology, 2007Co-Authors: Cameron N. Perry, Diego Bernal, Jeffrey B. Graham, Chugey A Sepulveda, Daniel P. Cartamil, Rebecca J. Theilmann, Lawrence R. FrankAbstract:T1-weighted magnetic resonance imaging (MRI) in conjunction with image and segmentation anal- ysis (i.e., the process of digitally partitioning tissues based on specified MR image characteristics) was eval- uated as a noninvasive alternative for differentiating muscle fiber types and quantifying the amounts of slow, red aerobic muscle in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis). MRI-determinations of red muscle quantity and position made for the mid-body sections of three mako sharks (73.5-110 cm fork length, FL) are in close agreement (within the 95% confidence intervals) with data obtained for the same sections by the conventional dissection method involving serial cross-sectioning and volumetric analyses, and with previously reported findings for this species. The overall distribution of salmon shark red muscle as a function of body fork length was also found to be consistent with previously acquired serial dissec- tion data for this species; however, MR imaging revealed an anterior shift in peak red muscle cross-sectional area corresponding to an increase in body mass. Moreover, MRI facilitated visualization of the intact and anatomi- cally correct relationship of tendon linking the red mus- cle and the caudal peduncle. This study thus demon- strates that MRI is effective in acquiring high-resolution three-dimensional digital data with high contrast between different fish tissue types. Relative to serial dis- section, MRI allows more precise quantification of the position, volume, and other details about the types of muscle within the fish myotome, while conserving speci- men structural integrity. J. Morphol. 268:284-292, 2007. 2007 Wiley-Liss, Inc.
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Quantification of red myotomal muscle volume and geometry in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis) using T1‐weighted magnetic resonance imaging
Journal of morphology, 2007Co-Authors: Cameron N. Perry, Diego Bernal, Jeffrey B. Graham, Chugey A Sepulveda, Daniel P. Cartamil, Rebecca J. Theilmann, Lawrence R. FrankAbstract:T1-weighted magnetic resonance imaging (MRI) in conjunction with image and segmentation analysis (i.e., the process of digitally partitioning tissues based on specified MR image characteristics) was evaluated as a noninvasive alternative for differentiating muscle fiber types and quantifying the amounts of slow, red aerobic muscle in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis). MRI-determinations of red muscle quantity and position made for the mid-body sections of three mako sharks (73.5-110 cm fork length, FL) are in close agreement (within the 95% confidence intervals) with data obtained for the same sections by the conventional dissection method involving serial cross-sectioning and volumetric analyses, and with previously reported findings for this species. The overall distribution of salmon shark red muscle as a function of body fork length was also found to be consistent with previously acquired serial dissection data for this species; however, MR imaging revealed an anterior shift in peak red muscle cross-sectional area corresponding to an increase in body mass. Moreover, MRI facilitated visualization of the intact and anatomically correct relationship of tendon linking the red muscle and the caudal peduncle. This study thus demonstrates that MRI is effective in acquiring high-resolution three-dimensional digital data with high contrast between different fish tissue types. Relative to serial dissection, MRI allows more precise quantification of the position, volume, and other details about the types of muscle within the fish myotome, while conserving specimen structural integrity.
