Ecological and morphological insights into Hippocampus haema (Han, Kim, Kai & Senou, 2017) in Geoje-Hansan bay, Korea

Abstract

The Korean seahorse, Hippocampus haema, was formerly misidentified as H. coronatus but has since been described as a distinct species, and its ecology remains poorly understood. This study examined the morphological characteristics of H. haema to enhance ecological understanding. A total of 913 seahorses collected from Geoje-Hansan Bay, Republic of Korea were measured for snout length (SnL), head length (HL), coronet height (CH), trunk length (TrL), tail length (TaL), height (Ht), and standard length (SL). Specimens were further categorized by sex and maturity to assess morphological differences. Males had significantly larger size-adjusted dimensions than females, with the exception of trunk length (t-test and Mann–Whitney U test, p < 0.01). Immature seahorses displayed significantly lower SnL/SL but higher HL/SL, CH/SL, and Ht/SL compared to mature individuals (Mann–Whitney U test with Bonferroni correction, p < 0.01). Seasonal variations were evident across all groups: males showed significant differences in HL/SL, CH/SL, TrL/SL, and TaL/SL, while females displayed seasonal variations in all morphometric proportions except for TaL/SL (Kruskal–Wallis test, p < 0.01). Immature seahorses exhibited significant seasonal changes in HL/SL, CH/SL, and TaL/SL (Kruskal–Wallis test, p < 0.01). Morphological variations in H. haema were associated with reproductive activity, feeding behavior, and attachment ability. These findings provide valuable insights into the species’ ecological adaptations and contribute to its conservation and management.