SILICATE AND THE FUNCTIONAL GEOMETRY OF MARINE-PHYTOPLANKTON

The impact of nutrient supply ratios on the functional geometry of phy toplankton has been studied by means of competition experiments with p hytoplankton communities from the Arabian Sea. Cell length and deviati on from spherical shape of dominant competitors increased with Si:N ra tios. Surface:volume ratios were minimal at intermediate Si:N ratios. Grazing by the rotifer Brachionus plicatilis did not lead to a qualita tive shift in the response of geometric properties to Si:N ratios; how ever, mean cell lengths increased while surface:volume ratios decrease d.