Habitat Preference and Population Structure of Two Data Deficient Seahorse (Syngnathidae) Species

N Perera,S Udagedara,D D G L Dahanayaka

doi:10.4038/ouslj.v12i2.7408

N Perera, S Udagedara + Show 1 more

Open Access

https://doi.org/10.4038/ouslj.v12i2.7408

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Abstract

Ecological studies of seahorses are sparse in the Indian Ocean. The vulnerability of seahorses to overfishing and increased anthropogenic impacts on coastal habitats necessitates better management of wild seahorse populations that in turn requires understanding habitat preferences and population structure. The distribution patterns and population structure of two species of seahorse (Hippocampus fuscus and H. spinosissimus) were assessed for the first time in a tropical estuary in north-western Sri Lanka. Both species have previously not been studied in the wild and have not been known to occur in estuaries. H. fuscus was the more abundant and widely distributed species, and was significantly larger than H. spinosissimus. Both species had significant differences in size between sexes, and the mean height was towards the lower end of the range know for both species. Some sexually mature males were smaller than the size reported in the literature. Seahorses occurred in low densities with patchy distribution, with abundance being higher in areas with the seagrass species Enhalus acoroides and Cymodocea serrulata that appear to be the favored habitat of seahorses within the study area.

Highlights

Seahorses are marine fish belonging to the genus Hippocampus, found in both temperate and tropical waters in the Atlantic and Indo-Pacific marine eco regions (Lourie et al, 2004)
Thirty eight (38) species of seahorses have been listed on the IUCN Red List of Threatened Species (IUCN, 2010) and the entire genus Hippocampus has been added to Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in order to monitor and regulate international trade (Martin-Smith & Vincent, 2006)
Distribution patterns This study found two species of seahorse, H.fuscus and H. spinosissimus in the Puttalam Lagoon, Sri Lanka, a shallow, seagrass dominated habitat

Summary

Introduction

Seahorses are marine fish belonging to the genus Hippocampus (family Syngnathidae), found in both temperate and tropical waters in the Atlantic and Indo-Pacific marine eco regions (Lourie et al, 2004) They inhabit a variety of habitats such as coral reefs, seagrass meadows, mangroves, estuaries and open bottom habitats, their distribution can be patchy and sparse (Perante, 2002; Foster & Vincen, 2004; Rosa et al, 2007). Seahorses are weak swimmers and tend to anchor themselves to vegetation or the substrate using a strong prehensile tail (Kendrick & Hyndes, 2005), and rely on prey coming within close range instead of actively pursuing them (Foster and Vincent, 2004; Lourie et al, 2004; Felício et al, 2006). Thirty eight (38) species of seahorses have been listed on the IUCN Red List of Threatened Species (IUCN, 2010) and the entire genus Hippocampus has been added to Appendix II of the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES) in order to monitor and regulate international trade (Martin-Smith & Vincent, 2006)

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