Genetic conectivity patterns in Holothuria Mammata considering different spatial scales

Dissertação de Mestrado, Biologia Marinha, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2015

As a consequence of the world population growth, the demand for sea food resources is increasing. Consequently, worldwide fisheries transition from depleted finfish resources to alternative invertebrates species created a massive industry. Sea cucumber stocks have been overfished in Indo-Pacific Oceans as result of lack of effective management, non-regulated fisheries and an increasing demand from Oriental countries. The “beche de mer” demands have induced expansion of their fisheries worldwide and have resulted in catches of new target species from the Mediterranean Sea and NE Atlantic Ocean. With high commercial value and fragile life-history traits, sea cucumbers are particularly vulnerable to commercial fisheries, especially when there are no scientific knowledge to support their effective management. This study aims to fill in some of the gap in scientific data about sea cucumber populations, namely Holothuria mammata. It was assessed the genetic diversity and structure, connectivity and effective population size with novel polymorphic molecular markers (microsatellites). This analysis was done in several spatial scales and considering oceanographic patterns. Some morphometric traits were also analysed, such as the distribution of length and weight classes. The results showed that Holothuria mammata has globally high genetic diversity, higher genetic connectivity between Atlantic populations and genetic differentiation between Atlantic/Mediterranean and eastern/western Mediterranean basins. Effective population sizes were smaller in the Atlantic, showing some mutationdrift disequilibrium. Oceanographic patterns were strongly correlated with the genetic differentiation patterns. Atlantic populations presented bigger individuals (i.e. length and weight) than Mediterranean ones, clearly associated with environmental conditions, and ecology features. Biometric data and genetic analysis allowed us to establish the three potential stocks inhabiting the geographic area and improve the biological knowledge of this new target species. This information will be useful to suggest the first recommendations to its effective fishery management, and future comparisons in order to assess the fishery effects either at genetic and/or morphometric level.