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DNA damage is one of the most important effects induced by chemical agents. We report a comparative analysis of DNA fragmentation on three different cell lines using terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL) assay, generally applied to detect apoptosis. Our approach combines cytogenetic techniques and investigation in detached cellular structures, recovered from the culture medium with the aim to compare the DNA fragmentation of three different cell line even beyond the cells adherent to substrate. Consequently, we detect any fragmentation points on single chromosomes, whole nuclei and other cellular structures. Cells were exposed to resveratrol (RSV) and doxorubicin (Doxo), in single and combined treatments. Control and treated astrocytes showed DNA damage in condensed nuclei and detached structures. Caco-2 cells showed fragmented DNA only after Doxo-treatment, while controls showed fragmented chromosomes, indicating DNA damage in replicating cells. MDA-MB-231 cells showed nuclear condensation and DNA fragmentation above all after RSV-treatment and related to detached structures. This model proved to perform a grading of genomic instability (GI). Astrocytes show a hybrid level of GI. Caco-2 cells showed fragmented metaphase chromosomes, proving that the DNA damage was transmitted to the daughter cells probably due to an absence of DNA repair mechanisms. Instead, MDA–MB-231 cells showed few or no fragmented metaphase, suggesting a probable activation of DNA repair mechanisms. By applying this alternative approach of TUNEL test, we obtained data that can more specifically characterize DNA fragmentation for a suitable application in various fields. [ABSTRACT FROM AUTHOR]

This paper introduces and summarises the main outcomes of the 19th workshop of the International Association for Phytoplankton Taxonomy and Ecology held in Tiszafüred, Hungary, Tisza Balneum Hotel, from 23 to 30 September 2022. The selected theme of the workshop was "Trait-Based Approaches in Micro-Algal Ecology". The discussions presented during the workshop sessions resulted in the 18 articles contained in this Special Issue. There are 6 main thematic aspects developed by the participants: 1. Shape and size: are these traits easy to measure? 2. Spatial scales: when and where to look for microalgae? 3. Climate and extremes of ecological gradients: hot topics of this century. 4. Metaphyton and metaphytic habitats: life beyond plankton and benthos. 5. Microalgae in water management: phycology in practice. 6. Traditional and new methods: perspectives and comments. Trait-based approaches in microalgae ecology, although requiring further investigation and methodological development, represent a valid tool for refining the analysis of environmental variability in aquatic ecosystems. The papers presented in this Special Issue demonstrate that these approaches are extremely useful not only in the study of planktic algae but constitute a thoughtful method for the analysis of benthic and metaphytic microalgae in a wide variety of aquatic ecosystems. [ABSTRACT FROM AUTHOR]

Understanding the dynamics of phytoplankton assemblages in various and variable aquatic ecosystems is of paramount importance, given the strategic supporting services offered by these organisms. Such knowledge is implicitly based on the analysis of the realized niche of the different populations, i.e. of the sets of conditions within which populations show a positive growth. The range of phytoplankton morphological traits variability is evolutionarily selected to maximize the ecological performance of species while they are entrained in the spectrum of turbulent flows. In addition, most phytoplankton species exhibit high morphological plasticity that can further optimize their performance under reduced environmental variability. Although this plasticity is well known, it is seldom considered in phytoplankton studies. Morphological analysis could therefore be used as a tool to estimate the environmental variability within which a species can persist and, ultimately, the niche width of phytoplankton populations. This opinion paper tries to answer the questions: to what extent can the morphological variability of phytoplankton offer a synthesis of the environmental variability of aquatic ecosystems?. Do the morphological traits contain sufficient information to describe the width of the realized niche of phytoplankton species? What can we do to fill eventual gaps in our knowledge? [ABSTRACT FROM AUTHOR]

Even in a biodiversity hotspot such as the Mediterranean basin, aspects relating to the distribution of some groups of microcrustaceans still need clarification. In this paper, we critically analyse the available information on diaptomid copepods in Tunisian inland waters and, based on the largest sampling campaign to date carried out in the country, report new data on their distribution. In the frame of this study, 248 crustacean samples were collected from 190 sites, and 10 diaptomid species belonging to 7 genera and 2 subfamilies were found in the samples. Their distribution follows a climate gradient determined by precipitation, and ecological variables mainly affect diaptomid distribution in the study area, while pure spatial factors are of negligible importance. Diaptomid biodiversity is therefore strongly linked to the diversity of inland waters that characterise the country. This is especially true in the wetlands of the Medjerda alluvial plain, where six diaptomid species co-occurred sympatrically, with up to four or five species coexisting syntopically and synchronically in some sites. Unfortunately, the natural water bodies of this plain are currently strongly threatened by urban expansion and agricultural reclamation, and the risk of local extinction for the species they host is increasingly high. [ABSTRACT FROM AUTHOR]

