ODF Sweden Webinar Series – Survey of Oysters

The European flat oyster Ostrea edulis beds are ecologically and economically important ecosystems, but are also one of the most endangered benthic habitats. The drastic population decline in Europe is largely due to overexploitation, pathogens, pollution, habitat destruction and competition from invasive species such as the Pacific oyster Magallana gigas. O. edulis beds are listed as one of the priority habitats in EU Habitats Directive. In Sweden, the knowledge of their prevalence and abundance is limited, and the environmental preferences and quality of the species are poorly documented. 

European flat oyster Ostrea edulis (left) and Pacific oyster Magallana gigas (right). (Photo Credit: Andrea Cabrera)

Andrea Cabrera, from IVL Swedish Environmental Research Institute and her team use a cost-effective and low-impact method to monitor the oysters in 435 different sites. They mounted a camera on a sled and dragged along the bottom along predetermined transects in the Koster archipelago in the Swedish west coast. This non-destructive method is an ideal way to monitor sensitive environments and generates permanent data-rich records that can be used to explore various research and management-related questions.

In the webinar Andrea talked about the challenges they face in this work, such as in distinguishing between live and dead oysters. Dense vegetation cover, turbid water, and the abundance of other marine species also increase the difficulty in identifying oysters. She also discussed the potential for automated image analysis, but acknowledged the underlying difficulties in underwater image processing and the need for appropriately annotated large-scale datasets.

Equipment used in obtaining underwater videos. (Photo Credit: Andrea Cabrera)

This webinar marks the end of our ODF webinar 2021 spring series. We look forward to being back with more interesting talks after the summer!