ECOSYSTEM SERVICE TRADEOFFS IN AQUACULTURE  

Natural ecosystems provide beneficial ecosystem services to aquaculture that are essential to production.  Examples include provisioning ecosystem services (e.g., forage fish production from marine fisheries) and regulating ecosystem services (e.g. waste treatment/water purification).  Ecosystem services flow to aquaculture production systems in a spatially explicit way. The supply of ecosystem services is limited at local to global scales.  Producers have a greater incentive to protect ecosystem services that are provided at a facility or local scale than those provided at a global scale.

Ecosystem service tradeoffs occur in situations where one service increases while another decreases.   There are tradeoffs between aquaculture production, the provision of ecosystem services and biodiversity conservation.  These are usually considered as tradeoffs between aquaculture production and regulating services or between aquaculture production and biodiversity.  Ecosystem service tradeoffs can be evaluated in terms of spatial scale, temporal scale and reversibility.  Tradeoffs at a local spatial scale, rapid temporal scale and that are reversible are more certain and easier to manage.  Better management practices can be applied to reduce or mitigate tradeoffs.  The relative importance of ecosystem services can be understood in the context of the most limiting service at a local level.   

Economic evaluations of ecosystem services are problematic.  Use of ecosystem services can be evaluated in economic terms (use value), but valuation of biodiversity is complicated by its intrinsic, non-use value.  As natural ecosystems become progressively more converted to other uses, the marginal benefits of conservation increase and the marginal costs decrease. Once benefits exceed costs, it makes economic sense to implement conservation.