A. There are two primary good sources for aquatic organisms. First are the diatomes, single-celled algae cells which cover all solid objects wherever light and nutrient supplies are sufficient. These are utilized by organisms that feed by actively grazing or scraping the algae from the surfaces; common organisms include many snails and several caddisflies and mayflies whose mouthparts are adapted for this mode of feeding. The second largest source of food is fine particulate organic matter (FPOM) and this is defined as any particle of organic matter less than 1 millimeter in size. These come from many sources, including breakdown of dead algal filaments and terrestrial plant material that reaches the stream, production of fecal pellets by organisms feeding on larger organic particles, ect. ~ Stream Doctor

The 'Stream Doctor' is a retired professional stream ecologist and author, now living in the West and spending way too much time fly-fishing. You are invited to submit questions relating to stream-ecology directly to him for use in this Q & A Feature at streamdoctor@aol.com.