Effects of cyclone Fani on the copepod community of the Ganges River estuary of India
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ORIGINAL RESEARCH
Effects of cyclone Fani on the copepod community of the Ganges River estuary of India Sourav Paul & Samya Karan & Bhaskar Deb Bhattacharaya
Received: 31 July 2020 / Accepted: 3 November 2020 # Springer Nature Switzerland AG 2020
Abstract A cyclone temporarily disrupts copepod community structure of an estuary, and during the community rebuilding process, omnivorous copepods dominate. This hypothesis was tested after cyclone Fani affected the Ganges River estuary of India on 5 May 2019. Copepod assemblages and environmental parameters were collected before (25 February 2019), after (24 August 2019) and immediately after (daily between 8 and 14 May 2019) cyclone Fani from three sites of the estuary. Immediately after cyclone Fani, spatial heterogeneity of the estuarine environment was washed away, salinity and temperature levels of the estuary increased, pH level declined, while the total dissolve solids remained constant at high levels of concentration. Copepod diversity and abundance were drastically reduced by cyclone Fani with the exception of the omnivorous Bestiolina similis, which tolerated a wide variability of the environment and dominated the community. Led by small and medium-sized copepods, within days, the community recovered from its initial disruption. Immediately after cyclone Fani, mediumsized omnivorous copepod Acartiella tortaniformis became the second most abundant species replacing the small-sized herbivorous Paracalanus parvus. Changes in species composition and abundance hierarchy
S. Paul (*) : S. Karan : B. D. Bhattacharaya Coastal and Quantitative Ecology Research Laboratory, Department of Zoology, University of Calcutta, 35 Ballygunge Circular Road, Kolkata 700019, India e-mail: [email protected] e-mail: [email protected]
observed immediately after cyclone Fani lasted for a few months. The intensity of cyclones is increasing in the Indian Sundarban; therefore, following a cyclone, more severe and prolong disruptions of the copepod community are likely. Institutionalized monitoring of the cyclone-mediated ecological changes of the Ganges River estuary is therefore strongly recommended. Keywords Diversity . Abundance . Dominance . Community recovery . Sundarban
Introduction A concern of the modern era is how estuarine plankton communities may respond to extreme environmental changes like cyclones (also known as typhoon or hurricane in the different regions of the world) (Wetz and Yoskowitz 2013; Paerl et al. 2018; Zink et al. 2020). Recovery of plankton communities after an extreme event is best understood through long-term studies sustained during ecological stability and disturbance (Paerl et al. 2001, 2018). Such studies are rare in developing countries where access to resources immediately after a cyclone is less feasible (Paul et al. 2020). Cyclones are discrete events that can disrupt an estuary and its plankton community by drastically altering the physicochemical environment and/or altering the natural equilibrium of the top-down processes of a food web (B
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