Fish assemblages

Abstract

An individual fish lives out its life within complex webs of interactions and processes which can both affect and be affected by the individual. The interactions include predator-prey relations (see Chapter 3 and 8), competition (see Chapter 9) and reproductive activities (see Chapter 7). The processes include the flow of energy and nutrients through the web (see Chapter 3 and 4). All those organisms in a defined area or habitat, irrespective of taxonomic identity, that interact either directly or indirectly form a community. Those organisms of the same taxonomic identity, for example all the fishes in a community, form a subcommunity (Giller and Gee, 1987). A guild describes a group of species in a community which exploit the same class of resources in a similar way (Root, 1967). The term assemblage will be used to describe all the fish species in a defined area irrespective of whether they interact or not. This chapter discusses the factors that determine the species richness of fish assemblages. It also briefly considers the effects that the fishes have on the community of which they are a part.