The use of log-normal statistics to describe phytoplankton populations from the Firth of Lorne area

An attempt has been made to use sample estimates of the three parameters of the truncated continuous log-normal distribution as descriptive macroscopic statistics for the diversity and abundance of phytoplankton populations from the Firth of Lorne and Loch Etive on the west coast of Scotland. A log-normal model was found to provide a reasonable description of the distribution of entily¹ 1 By "entity" is meant the various species-groups delineated in text: nothing is inferred regarding any relations within these "entities". abundances in most samples. Sample estimates of median abundance, total number of entities in the population, and standard deviation, as well as of the total phytoplankton abundance, were used to describe changes taking place in the population at the station in the Firth of Lorne during the course of a year from June 1970 to June 1971, and to compare the populations of the upper and lower basins of Loch Etive during May to November 1970. An attempt has been made to explain the ecological meaning of the statistics and, in the case of the Loch Etive samples, to explain differences between values for the populations from the two basins resulting from the effects of a lower and more variable salinity in the upper basin.