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Since its publication, the article ‘Towards\ud a functional classification of the freshwater phytoplankton’ (Reynolds et al., J Plankton Res 24: 417–428, 2002), has attracted the attention of dozens of phytoplankton ecologists worldwide. These numerous applications of the functional classification to describe phytoplankton patterns in various aquatic ecosystems allowed the recognition of some uncertain features of this concept originating from various reasons. In this article, we attempt to facilitate the application of the functional classification, by providing a detailed description of the typical misplacements and by modifying some of the original habitat templates and species allocations. Furthermore, we discuss in this review those coda that were additionally described after the publication of the original article, and attempt giving an overview, as complete as possible, of the state of art

According to the Intergovernmental Panel on Climate Change report released in September 2014, unprecedented changes in temperature and precipitation patterns have been recorded globally in recent decades and further change is predicted to occur in the near future, mainly as the result of human activity. In particular, projections show that the Mediterranean climate zone will be markedly affected with significant implications for lake water levels and salinity. This may be exacerbated by increased demands for irrigation water. Based on long-term data from seven lakes and reservoirs covering a geographical gradient of 52°of latitudes and a literature review, we discuss how changes in water level and salinity related to climate change and water abstraction affect the ecosystem structure, function, biodiversity and ecological state of lakes and reservoirs. We discuss mitigation measures to counteract the negative effects on ecological status that are likely to result from changes in climate and water abstraction practices. Finally, we highlight research required to improve knowledge of the impacts of anthropogenically induced changes on lake water level and consequent changes in salinity.

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SUMMARY1. Ecologists often group organisms based on similar biological traits or on taxonomic criteria. However, the use of taxonomy in ecology has many drawbacks because taxa may include species with very different ecological adaptations. Further, similar characters may evolve independently in different lineages. 2. In this review, we examine the main criteria that have been used in the identification of nine modes of classifying phytoplankton non-taxonomically. These approaches are based purely on morphological and/or structural traits, or on more complex combinations including physiological and ecological features. 3. Different functional approaches have proved able to explain some fraction of the variance observed in the spatial and temporal distribution patterns of algal assemblages, although their effectiveness varies greatly, depending on the number and characteristics of functional traits used. The attribution of functional traits to single species or broad groups of species has allowed a few classifications (e.g. Functional Groups, FG) to be used in the assessment of ecological status. 4. We stress that the misuse of functional classifications (by applying them under conditions other than those intended) can have serious consequences for interpreting ecological processes. Assigning functional traits or groups cannot be considered a surrogate for the knowledge of species or ecotypes, and the use of specific traits must always be justified and circumscribed within the limits of ecological questions and hypotheses. 5. An important future challenge will be to integrate advances in molecular genetics, metabolomics and physiology with more conventional traits; this will form the basis of the next generation of functional classifications.

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Water-level fluctuations, often linked to seasonal climatic trends, are a natural phenomenon which occur in almost all aquatic ecosystems. In some climatic regions, as the Mediterranean one, they are particularly wide due to the occurrence of two well separated periods: the rainy winter and the almost completely dry summer. Precipitation is concentrated in the first period, whereas in the second strong evaporation losses take place. According to these climatic features, and to ensure a continuous supply of water throughout the year, man-made lakes store water during winter and are subjected to dewatering during summer to compensate the lack of precipitation. These ecosystems are thus characterised by rather wide water level fluctuations which were observed to transform them from potentially warm monomictic lakes into polymictic or atelomictic ones. These changes deeply affect the biological structure and the functions of the water bodies impairing the response of some ecosystem properties, as resilience and resistance, since the impacts are immense enough to move the systems out of their homeostatic plateau of, respectively, deep or shallow lakes. In order to understand to what extent a reservoir can be ''emptied'' without changing its ecosystemic identity (deep or shallow lake sensu Padisa´k & Reynolds, 2003) and to set a ''dewatering threshold'', the results from two different hydrological years, one with a dewatering so intense as to disrupt thermal stratification in midsummer, and the other one with water enough to allow the maintenance of the reservoir's thermal structure throughout the summer, are compared. Former investigations have shown that the persistence of thermal stratification has a positive value in Sicilian reservoirs: a notable decrease in total phytoplankton biomass and in the relative occurrence of cyanoprokaryotes was observed in the highlevel year with a stable thermal stratification. Although the solving of the external load problems causing eutrophication phenomena remain the main task to improve the water quality of this Mediterranean island, a management procedure, based on the maintaining of the ecosystem within its homeostatic plateau through the setting of a dewatering threshold, is suggested.

This paper summarises the outcomes of the 14th Workshop of the International Association of Phytoplankton Taxonomy and Ecology (IAP). The authorsmostly addressed their contributions on the following topics: morphological and morphofunctional descriptors of phytoplankton, size and shape structure of phytoplankton related to different kinds of environmental variables and the role of morphological and physiological plasticity of phytoplankton in maintaining the (apparently) same populations under different environmental conditions. Case studies from different kinds of aquatic environments (deep and shallow lakes, reservoirs with different age, purpose and trophic state, floodplain wetlands mostly in the temperate region but also from subtropical and tropical ones) have shown that similar environmental forcing calls for similar morpho-functional properties even though the corresponding associations can be markedly different on species level