The increasing exploitation of mangrove forests, without any sustainable planning, has been seriously
compromising the survival of this ecosystem and of its exclusive resources. Scylla serrata is one of the
most commercially exploited crabs inhabiting mangroves and estuaries of the Indo-Pacific region. This
species is extensively harvested, mainly for selling to the tourist market, and, as a consequence, its
populations are in constant decline. The aim of the present study was to assess the level of genetic
exchange of S. serrata within the Western Indian Ocean (WIO), using a population genetic structure
approach. To achieve this goal, we reconstructed the intra-specific geographic pattern of genetic variation
by partial sequencing the mitochondrial DNA cytochrome oxidase subunit I, in samples from seven
mangrove sites of the WIO. Our data set then encompassed all the sequences for the same genetic marker
deposited in Genbank and corresponding to samples from South East Asia, Australia and some Pacific
Islands: this allowed us to estimate the level of connectivity among S. serrata populations within its
distribution area.