The text is a preface to a special issue of the journal Hydrobiologia, titled "Trait-Based Approaches in Micro-Algal Ecology." The preface provides an overview of the 19th workshop of the International Association of Phytoplankton Taxonomy and Ecology (IAP), which focused on trait-based approaches in micro-algal ecology. The workshop brought together scientists and students from various countries to discuss ecological topics and practice species identification. The preface also mentions the history of the IAP workshops and the special issue's dedication to Colin S. Reynolds, a prominent phytoplankton ecologist. The special issue includes a selection of review and research papers covering a wide range of spatial and temporal scales and aquatic habitats. The authors express gratitude to the referees, editorial staff, and workshop participants. [Extracted from the article]

Phytoplankton, the ecological group of microalgae adapted to live in apparent suspension in water masses, is much more than an ecosystem's engineer. In this opinion paper, we use our experience as phytoplankton ecologists to list and highlight the services provided by phytoplankton, trying to demonstrate how their activity is fundamental to regulate and sustain Life on our Planet. Although the number of services produced by phytoplankton can be considered less numerous than that produced by other photosynthetic organisms, the ubiquity of this group of organisms, and their thriving across oceanic ecosystems make it one of the biological engines moving our biosphere. Supporting services provided by phytoplankton include almost half of the global primary and oxygen production. In addition, phytoplankton greatly pushes biogeochemical cycles and nutrient (re)cycling, not only in aquatic ecosystems but also in terrestrial ones. In addition, it significantly contributes to climate regulation (regulating services), supplies food, fuels, active ingredients and drugs, and genetic resources (provisioning services), has inspired artistic and craft works, mythology, and, of course, science (cultural services), and much more. Therefore, phytoplankton should be considered in all respects a true biosphere's engineer. [ABSTRACT FROM AUTHOR]

Guest editors: Verónica Ferreira, Luis Mauricio Bini, Katya E. Kovalenko, Andre A. Padial, Judit Padisák & María de los Ángeles González Sagrario / Aquatic Ecosystem Services Introduction to ecosystem services Millennium Ecosystem Assessment The dependency of human wellbeing from ecological systems has been long recognized. The ecosystem services approach has provided background and motivated international legislation and agreements aiming to halt and reverse ecosystem degradation and biodiversity loss, such as the Intergovernmental Platform on Biodiversity and Ecosystem Services (IPBES), the UN Decade on Ecosystem Restoration, and the EU Nature Restoration Law. The papers included in this Special Issue, together with reviews on ecosystem services provided by other aquatic ecosystems and organisms (e.g., Barbier et al., [2]; Macadam & Stockan, [25]; Hilt et al., [14]; Riis et al., [37]; Janssen et al., [16]), contribute to highlighting the relevance of these ecosystems and organisms to human wellbeing, and emphasizing the need for their conservation and restoration. This is followed by 6 reviews addressing ecosystem services provided by specific aquatic ecosystems and 12 reviews addressing ecosystem services provided by different groups of aquatic organisms (Table 2). [Extracted from the article]

The relationship between species diversity and ecosystem functioning is one of central topics in modern ecology, but variable and controversial patterns have been found depending on ecosystem type, organism type and scale. Such patterns call for mechanistic exploration within an integrative modelling framework. Lakes, especially reservoirs, are highly disturbed ecosystems, and the relationships between species diversity and ecosystem functioning likely differ from those of terrestrial ecosystems. Disturbance can have a great impact on local diversity and resource use efficiency (RUE) of phytoplankton assemblages and thereby influence these relationships. To elucidate how disturbance influences the diversity of phytoplankton and its relationship with ecosystem functioning, we analysed datasets from two groups of waterbodies (large-sized reservoirs and small-sized reservoirs) subjected to different disturbance regimes. We also investigated the mechanisms potentially underlying the relationships using structural equation modelling. A unimodal relationship between species richness and productivity was found in large-sized reservoirs and in small-sized reservoirs in dry seasons, while a positive linear relationship was detected in small-sized reservoirs in wet seasons. Cyanobacteria dominance increased the RUE of phytoplankton and decreased its evenness more significantly in large-sized reservoirs than in small reservoirs. The effects of water temperature and resources availability (TP) on species richness also changed with disturbance regimes. Disturbance is an important factor modifying the responses of phytoplankton communities to environmental gradients, and disturbance regimes at regional scale can largely shape the relationship between phytoplankton diversity and ecosystem functioning. [ABSTRACT FROM AUTHOR]

