The algal plankton of Loch Leven, Kinross

The species composition and succession of the algal plankton are described. Population density changes, as indicated by chlorophyll a cell volume and numbers are discussed in relation to physical, chemical and biological factors in the environment. The quality and the amounts of the plankton vary considerably from year to year. However. for most of the period reviewed it has been dominated by dense developments of nanno and other small algae belonging to the diatom and blue-green groups. Factors of particular importance affecting the high observed biomass and production include the water depth, adequate mixing and a rich supply of nutrients from the inflows and the sediments. Competition from other green plants appears to be low. Utilisation of living algal cells in the plankton by crustacean and protozoan grazing and fungal parasitism is rarely important. The composition of the phytoplankton is discussed in relation to the eutrophic nature of the loch.