Bioluminescent bloom dynamics of Gonyaulax spinifera at Kumbalangi, Kochi, south-west coast of India

Padua, Shelton and Sasi, Anjitha T and Prema, D and Sobhana, K S and George, Grinson and Lavanya, R and Sreesanth, L and Raju, Aju K and Joseph, Reena V and Sini, M B and Prince, A and Vysakhan, P and Thobias, P A (2026) Bioluminescent bloom dynamics of Gonyaulax spinifera at Kumbalangi, Kochi, south-west coast of India. Indian Journal of Fisheries, 73 (2). pp. 57-68. ISSN 0970-6011

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Abstract

Several bioluminescent bloom events have been reported in the coastal, oceanic, and island waters of India since 1890. In recent years, Kerala has experienced multiple episodes of bioluminescent blooms, with Kumbalangi, a well known bioluminescent bloom hotspot on the south-west coast of India, repeatedly witnessing such events for the past several years. To investigate the bloom dynamics and associated environmental drivers, the Kumbalangi bloom area was monitored regularly from May 2023 to September 2024. During this period, a total of 67 species of diatoms, 19 species of dinoflagellates, 10 species of Chlorophyceae, 11 species of Cyanophyceae, and a few representatives of Euglenophyceae and Amoebozoa, were identified, with diatoms constituting the dominant component of phytoplankton community. Bioluminescent blooms of the dinoflagellate Gonyaulax spinifera were observed during the pre-monsoon season from ,,,,,,,,,,,,,. Principal component analysis (PCA) revealed that the aquatic environment was mainly influenced by salinity, dissolved inorganic nitrogen (DIN), and dissolved inorganic silicate (DISi). G. spinifera exhibited a strong positive correlation with salinity (r=0.75, p<0.05), suggesting that elevated salinity favoured its proliferation. The high Simpson dominance index, coupled with low Simpson diversity index and Shannon‒Wiener diversity index values, confirmed the occurrence of a monospecific bloom of G. spinifera during the bloom period. Presence of G. spinifera cysts was also recorded from the area, which indicates its potential for persistence and recurrence under favourable environmental conditions.

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