MONITORING THE MARINE-ENVIRONMENT WITH IMAGING METHODS

Imaging techniques are being used in both pure and applied studies and they can be applied in subtidal and intertidal studies of hard and so ft substrata. They can be used in quality status assessments of aquacu ltural areas, sewage sludge and dredge-spoil disposal areas, areas sub jected to bottom commercial trawling and the delineation of areas subj ected to desoxygenation. They have potential in fisheries and shell-fi sheries stock assessment. They also have an important role in increasi ng the understanding of fundamental biological aspects of the marine e nvironment such as autecology, zoogeography, behavior, taxonomy. They can be used in determining the biological processes linked to physical structures such as fronts and in studies on the water column (plankto nic features). The techniques, however, are most successfully used as a precursor or complement to conventional techniques used for studying marine systems and indeed their use to makes conventional survey tech nique more effective. Imaging methods are not intended to replace conv entional analytical techniques but, by their use in sea-bed mapping of basic topographical features, they can allow conventional techniques to be used more effectively. In particular, they will improve sampling design of the latter techniques. Many of the carriers for the imaging systems are able to achieve a precision in sampling positioning which is not possible with conventional techniques. The maneuverability of ROV (Remotely Operated Vehicle) systems and their non-disturbance of t he system under study provides a very effective technique. With the ad dition of environmental sensors, biological phenomena can be studied t ogether with physico-chemical processes. Video and still camera system s now give an excellent quality of image but improvements to the calib ration of the field of view are still needed in order to produce semi- or fully-quantitative measurements of marine attributes. Furthermore ROV and associated video systems can be used to assess the megafauna w hich are often under-sampled by conventional techniques. The advantage of the imaging approach especially in environmental monitoring, is in quick data retrieval and its application in informing and convincing non-scientists. The disadvantage is the semi-quantitative nature of mo st of the results gained which need furher verification by traditional , quantitative sampling methods. In the future joint activities on the individual, institutional and on an European scale should be stimulat ed to retrieve and the analyse environmental image documents to furthe r develop the somewhat conservative sampling technology in benthos eco logy.