In search of the Kumamoto oyster Crassostrea sikamea (Amemiya, 1928) based on molecular markers: is the natural resource at stake?

Abstract

A cornerstone in conserving wildlife is to resolve taxonomic uncertainties over organisms so that conservationists can define the entity that should be conserved. This is the case for two closely related Crassostrea oysters inhabiting the Ariake Sea (Kyushu, Japan) in sympatry, the kumamoto oyster C. sikamea and Pacific oyster C. gigas, where molecular markers have shed light on their taxonomic separation and species diagnosis. In the past, there was a concern that Kumamoto oysters may be at risk of extinction. However, several field surveys equipped with species-diagnosis molecular markers have provided solid evidence that this perception is incorrect. Nevertheless, previous studies have sometimes given conflicting results, throwing us into confusion about the resource status. Research on natural Kumamoto oysters that the author hopes could help to enhance our understanding of the conservation of this invaluable oyster is reviewed here.