What is the future fate of estuaries given nutrient over-enrichment, freshwater diversion and low flows?

Abstract

Freshwater inflow is central to the definition of estuaries and if we lose control of the quantity of freshwater flow or discharge (including seasonal timing) to estuaries, then freshwater water quality has the potential to become a moot issue in estuarine ecosystems ( Definition of estuaries: estuaries (aestus = tide) are physico-chemically, geomorphically, and biotically diverse ecosystems. Although numerous definitions of estuaries exist, we prefer the following: an estuary is a partially enclosed coastal water body in which freshwater runoff, often seasonally and episodically pulsed, dilutes salty ocean water and the biotic structure is influenced by dynamic tidal action and associated salinty gradients and reef building organisms and wetlands influence development and evolution of ecological structure and function (see Kjerfve, B., 1989. Estuarine geomorphology and physical oceanography. In: Day, J.W. Jr., Hall, C.A.S., Kemp, W.M., Yanez-Aranciba, A. (Eds.), Estuarine Ecology. John Wiley, for expanded definition)).