Pathogenic Regulation of Running Water Macroinvertebrate Populations: Progress Report

摘要

The emphasis was on the interaction between food quality and growth of representatives of the shredder, collector and scraper functional groups. However, extensive effort also was directed toward aspects of invertebrate mortality in a range of studies during the project period. Three procedures were developed for separating populations of stream macroinvertebrates into groups of individuals which exhibit differential mortality. The differences in survival observed in these population components, are not due to predation, starvation, competition or obvious physical damage or chemical insult. Based on our preliminary experiments and observations, we hypothesize that the major cause of mortality is pathogenic infection, particularly by anaerobic bacteria. The suspected pathogens are routinely present in the digestive tracts of stream invertebrates. Infection is most likely to occur at molting, the specific sites of infection probably being lesions developing at the junction of the midgut and hindgut when the lining of the hindgut is shed. (ERA citation 12:046212)