Servicio de Información Comunitario sobre Investigación y Desarrollo - CORDIS


MED-CORE Informe resumido

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

Data bases on animal biodiversity in Mediterranean beaches

Changes in abundance, species richness, evenness and diversity of terrestrial beach invertebrates were assessed at increasing distance from the delta of the Ombrone river along the Tyrrhenian coast of Italy. During the study it was pointed out that the composition of the arthropod population changed according to its distance from the river mouth and that the increase in diversity was related to the increase of habitat diversity. Eroded areas, close to the river delta, were generally characterised by a small number of species and of individuals per species. Human disturbance (trampling) had also been considered as an important influencing factor and this was confirmed by seasonal comparisons. The analysis of beach morphology and of the chemical and physical characteristics of the substrate had also given important indications of the parameters implicated in the phenomenon.

A further step in the knowledge of how terrestrial beach arthropod communities changed in relation to their position occupied in space with respects to the mouth of a river is represented by a recent research conducted along a sandy beach ecosystems of Morocco. In this case species richness, abundance and diversity were studied on both sides of the Oued Laou river mouth and comparisons were made. Also the physical characteristics of the environment and the chemical and physical characteristics of the substrate were also assessed in order to find relationships with the biotic components of the system.

The main questions addressed were:
- Are the physical and chemical characteristics of the substrate the same on the stretch of coast to the left and right of a river mouth?
- Does beach morphology change according to the side of the river bank?
- If so are arthropod populations the same or do they change in relation to the side of the river mouth inhabited?
- How is species richness, diversity and abundance influenced by the environmental conditions found on the two sides of the river?

The recorded data give some interesting indications of the species distribution on the two sides of the Oued Laou river mouth. It is clear that the stations on the left side of the river mouth both supported a lower number of species and of individuals compared to the ones on the right side. This was particularly evident for the crustacean species.

The analysis of the sand parameters showed that finer sand was found at on the right side of the river whereas less compact sand and higher pH values were found on the left. Trends in beach slope were different on the two sides of the river mouth: a greater slope was found farther away from the mouth on the right side and closer to the river mouth on the left side. Regression analysis showed that negative correlations were always found between species abundance and environmental parameters, such as salinity and pH, indicating their importance in regulating species distribution.

Comparisons with the results obtained at the Maremma Regional Park showed substantial differences. At the Maremma beach the erosion process taking place at the river mouth had a great influence over species richness and abundance, whereas at Oued Laou being a more stable beach other environmental factors (presence/absence of a beach dune, more/less stable vegetation, low/high human impact) probably dominated the scenario. The higher alfa value found at the Maremma beach was probably in relation to the presence of a well developed and stable dune that in the case of Oued Laou was almost entirely absent or reduced as a relict presence.

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Istituto per lo Studio degli Ecosistemi, CNR
via Madonna del Piano
50019 Firenze
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