HORIZONTAL DISTRIBUTION PATTERNS DURING A CYANOBACTERIAL BLOOM

A hierarchical sampling was performed in order to give a picture of th e horizontal distribution of cyanobacterial colonies. It showed how th e importance of different scales in distance changed during the summer bloom of Gloeotrichia echinulata in the moderately eutrophic and stra tified Lake Erken in southeastern Sweden. G. echinulata colonies occur red in patches at a distance of similar to 1000 m and the variance at smaller scales was low. For colony content of phosphorus, chlorophyll a and size, however, the largest variances were found at the 20 m (and error) scale if the variances between dates are not taken into accoun t. It was concluded that in order to estimate the lake population of c yanobacterial colonies properly these variances must be considered whe n deciding the sampling program.