Using Isoscapes to Trace the Movements and Foraging Behavior of Top Predators in Oceanic Ecosystems

Graham, Brittany; Koch, Paul L.; Newsome, Seth D.; McMahon, Kelton W.; Aurioles, David

doi:10.1007/978-90-481-3354-3_14

Cited by 350 publications

(476 citation statements)

References 54 publications

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“…Other speciesspecific isoscapes on marine predators have been developed for albatrosses equipped with tracking devices (n ¼ 45) in the Southern Ocean (Jaeger et al 2010) and for untracked bigeye (n ¼ 196) and yellowfin (n ¼ 387) tuna that were sampled in conjunction with fishery operations in the Pacific Ocean (Graham et al 2010). However, with tuna the isotopic values were assumed to reflect the signature of the capture location, although they may have been in transit (i.e., sampled during migration).…”

Section: Isoscape Patternsmentioning

confidence: 99%

“…15 N values of their nutrient pools (e.g., nitrate, ammonium, N 2 ), biological transformations (e.g., denitrification increases d 15 N while nitrogen fixation lowers d 15 N as these processes preferentially choose v www.esajournals.org 14 N), and isotopic fractionation (Sigman and Casciotti 2001, Montoya et al 2007, Graham et al 2010. Loggerheads in the SNWA reside in areas with higher rates of N 2 fixation, with a more depleted isotopic composition (Montoya et al 2002(Montoya et al , 2007, while turtles at higher latitudes are in a region with higher rates of denitrification, leading to enriched phytoplankton d 15 N (Fennel et al 2006).…”

Section: Differences In Loggerhead Dmentioning

confidence: 99%

“…Stable isotope ratios originating at the base of food webs can be discerned at higher trophic levels. Thus, stable isotopes act as forensic tracers, i.e., individuals that move between isotopically distinct landscapes maintain measurable isotopic differences in their tissues that can be related to past locations (Wassenaar 2008, Graham et al 2010.…”

Section: Introductionmentioning

confidence: 99%

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Modeling and mapping isotopic patterns in the Northwest Atlantic derived from loggerhead sea turtles

et al. 2014

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Abstract. Stable isotope analysis can be used to infer geospatial linkages of highly migratory species.Identifying foraging grounds of marine organisms from their isotopic signatures is becoming de rigueur as it has been with terrestrial organisms. Sea turtles are being increasingly studied using a combination of satellite telemetry and stable isotope analysis; these studies along with those from other charismatic, highly vagile, and widely distributed species (e.g., tuna, billfish, sharks, dolphins, whales) have the potential to yield large datasets to develop methodologies to decipher migratory pathways in the marine realm. We collected tissue samples (epidermis and red blood cells) for carbon (d 13 C) and nitrogen (d 15 N) stable isotope analysis from 214 individual loggerheads (Caretta caretta) in the Northwest Atlantic Ocean (NWA). We used discriminant function analysis (DFA) to examine how well d 13 C and d 15 N classify loggerhead foraging areas. The DFA model was derived from isotopic signatures of 58 loggerheads equipped with satellite tags to identify foraging locations. We assessed model accuracy with the remaining 156 untracked loggerheads that were captured at their foraging locations. The DFA model correctly identified the foraging ground of 93.0% of individuals with a probability greater than 66.7%. The results of the external validation (1) confirm that assignment models based on tracked loggerheads in the NWA are robust and (2) provide the first independent evidence supporting the use of these models for migratory marine organisms. Additionally, we used these data to generate loggerhead-specific d 13 C and d 15 N isoscapes, the first for a predator in the Atlantic Ocean. We found a latitudinal trend of

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Section: Isoscape Patternsmentioning

confidence: 99%

Section: Differences In Loggerhead Dmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Modeling and mapping isotopic patterns in the Northwest Atlantic derived from loggerhead sea turtles

et al. 2014

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“…How d 13 C and d 15 N values of primary producers and prey change across the strong environmental gradient present in the NPTZ is unknown; however, they may change significantly, as has been demonstrated in other areas with strong productivity gradients [17,45]. The low variability in [46,47].…”

Section: (A) Nursery and Juvenile Habitatsmentioning

confidence: 96%

“…The broad distribution of salmon sharks extends across several biogeographic provinces in the ENP [27]. Variability in oceanographic and biogeochemical processes [28] drives differences in baseline stable isotope values among these provinces [17]. This isoscape over which salmon sharks migrate and forage allows the stable isotope composition of their tissues to be used to discern broad-scale patterns of ecoregion use.…”

Section: Introductionmentioning

confidence: 99%

Stable isotope analysis of vertebrae reveals ontogenetic changes in habitat in an endothermic pelagic shark

et al. 2015

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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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Cetaceans, Past and Present

Marx¹,

Lambert²,

Uhen³

2016

Cetacean Paleobiology

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Using Isoscapes to Trace the Movements and Foraging Behavior of Top Predators in Oceanic Ecosystems

Cited by 350 publications

References 54 publications

Modeling and mapping isotopic patterns in the Northwest Atlantic derived from loggerhead sea turtles

Modeling and mapping isotopic patterns in the Northwest Atlantic derived from loggerhead sea turtles

Stable isotope analysis of vertebrae reveals ontogenetic changes in habitat in an endothermic pelagic shark

Cetaceans, Past and Present

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