STP 1007 marks the beginning of the second decade of aquatic toxicology as a mature science. Papers address: Large scale cumulative effects of multiple pollution sources on regional communities and populations; effects of spills, storm runoff, and other non routine exposures with complex temporal dynamics; effects of variation in organism condition on susceptibility; predicting effects of new chemicals whose mode of action is unknown; cumulative effects of pollution, harvesting, modifications of the physical environment, and natural stochastic processes; and balancing risks and benefits of different levels of testing, monitoring, and waste treatment.