- Dona Paula, Goa, India.
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| Abstract Submission No. | ABS-2022-05-0197 |
| Title of Abstract | Seasonality in phytoplankton community structure in the surface and subsurface chlorophyll maxima layers in the southeastern Arabian Sea |
| Authors | Sujata K. Nilajkar*, Mangesh U. Gauns, Bhagyashri R. Naik |
| Organisation | CSIR-National Institute of Oceanography |
| Address | A-4, NIO colony DonaPaula, Goa, India Pincode: 403004 Mobile: 8007281171 E-mail: nilajkarsuja.sn@gmail.com |
| Country | India |
| Presentation | Poster |
| Abstract | The southeastern Arabian Sea (SEAS) is characterized by large hydrographical changes associated with seasonally reversing monsoonal winds and coastal currents. Coastal upwelling dominate the hydrography of the SEAS during the southwest Monsoon, whereas, low saline, warmer and oligotrophic Bay of Bengal waters plays a major role during the Northeast and Pre-Monsoon seasons. This study presents the phytoplankton (>10µm in size) composition, abundance and distribution in the SEAS during the peak Southwest Monsoon (July⿿ 2018) and Northeast Monsoon (February⿿ 2019) seasons. Samples from surface waters and subsurface chlorophyll maxima (SCM) layer from nine stations (30m, 300m and 600m depths) along three cross shore transects off Goa, Mangalore and Trivandrum were considered in this study. The results showed lower phytoplankton diversity in the surface waters during the Northeast Monsoon (47 genera) as compared to the Southwest Monsoon (59 genera). The surface water community was largely dominated by dinoflagellates particularly during the Northeast Monsoon when the study region was influenced by low saline and warmer Bay of Bengal waters. Contrarily, the phytoplankton community in the SCM layer was more diverse during the Northeast Monsoon (39 genera) as compared to the Southwest Monsoon (28 genera). SCM community was composed mainly of diatoms (Amphora, Asterolampra, Attheya, Coscinodiscus, Ditylum, Leptocylindrus,. Odontella, Striatella, Planktoniella, Pleurosigma, Pseudo-nitzschia) and dinoflagellates (Chattonella, Gyrodinium, Prorocentrum, Scrippsiella). It seems that the concentration of diatom dominant phytoplankton assemblage in the SCM may favor an increase in abundance of specific plankton grazers there. |