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MED-CORE Informe resumido

Project ID: ICA3-CT-2002-10003
Financiado con arreglo a: FP5-INCO 2
País: Italy

Bio-assays of beach degradation based on behavioural variation

Bioassays to monitor environmental changes are based on the fact that organisms interact holistically with their environment, and any change in one or more environmental parameters (even unknown) can in principle be detected by observing changes in the organism. Bioassays can be used as early warning indicators of impacts and changes and are very sensitive. Some environmental changes cannot be detected instrumentally unless very sensitive (and generally costly) instruments are used, and some relevant variables can be overlooked by human observers. Organisms can be extremely sensitive, they integrate trends of changes and respond to several factors as an unit, which separately could be not detected. Another good reason to use bioassays in monitoring programmes is that we humans are organisms, and it is likely that an impact negative to an animal would be negative also to humans. Exploiting sympathy towards animals, the public can easily be convinced of the importance of the adoption of measures to protect environment against impacts. For this reason, campaigns to protect some flag animals have helped to protect important habitats.

This is the case of marine turtles for beaches. But, when beaches start degrading, turtles simply do not come to these beaches, which are then considered dead habitats. This is by no means true. Beach ecosystems are valuable in themselves and all possible measures should be undertaken to preserve beaches and warn against their degradation. We have proposed simple bioassays based on behavioural variation of very common animals, the talitrid sandhoppers, small crustaceans living on sand beaches.

These are abundant in most temperate beaches, with a number of related species. They are strictly adapted to the beach environment, rather robust and capable to rapidly re-colonise impacted beaches. We developed bioassays based on behavioural variation, which can be easily and rapidly estimated with simple tests on the beach self. Orientation to the shoreline is a quantitative behaviour, easily to analyse and interpret (results 38301 and 38224).

At one of the study sites of the MEDCORE project, in southern Tuscany, Italy, we tested the possibility of applying a bioassay based on orientation of sandhoppers to monitor beach erosion/accretion trend. Beach profiling is the usual method to monitor beach erosion, but it shouldn’t be used as a snapshot monitoring because it is strongly dependent on seasonal, climatic and tidal changes. Our hypothesis was that animals living on a beach know its trend of change and will orient accordingly. We tested this hypothesis by comparing four points distant one kilometer from each other on a beach subject to erosion near the river mouth and accretion at the opposite side. Comparing the distributions of orientation of sandhoppers tested in the four points at the same time by different teams, we could determine which was the equilibrium point of the shoreline. In fact the orientation of sandhoppers at that point was perfectly adapted to the orientation of the shoreline, while at the eroded and the accreting point we found higher scatter in orientation.

At another study site, on the north-western Mediterranean coast of Morocco, we found differences in orientation depending on the different uses of the beach: at one point there was no human impact except trampling in summer, while at the other site constructions directly impacted the beach. The application of this bioassay in monitoring beach degradation in long term monitoring, seems too simple when it is proposed to coastal managers. However it is based on a sound scientific background (see the documentation). We are further testing the method to compare beaches subject to different impacts on other coasts (eastern and southern Atlantic, Pacific, Baltic), with the collaboration of different teams of ecologists and geo-morphologists. We look forward to enhance the awareness of coastal mangers towards the organisms living on beaches and the importance of monitoring impacts.

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Felicita SCAPINI, (Professor)
Tel.: +39-055-2288217
Fax: +39-055-222565
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