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Intraspecific differences in relative isotopic niche area and overlap of co-occurring sharks

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Few studies have assessed whether patterns of resource partitioning among sympatric marine predators vary between different habitats. This type of data is important for understanding food web functioning as well as for supporting an ecosystem-based fisheries management plan. In this study, we used d 13 C and d 15 N stable isotope analysis to assess the relative isotopic niche area (i.e., which species has the largest and smallest isotopic niche area within a study site) and core isotopic niche overlap between 299 sharks of 11 co-occurring shark species that vary in size, diet and behavior in three coastal study areas in South Florida. Overall, results show that the relative isotopic niche area and patterns of core isotopic niche overlap between some sympatric shark species varied between sites, suggesting plasticity in resource use and competitive interactions between shark species (e.g., 85% of blacktip shark Carcharhinus limbatus standard ellipse area overlapped with the blacknose shark C. acronotus ellipse in Biscayne Bay, but there was no overlap between these species' ellipses in nearby Florida Bay). Therefore, patterns of resource use and trophic interactions documented among species from one site may not be applicable to a neighboring location. These findings may have implications for food web models that incorporate trophic data from different areas for a species when local data are unavailable.
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Intraspecific differences in relative isotopic niche area
and overlap of co-occurring sharks
David Samuel Shiffman .Les Kaufman .Michael Heithaus .Neil Hammerschlag
Received: 11 September 2018 / Accepted: 8 March 2019 / Published online: 28 March 2019
ÓSpringer Nature B.V. 2019
Abstract Few studies have assessed whether pat-
terns of resource partitioning among sympatric marine
predators vary between different habitats. This type of
data is important for understanding food web func-
tioning as well as for supporting an ecosystem-based
fisheries management plan. In this study, we used d
13
C
and d
15
N stable isotope analysis to assess the relative
isotopic niche area (i.e., which species has the largest
and smallest isotopic niche area within a study site)
and core isotopic niche overlap between 299 sharks of
11 co-occurring shark species that vary in size, diet
and behavior in three coastal study areas in South
Florida. Overall, results show that the relative isotopic
niche area and patterns of core isotopic niche overlap
between some sympatric shark species varied between
sites, suggesting plasticity in resource use and com-
petitive interactions between shark species (e.g., 85%
of blacktip shark Carcharhinus limbatus standard
ellipse area overlapped with the blacknose shark C.
acronotus ellipse in Biscayne Bay, but there was no
overlap between these species’ ellipses in nearby
Florida Bay). Therefore, patterns of resource use and
trophic interactions documented among species from
one site may not be applicable to a neighboring
location. These findings may have implications for
food web models that incorporate trophic data from
Handling Editor: Te
´lesphore Sime-Ngando.
Electronic supplementary material The online version of
this article (https://doi.org/10.1007/s10452-019-09685-5) con-
tains supplementary material, which is available to authorized
users.
D. S. Shiffman (&)N. Hammerschlag
Shark Research and Conservation Program, University of
Miami, 4600 Rickenbacker Causeway, Miami, FL 33149,
USA
e-mail: David.Shiffman@gmail.com
D. S. Shiffman N. Hammerschlag
Leonard and Jayne Abess Center for Ecosystem Science
and Policy, University of Miami, 1365 Memorial Drive,
Coral Gables, FL 33146, USA
L. Kaufman
Department of Biology, Boston University Marine
Program, 1 Silber Way, Boston, MA 02215, USA
M. Heithaus
School of Environment, Arts, and Society, Florida
International University, North Miami, FL 33181, USA
N. Hammerschlag
Rosenstiel School for Marine and Atmospheric Science,
University of Miami, 4600 Rickenbacker Causeway,
Miami, FL 33149, USA
Present Address:
D. S. Shiffman
Earth to Oceans Group, Department of Biological Sciences,
Simon Fraser University, 8888 University Drive, Vancouver,
BC, Canada
123
Aquat Ecol (2019) 53:233–250
https://doi.org/10.1007/s10452-019-09685-5(0123456789().,-volV)(0123456789().,-volV)
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