Spatio-Temporal Dynamics of Phytoplankton in the Mandovi Estuary, on the Central West Coast of India During Post Monsoon
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Reshmitha Ramakrishnan [1] ; Veronica Fernandes [1]
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[1] National Institute of Oceanography
National Institute of Oceanography
India
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- Localización: Thalassas: An international journal of marine sciences, ISSN 0212-5919, Vol. 38, Nº. 2 (October 2022), 2022, págs. 1025-1040
- Idioma: inglés
- Texto completo no disponible (Saber más ...)
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Resumen
The abundance and assemblages of phytoplankton were studied monthly in the Mandovi estuary, on the central west coast of India during the post-monsoon season of 2019. Surface and bottom waters were sampled at three locations along the salinity gradient during October, November and December. Chlorophyll concentration was highest during November at the upstream station (M3), coinciding with low salinity (12–15 psu) and warm water temperature (30–31 °C). The pigment analysis revealed that picoplankton contributed ~ 70% of the phytoplankton biomass during October. On the other hand, during December picoplankton and microphytoplankton were equally represented. Microscopic analysis revealed 44 genera of microphytoplankton which was dominated by the diatoms. Their abundance was higher in the bottom waters and correlated significantly with higher salinity (p < 0.05). The species dominance was poor in October. However, during November when salinity was the lowest and the silicate and phosphate concentrations was higher, a bloom forming species of centric diatom Ditylum brightwellii was observed. It contributed up to 60% of the microphytoplankton abundance. Microphytoplankton abundance was highest during December which was cooler and salinity was high. A co-dominance of Bacteriastrum spp, Chaetoceros spp and Thalassionema nitzschioides during this period and it was relatable to high concentration of nitrate and phosphate. The results of this study indicated that salinity and nutrients are dynamic factors which play an important role in the abundance, spatio-temporal composition and variation including blooms in the Mandovi estuary.
