Beschreibung:
<p>Phytoplankton and environmental conditions in Lake Washington, Seattle, Washington, are discussed from the perspective of dynamic relationships between taxon-specific growth rates and environmental variables. More than four decades of measurements permit inspection of conditions associated with net increase and decrease for 40 phytoplankton species or species groups. Reproducible patterns exist for growth responses to over 25 environmental factors including nutrient chemistry, physical variables, and herbivorous zooplankton species. There appear to be no more than six main modalities of response to environmental factors, and responses to chemical and physical variables show coherence across taxa. Diatoms show a near uniform positive growth response to abundant inorganic nutrients, cold and transparent water, deep mixing, and intolerance for virtually all zooplankton grazers. Many chlorophytes and cyanobacteria show equally uniform growth responses to chemical and physical variables, although their preferences are virtually opposite from the diatoms. They benefit from the presence of copepods but show highly specific growth rate responses to different cladocerans and rotifers. Growth rate variations among the diatoms sort out along gradients of resource and physical factors, but there is coherence to the rise and fall of multiple species. Among the other algal divisions, despite a common set of physical and chemical conditions that promote growth rates, the species do not increase and decrease together. Instead, the prevailing grazer community appears to shape the phytoplankton community by admitting only certain species from the large pool of contenders.</p>