Gw. Whitledge et Cf. Rabeni, ENERGY-SOURCES AND ECOLOGICAL ROLE OF CRAYFISHES IN AN OZARK STREAM -INSIGHTS FROM STABLE ISOTOPES AND GUT ANALYSIS, Canadian journal of fisheries and aquatic sciences, 54(11), 1997, pp. 2555-2563
Energy sources for the crayfishes Orconectes luteus and O. punctimanus
in the Jacks Fork River, Missouri, were quantified using stable isoto
pes (delta(13)C and delta(15)N) and gut-content analysis. A dual-isoto
pe mixing model indicated that about two thirds of crayfish production
originated from allochthonous carbon sources, and 30-50% of crayfish
production was derived from direct consumption of animal matter. Young
-of-the-year crayfishes and adult O. luteus were more carnivorous than
the larger adult O. punctimanus. Contributions of energy sources dete
rmined using the stable isotope mixing model were similar to results o
f gut-content analysis corrected for differential assimilation of diet
ary components. proportions of crayfish production attributed to anima
l matter by these two methods were four to five times greater than est
imates derived from uncorrected gut-content analysis. Unadjusted gut-c
ontent analysis overestimated the percentage of crayfish production fr
om feeding directly on detritus. Production-based calculations of cray
fish food consumption rates indicated that crayfishes were the dominan
t consumers of benthic invertebrates, detritus, and algae and may stro
ngly influence lower trophic levels, organic matter processing, and en
ergy flow in this system.