An overview of ecological status, vulnerability and future perspectives of European large shallow, semi-enclosed coastal systems, lagoons and transitional waters. Estuarine, Coastal and Shelf Science,

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ABSTRACT1. Transitional waters, described as critical transition zones because of their position at terrestrial, freshwater and marine interfaces, provide essential goods and services to the biosphere including human populations. These ecotones face increasing human influence mainly due to population density increase in coastal areas.2. Transitional water bodies have, to date, received little attention in the development of ecological status indicators; this is a critical deficiency when trying to meet the Water Framework Directive objective of all significant water bodies achieving good ecological status by the year 2015.3. In order to assess changes in transitional water communities many taxonomic-based indicators have already been proposed but there are a number of concerns for their use such as taxonomic classification difficulties, their unsuitability for multi-site comparisons and their inconsistent relationships with disturbance or stress.4. Alternative methods based on body size, abundance distribution among functional groups, functional diversity and productivity descriptors are proposed. These methods offer the opportunity to compare sites with different taxonomic compositions and allow derivation of indicators related to ecological status of communities under scrutiny.5. Finally, the suitability of these taxonomic-free descriptors to provide relevant information for each of the four main biotic compartments in coastal lagoons is discussed. The use of biomass distribution among functional groups for fish, benthos and macrophyte and to use body-size distribution for benthos and plankton is proposed.

ABSTRACT1. Benthic community parameters were studied in six coastal brackish-water lagoons located in western Greece (Ionian Sea). Five of the lagoons studied are around the coast of the Amvrakikos Gulf under the influence of the Rivers Louros and Arachthos and one lagoon is situated in northwest Peloponissos.2. All the lagoons experienced a wide range of temperatures, salinities and dissolved oxygen due to their high degree of confinement and shallow depths. Confinement and sediment composition were the major factors affecting number of species and biodiversity of benthic communities.3. The Shannon diversity index does not appear to be efficient in discriminating between natural stress and anthropogenic disturbance in lagoonal ecosystems.

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ABSTRACT1. Transitional waters are ecotones between terrestrial, freshwater and marine ecosystems, being characterized by high spatial heterogeneity and temporal variability.2. The EU Water Framework Directive (WFD) posed to the scientific community the challenge to classify these ecosystems into a small number of types, while retaining a functional classification of ecosystem types.3. A niche theory approach is proposed to identify the limiting forcing factors organizing biological quality elements, i.e. the limiting niche dimensions.4. The analysis of a macro-invertebrate dataset from published papers on 36 Italian lagoons suggested a two-level typological classification of Mediterranean lagoons.5. Basic ecological theories, such as niche and island biogeography theories, have fundamental implications for the process of developing a typological classification for all aquatic ecosystems, as required by the WFD.

Abstract. The temporal variations of nutrients, chlorophyll a (chl a), suspended particulate matter (SPM) and particulate organic carbon (POC) were measured over 12 months in three shallow coastal brackish water lagoons of the Amvrakikos Gulf, Ionian Sea. Two of the lagoons, Tsoukalio and Rodia, are interconnected but separated from Logarou by a narrow strip of land. Logarou has a better water exchange with the sea as indicated by the higher salinity and dissolved oxygen concentrations and the smaller variation of the above‐mentioned parameters. Nitrate concentrations were largely the same in the three lagoons and higher than in the Amvrakikos Gulf. Phosphate concentrations in Logarou exceeded by far those of Tsoukalio/Rodia; the increased phosphate levels recorded in January caused an extended phytoplankton bloom with chl a concentrations higher than in the other two lagoons. Chl a in Tsoukalio was positively correlated with nitrate whereas in the most shallow lagoon, Logarou, it showed a positive correlation with light winds (force 4 and lower), probably caused by resuspension from the sediment. Increased phytoplankton biomass in Logarou coupled with the better water exchange may be related to the higher fish production in this lagoon.

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