Aquatic organisms can be classified into four major groups, varying in biological characteristics, habitat, and adaptations, but linked within a complex network of ecological roles and relationships:
The aquatic ecosystem of a river system is generally comprised of its fish, aquaticinvertebrates, riparian plants, and microorganism components. Key issues related to aquatic habitat and riparian vegetation are described below, in terms of system drivers and habitat response to stressors.
 African Fish Eagle. Source:De Wet 2006 ( click to enlarge ) |
 Small Mouth Yellowfish (Rubber Lips). Source:Inkwazi Fly Fishing 2009 ( click to enlarge ) |
