Phytoplankton of the Tystrup-Bavelse Lakes Primary Production and Standing Crop

Abstract

Five main stations were established in Trystrup So, and one in Balvelse So in Zealand Denmark. The two lakes are at the same level and are connected by a channel. Their inlet and outlet is the River Susa. Primary production was determined by the C14 method, and simultaneous samples were obtained for quantitative estimates of the phytoplankton. The period of study was May 1959 to May 1962, with special emphasis on the year 1961-1962. The quantitative distribution of the phytoplankton, along with the opacity of the water and the amount of primary production increased along the lake complex, with Bavelse So having the heaviest crop, the highest production and the least transparency. There were three phytoplankton maxima between April 1961 and May 1962, namely one in each spring and one in the fall. The fall maximum was dominated by Cyanophyta and the spring by diatoms. During the summer the Chlorophyceae and Ceratium were the most abundant. The quotient: gross production per day was greatest (1-3.4) in spring and summer, and standing crop summer, and was only 0.2 in the winter.