Dinoflagellate cysts in recent marine sediments from Tasmania, Australia

Thirty-four cyst types capable of seeding plankton dinoflagellate populations have been identified in Tasmanian estuarine sediments. The most common cysts were those of Gonyaulax grindleyi, G. spinifera, Gymnodinium catenatum, Gyrodinium sp., Polykrikos schwartzii, Protoperidinium conicum, P. pentagonum, P. subinerme, Scrippsiella spp. and Zygabikodiniwn lenticuiatum. Also common were ovoid to spherical Alexandrium tamarense-like cysts, which lack distinctive taxonomic features and mucilaginous covering. These latter cysts could only be identified by incubation experiments, which produced living cells of Scrippsiella (2 spp.), Gyrodinium sp. and Alexandrium cf. excavatum. While Tasmanian dinoflagellate cyst assemblages resemble those of New South Wales, Australia, and New Zealand, one notable difference is the cyst of the toxic dinoflagellate Gymnodinium catenatum which appears to be confined to south-eastern Tasmania.