Intense bloom of the diatom Hemidiscus hardmanianus (Greville) in relation to water quality and plankton communities in Tuticorin coast, Gulf of Mannar, India

• Published in: Marine pollution bulletin Vol. 163; p. 111757
• Main Authors: Sathishkumar, R.S., Sundaramanickam, A., Sahu, Gouri, Mohanty, A.K., Ramesh, T., Khan, S. Ajmal
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 01.02.2021; Elsevier BV
• Subjects: Animals; Ballast water; Biddulphia biddulphiana; Blooms; Cells; Chlorophyll; Chlorophyll a; Coastal waters; Coasts; Diatom bloom; Diatoms; Discoloration; Gulf of Mannar; Harbors; Hemidiscus hardmanianus; India; New records; Phytoplankton; Plankton; Relative abundance; Surface water; Surveying; Tuticorin harbor; Water Quality; Zooplankton; India; Gulf of Mannar; Biddulphia biddulphiana; Zooplankton; Diatom bloom; Ballast water; Tuticorin harbor
• ISSN: 0025-326X; 1879-3363
• DOI: 10.1016/j.marpolbul.2020.111757

The present study reports a dense bloom of the marine-diatom Hemidiscus hardmanianus observed off the Tuticorin coast in the Gulf of Mannar (GoM), India. The surface water discoloration (pale green) was observed during a coastal survey conducted in the initial period of the northeast monsoon (October 2018). The bloom extended over an area of approximately 5 km2 around the Tuticorin harbor. Distribution and relative abundance of the phytoplankton and zooplankton species together with the water quality and Chlorophyll-a were studied in the area of bloom. H. hardmanianus density was maximum (10.57 × 104 cells L−1) in the bloom site, which was almost 97% of the total phytoplankton population. The present report is the first record of H. hardmanianus bloom in the Gulf of Mannar. The chain-forming diatom Biddulphia biddulphiana was also observed in strong numbers (802 and 432 cells L−1), which has been rarely reported from the Indian coastal waters. •Dense bloom formation by the marine diatom Hemidiscus hardmanianus in Gulf of Mannar, India•The chain forming diatom of Biddulphia biddulphiana was found first time in Tuticorin coast at Gulf of Mannar.•The concentration of chlorophyll-a was much higher in the bloom regions.•Oithona nana might be the potential key factor for controlling the diatoms bloom through grazing.