2 - An overview of freshwater habitats

Abstract

The contribution of inland waters to the total biospheric water content is insignificant in terms of percentage but crucial from the perspective of terrestrial and freshwater life. Although inland lakes contain 100 times as much water as the surface rivers, most of the lake water is held within massive basins, such as the Laurentian Great Lakes of North America, Lake Baikal of Siberia, and Lake Tanganyika of East Africa. Because most freshwater invertebrates are clustered within shallow, well-lighted zones of lakes, the relative importance of small ponds, creeks, and rivers as habitats for aquatic invertebrates is much greater than their volume percentages would otherwise indicate. Composition, species richness, and total density of invertebrates vary considerably among inland water habitats, as discussed in this chapter. Distributions of invertebrates are influenced by interactions among physical, chemical, and biological characteristics. The general importance of these abiotic and biotic factors is examined in the chapter. Detailed information on the ecology of individual taxa in inland water ecosystems can also be obtained from the data provided in the chapter.