The analysis of ecological niche is an important task to correctly identify the role exerted by species within ecosystems, to assess their vulnerability, to plan effective measures addressed at fulfilling the postulates of biological conservation, and ultimately to prevent biodiversity loss. However, for the majority of organisms our knowledge about the actual extent of their ecological niche is quite limited. This is especially true for microscopic organisms. Evidence exists that in different geographical areas allegedly conspecific populations can show different, if not antithetical, ecological requirements and not-overlapping ecological niches. This opinion paper discusses whether this "niche displacement" effectively occurs between conspecific populations or if the pattern is rather due to an inaccurate identification of species and/or to an insufficient knowledge about population and community ecology. Hence, some subjectively selected study cases when alleged phenomena of niche displacements take place are presented, and shortfalls in the correct assessment of the identity and ecological niches of microscopic aquatic eukaryotes, namely phytoplankton, zooplankton, and meiofauna are shown. [ABSTRACT FROM AUTHOR]

The aim of the present work is the evaluation of biological effects of natural stilbenoids found in Vitis vinifera, with a focus on their activity as epigenetic modulators. In the present study, resveratrol, pterostilbene and for the first time their dimers (±)-trans-δ-viniferin, (±)-trans-pterostilbene dehydrodimer were evaluated in Caco-2 and HepG-2 cell lines as potential epigenetic modulators. Stilbenoids were added in a Caco-2 cell culture as a model of the intestinal epithelial barrier and in the HepG-2 as a model of hepatic environment, to verify their dose-dependent toxicity, ability to interact with DNA, and epigenomic action. Resveratrol, pterostilbene, and (±)-trans-pterostilbene dehydrodimer were found to have no toxic effects at tested concentration and were effective in reversing arsenic damage in Caco-2 cell lines. (±)-trans-δ-viniferin showed epigenomic activity, but further studies are needed to clarify its mode of action. [ABSTRACT FROM AUTHOR]

The current trend of continuous biodiversity loss resulted in several international and national regulations and funding schemes to target biodiversity protection and halt its loss. Conceiçao et al. ([3]) use niche-based models to predict changes in ostracod diversity in South America as a result of future climate change in order to formulate evidence-based management plans for aquatic ecosystems. Guest editors: Koen Martens, Sidinei M. Thomaz, Diego Fontaneto & Luigi Naselli-Flores / Emerging Trends in Aquatic Ecology IV Our understanding of aquatic ecology and ecosystem functioning continuously improves. [Extracted from the article]

Van Rees et al. ([6]) make it the first of their 14 Special Recommendations for global freshwater biodiversity conservation, that freshwater should be considered a true ecological "third realm that deserves legal and scientific prominence in future frameworks and strategies" and provide solid arguments for this. The Alliance for Freshwater Life (https://allianceforfreshwaterlife.org/) launched a global call to unite efforts for freshwater biodiversity in science and conservation (Darwall et al., [1]). This year 2023, we have two milestones to celebrate for Hydrobiologia. [Extracted from the article]

This editorial is aimed at explaining why the editors of Hydrobiologia are so concerned with biological nomenclature and why we ask our authors the utmost precision when referring to species in their papers. In fact, the name of the describer that follows the binomen (genus name + species epithet) not only offers information about who described that species (and eventually when) but in some way summarises the "history" of the classification work that was necessary to describe that species. E.g., I Anguilla anguilla i (Linnaeus, 1758): Linnaeus described this species as I Muraena anguilla i and later on the species was moved to the genus I Anguilla i . [Extracted from the article]

