| dc.description.abstract | The plankton community plays a significant role in the stability of coastal ecosystems. They serve as key players in
marine food webs. The present study investigated the plankton diversity in coastal waters near Kalu Ganga river
mouth. Six sampling locations were chosen randomly, three along the right side of the coastline (CR1-CR3) and
three along the left-side (CL1-CL3) from the river mouth. Zooplankton and phytoplankton at each location were
sampled from September 2020 to February 2021 using a 55µm plankton net in surface waters on a monthly basis.
Plankton were morphologically identified to the nearest possible taxonomic level. The Shannon-Weiner diversity
index (H) and Simpson's Index of Diversity (SID) were calculated to determine plankton diversity. The number of
phytoplankton species found during the wet months (September-October) and dry months (January-February) were
62 and 68 respectively, while a similar number of zooplankton species (43) were recorded in both periods.
Altogether, 81 phytoplankton species and 53 zooplankton species were identified during the research period.
Bacillariophyta (72%) and Copepods (68%) were identified as the dominant phytoplankton and zooplankton groups
respectively. Dinoflagellates including, Peridinium sp., Protoperidinium sp., Ceratium sp., Noctiluca sp.,
Gonyaulax sp., and Alexandrium sp., which are well-known to form harmful algal blooms (HABs) accounted for
17%. Chlorophyta and Cyanophyta were less dominated and found only during wet months at nearest sampling
locations (CL1 and CR1) to river mouth. Rotifera (11%), foraminifera (9%), protozoa (10%) and ichthyoplanktons
(<1%) were also reported. The H and SID values for plankton were recorded to be between 2.7 to 3.1 and 0.90 to
0.96 respectively. The both values were not significantly different (p>0.05) between wet months and dry months at
each location. According to the H and SID values, the study area has a moderate-high level of plankton diversity.
Further research should be conducted to determine the temporal and spatial variation of plankton diversity in the
study area. | en_US |