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Comparative studies of high performance swimming in sharks I. Red muscle morphometrics, vascularization and ultrastructure
The Journal of Experimental Biology, 2003Co-Authors: Diego Bernal, Chugey A Sepulveda, Odile Mathieu-costello, Jeffrey B. GrahamAbstract:SUMMARY Tunas (family Scombridae) and sharks in the family Lamnidae are highly convergent for features commonly related to efficient and high-performance (i.e. sustained, aerobic) swimming. High-performance swimming by fishes requires adaptations augmenting the delivery, transfer and utilization of O 2 by the red myotomal muscle (RM), which powers continuous swimming. Tuna swimming performance is enhanced by a unique anterior and centrally positioned RM (i.e. closer to the vertebral column) and by structural features (relatively small fiber diameter, high capillary density and greater myoglobin concentration) increasing O 2 flux from RM capillaries to the mitochondria. A study of the structural and biochemical features of the mako shark ( Isurus oxyrinchus ) RM was undertaken to enable performance-capacity comparisons of tuna and lamnid RM. Similar to tunas, mako RM is positioned centrally and more anterior in the body. Another lamnid, the salmon shark ( Lamna ditropis ), also has this RM distribution, as does the closely related common thresher shark ( Alopias vulpinus ; family Alopiidae). However, in both the leopard shark ( Triakis semifasciata ) and the blue shark (Prionace glauca ), RM occupies the position where it is typically found in most fishes; more posterior and along the lateral edge of the body. Comparisons among sharks in this study revealed no differences in the total RM quantity (approximately 2–3% of body mass) and, irrespective of position within the body, RM scaling is isometric in all species. Sharks thus have less RM than do tunas (4–13% of body mass). Relative to published data on other shark species, mako RM appears to have a higher capillary density, a greater capillary-to-fiber ratio and a higher myoglobin concentration. However, mako RM fiber size does not differ from that reported for other shark species and the total volume of mitochondria in mako RM is similar to that reported for other sharks and for tunas. Lamnid RM properties thus suggest a higher O 2 flux capacity than in other sharks; however, lamnid RM aerobic capacity appears to be less than that of tuna RM.
Kenneth J. Goldman - One of the best experts on this subject based on the ideXlab platform.
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Prey consumption estimates for salmon sharks
Marine and Freshwater Research, 2019Co-Authors: Kaitlyn A. Manishin, Kenneth J. Goldman, Margaret B. Short, Curry J. Cunningham, Peter A. H. Westley, Andrew C. SeitzAbstract:Top predators, such as salmon sharks (Lamna ditropis), can influence the abundance and population structure of organisms at lower trophic levels through direct effects, such as predation mortality, and indirect interactions. As a first step towards better understanding the average annual prey consumption for individual adult salmon sharks, we bracketed consumption estimates using three methods: (1) daily ration requirement; (2) bioenergetic mass balance; and (3) a Bayesian model of shark growth. In the first method, we applied ration estimates for related lamnid shark species that yielded salmon shark estimates of 1461 and 2202kgyear–1. The second method used a mass–balance technique to incorporate life history information from salmon sharks and physiological parameters from other species and produced estimates of 1870, 2070, 1610 and 1762kgyear–1, depending on assumed diet. Growth modelling used salmon shark growth histories and yielded estimates of 16900 or 20800kgyear–1, depending on assumed assimilation efficiency. Of the consumption estimates, those from the mass–balance technique may be the most realistic because they incorporated salmon shark life history data and do not produce extreme values. Taken as a whole, these estimates suggest that salmon sharks have similar energetic requirements to piscivorous marine mammals.
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Reconstructing habitat use by juvenile salmon sharks links upwelling to strandings in the California Current
Marine Ecology Progress Series, 2015Co-Authors: Aaron B Carlisle, Kenneth J. Goldman, Elliott L. Hazen, Steven Y Litvin, Daniel J Madigan, Robert N. Lea, Barbara A BlockAbstract:The use of nursery areas by elasmobranchs is an important life history strategy that is thought to reduce juvenile mortality and increase population growth rates. The endothermic salmon shark Lamna ditropis uses the California Current System (CCS) as a nursery area, though little is known about how juveniles use this ecosystem. Juvenile salmon sharks consistently strand along the west coast of North America. Strandings in the southern CCS occurred throughout the year, while those in the northern CCS were limited to summer and autumn, when mean sea sur- face temperatures were warmest. Strandings primarily occurred when water temperature was between 12 and 16°C, suggesting that juveniles occupy a relatively narrow thermal niche. Stable isotope analysis (SIA) indicated that juveniles primarily feed on offshore meso- and epipelagic prey from the outer shelf, slope, and oceanic habitats as opposed to inshore and coastal habitats, although sharks appeared to move closer to shore prior to stranding. Generalized additive models indicate that the probability of stranding was greatest when mean water temperatures were rela- tively high (~14°C) and sharks were exposed to acute cold-water events (~9°C) during coastal upwelling. This suggests that juveniles are thermally limited and stressed by upwelling events, resulting in bacterial infections that are the proximate cause of the strandings.
