Coastal hydrodynamics drive microplastic retention in filter-feeders

Area of Science:

• Marine Biology
• Environmental Science
• Oceanography

Background:

• Microplastic contamination in filter-feeding bivalves is a growing concern.
• Land-derived inputs are known sources, but hydrodynamic processes' role is unclear.
• Understanding these processes is crucial for coastal ecosystem health.

Purpose of the Study:

• To investigate microplastic retention in bivalves related to coastal circulation.
• To differentiate the impact of hydrodynamic processes versus land-based inputs.
• To assess the potential for natural depuration in bivalves.

Main Methods:

• Analysis of microplastic composition in bivalve tissues.
• Correlation of microplastic levels with observed coastal circulation patterns in the Tyrrhenian Sea.
• Monitoring of nearshore and offshore water mass movements.

Main Results:

• Microplastic composition reflected an interplay between inland inputs and coastal currents.
• Higher microplastic concentrations in bivalves occurred when water masses stayed nearshore.
• Offshore water inflows led to a significant decrease in retained microplastics, indicating natural depuration.

Conclusions:

• Coastal circulation regimes significantly impact microplastic contamination in filter-feeding bivalves.
• Bivalves demonstrate a capacity for natural depuration, limiting long-term bioaccumulation.
• Aquaculture practices could benefit from offshore depuration periods to reduce microplastic levels in shellfish.