The project ‘’Monitoring & assisted recruitment of the Critically Endangered Pinna nobilis’’, funded by Cyprus Environment Foundation and run by Enalia Physis Environmental Research Centre, aimed to collect scientific data on the presence, health status, and mortality rates of Pinna nobilis, the largest endemic bivalve species of the Mediterranean Sea. Once common in our Sea, the species is now on the brink of extinction and listed as Critically Endangered on the IUCN’s Red List. An ongoing mass mortality is, in fact, affecting P. nobilis populations. Mass mortalities were first observed in Spain in 2016 and then reported in other several Mediterranean countries with mortality rates of the animals of 80-100%. The causes of the mortalities of P. nobilis are still unclear and various microorganisms as well as seawater temperature and salinity may play a role in these events. In Cyprus, there is evidence that P. nobilis started to be affected by mass mortalities in late 2018 and 2019. However, to the best of our knowledge, no accurate research and conservation efforts have been made since the onset of these events.
During the present project, visual surveys by SCUBA diving were performed at selected locations where the species was known to be present. A total area of 1.180 m2 was inspected. Moreover, larval collectors, which consist of plastic mesh bags filled with entangled nylon filament and attached to a main rope, were placed underwater at different depths in two Marine Protected Areas (MPAs), aiming to enhance the natural recruitment and settlement of P. nobilis’ larvae, following methodologies already applied in other countries.
The results of the project are not very encouraging. The conservation status of the species in Cyprus is very critical and local extinctions have been recorded. Additionally, no P. nobilis recruits were found inside the collectors, while the preliminary results suggest that species – both native and non-indigenous species – belonging to 26 different families, settled inside the bags. Therefore, the larval collectors proved to be an effective and low-cost method for larvae collection of various taxa. The impossibility of detecting any P. nobilis larvae in the collectors suggests a disruption of P. nobilis larval recruitment after the beginning of the mass mortalities.
There is always the probability of yet undetected larvae and communities, as the possibility of future larvae transportation from donor sites, to result in established colonies in Cyprus. For these reasons, the continuation of this study is important on a larger scale, in order to keep contributing to international conservation efforts to evaluate the effects of mass mortalities and to increase the potential for P. nobilis perseverance in the Mediterranean Sea.