Solitary as an oyster? Neighbours, inquinilism, commensals and parasites of Ostrea puelchana

DOLDAN, M. SOCORRO; RUBILAR, TAMARA; OEHRENS KISSNER, ERICA; KROECK, MARINA; MORSAN, ENRIQUE M.

Praga

Congreso; Euromal 2021 - 9th European Congress of Malacological Societies, Prague; 2021

Malacological Societies, Prague

Oyster species play an important role in marine ecosystems, hosting a wide diversity of organisms.It has been stated that epibiosis entails both benefits and disadvantages for the oysters. However,studies of multiple biological interactions of organisms associated with oyster reefs are scarse. Inthe Northern Patagonian gulfs, Argentina, Ostrea puelchana presents low-density beds; it is nota reef-forming species but it generates a three-dimensional structure as a result of successive settleof oyster larvae on the shells of a “founder” oyster. The aim of this study was to investigate thebiodiversity of associated organisms to O. puelchana at multiple spatial scales. We described thecommunity associated to the oyster beds of Northern Patagonian gulfs, and performed nonparametric multidimensional analyses to test whether oyster beds were similar in terms ofcommunity components. We also tested the effect of biological interactions such as theinquinilism of Tumidotheres maculatus -living inside the pallial cavity of the oyster-, theparasitism of Lithophaga patagonica –a shell burrower-, and the effect of the grazer chitonChaetopleura sp. We recorded a total of 85 taxa in the community associated to oyster beds,mainly molluscs (30%), crustaceans (20%) and echinoderms (10%). The similitude among bedswas moderate (non-transformed < 40%; square root transformation: 40-65%) and was influenceby the dominance of the echinoderm Ophioplocus januarii and the slipper limpet of the genusCrepidula. A total of 31 taxa were recorded as epibionts, mainly polychaetes and molluscsCrepidula sp. and Tegula sp. Condition index of oysters was significative lower for oystershosting T. maculatus or L. patagonica. Chaetopleura density correlated negatively with oysterrecruits. Our findings contribute to the knowledge on the functional role that oysters of O.puelchana play in benthic ecosystems at San Matías Gulf (Northern Patagonia, Argentina),hosting a diverse assemblage of organism