Shell Infestation of the Farmed Pacific Oyster Magallana gigas by the Endolith Bivalve Rocellaria dubia

Barbara Mikac,Federica Costantini,Marco Abbiati,Alessandro Tarullo,Marina Antonia Colangelo

doi:10.3390/d13110526

Barbara Mikac, Federica Costantini + Show 3 more

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https://doi.org/10.3390/d13110526

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Abstract

Oyster shells are substratum for different epibiontic and endobiontic organisms, including pests and parasites. Rocellaria dubia is endolithic and facultative tube-dwelling bivalve, boring in different calcareous substrates, including the shells of bivalves. In 2020, R. dubia was found as endolithic in the shells of the Pacific oyster Magalana gigas, from an oyster farm off the Sacca di Goro lagoon (Emilia-Romagna region, Northern Adriatic Sea, Italy). The purpose of this study was to describe this newly recorded association. Altogether, 136 specimens of R. dubia were found in 15 oysters, photographed under a stereoscope, and their length was measured. Heavily infested oysters hosted tens of R. dubia borers, which were perforating the whole thickness of the oyster valves. The flesh of these oysters was heavily damaged, suggesting parasitic association. R. dubia specimens were categorized into three age classes (0–1, 1–2, and 2–3 years old). M. gigas/R. dubia might be a widespread association, overlooked due to the very scarce research on macrofauna associated with M. gigas. Considering the negative effects of R. dubia endobiosis on oyster fitness, and possible impacts on oyster aquaculture, further research should be conducted in order to elucidate the distribution and ecological characteristics of this parasitic association.

Highlights

Rocellaria dubia (Pennant, 1777) is an endolithic and facultative tube-dwelling bivalve from the family Gastrochaenidae
Other heavily infested oysters, R. dubia was perforating the whole thickness of the valves, and the holes were internally visible
The endolitic bivalve R. dubia was found for the first time boring into the shells

Summary

Introduction

Rocellaria dubia (Pennant, 1777) is an endolithic and facultative tube-dwelling bivalve from the family Gastrochaenidae. It bores in a wide variety of natural and artificial nonbiogenic and biogenic calcareous substrates, from shallow subtidal habitats down to 200 m depth [1,2,3]. It is an important bioeroder [4,5], and it can be found as a fossil in deposits of marine origin [6,7,8]. Some studies suggest a negative impact of this borer on host bivalves [19]

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