L-livin has the concept correct. Generally or almost always some type of plant will utilize the available nutrients - often it is several types or species of plants. Killing one often results in a surge of the other plants. Ideally one would want that plant surge to be beneficial phytoplankton. There are nuisance species of phytoplankton - mostly Cyanobacteria - aka bluegreen algae. Sometimes as in L-livin's case the grass carp ate the plants with roots and phytoplankton flourished to make water still plant productive but with low water transparency due to phytoplankton.
