Role of Microbial Enriched Detritus in the Nutrition of Gammarus Minus (Amphipoda)

Microbial enriched detritus is an important food source for many stream invertebrates. Results of laboratory feeding experiments showed significant differences in survivorship of Gammarus minus Say on 10 different diet combinations over a 10 week period. Highest survivorship was recorded on fungus enriched leaves; intermediate rates were obtained for leaves with a viable bacterial flora and leaves on which the microflora had been killed. Low survival rates were recorded on sterile leaves and leaves with reduced microfiora. The results of food preference studies showed that leaves having a viable fungus flora were most preferred while sterile leaves were least preferred. Overall, Gammarus showed a preference for those diets affording the best survivorship in the feeding experiments. Evidence indicates that the nutrition of G. minus is based on a food chain of detritus and the associated fungi.