Coastal oceans are key to maintaining of global scale ecosystem processes including biogeochemical cycling and contribute to blue economy. In Global South, coastal oceans are crucial for offering direct livelihood to millions of coastal communities and contributing to pan regional GDPs. Resident aquatic microbial communities are crucial in maintaining health and functioning of coastal oceans. Multiple combinations of interactions and associations between microbes, known as microbial network, aid in the transfer of energy through the marine food web. The importance of development of traits and resulting microbial guilds can vary in coastal oceans across continents including in Asia and Africa. In particular, increasing anthropogenic stressors in a changing climate have led to ‘urbanization’ of coastal oceans. Coastal oceans are also becoming ‘hotspots’ of antibiotic-resistant genes (ARGs) and can become significant from the viewpoint of public health in parts of Asia and Africa. The aquatic microbial communities are exhibiting signatures of resilience including plasticity in coastal ocean as a result of metabolic interactions with different types of anthropogenic pollutants. There is an urgent need to understand trait development and resilience of aquatic microbial communities in coastal oceans of South to truly achieve nexus towards understanding of health of global oceans. In this session, contributions are welcome from that focuses on coastal ocean microbiome, functional traits in aquatic microbial communities, resilience of microbial communities and linking with broader ecological processes encompassing Global South. In particular, contributions are most welcome from early career researchers who are using multifaceted approaches ranging from ecophysiology, deep- sequencing to ecological modelling towards understanding of aquatic microbial communities in coastal oceans. Submissions are also welcome from authors who are working on aquatic microbial communities of coastal biotopes including mangroves, lagoons, estuaries, coral reefs, seagrass habitat and salt marsh.

Lead Organizer: Anwesha Ghosh, Indian Institute of Science Education and Research Kolkata, India (anweshag91@gmail.com)

Co-organizers:

Punyasloke Bhadury, Centre for Excellence in Blue Economy, Indian Institute of Science Education and Research Kolkata, India (pbhadury@gmail.com)

Krishna Ray, West Bengal State University, India (krishna@wbsu.ac.in)

Amit Kumar, Sathyabama Institute of Science and Technology, India (amitkumar.cccs@sathyabama.ac.in)

Presentations

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06:30 PM

Unusual abundance of bloom forming Aulacoseira spp. Diatom populations in an anthropogenically impacted stretch of lower part of the Hooghly estuary (4741)

Primary Presenter: Chakresh Kumar, IISER Kolkata (chakreshchanda2@gmail.com)

The Hooghly estuary is reeling from pressures of rapid urbanization and resulting anthropogenic forcings. In this study, phytoplankton community assemblages were deduced from the Dakshineswar site located in the Hooghly estuary to quantify and understand the health status of Hooghly estuary. Surface water samples were collected from six pre-defined stations of Dakshineswar spanning across monsoon and post-monsoon seasons of 2019 and 2020. Stations were categorized into point source and surface water based on proximity to municipal discharges. Measurement of in situ environmental parameters showed significant differences in values for dissolved oxygen, total dissolved solids, electrical conductivity and suspended particulate matter between the two seasons during the study period. In particular, concentrations of dissolved nitrate and silicate were found to be higher in point source stations compared to surface water stations. The concentration of Chlorophyll-a (Chl-a) was found to be higher in post-monsoon compared to monsoon seasons. Phytoplankton communities consisted of 23 diatom taxa and 14 green algal taxa and they showed distinct seasonal and spatial variations in the study site. Phytoplankton communities were dominated by diatom taxa, Aulacoseira, Bacillaria, Coscinodiscus, and green algal taxa such as Ulothrix Chlorella, and Scenedesmus. A dramatic increase in cell abundance of Aulacoseira spp. in post-monsoon seasons indicates a bloom-like scenario. Moreover, the rapid increase in cell abundance of Aulacoseira spp. also coincided with an increase in Chl-a and a sharp fall in the concentration of dissolved silicate. Some of the encountered phytoplankton taxa such as Tetraedron, Cosmarium, Nitzschia, and Scenedesmus showed strong co-occurrence patterns indicating possible association at ecological scales. Four distinct clusters were formed innMDSordination plot based on the influences of environmental variables on encountered phytoplankton taxa. Network analysis revealed evidence of co-occurrence patterns between several diatoms and green algal taxa.

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06:30 PM

Investigating the microplastic pollution and revealing the xenobiotics degrading potential of mangrove microbiome through “omics” approach from Indian Sundarbans (4761)

Primary Presenter: Nirupama Saini, Indian Institute of Science Education and Research Kolkata (nirupamasaini15@gmail.com)

Mangroves are facing varying degrees of anthropogenic stresses due to overexploitation, urbanization, discharge of industrial effluents, domestic sewage, and pesticide residues from agricultural land. These anthropogenic activities result in the accumulation of a wide range of toxic xenobiotic compounds in the ecosystem, microplastics being one of them. The present study investigated the abundance and composition of microplastics in surface water of Indian Sundarbans along with the application of metagenomic approach in exploring the microbial community structure and mining the genes involved in the biodegradation of various xenobiotics. The world's largest contiguous mangrove forest, Sundarbans, is a UNESCO world heritage site and a Ramsar site. Sundarbans is shared between Bangladesh and India, which are among the top mismanaged plastic waste generating nations and are discharging plastic waste downstream through rivers and coasts, making the Sundarbans a cesspit for plastic waste. The observed mean abundance of microplastics is 22.27±11.8 Particles/Liter in monsoon and 14.52±7.97 Particle/Liter in post-monsoon. Fiber constituted the major portion amongst the different forms of microplastics including fragment, microbead and foam. Moreover, chemical characterization of microplastics revealed polypropylene as the most abundant type of polymer. Mangroves are the hotspots for microbial diversity and harbor microbiota involved in producing a variety of degrading enzymes, antibiotics, etc. Metagenomic profiling of the surface water samples reported Proteobacteria as a dominant phylum, with Bacteroidetes and Firmicutes the second-most in prevalence. The functional profiling revealed the presence of enzymes involved in the biodegradation of xenobiotic compounds such as Benzoate compounds, Nitrotoluene, Chlorocyclohexane, and Chlorobenzene, Polycyclic aromatic hydrocarbons (PAH), xylene, bisphenol, and Dioxin. The results also showed the presence of potential genes associated with the biodegradation of different types of plastic polymers such as PHA (Polyhydroxyalkanoates), PBAT (Poly(butylene adipate-co-terephthalate)), PET (Polyethylene terephthalate), LDPE (Low-density Polyethylene), PS (Polystyrene), Nylon. The study not only fills up the scientific gap in our knowledge regarding the microplastic pollution in Indian Sundarbans but also provides an insight into the rich source of the gene pool, which is actively involved in the degradation of various xenobiotic compounds.   

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