# Spiders in oyster shells: shellfish farming benefits an endangered terrestrial species

Julien Pétillon, Nela Glorikova

► To cite this version:

Julien Pétillon, Nela Glorikova. Spiders in oyster shells: shellfish farming benefits an endangered terrestrial species. Frontiers in Ecology and the Environment, 2024, 22 (4), pp.e2744. 10.1002/fee.2744. hal-04653804

HAL Id: hal-04653804

https://hal.science/hal-04653804v1

Submitted on 19 Jul 2024

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FrontiersEcoPics

Spiders in oyster shells: shellfish farming benefits an
endangered terrestrial species

Along the shore of Mont-Saint-Michel Bay in western France, large numbers of non-native Pacific oyster (Crassostrea gigas) and native blue mussel (Mytilus edulis) shells are deposited as waste from marine aquaculture operations. The resulting “shell beds” (above) cover hundreds of hectares and form a distinctive habitat that over time has become integrated into the salt marsh vegetation (mostly native Atriplex portulacoides) through sediment accretion. The shell beds appear in the form of banks, typically 1–2 m high, up to 200–300 m long, and 50 m wide. Both sexes of an endangered wolf spider (Arctosa fulvolineata) use the shells as a refuge and as breeding habitat (below). During May 2021, the species was found on several occasions near Vivier-sur-Mer along the center of the Bay, hiding under the shells during the day and hunting for amphipods at night. A fulvolinea likely uses shells as a daytime shelter during high tides, as reported for intertidal spiders (Desis spp) on South African coasts. While the importance of anthropogenic resource subsidies for predatory spiders has been known for decades, examples documented in the scientific literature remain rare.

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Julien Pétillon¹,² and Nela Gloriková³
¹University of Rennes, Rennes, France;

²Nelson Mandela University, Port Elizabeth, South Africa;

³Crop Research Institute, Prague, Czech Republic
doi:10.1002/fee.2744

Image credits: ©N Gloriková