Integrating citizen science and spatial ecology to inform management and conservation of the Italian seahorses

Citizen science and spatial ecology analyses can inform species distributions, habitat preferences, and threats in elusive and endangered species such as seahorses. Through a dedicated citizen science survey submitted to the Italian diving centers, we collected 115 presence records of the two seahorses occurring along the Italian coasts: Hippocampus hippocampus and H. guttulatus. From this dataset, we used 85 seahorse valitaded records to identify the ecological features of these two poorly known species and quantify the effects of human activities on their habitat suitability through geographic information systems and species distribution modelling. Our results indicated a continuous suitable area for both seahorses along the Italian coasts, with a single major gap in the central Adriatic Sea (Emilia-Romagna and Marche regions). They co-occurred in most of their Italian range, particularly in the central and southern Tyrrhenian coasts, and their ecological niches resulted to be significantly similar, although not equivalent. The least-cost paths of both species were concentrated in southern Italy (Apulia, Calabria, and Sicily), suggesting that more data is needed to improve the spatial resolution of the available information, especially in the northern and central Italy. Human activities influenced 38% and 42% of the habitat suitability of H. hippocampus and H. guttulatus, respectively, while only 25% and 30% of their potential distributions, respectively, are protected by Italy's existing conservation area system, in accordance with the global average for seahorses. In particular, the central Adriatic Sea represents a critical area where the occurrence of these seahorses is lower and the anthropic impact is higher. Considering all the Italian regions, fishing effort is the main human activity impacting both species. These findings will support the implementation of more efficient conservation actions. We encourage the application and interaction of citizen science and spatial ecology analyses to facilitate the assessment and sustainable management of elusive organisms.