Linkages between Aquatic Sediment Biota and Life Above Sediments as Potential Drivers of Biodiversity and Ecological Processes

A great deal of attention has been given to declining species diversity in terrestrial systems, and certainly the rate of species loss in tropical forests is staggering. Recently, increasing attention has been focused on the loss of species in aquatic ecosystems. Indeed, Ricciardi and Rasmussen (1999) report that freshwater extinctions in North America far exceed extinctions in terrestrial environments. For example, an increasing number of freshwater fish and bivalves are being added to endangered species lists In contrast to our knowledge of fish and bivalves, information on species extinctions or even inventory lists are lacking for most inhabitants of the bottom sediments of lakes, streams, ground waters and wetlands, even though these "invisible" habitats harbor diverse and abundant biota (e.g., estimated at more than 100,000 species of sediment invertebrates globally, 10,000 species of algae, and more than 20,000 species of protozoans and bacteria; Although the local and global environmental