Rare beaching event of the neustonic blue dragon (Glaucus atlanticus) and blue button jellyfish (Porpita porpita) along the Odisha coast, India

Abstract

The current study reports an unusual beaching event of the neustonic blue dragon sea slug (Glaucus atlanticus) along the coast of Gopalpur, Odisha, India (19° 15′ 05″ N 84° 54′ 08″ E). More than 100 individuals of the sea slug, an oceanic species, along with blue button jellies (Porpita porpita), were washed ashore on the beach in the late afternoon of April 14, 2024. They were found trapped in the intertidal pools during the ebb tide. Images and videos of the organisms were captured, and morphometric measurements of G. atlanticus and P. porpita were taken randomly. To identify the potential drivers of this beaching event, satellite-derived sea surface temperature (SST), sea surface wind, tide and ocean currents were analysed. It was found that the observed rare beaching event was caused by the combined effect of the strong wind and tide, and also the proximity of the strong warm East India Coastal Current. Even though records are available on the presence of G. atlanticus in Indian waters, this forms the first report ever made on their unusual beaching along the Indian coast. The study also showed the preferred distribution of the species in warm surface currents across the globe.