Fine-scale responses of phytoplankton to freshwater influx in a tropical monsoonal estuary following the onset of southwest monsoon

Journal of Earth system science

Suraksha M Pednekar1³  Vijaya Kerkar3¹  Helga Do R Gomes2²  Joaquim I Goes2²  S G Prabhu Matondkar1³  Sushma Parab1³ 

[1] Department of Botany, Goa University, Taleigao, Goa 403 004, India.$$;Bigelow Laboratory for Ocean Sciences, West Boothbay Harbor, Maine 04575, USA.$$;National Institute of Oceanography, Dona Paula, Goa 403 004, India.$$

关键词: Chlorophyll 𝑎;    rainfall;    phytoplankton;    species diversity;    salinity;    tide.;   

DOI  :  

学科分类：天文学(综合)

来源: Indian Academy of Sciences

【 摘 要 】

In May of 2007, a study was initiated by the National Institute of Oceanography (NIO), Goa, India, to investigate the influence of monsoonal rainfall on hydrographic conditions in the Mandovi River of India. The study was undertaken at a location ∼2 km upstream of the mouth of this estuary. During the premonsoon (PreM) in May, when circulation in the estuary was dominated by tidal activity, phytoplankton communities in the high saline (35–37 psu) waters at the study site were largely made up of the coastal neritic species Fragilaria oceanica, Ditylum brightwellii and Trichodesmium erythraeum. During the later part of the intermonsoon (InterM) phase, an abrupt decline in salinity led to a surge in phytoplankton biomass (Chlorophyll 𝑎 ∼14 mg m−3), of a population that was dominated by Thalassiosira eccentricus. As the southwest monsoon (SWM) progressed and the estuary freshened salinity and Chlorophyll 𝑎 (Chl 𝑎) concentrations decreased during the MoN, Skeletonema costatum established itself as the dominant form. Despite the low biomass (Chl 𝑎 > 2 mg m−3), the phytoplankton community of the MoN was the most diverse of the entire study. During the postmonsoon (PostM), the increase in salinity was marked by a surge in dinoflagellate populations comprising of Ceratium furca, Akashiwo sanguinea, and Pyrophacus horologium.

【 授权许可】

Unknown