Coastal waters are vital to humanity for food, important for trade and increasingly relied on as a key source of income through tourism. Scientists are therefore using satellite data provided by the European Space Agency (ESA) to monitor coasts around the world. They are evaluating these data to check that these delicate ecosystems are not at risk from pollution or over-use. This information will encourage future developments to be carried out sustainably with the least impact on coastal waters.
This research is part of ESA's CoastColour project, which allows scientists to take full advantage of the unique capabilities of the Medium Resolution Imaging Spectrometer (MERIS) sensor on its Envisat satellite. With a resolution of 300 metres, MERIS provides the sharpest available views of coastal waters. It also includes spectral bands designed specifically to characterise the complex mixing of pollutants, suspended sediments and phytoplankton typically found in coastal zones.
Forty organisations have already signed up to the CoastColour project, which is now processing MERIS data from 27 high-priority coastal regions. One of the organisations making the most of this technology is a team from Australia's Commonwealth Scientific and Industrial Research Organisation (CSIRO). Led by Dr Arnold Dekker, Team Leader of the Environmental Remote Sensing Group in CSIRO's land and water department, the organisation is working with CoastColour to develop techniques to monitor the health of Australia's Great Barrier Reef.
CSIRO is concerned about the large plumes of sediment-laden river water that flow into the reef lagoon during the wet season. Sediments can smother corals and deprive them of the sunlight they need to survive, while river-borne nutrients may influence the frequency of naturally occurring algal blooms. 'ESA is to be commended for supporting the use of Earth observation to help solve the management issues of these truly complex coastal aquatic ecosystems,' Dr Dekker said.
MERIS data are also being used to monitor harmful algal booms along the west coast of South Africa in the Southern Benguela upwelling system. Red tides and algal blooms with extremely high phytoplankton concentrations frequently occur in the region's bays, threatening fisheries and tourism. Dr Stewart Bernard from South Africa's Council for Scientific and Industrial Research (CSIR) is developing systems aimed at integrating the satellite data with hydrodynamic models to monitor and predict harmful algal blooms operationally. Coastal resource managers and the regional aquaculture industry greatly need these predictions to minimise risks to public safety and financial losses, according to Dr Bernard.
'The involvement of local scientists in CoastColour has already increased South Africa's technical ocean-colour capability, and is expected to significantly aid the implementation of the ocean-colour components of developing African operational oceanography systems,' he said.
Scientists also hope that the satellite data can help alleviate pollution problems in the Baltic Sea, where the sustainable development of seaports requires shipping channels to be dredged every two years. Dredging mixes large amounts of suspended sediments into the water, affecting coastal water quality which is regulated by internationally agreed standards.
Dr Liis Sipelgas of the Tallin University of Technology in Estonia is working with the Port of Tallinn, which runs four harbours on the Estonian coast, to understand the environmental impact of their dredging operations by mapping sediment plumes.
'The new site-specific CoastColour water quality products improve significantly the operational environmental monitoring of harbour dredging activities,' Dr Sipelgas explained.'The products also enable us to estimate and quantify the long-term water quality changes in the harbour area.'