5 - Estuarine ecological structure and functioning

Abstract

To benefit from ecohydrology implies we have a good knowledge of the ecological structure and functioning of estuarine environments and especially their interaction with the physical and biogeochemical processes. The ecological structure of any ecosystem refers to the characteristics at any one time whereas functioning refers to rate processes. The structure of the system results from the creation of niches by the physico-chemical system and the more complex that system the more niches are created. Organisms then occupy those niches according to their environmental tolerances and preferences, for example, for a salinity regime, temperature threshold, sediment type, etc. Once the organisms have occupied the niches, then they interact with each other, both within and between species, in rate processes such as competition, predator–prey relationships, reproductive interactions, mutualism/parasitism, and other interactions. It is axiomatic that organisms, at all levels, require three fundamental resources—food, space and reproductive agents/partners/propagules. Where any one of these is limiting, competition occurs. This chapter does not aim to reproduce other books about estuarine ecology, but rather focuses on those elements central to an understanding of ecology-hydrology links and hydrology control.