GENETIC VARIABILITY WITHIN AND ACROSS SEA CUCUMBER POPULATIONS FROM DIFFERENT MEDITERRANEAN SITES

Sea cucumbers (class Holothuroidea, phylum Echinodermata), also named holothurians, are widespread all over the world seas and play an important ecological role for their bioturbation and alkalinization activities of the seabed. These species are also considered economically relevant for Asian luxury food (e.g. trepang) and traditional medicine markets, as well as for the production of pharmaceutical and cosmetic bioactive compounds. Their economic relevance has caused an overexploitation of holothurians to supply these specific markets, especially in the Mediterranean area where the excessive fishing is a quite recent phenomenon. The massive withdrawal of sea cucumbers from the Mediterranean Sea (hundreds of tons of holothurians per year) has been demonstrated to have a negative impact on the marine benthonic ecosystem and caused a biodiversity loss among populations and in some places their complete extinction. For these reasons, few initiatives are recently evaluating sea cucumbers as novel aquaculture species. The aim of this study was to evaluate the level of genetic diversity within two Mediterranean sea cucumber species, Holothuria polii and Holothuria tubulosa, across different Mediterranean areas, before considering the implementation of conservation actions and as a first step in establishing cultivated stock populations. We analyzed portions of cox1 and 16S mitochondrial gene sequences because of their informativeness both for species identification across the genus Holothuria and for genetic variability estimations within and across different populations.