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CORRESPONDENCE OF STABLE ISOTOPE AND GUT CONTENTS ANALYSES IN DETERMINING TROPHIC POSITION OF STREAM FISHES
Citation:
RYBCZYNSKI, S., DAVID M. WALTERS, K. M. FRITZ, AND B. R. JOHNSON. CORRESPONDENCE OF STABLE ISOTOPE AND GUT CONTENTS ANALYSES IN DETERMINING TROPHIC POSITION OF STREAM FISHES. Presented at North American Benthological Society, Anchorage, AK, June 04 - 09, 2006.
Impact/Purpose:
The goal of this research is to develop methods and indicators that are useful for evaluating the condition of aquatic communities, for assessing the restoration of aquatic communities in response to mitigation and best management practices, and for determining the exposure of aquatic communities to different classes of stressors (i.e., pesticides, sedimentation, habitat alteration).
Description:
It is generally accepted that both stable isotope analysis (SIA) and gut contents analysis (GCA) be used in food web studies; however, few researchers have analyzed these data in concert. We utilized SIA and GCA to determine if longitudinal and seasonal variation in diet affects the trophic position of six species of fishes from Twelve Mile Creek, Clemson, SC, USA. Diets of Nocomis leptocephalus, Notropis lutipinnis, and Etheostoma inscriptum varied seasonally, with a greater proportion of leaves ingested by omnivores and Ephemerellidae by insectivores in the spring. Diet varied longitudinally for only N. leptocephalus. Trophic position based on SIA did not differ from spring to fall. Regression analysis revealed that trophic position as determined by GCA and SIA was comparable, yet was generally higher as estimated by GCA. These results suggest seasonal variability in diet was greater than longitudinal variability, and short term diet variability may not be reflected in the isotopic signature of these fishes.