Gender is not a relevant matter in habitat selection of the longsnout seahorse Hippocampus reidi Ginsburg, 1933 (Teleostei: Syngnathidae)

Abstract

Habitat selection in certain species may vary according to context and environmental conditions. Sexual differences regarding habitat use have been reported for several species, such as mammals, birds and fish, and have been explained by protection and food resource contexts. This issue is not well studied in seahorses, but it may provide useful data for the management of threatened species. The Longsnout Seahorse has recently been considered near threatened, but many gaps regarding its habitat use are still noted. Seahorses display a particular breeding characteristic, in which males carry the embryos inside a breeding pouch, therefore leading to supposed careful selection of breeding habitats, avoiding predation risks and choosing habitats with high prey availability. In this context, this study aimed to verify differences in habitat selection between male and female Longsnout Seahorse Hippocampus reidi specimens along the coast of the state of Rio de Janeiro. This study took place at 11 sites along the Rio de Janeiro coastline, in southeastern Brazil. Random belt transects (20x5m) were assessed, searching for seahorses and their holdfasts. Random quadrats (50x50cm) divided into 100 cells/each were placed along the transects and benthic cover was counted, in order to establish substrate availability. Results suggested that males select fewer substrate types than females, but no statistical difference was detected. Both male and female H. reidi specimens select mostly Sargassum vulgare as a frequent habitat. The strong association of H. reidi to these seaweed beds suggests vulnerability concerning the degradation of this habitat.