Morphological and molecular characterisation of ghost jellyfish Cyanea nozakii (Cnidaria: Scyphozoa) forming a swarm in the Bay of Bengal, Indian Ocean

Abstract

The swarm of Scyphozoa, Cyanea nozakii is considered as a nuisance since it causes ecological catastrophe and dangerous stings to humans. This species is distributed in the Pacific and Indian Ocean. The present study reports the first swarm of C. nozakii Kishinouye, 1891 from the coastal waters of Northwestern Bay of Bengal during winter monsoon, 2021. The species was identified by using integrated tools of morphometry and molecular taxonomy. DNA barcoding of mitochondrial Cytochrome c Oxidase subunit I (COI) was used to confirm the species identity after taxonomic identification. Our sample clustered closely with previously published sequences of C. nozakii from the coastal waters of China. The COI sequence alignment translated into 242 amino acid residues, comprising of 36 variable sites, 199 conserved sites and 15 parsimony informative sites. C. nozakii was present with a mean abundance of 270 ± 50 ind. m−3 in the study area. This study was undertaken to monitor the geospatial spread of jellyfish species diversity and to document the recent increase in jellyfish swarms from Indian waters.