A multidisciplinary approach to identify priority areas for the monitoring of a vulnerable family of fishes in Spanish Marine National Parks

Abstract

AbstractBackgroundSyngnathid fishes (Actinopterygii, Syngnathidae) are flagship species strongly associated with seaweed and seagrass habitats. Seahorses and pipefishes are highly vulnerable to anthropogenic and environmental disturbances, but most species are currentlyData Deficientaccording to the IUCN (2019), requiring more biological and ecological research. This study provides the first insights into syngnathid populations in the two marine Spanish National Parks (PNIA—Atlantic- and PNAC—Mediterranean). Fishes were collected periodically, marked, morphologically identified, analysed for size, weight, sex and sexual maturity, and sampled for stable isotope and genetic identification. Due the scarcity of previous information, habitat characteristics were also assessed in PNIA.ResultsSyngnathid diversity and abundance were low, with two species identified in PNIA (Hippocampus guttulatusandSyngnathus acus) and four in PNAC (S. abaster,S. acus,S. typhleandNerophis maculatus). Syngnathids from both National Parks (NP) differed isotopically, with much lower δ15N in PNAC than in PNIA. The dominant species wereS. abasterin PNAC andS. acusin PNIA. Syngnathids preferred less exposed sites in macroalgal assemblages in PNIA andCymodoceameadows in PNAC. The occurrence of very large specimens, the absence of small-medium sizes and the isotopic comparison with a nearby population suggest that the population ofSyngnathus acus(the dominant syngnathid in PNIA) mainly comprised breeders that migrate seasonally. Mitochondrial cytochrome b sequence variants were detected forH. guttulatus,S. acus,andS. abaster, and a novel 16S rDNA haplotype was obtained inN. maculatus. Our data suggest the presence of a cryptic divergent mitochondrial lineage ofSyngnathusabaster species in PNAC.ConclusionsThis is the first multidisciplinary approach to the study of syngnathids in Spanish marine NPs. Habitat preferences and population characteristics in both NPs differed. Further studies are needed to assess the occurrence of a species complex forS. abaster, discarding potential misidentifications of genusSyngnathusin PNAC, and evaluate migratory events in PNIA. We propose several preferential sites in both NPs for future monitoring of syngnathid populations and some recommendations for their conservation.