AUTHOR=Spatafora Davide , Gristina Michele , Quattrocchi Federico , Pierri Cataldo , Lazic Tamara , Palma Jorge 

TITLE=Different behavioral strategies of two sympatric seahorses: habitat availability and increased density of Hippocampus guttulatus alter the behavior of Hippocampus hippocampus

JOURNAL=Frontiers in Marine Science

VOLUME=10

YEAR=2023

URL=https://www.frontiersin.org/journals/marine-science/articles/10.3389/fmars.2023.1138296

DOI=10.3389/fmars.2023.1138296

ISSN=2296-7745

ABSTRACT=<p>In the light of future ocean warming scenarios and habitat fragmentation, coastal fishes must adjust their physiological and behavioral traits to face the combined effect of global warming and ecological interactions. Seahorses (<italic>Hippocampus</italic> spp.) are charismatic fishes with peculiar life cycle traits, which make them vulnerable to several anthropic pressures and natural disturbances. In this study, we investigated the behavior of two sympatric seahorse species, the long-snouted <italic>Hippocampus guttulatus</italic> (Cuvier, 1829) and the short-snouted <italic>Hippocampus hippocampus</italic> (Linnaeus, 1758). Specifically, we carried out two manipulative experiments to assess (i) the effect of temperature and habitat availability on both <italic>H. hippocampus</italic> and <italic>H. guttulatus</italic> behavior and (ii) the effect of temperature and an increased density of <italic>H. guttulatus</italic> (by 3×) on the activity level of congeneric species <italic>H. hippocampus.</italic> Our results showed that +3°C warming did not affect seahorse behavior in both experiments, suggesting greater behavioral tolerance to thermal variation. However, a significant reduction of the active behavior of <italic>H. hippocampus</italic> was observed when the artificial habitat was introduced in the tank, while <italic>H. guttulatus</italic> maintained its activity. Furthermore, a significant decrease of the <italic>H. hippocampus</italic> activity was observed with an increased relative dominance of <italic>H. guttulatus.</italic> Our results suggest that both increased density of <italic>H. guttulatus</italic> and habitat availability, but not ocean warming, will affect the behavior of <italic>H. hippocampus</italic>. Therefore, different interspecific behavioral strategies may occur, thus affecting the distribution of the two species among shallow habitats when they occur in sympatry.</p>