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stable isotope analysis of vertebrae reveals ontogenetic changes in habitat in an endothermic pelagic shark
Proceedings of The Royal Society B: Biological Sciences, 2015Co-Authors: Aaron B Carlisle, Kenneth J. Goldman, Steven Y Litvin, Daniel J Madigan, Jennifer S Bigman, Alan M Swithenbank, Thomas C Kline, Barbara A BlockAbstract: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.
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Notes on the Reproductive Biology of Female Salmon Sharks in the Eastern North Pacific Ocean
Transactions of the American Fisheries Society, 2014Co-Authors: Christina L. Conrath, Cindy A. Tribuzio, Kenneth J. GoldmanAbstract:AbstractLittle is known about the reproductive biology of the Salmon Shark Lamna ditropis from the eastern North Pacific Ocean. Female Salmon Shark specimens were collected from Alaskan waters in the summer, autumn, and winter to examine reproductive seasonality, the reproductive interval, fecundity, and embryonic development. Female Salmon Sharks were found to ovulate during the autumn months of September and October, and those captured in July were either in a resting or postpartum state, indicating a short gestation time of 9–10 months. The presence of two mature reproductive states in both the summer and autumn months indicates a biennial reproductive cycle and a resting period of at least 14 months between parturition and ovulation. This study found mean fecundity was 3.88 pups per litter (n = 8; SE = 0.13), with the majority of pregnant Salmon Sharks having a fecundity of four sharks per litter. These results provide new information on the reproductive biology of Salmon Sharks and will aid in the de...
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R EPORTS Satellite Tagging and Cardiac Physiology Reveal Niche Expansion in Salmon Sharks
2013Co-Authors: Kevin C Weng, Kenneth J. Goldman, Pedro C Castilho, Jeffery M Morrissette, David B Holts, Robert J Schallert, Ana M. L, Barbara A BlockAbstract:Shark populations are declining globally, yet the movements and habitats of most species are unknown. We used a satellite tag attached to the dorsal fin to track salmon sharks (Lamna ditropis) for up to 3.2 years. Here we show that salmon sharks have a subarctic-to-subtropical niche, ranging from 2- to 24-C, and they spendwinterperiodsinwatersascoldas2- to 8-C. Functional assays and protein gels reveal that the expression of excitation-contraction coupling proteins is enhanced in salmon shark hearts, which may underlie the shark’s ability to maintain heart function at cold temperatures and their niche expansion into subarctic seas. Many sharks are threatened by fishing around the world (1), and biological knowledge is urgently needed to design management strategies. Sharks have been tracked using shortterm acoustic telemetry (2) and towed satellite tags, which are attached to large, slow-moving basking and whale sharks (3, 4). Pop-up satellit
Chugey A Sepulveda - One of the best experts on this subject based on the ideXlab platform.
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Quantification of red myotomal muscle volume and geometry in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis) using T1‐weighted magnetic resonance imaging
Journal of Morphology, 2007Co-Authors: Cameron N. Perry, Diego Bernal, Jeffrey B. Graham, Chugey A Sepulveda, Daniel P. Cartamil, Rebecca J. Theilmann, Lawrence R. FrankAbstract:T1-weighted magnetic resonance imaging (MRI) in conjunction with image and segmentation anal- ysis (i.e., the process of digitally partitioning tissues based on specified MR image characteristics) was eval- uated as a noninvasive alternative for differentiating muscle fiber types and quantifying the amounts of slow, red aerobic muscle in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis). MRI-determinations of red muscle quantity and position made for the mid-body sections of three mako sharks (73.5-110 cm fork length, FL) are in close agreement (within the 95% confidence intervals) with data obtained for the same sections by the conventional dissection method involving serial cross-sectioning and volumetric analyses, and with previously reported findings for this species. The overall distribution of salmon shark red muscle as a function of body fork length was also found to be consistent with previously acquired serial dissec- tion data for this species; however, MR imaging revealed an anterior shift in peak red muscle cross-sectional area corresponding to an increase in body mass. Moreover, MRI facilitated visualization of the intact and anatomi- cally correct relationship of tendon linking the red mus- cle and the caudal peduncle. This study thus demon- strates that MRI is effective in acquiring high-resolution three-dimensional digital data with high contrast between different fish tissue types. Relative to serial dis- section, MRI allows more precise quantification of the position, volume, and other details about the types of muscle within the fish myotome, while conserving speci- men structural integrity. J. Morphol. 268:284-292, 2007. 2007 Wiley-Liss, Inc.
