Modelling bivalve culture - Eutrophication interactions in shallow coastal ecosystems

Area of Science:

• Marine ecology
• Ecosystem modeling
• Aquaculture sustainability

Background:

• Aquaculture farm siting requires ecosystem carrying capacity assessment.
• Malpeque Bay (PEI, Canada) is a focus for potential mussel farm expansion.
• Existing models need enhancement to capture complex ecological interactions.

Purpose of the Study:

• To assess the carrying capacity of Malpeque Bay for aquaculture expansion.
• To understand nutrient dynamics and ecological competition within the bay.
• To evaluate the impact of aquaculture on local ecosystems.

Main Methods:

• Coupled existing ecosystem model with sub-models for sea lettuce, wild/cultured oysters, and wild softshell clams.
• Utilized numerical simulations to analyze nutrient dynamics and carrying capacity.
• Assessed impacts of sea lettuce and bivalve filtration on nutrient competition.

Main Results:

• Nutrient competition between phytoplankton and sea lettuce, plus bivalve filtration, mitigates eutrophication.
• Sea lettuce reduced mussel growth by 2% (up to 9% near estuaries).
• Projected mussel farms reduced growth by 2%, indicating bay's carrying capacity may not be reached.

Conclusions:

• Malpeque Bay exhibits resilience to current and projected aquaculture expansion.
• Aquaculture activities show limited impact on natural bivalve populations.
• Ecosystem modeling provides crucial insights for sustainable aquaculture development.