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| Abstract Submission No. | ABS-2022-06-0112 |
| Title of Abstract | DISTRIBUTION AND ABUNDANCE OF GELATINOUS ZOOPLANKTON IN SOUTH EAST ARABIAN SEA (SEAS) |
| Authors | P. Hari Praved *, S. Bijoy Nandan, M. Suhaana Nazar |
| Organisation | Cochin University of Science and Technology |
| Address | Punnakkal house, Purangu post, Maranchery, Ponnani Ponnani, Kerala, India Pincode: 682016 Mobile: 9567701273 E-mail: praved.hari07@gmail.com |
| Country | India |
| Presentation | Oral |
| Abstract | The present work focused on studying the gelatinous zooplankton distribution in the coastal waters and of shore regions of South East Arabian Sea (SEAS) from the September 2018 to July 2019 period. Samples were collected from selected stations by using a bongo net having 200 µm mesh with a diameter of 50 cm from a motorized boat or from FORV Sagar Sampada. Specimens were preserved in 4% neutralized formalin solution. In the laboratory, they were identified up to higher taxon levels using standard reference material and photographed using a camera attached to the microscope. A total of 16 species belonging to seven groups such as chaetognaths, siphonophores, hydrozoa, and scyphozoan of the phylum Cnidaria, ctenophores, appendicularians, and thaliaceans. The average value of biomass and abundance of mesozooplankton were 1.89 ± 1.13 ml/ m3 and 856 ± 568 No/ m3 respectively. In mesozooplankton composition, 7.4 % were contributed by gelatinous zooplankton community and density of was 93 ± 159 No/m3. Chaetognaths were the dominant (48 %) and most abundant group among gelatinous zooplankton, followed by thaliaceans (43 %). Though various species of gelatinous organisms were recorded, few species have been attained the population size to form large blooms. They were Netrostoma coerulescens, Lychnorhiza malayensis, Aequorea pensilis. Pelagia nocticula, Beroe ovata, Doliolum sp. and Porpita porpita. The present study also provides formal record of Beroe ovata, a predatory ctenophore species from Indian waters for the first time; they are native to the Atlantic coasts of North and South America. This species has been previously reported from the Black Sea, Azov Sea, Marmara and the Mediterranean. Most of the jellyfishes are voracious predators and a threat to ichthyoplankton and other zooplankton. World oceans are reported to be losing many species of meso and micro planktonic groups and their ecological niche replaced by the pervading gelatinous species possibly altering food web structure. In addition, jellyfishes are adapted to live in reduced oxygen conditions and their blooms could interfere with fisheries by clogging fishing nets. They show a rapid increase in numerical density is deeply rooted in evolutionary character. Therefore, a better understanding of how these gelatinous zooplankton communities are structured by local hydrography and physical force has important implications for different trophic levels in the marine environment and their ecosystem services. Unfortunately, studies on gelatinous zooplankton distribution are scanty from the Arabian sea, so that the correct identification, documentation of physical and ecological information related to their ecology is important to understand their response to climate-related issues from the Indian Ocean region. |