Creating environmental kidneys: wetlands ecosystems as pollution filters and habitat restoratives

Abstract

Wetlands are now recognised as important wildlife habitats and as ecosystems which enhance the quality of water that flows through them. Wetland creation and restoration are forms of ecosystem manipulation requiring a scientific understanding of wetland function. This paper reviews the concept of the ecosystem in general and how it applies to wetlands in particular. Wetlands, because of seral processes, are transitional and dynamic features of the landscape. The rate of successional change varies from wetland to wetland but may be rapid enough to challenge wetland conservation efforts. Human-induced disturbances and perturbations can also alter wetlands significantly and these case studies: Book Lagoon, South Australia; Waigani Lake, Papua New Guinea and the Norfolk Broads, England are presented to illustrate the impact of alterations in features such as water level and nutrient supply. In constructing and rehabilitating wetlands, clear objectives and goals should be set. Wetlands constructed for water quality enhancement will need to be assessed on their nutrient removal performance and how, or whether this performance can be sustained. A thorough understanding of wetland hydrology, nutrient uptake dynamics by selected plant species, biofilm function and sediment-water column interactions will be needed. Wetland constructed with conservation goals will largely be assessed on their biodiversity. Greater consideration will need to be paid to featured such as life-history strategies, seasonality, inter- and intra-specific competition and maintenance of biodiversity. Environmental impact assessments of developments affecting wetlands should not merely seek to minimise the impacts but should actively pursue ways to maintain and restore them. in many cases, reversing the trend of wetland degradation and destruction can achieve both an enhancement of downstream water quality and the provision of attractive wetland habitats. This is the challenge, the capability exists to meet it.