Trans-Atlantic Distribution of a Mangrove Oyster Species Revealed by 16S mtDNA and Karyological Analyses

Abstract

Three species of mangrove oysters, Crassostrea rhizophorae, C. brasiliana, and C. gasar, have been described along the Atlantic shores of South America and Africa. Because the distribution of these molluscs is of great biological and commercial interest, their taxonomy and distribution deserve further clarification. Therefore, 15 populations were sampled from both continents. Their 16S mitochondrial polymorphism was studied by sequencing and PCR-RFLP analysis. Two haplotypes were identified. Haplotype a was the only one observed in Africa, but it was also observed in South America together with haplotype b. Because C. gasar is the only mangrove oyster identified on the west coast of Africa, haplotype a was attributed to this species, which has thus been shown to occur in South America. Haplotype b is attributed to C. rhizophorae. The karyotypes of specimens of C. gasar, from Africa and from South America, were very similar, and both species were observed at the same location in Brazil. The occurrence of C. gasar in South America adds a third species-in addition to C. rhizophorae and C. brasiliana-to the list of species present along these coasts. The predominant surface circulation patterns in this part of the Atlantic Ocean favor the hypothesis that C. gasar was transported from Africa to America. Finally, a phylogenetic tree built with seven 16S sequences from Crassostrea and Saccostrea species showed that C. gasar is intermediate between the American Crassostrea species (C. virginica and C. rhizophorae) and the Asian species (C. gigas and C. ariakensis).

Unexpected mosaic distribution of two hybridizing sibling lineages in the teleplanically dispersing snail Stramonita haemastoma suggests unusual postglacial redistribution or cryptic invasion

“…Claremont et al. (2011) found the A lineage in Venezuela and suggested a transoceanic colonization, the widespread distribution in Eastern Atlantic and apparently limited distribution in America, and the reduced genetic diversity in Venezuela indicating an East to West migration by the South Equatorial Current (Boehm et al., 2013; Claremont et al., 2011; Lapègue et al., 2002). An invasion from America is therefore considered unlikely.…”

A Socio-Ecological Assessment Aiming at Improved Forest Resource Management and Sustainable Ecotourism Development in the Mangroves of Tanbi Wetland National Park, The Gambia, West Africa

“…Although they said no adverse effects of fishing on the mangrove vegetation occurs (89% in peri-urban and 73% in urban populations), some claim that oyster (Crassostrea cf. gasar) (species' name according to Lapègue et al 2002) harvesting practices through mangrove root cutting could damage the mangrove trees considerably. The collection of oyster shells (Fig.…”

Growth, mortality and susceptibility of oyster Crassostrea spp. to Perkinsus spp. infection during on growing in northeast Brazil

“…Additionally, they have wide geographical distribution, with C. rhizophorae inhabiting from the southern Caribbean to Uruguay and C. gasar from South America to Africa (LAPÈGUE et al, 2002).…”