Spatial and seasonal patterns of European short-snouted seahorse Hippocampus hippocampus distribution in island coastal environments

Abstract

This study represents the first report on seahorses in the Macaronesian islands (North-East Atlantic), determining the spatial and seasonal abundance, population structure and physical appearance of European short-snouted seahorse Hippocampus hippocampus. Animals were surveyed off Gran Canaria Island in two bays, Melenara and Sardina del Norte, within three habitats: rocky bottom, artificial substrata and seagrass. Populations were monitored over a 5-year period (spring 2006–winter 2011) using 15-minute visual fast count (VFC) surveys. Seahorses were characterised by low abundances, small proportions of subadults and roughly equal sex ratios at each site. We aimed to determine whether environmental conditions and geographical position could explain differences in seahorse abundance and population structure between the study sites. Melenara Bay (mean sighting rate = 0.44 individuals VFC–¹; SD 0.72) offered protected environments where seahorse distribution varied with substratum type, irrespective of season. Strong hydrodynamic forces in winter affected abundance and size at exposed locations in Sardina del Norte Bay (mean sighting rate=0.21 individuals VFC⁻¹; SD 0.52). Our findings contribute to the scarce available knowledge about this Data Deficient species (IUCN Red List), helping to establish future conservation strategies and management recommendations for the preservation of H. hippocampus populations around Gran Canaria Island and other localities with similar coastal environments.