There is hardly any sunshine exposed surface on this Earth, be it water or terrain, which would not support some biota. Still, many habitats offer harsh conditions requiring specialized physiological adaptations to survive. These environments are referred to as extremes; often inhabited by extremophilic organisms. In this review, characteristic species and assemblage properties of phytoplankton inhabiting extreme environments (especially lakes and pools where planktic life is potentially possible and independently of their origin) in terms of alkalinity, acidity, DOC, salinity, temperature, light and mixing regime will be outlined. Lakes characterized by more than a single extreme are common (e.g. saline + alkaline; acidic + high DOC + high metal content + low light). At the edge of extremes (e.g. pH of 1; salinity over ~ 100–150 g l−1) single species with appropriate physiological adaptation are selected and the phytoplankton is often dominated by a single species (monodominant) setting compositional diversity to zero. Under less extreme conditions permanent equilibria may persist; in many cases over several years in contrast to „average" lakes where equilibria are rare and ephemeral. Food webs depending on „extreme phytoplankton" are often atypical for example because the microbial loop is of prior importance or because birds are top predators. [ABSTRACT FROM AUTHOR]

The amazing morphological diversity of phytoplankton has to be considered an evolutionarily driven compendium of strategies to cope with the strong variability and unpredictability of the pelagic environment. Phytoplankton collects unicellular and colonial photosynthetic organisms adapted to live in apparent suspension in turbulent water masses. Turbulence represents a key driver of phytoplankton dynamics in all aquatic ecosystems and phytoplankton morphological variability is the evolutionary response of this group of photosynthetic organisms to the temporal and spatial scales of variability of turbulence. This paper reviews the existing literature on the effects exerted by turbulence on phytoplankton populations and is aimed at showing how deeply turbulence contributes to the shape and size structure of phytoplankton assemblages. Our aim is to explore how turbulence governs phytoplankton access to resources and, at the same time, how the shape and size structure of phytoplankton represent the evolutionary way in which this group of organisms has optimised its survival in the highly dynamic aquatic environment. The paper is intended to serve as an homage to the (phytoplankton) ecologist Colin S. Reynolds. His life-long work highlighted how profoundly the ecology of phytoplankton depends on the physical constraints governing the movements of the water masses in which phytoplankton evolved and lives. [ABSTRACT FROM AUTHOR]

The special issues of this series are organized by Hydrobiologia editors and at least one of the authors of each paper is a Hydrobiologia editor. The authors identified ecosystem and geographic bias in the literature which focused on ecosystem functions: freshwater received far more attention than marine ecosystems, and Europe and North America have been much more studied than any of the other continents. Also, the majority of studies which claim to study ecosystem functioning actually investigated ecosystem structure, while many studies investigated proxies instead of real functions. Braga et al. ([2]) conducted an experiment in mesocosms to investigate if invasive species impacts on native communities and ecosystem functions are related to synergistic, antagonistic or additive interactions between invasive species. [Extracted from the article]

Correctly identifying and mapping the distribution patterns of passively dispersing freshwater organisms is an important task to understand the mechanisms through which these organisms move across the world and to counteract the introduction of invasive alien species in a timely way; moreover, in the light of the growing evidence of the pervasiveness of cryptic species and cryptic biological invasions among all animal groups, the use of molecular identification tools is strongly advisable. In this context, we present the first record of the freshwater jellyfish Craspedacusta sowerbii Lankester, 1880 in the Mediterranean island of Sicily, Italy. This invasive species, native to China, was found during a routine survey campaign aimed at assessing the freshwater species richness in the Sicilian region. Individuals were collected in November 2017 and identified to species level through the sequencing of fragments of both mitochondrial and nuclear genes, and their comparison to the sequences available on public databases. The analysis of molecular data proved that the Sicilian population belongs to C. sowerbii s.s., i.e. one of the two major Craspedacusta lineages which have been discovered to have invaded Europe and which were until recently erroneously jointly reported under the binomen Craspedacusta sowerbii. In order to get a clearer picture of the history and patterns of freshwater jellyfish invasion worldwide, the need for molecular identification of all the non-native Craspedacusta populations currently reported as C. sowerbii, and the opportunity of monitoring human-impacted ecosystems is stressed. [ABSTRACT FROM AUTHOR]

