STABLE ISOTOPE ANALYSES DIFFERENTIATE BETWEEN DIFFERENT TROPHIC PATHWAYS SUPPORTING ROCKY-REEF FISHES

Stable isotope analyses of 5 reef-associated fishes, Decapterus puncta tus, Diplodus holbrooki, Rhomboplites aurorubens, Pagrus pagrus, and H aemulon aurolineatum, were conducted to determine the ability of stabl e isotope analysis to distinguish among the species and the trophic pa thways that support them. Analyses of deltaC-13, deltaN-15, and deltaS -34 from white swimming muscle yielded significant differences between species. Multiple stable isotope signatures of these 5 species indica ted that at least 2 trophic pathways, one planktonic and one benthic, supported these reef-associated species. Variability of isotopic signa tures within species was largely a result of collection site differenc es. DeltaC-13 and deltaN-15 values indicated that all fishes were feed ing at similar trophic levels. DeltaS-34 values proved to be useful su pplements to carbon and nitrogen isotope values in separating species by signature.