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Marine Ecology Progress Series

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MEPS 623:71-83 (2019)  -  DOI:

Diverse resource-use strategies in a large-bodied marine predator guild: evidence from differential use of resource subsidies and intraspecific isotopic variation

Oliver N. Shipley1,*, Austin J. Gallagher2,3, David S. Shiffman4, Leslie Kaufman5, Neil Hammerschlag3,6

1School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794, USA
2Beneath the Waves, PO Box 126, Herndon, VA 20172, USA
3Rosenstiel School of Marine and Atmospheric Science, University of Miami, Miami, FL 33146, USA
4Earth to Oceans Group, Department of Biological Sciences, Simon Fraser University, 8888 University Drive, Burnaby, British Columbia V5A 1S6, Canada
5Boston University Marine Program, Department of Biology, 1 Silber Way, Boston, MA 02215, USA
6Leonard and Jayne Abess Center for Ecosystem Science and Policy, University of Miami, Coral Gables, FL 33146, USA
*Corresponding author:

ABSTRACT: Observations of resource-use dynamics are sparse for higher trophic level species in marine systems, but important given their role in driving the distribution and functional roles of species. For a guild comprised of 7 large-bodied shark species captured in Florida Bay, we used multi-tissue stable isotope analysis to evaluate the extent of resource-use diversity within and between 2 time periods. We examined: (1) variation in community-wide isotopic niche structure across time (i.e. Layman’s community metrics); (2) variation in species’ trophic position; (3) reliance upon dominant resource pools (inland mangroves vs. coastal neritic [i.e. seagrass and/or reef-associated prey]; and (4) patterns of intraspecific isotopic variation across species (i.e. standard ellipse area, ellipse eccentricity E, ellipse inclination θ, and total isotopic overlap). Community-wide isotopic niche characteristics varied with tissue type, suggesting temporal plasticity in community resource use. Our novel approach integrating multiple isotopic baselines resulted in consistently high trophic position estimates (>5.0), but the utilization of available resource subsidies varied with species and tissue type. Whole blood suggested recent use of inland mangrove-derived prey resources, while fin tissue suggested differential use of both inland mangroves and coastal neritic-derived subsidies. Our results suggest that sharks display dynamic resource use in space and time, with limited functional complementarity across species. The adoption of diverse resource-use strategies, both within and among species, could facilitate the co-occurrence of large-bodied predator species and underscores the role of sharks as vectors of ecosystem connectivity.

KEY WORDS: Stable isotope analysis · Bayesian mixing model · Trophic position · Elasmobranch · Community dynamics

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Cite this article as: Shipley ON, Gallagher AJ, Shiffman DS, Kaufman L, Hammerschlag N (2019) Diverse resource-use strategies in a large-bodied marine predator guild: evidence from differential use of resource subsidies and intraspecific isotopic variation. Mar Ecol Prog Ser 623:71-83.

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