NUTRIENT COMPETITION EXPERIMENTS WITH PERIPHYTON FROM THE BALTIC SEA

Nutrient competition experiments were performed with periphytic microa lgae from the Kiel Fjord, western Baltic Sea. Diatoms were dominant co mpetitors al high Si:N ratios (under N-limited conditions) and high Si :P ratios (under P-Limited conditions). Under low silicate supply, cya nobacteria became dominant at low N:P ratios and chlorophytes at high ones. Changes in Light intensity influenced the outcome of competition at the species level but not at the level of higher taxa. The nitroge n source (ammonium or nitrate) had no impact on the outcome of competi tion.