"Phytoplankton and zooplankton — tiny drifting plants and animals — are vital components of the marine and freshwater aquatic food chains, and our waterways. Plankton communities reflect the effects of water quality and cannot isolate themselves as oysters do by closing their shells in adverse conditions. Plankton are effectilvely our aquatic 'canaries-in-a-cage' — they accumulate over days the effects of hourly changes in water quality."