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

Lucy C Woodall,Miguel Correia,Francisco Otero-Ferrer,Neil Garrick-Maidment,Janelle M R Curtis,Heather J Koldewey,Paul W Shaw

doi:10.1007/s00227-017-3274-y

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.

Highlights

The paucity of species-specific data is among the many challenges to designing effective marine conservation measures that are resilient to the enduring threats of climate change, coastal development, over-fishing, by-catch effects and invasive species (Klein et al 2013; Selig et al 2014)
There is ongoing discussion as to whether H. ramulosus is a simple synonym of H. guttulatus, and whether the regional morphological differences observed across the seahorse populations in the region are indicative of different species (Kuiter 2009)
As most ecological studies of seahorses in Europe have used the nomenclature of H. hippocampus and H. guttulatus to define their focal species (e.g. Curtis and Vincent 2005; Kitsos et al 2008; Ben Amor et al 2011; Caldwell and Vincent 2012; Filiz and Taskavak 2012; Gristina et al 2015), there is some consensus for a conservative view of seahorse taxonomy

Summary

Introduction

The paucity of species-specific data is among the many challenges to designing effective marine conservation measures that are resilient to the enduring threats of climate change, coastal development, over-fishing, by-catch effects and invasive species (Klein et al 2013; Selig et al 2014). These challenges are further compounded when the taxonomy of species is uncertain. Genetic data are useful to clarify taxonomy and complement morphological data (Padial et al 2010)

Methods

Results

Conclusion