ABSTRACT
The arthropods constitute a vast assemblage of animals. At least 75,000 species have been described — more than three times the number of all other animal species combined (Dorit et al., 1991). The arthropods successfully invaded a variety of habitats, such as wetlands, ponds, lakes, streams and rivers where they perform a variety of critical ecological functions, such as detritus processing (Wallace and Webster, 1996). They are relatively sessile and long-lived, and exhibit a range of sensitivities to various environmental stressors (Rosenberg and Resh, 1993). They also have a long history of serving as sentinels of water quality (Carpenter, 1924). Freshwater ecosystems are faced with a variety of insults including urbanization, agriculture, industrial effluent, and climate change. It is imperative that we understand how aquatic ecosystems are affected by these stresses and how they respond to management actions aimed at alleviating such insults. Because of their tremendous diversity, longevity, sensitivity, and critical roles in ecosystem function, benthic invertebrates provide excellent model systems for examining the effects of anthropogenic disturbances on aquatic ecosystems.
