​Sat-Tagis
Modelling the habitats of primary producers, invertebrates and birds in intertidal flats of the Tagus estuary, using satellite images and GIS
2000-2004
Project Summary
Estuaries are areas of great commercial and ecological significance and have, for centuries, been usefully exploited by man for communication, transportation, waste disposal, power generation and amenity development. An understanding of the dynamics and ecology of coastal systems is a fundamental requirement to the investigation of this human impact.
The Tagus estuary is one of the most important European wetlands, wherein a large area is protected by national legislation and international treaties. The vast sediment flats of the Tagus estuary are spatially heterogeneous, offering variable ecological conditions for primary producers, invertebrates and birds. Aquatic birds are the most conspicuous element of estuarine areas. Waders, in particular, strongly depend on the extensive sediment flats periodically exposed by tides to find their food. The beauty and diversity of aquatic birds constitute a social value. Microphytobenthonic algae support most of the invertebrate communities living in these intertidal flats. The latter constitute a critical food resource for birds, and play an essential role in estuarine food chains. Some of these invertebrate species are locally harvested in a sustainable way, and therefore possess a high economical and social value.
Despite its critical ecological, social and economic importance, these flats are still poorly mapped and require regular surveying. This situation calls for the use of expeditious mapping methods, and satellite imagery is clearly a good base for the development of such methods. These recent technological developments offer very good prospect for a further refinement of the habitat classification accuracy, and therefore may contribute towards meeting the finer-scale requirements of wetlands' managers and decision-makers.
Hence, the objectives of this project are: a) to refine methods to use satellite image to map and monitor spatial variation in sediments, b) to develop predictive models of habitat suitability for primary producers, invertebrates and birds, c) to map the surface characteristics of the sediment banks of the estuary, and d) to combine this information to generate ecological zonations for primary producers, and for the needs of invertebrates and birds.
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Classification of satellite images will highlight the features relevant to benthic primary producers, invertebrate and bird distribution. Finally, the integration of this information in a GIS environment with other relevant variables will produce maps indicating habitat suitability for invertebrates and birds. Both Landsat TM and Ikonos images will be used to assess the advantages of the two different types of data.
One of the major deliverables of the project will be to provide a good starting point for the establishment of monitoring programmes of ecological changes of coastal wetlands, since it will provide extensive reference data and new methods for expeditious ecological zonation. It will further enhance the assessment of impact of human activities (such as land reclamation, sediment drainage, tourism, and aquaculture) on birds and invertebrate communities.
With this project we hope to give a valuable contribution to the knowledge of intertidal and saltmarsh communities. Due to their importance as natural coastal defences and pollution buffers the information concerning the past and future trends of this communities will have significant importance in helping decisions and management of sustainable on-going development. By bringing together information from sediments, primary producers, invertebrates and bird populations, this project integrates information across several trophic levels, and therefore it has the potential to significantly enhance our understanding of estuarine processes and functioning. Apart from a scientific output, resulting in peer-reviewed papers, this proposal intends to produce scientific information addressed to the general public, by internet, and in particular to local citizens and visitors of "Reserva Natural do Estuário do Tejo", which will constitute a direct end-user of this proposal's outcome. Training of graduate students will be another main deliverable of the present proposal.
Funding
Fundação para a Ciência e Tecnologia (FCT). Portugal.