The COLASU research project focused on the study of Nador lagoon in Morocco, the second largest lagoon complex of northern Africa, and on El Meleh, a small coastal lagoon located near the town of Slimene in Tunisia.

Detailed insight into the existing knowledge on both study areas from a climate, geological, geomorphological, hydrogeological, legislative and socio-economic point of view was achieved through a bibliographic synthesis.

Sampling campaigns of different types of samples (water, sediment, soil) constituted a very important component of this project, as these provided essential information to establish possible evolution scenarios.

Locations of sediment and soil samples in Winter 2003 Campagin

Considerable attention was given to the formulation of a sampling protocol, which among other, provided standardized criteria to document the sample collection during fieldwork and to report on the various analyses, performed at the different partner laboratories. In accordance with the established protocol, the chemical and mineralogical composition of sediments and soils, as well as micropaleontology, organics, mobility, bioavailability and Fe speciation (Mössbauer spectroscopy) in selected sediments were analyzed by different methods, and compiled in a database of analytical results. A geochemical interpretation based on the normalization of trace and major elements was used to produce a present state water contamination map in both lagoons.

To guide the morphodynamic assessment, GIS was used as a spatial analytical tool to document the geological, geomorphological, hydrological data layers, as well as the anthropogenic activities, resulting in a substantial increase of the database of regional maps for both study areas.

Two groups of benthic organisms, ostracoda and foraminifera, were selected as tracers of the environmental conditions in the coastal lagoons, and resulted in the delineation of the main ecosystem assemblages in both lagoons.

Ecological zonation of Nador and El Meleh lagoon

Based on the spatial variations of water parameters, sediment and soil properties and microfauna, a morphodynamic scenario for both lagoons emerged.

The delineation of zones with common characteristics in terms of pollution levels within each of the lagoons, was then evaluated in relation to the anthropogenic activities found within their catchment. A very high heavy metal pollution in the bottom sediments and the almost disappearance of the bottom microfauna was observed in the confined, northwestern part of Nador lagoon, most likely caused by the absence of environmental controls on the tailing pond of the Atalayoum old iron mine. The Slimene water treatment plant produces an important impact in the southwestern confined area of El Meleh lagoon, with the presence of polyhaline, nearly oligohaline waters with the highest nutrient concentrations of the lagoon.

Integrated Environmental Assessment of Water, Soil and Ostracod Assemblages

Comparison of the present state maps with two old bathymetric maps of Nador and two historical earlier photographs of El Meleh, allowed to outline some future trends in the evolution of both lagoons. This revealed that in the case of Nador, it is essential to maintain the connection with the Mediterranean Sea through the sandy barrier, since an interruption of the marine inputs will cause drastic changes in the lagoon ecosystem and the acceleration of the natural evolution from the present lagoon to a broad sebkha.? The trend in El Meleh suggests a continued, gradual isolation of the very shallow zones with permanent water from tidal fluxes and their conversion into salt marshes.

At the site specific scale, the Life Cycle Assessment (LCA), a standard tool to assess the environmental impact of a system from the production of raw materials to the disposal of the final waste products (ISO 14040) was applied to three anthropogenic activities: the water treatment stations of Nador and Slimene, and the Marost aquaculture concern in Nador lagoon.

Two PhD students from Morocco and Tunisia together with 2 MSc students in Environmental Sciences received training in LCA and then progressed with the collection of data as required to complete each of the four logical steps that are found in the classical LCA approach: 1) goal and scope definition, 2) inventory analysis, 3) impact assessment, and 4) interpretation. This result could not have been achieved without the active support and assistance of RADEEN, ONAS and MAROST, who welcomed the Colasu researchers.

Research into a possible coupling or linkage between the "site specific" and the "catchment scale", led to the development of a new approach to the LCA, in which it is recognized that the system under investigation is not an industrial process but an ecosystem. This novel approach was tested by assessing the impact factors on the eutrophication potential in both lagoons.

LCA methodology applied to an ecosystem: a novel approach

Finally, in terms of lagoon management, the site specific scale provides guidelines, drawn up in the format of technical cards, aimed particularly to assist the above mentioned organisations concerned with wastewater treatment and aquaculture. Recommendations at the catchment scale, which are likely to be of interest to a larger group of stakeholders concerned with the management of coastal zones, provide an outline description of the harmful effects of individual heavy metals on human health; good practice for the identification of heavy metals in water, sediments and soils; and a summary of the research outputs aimed at demonstrating the use of two distinct tools that were used in Colasu for the purpose of lagoon management: GIS and LCA.

In addition to two Moroccan and Tunisian PhD, and two MSc degrees in the framework of Colasu, the AUF (Agence Universitaire de la Francophonie) has awarded a PhD bursary to study the impact of heavy metals and pesticides on El Meleh lagoon.? This thesis will employ the LCA, adapted in Colasu to study an ecosystem rather than an industrial process, and will continue to monitor the pollution transfer within the lagoon until 2007, i.e. up to two years after the end of the Colasu project.