Ecological and socio-economic feasibility of scallop bottom culture in Sechura Bay, Northern Peru

Sechura Bay in northern Peru recently developed into a center for the cultivation of the Peruvian bay scallop Argopecten purpuratus. Today, aquaculture-related activities constitute an important socio-economic sector for the region, with about 25000 people involved and annual export values of 150 million US$. By providing settling substrate to other organisms in an otherwise soft-bottom habitat the bivalves may potentially function as ecosystem engineers in the system. Overstocking of scallops may cause mass mortalities, potentially impacting other organisms and overall ecosystem functioning. Accordingly, the assessment of the current situation and the determination of long-term sustainable limits are crucial. The overall objective of this thesis was to develop a holistic approach for the ecosystem-based exploration of bivalve aquaculture impact and the estimation of ECC that should be applicable to other coastal settings. The results of the thesis suggest that scallop aquaculture has essentially altered the systema s trophic flow structure and functioning. As a major output, a general ecosystem approach to aquaculture is proposed that is based on several novel methodologies for the integrated assessment of (1) impacts of aquaculture on ecosystem functioning and resilience, (2) effects of management decisions on harvest through ECC simulations, and (3) societal and environmental factors important for long-term sustainability. Results are expected to guide local decision makers to contribute substantially to our understanding of ecosystem responses to bivalve aquaculture. With an ever expanding aquaculture industry worldwide, the approach provides guidance for future studies in different aquaculture settings that aim at determining sustainable limits to growth.