Dinoflagellate cyst distribution in recent sediments along the south-east coast of India

Abstract

The spatial variation in the dinoflagellate cyst assemblage from the south-east coast of India is presented along with a comparison of the cyst abundance from other regions of the world. Samples from 8 stations revealed the presence of 24 species from the genera Protoperidinium, Zygabikodinium, Gonyaulax, Lingulodinium and Gyrodinium. Cyst abundance was comparatively high at northern stations and was well correlated with the fine-grained (silt-clay dominated) sediments. In contrast, low cyst abundance was recorded in sandy sediments at southern stations. Fourteen cyst-forming dinoflagellate species previously unrecorded in planktonic samples were detected in the sediments. The cyst abundance recorded here is low (29–331 cysts g⁻¹ dry sediment) as compared to sub-tropical and temperate regions, but it is on a par with tropical regions, including the west coast of India. Comparison of the cyst assemblage along the Indian coast revealed a smaller number of potentially harmful and red-tide-forming dinoflagellate species on the south-east coast (6 species) than on the west coast (10 species). Calcareous cysts of the genus Scrippsiella reported from the west coast and Visakhapatnam harbour (south-east coast) were not observed in this study although their planktonic cells have been reported.