Invasive oyster

Description:

It is a small bivalve mollusc that is usually between 50 and 65 millimeters in length, but can reach 106 mm. The shell is thin, compressed, with growth rings and ribs on the upper surface. It varies in coloration, but is usually brown or red on the outside with a pearly interior and a light brown rim. More rarely, the shell can be green or bronze. Brown or dark red rays may mark the shell.

Habitat:

It was found on the underside of a stone on the rocky coast of La Punta de la Raja, La Manga, Mediterranean Sea. Because of its striking bright green color I took photos of it one day, not knowing exactly what it was. When I saw another specimen near the first one the next day, I thought I was facing a unique case, since I know almost 100% of the flora and fauna of the region where I spend the summer. I consulted expert biologists and they informed me that we were dealing with a very harmful invasive species from the Indo/Pacific, which is becoming accustomed to our western Mediterranean coasts and, what is worse, is penetrating through the communication channels in our delicate lagoon Mar Minor. At the moment most of the specimens that have been observed are juveniles, but we will be watching what will happen to this invasive population.

Notes:

The presence of alien species is among the top threats to biodiversity worldwide, but it is probably the main force driving extinction in freshwater and island ecosystems right now. Molluscs are not only a fundamental part of this problem (many exotic species are molluscs, some with relevant social, economic and health problems), but they are also excellent sensors of the rapid loss of biodiversity in ecosystems, usually much better than the charismatic megafauna (vertebrates) or macroflora (vascular plants). Its study must be a priority in high-level policies for the early detection of the main problems of ecosystems worldwide. Thus, it is also interesting to study the native populations of molluscs and how they are configured in the presence of foreign species.