TY - JOUR
T1 - Diverse resource-use strategies in a large-bodied marine predator guild
T2 - Evidence from differential use of resource subsidies and intraspecific isotopic variation
AU - Shipley, Oliver N.
AU - Gallagher, Austin J.
AU - Shiffman, David S.
AU - Kaufman, Leslie
AU - Hammerschlag, Neil
PY - 2019/7/30
Y1 - 2019/7/30
N2 - 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.
AB - 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.
KW - Bayesian mixing model
KW - Community dynamics
KW - Elasmobranch
KW - Stable isotope analysis
KW - Trophic position
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U2 - 10.3354/meps12982
DO - 10.3354/meps12982
M3 - Article
AN - SCOPUS:85069934156
VL - 623
SP - 71
EP - 83
JO - Marine Ecology - Progress Series
JF - Marine Ecology - Progress Series
SN - 0171-8630
ER -