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Effect of physico-chemical regimes and tropical cyclones on seasonal distribution of chlorophyll-a in the Chilika Lagoon, east coast of India

DRS at CSIR-National Institute of Oceanography

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Title Effect of physico-chemical regimes and tropical cyclones on seasonal distribution of chlorophyll-a in the Chilika Lagoon, east coast of India
 
Creator Sahoo, S.
Baliarsingh, S.K.
Lotliker, A.A.
Pradhan, U.K.
Thomas, C.S.
Sahu, K.C.
 
Subject Aquatic ecology, productivity
Chemistry and biogeochemistry
Aquatic communities
Meteorology and climatology
 
Description A comprehensive analysis on spatiotemporal variation in physico-chemical variables and their control on chlorophyll-a during 2013-14 was carried out in the Chilika Lagoon. Spatiotemporal variation in physico-chemical regimes significantly controlled the phytoplankton biomass of the lagoon. Further, precipitation-induced river/terrestrial freshwater influx and marine influence controlled the physico-chemical regimes of the Chilika Lagoon, such as nutrients (NH4+, NO3-, NO2-, PO43- and Si(OH)4), temperature, salinity, total suspended matter and dissolved oxygen. This study revealed significant effects of tropical cyclones Phailin (2013) and Hudhud (2014) on physico-chemical regimes and in turn the phytoplankton biomass of the lagoon. Although both cyclones Phailin (2013) and Hudhud (2014) were intense, Phailin (2013) had a greater impact on the Chilika Lagoon due to the proximity of its landfall. Heavy precipitation caused an influx of nutrient-rich freshwater, both during each cyclone’s passage, through rainfall, and after, through increased river flow and terrestrial run-off. The increase in nutrients, carried by the run-off, promoted phytoplankton growth, albeit in lag phase. In general, phytoplankton growth was controlled by nitrogenous nutrients. However, the addition of SiO4 through terrigenous run-off fuelled preferential growth of diatoms. The salinity pattern (which can be considered a proxy for fresh and marine water influx) indicated injection of freshwater nutrients into the northern, southern and central sectors of the lagoon through riverine/terrestrial freshwater run-off; marine influx was restricted to the mouth of the lagoon. Present and past magnitudes of salinity and chlorophyll-a were also compared to better understand the pattern of variability. A significant change in salinity pattern was noticed after the opening of an artificial inlet, because of the resulting higher influx of marine water. The overall phytoplankton biomass (using chlorophyll-a concentration as a proxy) remained consistent in the lagoon pre- and post-restoration. Due to the wide range of salinity and temperature tolerance, diatoms remained dominant in both pre- and post-restoration periods, but the overall phytoplankton diversity increased after the artificial inlet was dredged
 
Date 2017-09-27T13:08:45Z
2017-09-27T13:08:45Z
2017
 
Type Journal Article
 
Identifier Environmental Monitoring and Assessment, vol.189; 2017; No.153 doi.org/10.1007/s10661-017-5850-5
http://drs.nio.org/drs/handle/2264/5185
 
Language en
 
Rights An edited version of this paper was published by Springer. This paper is for R & D purpose and Copyright [2017] Springer.
 
Publisher Springer