Observations on standing crops of epipelic and epipsammic algal communities in Shear Water,Wilts

Methods of estimating the standing crops of epipsammic diatoms have been evaluated and compared with those used for epipelic algal crops.

Good correlations between chlorophyll a content and cell counts were obtained for epipelic populations, but because of the presence of large numbers of decaying cells, inseparable from living cells, such correlation was not obtained with epipsammic algae, even after correction of the pigment estimates for the presence of pheophytin a. The standing crop of epipsammic algae was at all times greater than that of epipelic algae at the same sampling station, and this was attributed to the differential effects of sediment disturbance by burrowing animals and water movements.