Not so shellfish after all: How native oysters (Ostrea lurida) may aid eelgrass (Zostera marina) restoration by nitrogen filtration

R/AQ-159F
Start/End: March, 2020 to January, 2022

Eelgrass populations have been declining on a global scale, faster even than the rate of tropical rainforest deforestation. These aquatic plants provide a number of important ecosystem services as food sources and habitat for marine species, and offer important benefits in shoreline resilience for addressing climate change. Eelgrass beds can help reduce the effects of sea-level rise and coastal erosion and sequester atmospheric carbon. 

As restoration efforts have begun throughout California, some locations, such as the Upper Newport Bay, have begun testing efforts to restore eelgrass in conjunction with native oysters. Eelgrass can help boost oyster productivity by reducing the acidity of surrounding waters, allowing oysters to invest more energy in reproduction rather than shell growth. Meanwhile, oysters can help eelgrass by filtering excess nutrients from the water, providing organic nitrogen through waste, and increasing water clarity for better photosynthesis.

Prior studies have shown that nitrogen enrichment can benefit eelgrass growth, however this will be the first study to test the Olympia oyster as a source of fertilization. This project will measure the nitrogen concentrations around the oyster and eelgrass beds in the Upper Newport Bay State Marine Conservation Area. The researchers will also measure the growth and productivity of eelgrass beds, both with and without oyster presence, to assess any correlation with oyster fertilization.

Coastal ecosystem restoration will play an important role in mitigating our risks from climate change and sea-level rise in the coming years. These results will help inform practices that can increase the efficiency and effectiveness of such programs through multi-habitat restoration.

  • Principal Investigators

    California State University Fullerton

Co-principal Investigators