Numerous issues were explored relative to scaling in time and space. Despite the excellent presentations at this symposium, numerous issues remain unresolved relative to scaling, fostering a variety of research needs. A primary unresolved scaling issue is to come to grips with delineation of the question of concern or objective in ecological risk assessment for pesticides in aquatic systems. One reason for the requisite clarity of purpose for these experiments is to ensure that the spatial and temporal scaling has included the ability to encompass the ecological effects of concern. Clearly, scaling contains numerous unresolved issues and needs additional research. One proposal from this workshop was that an additional symposium or activity was needed to discuss scaling and utilization of microcosms for ecological risk assessment for pesticides. Model aquatic systems such as microcosms or mesocosms have been used for many decades to evaluate the effects of pesticides and other materials on aquatic systems.