Assessing conservation status of the Mediterranean Seahorses: distribution, populations' consistency, habitat choice and diet preferences.

The unique life history features of seahorses (low mobility, site fidelity, low fecundity, high parental care) make them vulnerable to the environmental changes and anthropic pressures. Despite increasing concern over their conservation status, many biological and ecological aspects remain poorly documented therefore disabling and limiting management strategies. Most of the Mediterranean populations are threatened by human activities and a recent document drawn up by the Italian Committee of IUCN for marine fish of the Italian coasts defined the two species as Near Threatened (NT). During the last 15 years, despite the absence of specific funding projects and thanks to the large group of volunteers working alongside researchers, a considerable research group has been created, allowing investigation of several aspects of seahorse life cycle in an area that has never been studied before. In this period, we have conducted several studies on their spatial and temporal persistence, population structure, habitat preferences, and diet composition. Hippocampus guttulatus and H. hippocampus are two sympatric species distributed throughout the entire Mediterranean Sea. Thau lagoon was considered as the area with the highest seahorse density but, thanks to this research group, the importance of Taranto Mar Piccolo as a site of the extraordinary conservation interest has been highlighted. Both species display patchy distribution and a high spatial demographic heterogeneity despite the fact that the most abundant populations are unbalanced in terms of size classes, presumably indicating problems in the local recruitment or due to the anomalous mortality. They show a tendency for covered substrates (e.g. Corallina sp. and Cladophora sp. facies) offering complex and holdfast-rich microhabitats. Both species, however, can also exploit uncovered substrates as well as infralittoral habitats. The diet shows strong differences in diversity and abundance of preyed taxa related to the habitat of occurrence. Overall, amphipods, copepods and isopods are the major contributors to the diet. Although temporal persistence on a large scale was observed, indicating the capacity to resist and persist in time and space, seahorses are in a state of distress because of patchy distribution and unstructured populations. This, even more, highlights the need for suitable strategies to protect foraging habitats and ecosystems where there are numerous populations, like in Mar Piccolo of Taranto.