Dear Collegues, in the Workshop on “practical implementation of WFD in the transitional waters in the Mediterranean Ecoregion”, which was held at the Ferrara meeting, the following points were raised:

1. At the EU-level there is a need for the definition of the typologies for the organisation of all groundwater, lotic and lentic freshwater, transitional and coastal marine ecosystems, in order to select the ecosystems for intercalibration;
2. The EU- Working Group (WG) on Transitional and Coastal Waters already defined Typology for coastal waters, while Typology for the Mediterranean transitional waters is not yet defined;
3. A preliminary division into deltas/estuaries and lagoons/coastal lakes was proposed but there is a need to evaluate if the grouping of all Mediterranean lagoons into a single Typology is coherent with the WFD aims or if a subdivision is required, and in this case which one.
4. Gianna Casazza, which is the reference person in the Coastal and Transitional Waters WG, encouraged us to organize an international sub-group with the objective to propose to the WG a Typology of Mediterranean lagoons, which is coherent with the WFD aims;
5. The definition of Typology of Mediterranean lagoons was considered an interesting objective for the LaguNet Network;
6. Typology can be defined both a priory, comparing our experience and expertise in order to reach a common expert view definition, and a posteriori through collection of available data in the view of selecting a minimum set of abiotic lagoon features, which could minimise the variance of the WFD quality element descriptors.

Point 6 represent our operative objective. To this aim, at the Ferrara meeting we decided to coordinate the expertises of the LaguNet Network and of other Mediterranean research groups in the attempt to reach an a posteriori definition of Typology of Mediterranean lagoons. The proposed approach was an application of niche theory (or niche science), based on the following stages.

1. definition of a set of structural abiotic features as major environmental niche axes for transitional Mediterranean waters, as a result of the views of the expert groups;
2. identification of a set of Mediterranean lagoons for which data on these structural features are available;
3. collection of data on structural features and identification of the available data set on the quality elements considered in the WFD;
4. collection of the available data for the quality element descriptors of selected biological quality elements (as those for which more information area available);
5. LaguNet meeting (also as e-conference) to discuss the statistical tools which can be used to investigate environmental niche dimensions explaining the variability of quality element descriptors;
6. organisation of working groups for the analysis of the collected data-base, with the following objectives:
   • a. to propose an a priori derived Typology, based on an expert view comparison;
   • b. to propose an a posteriori derived Typology, derived from the environmental niche analysis;
   • c. to compare the a priori and a posteriori Typologies.

To accomplish these stages we are publishing a WebSite on TW Typology (http://www.ecologia.ricerca.unile.it/TWTypology, temporary available as http://193.204.79.48); the website is organised in a open, free shared area and in a protected area for each working group that will participate to this project. Each group interested in the participation to this Working Group on Typology of Mediterranean lagoons can send an e-mail to the following addresses alberto.basset@unile.it; letizia.sabetta@unile.it to ask the username and password for its own protected page. On the protected page, a table with major structural abiotic features of lagoon ecosystems and a table with the quality elements descriptors will be included. Each group, following the instructions on the web page, is required (a) to order the structural features according to their relevance for the definition of Typology, (b) to fill in a table for each lagoon on which data are available, (c) to indicate which data on quality elements and quality element descriptors are available on those ecosystems. The name of the group and the indication of the ecosystems on which data were available are going to be reported in two separate lists on the open, free shared, page. The data inserted will not be available to other participants; each contributor when entering his personal page will find only the information he inserted and updated. As for our first LaguNet activity, the LOICZ budget definition for the Italian lagoons, we are planning to find finalise these activities into a number of common publications with the contribution of each participant. There are two potential forums for these activities: the publication of an Instant Book on Mediterranean lagoons, reporting synthetic contributions describing the available knowledge on each of the lagoons registered into our data base and the publication of a common paper on the application of “niche theory” to practical implementation of Typology of the Mediterranean lagoons. We are investigating the interest of some of the most relevant publishers and editors to the potential end-products of these activities. We will update information of this topic directly on the website. As an editorial group of this activity we will encourage you to send us your suggestion to improve this proposal, to communicate your contribution sending us a request of username and password, to ask us any additional information you will find useful. Yours Sincerely, Alberto BassetJose-Manuel Zaldivar ComengesNicholas Murray