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sur le développement des zones arides et semi-arides

Titre : Diversity and distribution of freshwater mussels in Morocco

Diversidade e distribuição de mexilhões de água doce em Marrocos

Auteur : Santos, André Manuel Gomes dos

Université de soutenance : Universidade do Minho

Grade : Mestrado em Ecology 2017

Résumé
Freshwater mussels (Bivalvia : Unionoida) are in global decline, despite being responsible for important ecosystem services and functions. Morocco is a semi-arid country of Northern Africa inhabited by five native freshwater mussel species. In the last decades, Moroccan freshwater ecosystems and their biodiversity have been strongly degraded in consequence of the growing human population and economic development. In recent years, some work on freshwater mussels has been done in the area, but there are still many gaps regarding the diversity and distribution of these species. Given all this, the aims of this study were : 1) to assess the taxonomic composition of the species present in the country ; 2) update the current distribution of each species ; 3) asses the genetic diversity of each species ; and 4) make a preliminary assessment of the conservation status of each species. For that, an extensive sampling was carried throughout the main river basins of the country and phylogenetic and phylogeographic analyses were performed, using mtDNA cytochrome oxidase subunit 1 (COI) gene. Our results show the existence of five distinct native species, Anadonta anatina, Margaritifera marocana, Potomida littoralis, Unio foucauldianus and Unio gibbus. A. anatina was confirmed to be the species of the Anodonta genus present. Regarding the distribution, while A. anatina and M. marocana were the most restricted species, being only present in two basins, U. gibbus, P. littoralis and U. foucauldianus had a wider distribution. P. littoralis was the only species present in an endorheic basin. Additionally, the distribution of the invasive species Corbicula fluminea has increased since 2012. P. littoralis shown the highest haplotypic diversity, suggesting more stable and diverse genetic structure. On the other hand, the other four species revealed much lower haplotypic diversity, with all A. anatina individuals sharing the same haplotype. Due to their limited distribution and low genetic diversity, A. anatina and M. marocana were the most concerning cases regarding conservation. Nevertheless, all the species have been suffering declines in the last decades and are constantly exposed to various threats. Therefore, it is urgent to implement management and legislative actions to ensure the long-term persistence of these interesting and functional important species.

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