Ecohydrology as a new tool for sustainable management of estuaries and coastal waters

Abstract

Throughout the world, estuaries and coastal waters have experienced degradation. Present proposed remedial measures based on engineering and technological fix are not likely to restore the ecological processes of a healthy, robust estuary and, as such, will not reinstate the full beneficial functions of the estuary ecosystem. The successful management of estuaries and coastal waters requires an ecohydrologybased, basin-wide approach. This necessitates changing present practices by official institutions based on municipalities or counties as an administrative unit, or the narrowly focused approaches of managers of specific activities (e.g., farming and fisheries, water resources, urban and economic developments, wetlands management and nature conservationists). Without this change in thinking and management concept, estuaries and coastal waters will continue to degrade, whatever integrated coastal management plans are implemented. To help in this process of change there is a need to (1) develop a profound understanding of the effects of biota and biotic processes on mediating estuary response to changing hydrology, sediment and nutrient flux and of the biota on hydrology at the river basin scale, and (2) to develop science-based remediation measures at the river basin scale, with elements of ecohydrology and phytotechnology at their core, to strengthen the ability of the biota to sustain and adapt to human-induced stresses.

Ichthyoplankton dynamics in the Guadiana estuary and adjacent coastal area, South-East Portugal

“…A decrease in estuarine productivity might explain the reduced abundance of E. encrasicolus in comparison with Pomatoschistus spp., given that the latter species possesses benthonic eggs and larvae that are more highly developed and less dependent on the available food upon hatching, unlike E. encrasicolus larvae that emerge from pelagic eggs and are planktitrophic. Alterations in the amount of river flow into the estuary and adjacent coastal areas affect the concentration of nutrients, with consequences for the primary productivity and associated trophic chains (Wolanski et al, 2004). The Aswan High dam (Nile river, Egypt) is a classic example; after its construction the load of nutrients exported to the coastal area decreased more than 90%, leading to the collapse of fishing activity in the coastal area (Nixon, 2003(Nixon, , 2004.…”

An ecohydrology model of the Guadiana Estuary (South Portugal)

“…Throughout human history, the coastal plains and Lowland River valleys have usually been the most populated areas over the world (Wolanski et al, 2004). At present, about 60% of the world's population lives along the estuaries and the coast (Lindeboom, 2002).…”

Training hydrologists to be ecohydrologists and play a leading role in environmental problem solving

“…This sphere of ecohydrology therefore builds upon the preceding spheres, following runoff from its source on the landscape and through river corridors. This emphasizes again a fundamental tenet of ecohydrology, which is the consideration of processes operating at a full catchment scale even if the specific unit under study is a lake or estuary (Zalewski, 2002;Wolanski et al, 2004). Influxes of water from contributing rivers and groundwater dominate the water balance inputs of most lakes (excluding the great lakes) and control the salinity profiles of most estuaries (Hill et al, 1998;Klimmerer, 2002;Robins et al, 2005).…”

“…The most ubiquitous problem in this sphere is, however, eutrophication and the myriad ecological changes and potentially severe hypoxia it may cause (Cloern, 2001;Smith, 2003;Vadeboncoeur et al, 2003). Ecohydrological research addresses the interacting hydrological, biogeochemical, and ecological processes leading to eutrophication, as well as the full suite of catchment-scale management interventions that may help reduce harmful effects (Wolanski et al, 2004).…”