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Quantification of red myotomal muscle volume and geometry in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis) using T1‐weighted magnetic resonance imaging
Journal of morphology, 2007Co-Authors: Cameron N. Perry, Diego Bernal, Jeffrey B. Graham, Chugey A Sepulveda, Daniel P. Cartamil, Rebecca J. Theilmann, Lawrence R. FrankAbstract:T1-weighted magnetic resonance imaging (MRI) in conjunction with image and segmentation analysis (i.e., the process of digitally partitioning tissues based on specified MR image characteristics) was evaluated as a noninvasive alternative for differentiating muscle fiber types and quantifying the amounts of slow, red aerobic muscle in the shortfin mako shark (Isurus oxyrinchus) and the salmon shark (Lamna ditropis). MRI-determinations of red muscle quantity and position made for the mid-body sections of three mako sharks (73.5-110 cm fork length, FL) are in close agreement (within the 95% confidence intervals) with data obtained for the same sections by the conventional dissection method involving serial cross-sectioning and volumetric analyses, and with previously reported findings for this species. The overall distribution of salmon shark red muscle as a function of body fork length was also found to be consistent with previously acquired serial dissection data for this species; however, MR imaging revealed an anterior shift in peak red muscle cross-sectional area corresponding to an increase in body mass. Moreover, MRI facilitated visualization of the intact and anatomically correct relationship of tendon linking the red muscle and the caudal peduncle. This study thus demonstrates that MRI is effective in acquiring high-resolution three-dimensional digital data with high contrast between different fish tissue types. Relative to serial dissection, MRI allows more precise quantification of the position, volume, and other details about the types of muscle within the fish myotome, while conserving specimen structural integrity.
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Comparative studies of high performance swimming in sharks I. Red muscle morphometrics, vascularization and ultrastructure
The Journal of Experimental Biology, 2003Co-Authors: Diego Bernal, Chugey A Sepulveda, Odile Mathieu-costello, Jeffrey B. GrahamAbstract:SUMMARY Tunas (family Scombridae) and sharks in the family Lamnidae are highly convergent for features commonly related to efficient and high-performance (i.e. sustained, aerobic) swimming. High-performance swimming by fishes requires adaptations augmenting the delivery, transfer and utilization of O 2 by the red myotomal muscle (RM), which powers continuous swimming. Tuna swimming performance is enhanced by a unique anterior and centrally positioned RM (i.e. closer to the vertebral column) and by structural features (relatively small fiber diameter, high capillary density and greater myoglobin concentration) increasing O 2 flux from RM capillaries to the mitochondria. A study of the structural and biochemical features of the mako shark ( Isurus oxyrinchus ) RM was undertaken to enable performance-capacity comparisons of tuna and lamnid RM. Similar to tunas, mako RM is positioned centrally and more anterior in the body. Another lamnid, the salmon shark ( Lamna ditropis ), also has this RM distribution, as does the closely related common thresher shark ( Alopias vulpinus ; family Alopiidae). However, in both the leopard shark ( Triakis semifasciata ) and the blue shark (Prionace glauca ), RM occupies the position where it is typically found in most fishes; more posterior and along the lateral edge of the body. Comparisons among sharks in this study revealed no differences in the total RM quantity (approximately 2–3% of body mass) and, irrespective of position within the body, RM scaling is isometric in all species. Sharks thus have less RM than do tunas (4–13% of body mass). Relative to published data on other shark species, mako RM appears to have a higher capillary density, a greater capillary-to-fiber ratio and a higher myoglobin concentration. However, mako RM fiber size does not differ from that reported for other shark species and the total volume of mitochondria in mako RM is similar to that reported for other sharks and for tunas. Lamnid RM properties thus suggest a higher O 2 flux capacity than in other sharks; however, lamnid RM aerobic capacity appears to be less than that of tuna RM.
