AQUACULTURE WASTE IN THE AQUATIC ENVIRONMENT

Stable isotope signatures are used as tracers of foreign materials in ecosystems. Their applicability in aquaculture was evaluated in this study. The signatures of eight feed ingredients showed δ13C values between-12.92 to-25.85 ‰ and δ15N between 0.47 to 12.43‰. Three diets with different proportions of the above ingredients had δ13C values between-19.55 and-20.78 ‰ and δ15N values between 5.27 and 9.34‰. The signatures were identified in the feces and muscle of rainbow trout fed each diet, demonstrating the potential for isotope ratios to be used as tracers. Sediment from a commercial fish farm was sampled to determine if it had an isotope signature related to the feeds used (δ13C-20.12‰; δ15N 6.51‰). Results revealed isotope signatures more related to the control sites of δ13C-25.24 ‰ and δ15N 3.93 ‰ indicating that for this particular site, the feed isotopic signatures couldn’t be used as tracers of aquaculture-derived organic matter. Acknowledgements When it comes to thanking someone for their help, support and influence, I feel that neither in English nor in Spanish can I possibly say what I feel. Therefore, please consider this a humble attempt at doing so, and be sure that these words are spoken from the heart. A special recognition goes to my advisor, Rich Moccia for everything he did to help me get back on track with my career after so many years and for his infinite support in professional and personal matters. To my committee members Dominique Bureau and Michael Power, thanks for your suggestions, reviews an