Aquatic Environments

Major aquatic environments include: oceans; groundwater; glaciers and ice caps; snow and ice; and lakes and rivers, all of which contain diverse microbial populations. In this chapter we first define the main microbial habitat types including: planktonic (freely suspended); benthic (sediment associated); and biofilms and mats (surface associated). Following this, we examine the microbial lifestyles within these habitats including primary (photoautotrophy and chemoautotrophy) and secondary (chemoheterotrophy and photoheterotrophy) production. Subsequently, we describe general microbial characteristics of marine and freshwater systems including marine viruses. Finally, other notable aquatic environments are discussed including brackish, hypersaline and subterranean waters.