Prey composition and ontogenetic shift in coastal populations of longnose gar Lepisosteus osseus |
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| Authors: | V Shervette C McDonough |
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| Affiliation: | 1. Department of Biology and Geology, University of South Carolina Aiken, Aiken, U.S.A.;2. Marine Resources Division, South Carolina Department of Natural Resources, Charleston, SC, U.S.A. |
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| Abstract: | Longnose gar Lepisosteus osseus were collected from May 2012 to July 2013 in the Charleston Harbor and Winyah Bay estuaries (SC, U.S.A.). This study examined trends in stomach fullness, described major prey components and their importance in the diet of L. osseus, compared stomach content‐based trophic level estimates with the stable‐isotope‐based proxy: δ15N and tested for the occurrence of an ontogenetic diet shift using stomach content analysis and stable C and N isotopes (δ13C and δ15N). Dominant prey families were Clupeidae, Sciaenidae, Penaeidae, Fundulidae and Mugilidae, with the highest consumption rates in autumn. Trophic levels calculated using stomach contents did not correspond to δ15N (P > 0·05). Stomach contents and stable‐isotope signatures indicate ontogenetic prey composition shifts from low trophic level benthic prey (fundulids) to higher trophic level pelagic prey (clupeids) as the fish grow between 400 and 600 mm in standard length. Due to their biomass, abundance and top predator status, L. osseus play a significant ecological role in the estuarine community composition, although this effect has often been overlooked by past researchers and should be considered in future estuarine community studies. |
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| Keywords: | estuarine communities piscivore stable isotopes stomach contents trophic level |
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