A synthesis of European seahorse taxonomy, population structure, and habitat use as a basis for assessment, monitoring and conservation

Abstract

Accurate taxonomy, population demography, and habitat descriptors inform species threat assessments and the design of effective conservation measures. Here we combine published studies with new genetic, morphological and habitat data that were collected from seahorse populations located along the European and North African coastlines to help inform management decisions for European seahorses. This study confirms the presence of only two native seahorse species (Hippocampus guttulatus and H. hippocampus) across Europe, with sporadic occurrence of non-native seahorse species in European waters. For the two native species, our findings demonstrate that highly variable morphological characteristics, such as size and presence or number of cirri, are unreliable for distinguishing species. Both species exhibit sex dimorphism with females being significantly larger. Across its range, H. guttulatus were larger and found at higher densities in cooler waters, and individuals in the Black Sea were significantly smaller than in other populations. H. hippocampus were significantly larger in Senegal. Hippocampus guttulatus tends to have higher density populations than H. hippocampus when they occur sympatrically. Although these species are often associated with seagrass beds, data show both species inhabit a wide variety of shallow habitats and use a mixture of holdfasts. We suggest an international mosaic of protected areas focused on multiple habitat types as the first step to successful assessment, monitoring and conservation management of these Data Deficient species.Electronic supplementary materialThe online version of this article (10.1007/s00227-017-3274-y) contains supplementary material, which is available to authorized users.

Distribution and habitat preferences of Hippocampus species along the Apulian coast

“…At Taranto Mar Piccolo, and especially for H. guttulatus, specimens longer that 120 mm have never been recorded, even though more than 150 individuals have been measured. This finding strongly disagrees with data from the literature, which report adult individuals of up to 215 mm in the Atlantic Ocean (Curtis, Ribeiro, Erzini, & Vincent, 2007) and 225 mm in the Mediterranean Sea (Kitsos, Tzomos, Anagnostopoulou, & Koukouras, 2008;Woodall et al, 2018). At the other sites examined here, the maximum sizes of individuals fit with the literature data.…”

Field studies of seahorse population density, structure and habitat use in a semi‐closed north‐eastern Mediterranean marine area (Stratoni, North Aegean Sea)

“…Seahorse life history and behaviour renders them vulnerable to population decline (Vincent et al, 2011), which lead to the inclusion of many seahorse species in the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES Convention) (Pollom, 2014;2017). They are both typically present in coastal environment, and associated with habitats of different complexity (Correia et al, 2015a;Correia et al, 2018;Woodall et al, 2018). Despite the extended geographical distribution of both species there are only a few inshore locations where seahorse abundance, distribution and habitat use have been studied within the Mediterranean Sea (Louisy, 2011;Gristina et al, 2015;Ape et al, 2019).…”

Morphological and molecular evidence for first records and range extension of the Japanese seahorse, Hippocampus mohnikei (Bleeker 1853) in a bay-estuarine system of Goa, central west coast of India

“…On the other hand, molecular methods have proved helpful in resolving morphologically challenging seahorse taxonomy [16,18], phylogenetic relationships within the genus Hippocampus [19,20], natural species boundaries [21][22][23] and genetic variability [22,24] of many seahorse species. An integrated approach combining morphological and genetic analyses [25] would aid in the management of demographically separate populations as independent units and allow international legal mechanisms and international agreements such as the Convention on International Trade in Endangered Species (CITES) to work effectively [26].…”