Distribution and habitat preferences of Hippocampus species along the Apulian coast

Abstract

The aim of this study was to provide further knowledge of the ecological, spatial, and temporal distribution and life‐cycle traits of the sympatric seahorse species Hippocampus hippocampus and Hippocampus guttulatus. From 2011 to 2014, data were collected from 20 sites along the Apulian coast (Southern Italy) in order to cover a wide range of coastal marine, open water, and lagoon sites, from the surface to a depth of 48 metres. Seahorses were found at seven of the 20 sites investigated. Both species displayed temporal persistence, patchy distribution, and a high spatial demographic heterogeneity. This study revealed a smaller maximum size and size at maturity of H. guttulatus than has been reported elsewhere. Although it is possible that environmental factors are influencing the size of these animals, there may be genetic explanations, especially for lagoon populations. Despite the fragmented distribution and often low abundance found along the Apulian coast, some seahorse populations appear to be locally persistent and stable over time, suggesting that there is a need for appropriate location‐specific conservation strategies. Not just maintaining but increasing the area of artificial substrates, which enhance habitat complexity and provide holdfasts, could represent a possible approach to help conserve marine littoral biodiversity and to protect endangered species in lagoons.

Site fidelity of Hippocampus guttulatus Cuvier, 1829 at Mar Piccolo of Taranto (Southern Italy; Ionian Sea)

“…As for habitats, analyses did not reveal the existence of any relationship between habitat types and movement degree neither in terms of home range sizes nor in maximum distances. The availability of multiple habitats can induce specimens to choose and remain in a restricted area by moving from one habitat to another, which is an observation that seems consistent with the patchy distribution of seahorses (Curtis and Vincent 2005;Lazic et al 2018). However, the results of the present study indicated the seahorse preferences towards complex habitats (such as VS, rich in both animal and vegetal communities, and SBR in which many algal species grow), following previous studies (Gristina et al 2017;Lazic et al 2018), and the higher density of individuals in these habitats did not induce greater movements.…”

“…As for the Mediterranean Sea, although some data on space use of H. guttulatus are available (Curtis and Vincent 2006;Garrick-Maidment et al 2010;Caldwell and Vincent, 2012), further information on its ecological attributes, including spatial distribution and site fidelity, movement patterns and home range size, might be crucial for successful conservation of the species. Through mark-recapture experiment at Mar Piccolo of Taranto, a site that hosts one of the most important Mediterranean populations of seahorses (Gristina et al 2015;Lazic et al 2018;Ape et al 2019), the present study allowed the arguing of the importance of considering a combination of time scales and different processes when studying H. guttulatus movement patterns. Data indicated an overall high site fidelity and modest species movements, but also highlighted the existence of variability among individuals, probably due to both abiotic (habitat availability) and biotic (life cycle stage, sex) factors.…”

“…Like all seahorse species, it mostly practices ambush predation, but can also adopt active predation tactics when searching for the prey in the water column or on phanerogams beds (Curtis and Vincent 2005;Ape et al 2019). It shows a tendency to occupy sheltered and complex coastal habitats, although can be found in less complex habitats as well, at a depth from only a few centimetres to approximately 20 m of depth (Lazic et al 2018). In conservation terms, this feature can be interpreted as positive, since species able to occupy several habitats may be less prone to extinction (Clark 2000;Gage et al 2004;Işik 2011).…”

“…Unsurprisingly, data on population status are available for only a small number of sites throughout the entire species range. The most comprehensive data come from the studies undertaken in Ria Formosa lagoon in Portugal (Caldwell and Vincent 2012;Correia 2015;Curtis and Vincent 2005), Étang de Thau in France (Louisy 2011) and Mar Piccolo of Taranto in Italy (Gristina et al 2015(Gristina et al , 2017Lazic et al 2018;Ape et al 2019). The lagoon of Mar Piccolo of Taranto, together with Étang de Thau, hosts the most abundant seahorse populations in the Mediterranean Sea (Curtis and Vincent 2005;Caldwell and Vincent 2012;Gristina et al 2015;Lazic et al 2018).…”

“…The most comprehensive data come from the studies undertaken in Ria Formosa lagoon in Portugal (Caldwell and Vincent 2012;Correia 2015;Curtis and Vincent 2005), Étang de Thau in France (Louisy 2011) and Mar Piccolo of Taranto in Italy (Gristina et al 2015(Gristina et al , 2017Lazic et al 2018;Ape et al 2019). The lagoon of Mar Piccolo of Taranto, together with Étang de Thau, hosts the most abundant seahorse populations in the Mediterranean Sea (Curtis and Vincent 2005;Caldwell and Vincent 2012;Gristina et al 2015;Lazic et al 2018). Although there was an increased scientific interest in the last years, the knowledge on movement patterns, their determinants, and temporal variability in changing environment, though on the site fidelity and capacity to migrate from one habitat to another, is still limited (Curtis and Vincent 2006;Garrick-Maidment et al 2010;Caldwell and Vincent 2013).…”