Mixotrophy is a combination of photosynthesis and direct access to organic carbon sources, mainly through osmotrophy or phagotrophy. This strategy is adopted by several, phylogenetically distinct, phytoplankton groups and is commonly occurring in marine, brackish and freshwater ecosystems. Traditionally, it has been put in relation to both scarcity of inorganic nutrients and poor light conditions. However, we observed blooms of the mixotrophic, toxic haptophyte Prymnesium parvum in different periods of the year and under variable resources availability. The analysis of a 6.5-year data set of phytoplankton weekly records from a Sicilian shallow lake (Biviere di Gela, south-eastern Sicily) allowed us to hypothesise that a depleted condition as regards inorganic nutrients is not the main fuel to the growth of P. parvum, neither this is due to light limitation. The results achieved show that an increased availability in suitable preys can stimulate the growth of this phagotrophic photoautotroph. Contemporarily, it was not found any clear environmental patterns to explain species dominance and growth patterns as related to inorganic nutrient availability. Moreover, it is shown that these organisms tend to monopolise resources when these become available irrespective of seasons, and under variable conditions as regards inorganic nutrient availability. [ABSTRACT FROM AUTHOR]

Information about the 18th International Association of Phytoplankton Taxonomy and Ecology workshop held in Natal, Brazil from August 27 to September 3, 2017 is presented. During the event, attendees listened to the discussions of speakers about phytoplankton taxonomy, mixotrophic microalgae, and biotic interaction analysis.

Reservoirs are river-lake hybrid ecosystems characterized by a marked longitudinal zonation and variable flushing rates depending on the use of stored waters. The structure of their phytoplankton is therefore subjected to the interplay between the environmental conditions of the different zones (species sorting) and the strength of the unidirectional flow (mass effect). The spatial distribution of spring phytoplankton was investigated in a tropical reservoir across its different zones. Phytoplankton displayed heterogeneous spatial patterns from the turbulent, nutrient-rich riverine zones to the relatively stable lacustrine zone. The analysis of this spatial heterogeneity revealed the relative importance of species sorting and mass effect in this morphologically complex reservoir. Different taxonomic groups showed different spatial patterns due to their specific physiological and morphological features, and as a result of the local environmental filtering. In the studied reservoir, the strength of the homogenizing effect of water flow did not smooth the spatial heterogeneity and played a weak role in constraining spring phytoplankton. Actually, water flow contributed to the spatial heterogeneity of phytoplankton by enhancing the local environmental differences caused by an operational drop in water level, and species sorting resulted as the primary forcing in determining spring phytoplankton spatial distribution. [ABSTRACT FROM AUTHOR]

Objective and design: Epigenetic regulation is important in the activation of inflammatory cells. In the present study, we evaluated if DNA-methylation variations are involved in Interleukin-1β (IL-1β)-induced intestinal epithelial cells activation.Materials and methods: Differentiated Caco-2 cells were exposed to IL-1β or to 5-azadeoxycytidine (5-azadC) for 24 or 48 h. Genome-wide methylation status was evaluated, while DNA methylation status at the promoter region of the gene encoding interleukin-6, 8 and 10 (IL-6, 8 and 10) was estimated. The levels of the corresponding gene products as well as DNA methyltransferases (DNMTs) quantity were assessed.Results: IL-1β decreased genomic methylation of human intestinal epithelial cells and induced demethylation at cg-specific sites at the promoter of pro-inflammatory genes IL6 and IL8; conversely it did not change the methylation of the IL10 promoter. IL-1β also increased the release of IL-6 and IL-8 but did not change the IL-10 expression. Finally, cell exposure to IL-1β decreased the DNMT3b expression, increased DNMT3a and was not able to change DNMT1 expression.Conclusions: Our results suggest a potential role of IL-1β as modulator of DNA methylation in activated differentiated Caco-2 cell line. [ABSTRACT FROM AUTHOR]

