Preliminary report on tidepool fish diversity from a rocky shore in the Bay of Bengal

Abstract

Tidepools are one of the intertidal habitats providing homes to many marine species. This study investigated the diversity and abundance of tidepool fishes on a rocky shore from Bangladesh. Fish samples were collected from the east and west coasts of St. Martin’s Island between November 2018 and March 2019. There were 441 specimens distributed in 23 species belonging to 20 genera and 14 families. Among those, 11 species represented new records for Bangladesh, namely Allenbatrachus reticulatus, Bathygobius coalitus, Bathygobius curacao, Callogobius hasseltii, Crenimugil crenilabis, Halichoeres nigrescens, Istigobius decoratus, Istigobius ornatus, Ostorhinchus cookii, Siganus sutor and Yongeichthys nebulosus. The most speciose families were Gobiidae (6 species), Pomacentridae (3 species) and Blenniidae (2 species), and in terms of number of individuals, Gobiidae (42%) and Blenniidae (38%) were abundant. The mean abundance of fish in tidepools was decreasing with increasing intertidal elevations (i.e. lower > middle > upper intertidal zones), although the differences were not significant. Moreover, fish abundance and diversity were positively correlated with the surface area of tidepool. Six species were common in the sampling sites, and the east coast of St. Martin’s Island had higher species richness and diversity than the west coast. Temperature (31.8 ± 2.9 °C), salinity (31.8 ± 2.1‰) and pH (8.3 ± 0.1) of the tidepool waters were comparable to those reported for a range of rocky/reef environments across the Asia–Pacific region. This is the first report on tidepool fishes from the northern Bay of Bengal that can be useful for understanding the ecological importance of intertidal zones, and further expanding the knowledge of marine biodiversity and natural history in data-poor regions.