Letter to the Editor

摘要

A survey spanning 20 years (1991 to 2012) of the species and concentration of phytoplankton in the freshwater lake the Little Sea in Studland Dorset was published in the Quekett Journal of Microscopy (1). In this report I made the comment that that no alga had reached a bloom condition. This was premature; during October/ November of 2013 the green alga (chlorophyte) Closteriopsis acicularis reached a concentration of 40,000 cells/ml in February and gave the water a greenish-straw tint. This alga had been seen previously over some years but at peak concentrations some 10 times lower. Closteriopsis cells are about 130 microns long, curved or straight, tapering to fine points and about 4 microns maximum diameter. I think this concentration might be called a 'bloom' in so far as it coloured the water, although calculation showed that it is not very crowded even at such high concentration: even taking the longer dimension the algae are still separated by an average of 2 times their length.