Page 74 - restitution_book_MOW2023_EN

72 | STRENGTHENING OCEANOGRAPHY

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GROUPERS AND CORBS ARE SIGNS
OF A BALANCED ECOSYSTEM
Situated at the top of the food chain, these two
regulatory species are indicators of the quality of the
marine environment, "their abundance reflects the good
ecological state of the food chain as well as moderate
poaching and fishing pressure, explains Leonardo Tunesi,
research director at ISPRA. Highly coveted by fishermen
and underwater hunters, these species are in sharp
decline and are classified as vulnerable by the IUCN." A
coastal species, the corb now prefers the seabed, rich in
safe shelters, to the open waters it favours in protected
areas, such as in the Principality's waters.

THE NOBLE PEN SHELLS: TOWARDS A RENAISSANCE?

• Protected since 1992, this endemic bivalve, emblematic of the Mediterranean,
has been the victim of an epizootic since autumn 2016, causing 80 to 100%
mortality. In 2018, the noble pen shells in Monaco's Larvotto reserve were
decimated by the parasite. By 2021, the entire northern Mediterranean was
affected, except for a few specimens found in lagoons and ponds. Pinna nobilis is
classified as "critcally endangered" by the IUCN.

• "Citizen science makes an active contribution to observations of the mortality of
noble pen shells, and therefore to the state of populations of this shellfish, which
usually lives for almost 40 years," explains Nardo Vicente, Emeritus Professor of
Oceanology at the IMBE Aix-Marseille University. And among the studies carried
out, the inventory of populations still in good health in the Thau lagoon, in the
Occitanie region, points to certain sectors that are suitable for maintaining noble
pen shells. However, only four noble pen shells have been counted in the Urbinu
pond in Corsica.

• A new, smaller pen shell (Pinna rudis) from North Africa via Gibraltar has been
reported on the rocky Mediterranean coast. Genetic studies are carried out in
laboratories to determine the existence of hybrid species.
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