Population structure of long-snout seahorse Hippocampus reidi in Southwestern Atlantic and implications for management

Abstract

Hippocampus reidi represents the most abundant species of the genus Hippocampus along the Brazilian coast. Despite being charismatic, the species is globally threatened due to habitat degradation and commercial exploration, especially in Brazil, which is the leader in exportation and consumption of the species. Through mitochondrial (cytochrome b and control region) and nuclear (1st intron S7) data, the current study investigates the variation and genetic structure of H. reidi along the Brazilian coast, from Pará to Santa Catarina states. The mitochondrial data indicate the presence of two lineages: (1) North/Northeast and (2) South/Southeast, which was partially recovered by nuclear data. This scenario could be related to temperature differences and circulation patterns of the Brazil and North-Brazil currents, which define these groups into biogeographic sub-provinces. The lineages occur in sympatry in Bahia state, which can be explained by the occurrence of secondary contact during the last glacial maximum. Despite presenting two lineages, for management and conservation, three units are indicated: (1) North/Northeast, (2) Bahia, and (3) South/Southeast. The North/Northeast unit proved to be more vulnerable, presenting the lowest genetic diversity indices, representing a priority for future conservation actions.