Spatial patterns and β-diversity of phytoplankton assemblages depend on the relative importance of species dispersal capacity and species-sorting. Variability in species composition, composed by differences in species richness (nestedness) and/or species replacement, may be caused by niche availability and environmental selection. A field survey was carried out in Tibetan plateau on 38 lakes. Tibetan plateau lakes, located at high elevation, are harsh ecosystems characterized by low temperatures, low available nutrients, high UV amount, and strong salinity gradients. Only well-adapted species can survive in these environments. We therefore hypothesized that environmental filtering was the main factor determining phytoplankton assemblage structure in these lakes, and that species nestedness largely contributed to β-diversity. Spatial analysis showed that both environmental variables and broad-scale spatial variables accounted for the variation of phytoplankton assemblages. In particular, phytoplankton was mainly shaped by spatially structured environmental heterogeneity, which resulted in low α-diversity and high β-diversity. In contrast to our assumption, species turnover contributed to the majority of β-diversity of the studied assemblages. Local environments selected species with the corresponding stress-tolerant traits. Within the narrow range of available niches, environmental filtering of phytoplankton traits induced species’ replacement along environmental gradients. [ABSTRACT FROM AUTHOR]

We present a summary of responses to our call among scientists working on Anostraca to commemorate the late Professor Graziella Mura, a pioneer of modern studies on this group of animals. Colleagues from all over the world promptly answered and contributed their works among which we selected the fourteen papers published in the Hydrobiologia Special Volume 'New Challenges in anostracan research: a tribute to Graziella Mura'. Although Anostraca are widespread globally, they are among the least known taxonomic groups. Although some biogeographical data are available for some species and higher taxa, we are still far from a clear understanding of the phylogeny, ecology and biogeography of the order. The papers collected in this Special Volume are therefore intended to represent a step ahead to solve phylogenetic and ecological issues relative to this charming group of crustaceans. [ABSTRACT FROM AUTHOR]

An introduction to the journal is presented which focuses on the anostracan research of Graziella Mura.

An introduction is presented in which the editor discusses articles in the issue on topics including contribution of environmental heterogeneity; sedimentary diatom profiles in the U.S. Rocky Mountains; and cryptic diversity and speciation patterns in Cytherissa.

Phytoplankton in a complex network of reservoirs for drinking water supply was sampled in the dry and flood seasons to understand the role of dispersal through hydrochory and of environmental filters in determining the phytoplankton abundance and composition. The main assumptions tested in the present study are that (i) phytoplankton structure in these waterbodies is strongly dependent on the transportation with the river waters flowing through them and (ii) the importance of this stochastic transportation is decreasing as the connectivity with the river decreases allowing environmental filters to shape phytoplankton structure. The multivariate analysis showed that although phytoplankton was inoculated largely by Pearl River water inputs and inflow among the system, the hydraulic architecture of the reservoir network shaped and modulated the composition and abundance of phytoplankton. [ABSTRACT FROM AUTHOR]

Diaptomid copepods are an important component of biodiversity in inland aquatic ecosystems worldwide but to date little is known about the historical and ecological factors that determined their current distribution. In the present paper, a critical review of the available literature on diaptomid species distribution in the Western Palearctic was performed, and a biogeographical analysis was carried out on the roles that spatial, current environmental, and historical (paleoclimatic) factors played on their actual distribution in this large area. The results show a clear pattern of colonization which is only partially overlapping what has been recently proposed for other terrestrial and aquatic taxa. Disentangling beta diversity into its turnover and nestedness components, we hypothesized a complex post-glacial pattern of recolonization of the higher latitudes, encompassing the importance of extra-Mediterranean refugia in the West (due to mountain chains which represent effective barriers for recolonization coming from the Italian and Iberian peninsulas) and a more typical pattern of post-glacial recolonization from southern refugia in the East, where mountain chains are north-south oriented and therefore less effective as barriers. [ABSTRACT FROM AUTHOR]

The influence of spatial and environmental factors in explaining the structure of large branchiopod assemblages at different spatial scales is still poorly explored. We hypothesized that the extent of actual spatial connectivity, and thus the spatial distribution of a metacommunity, may depend on the environmental conditions as represented by climatic gradients and the structural characteristics of the landscape. To test this hypothesis, the distributional patterns of 14 large branchiopod species in a set of 177 temporary water bodies repeatedly sampled across Tunisia and on its main islands were analysed. Physical, chemical, morphological and climatic characteristics of the studied water bodies were collected as well, and spatial structures were described using distance-based Moran's Eigenvector Maps. Distance-based Redundancy Analysis and variance partitioning explained more than one-half of total variation. Mantel's autocorrelograms demonstrated that species composition was spatially autocorrelated at shorter distances in the Mediterranean part of the country than in the southern, more arid part. These results suggest that both dispersal limitation and species response to spatially structured environmental gradients might be involved in determining large branchiopod distribution in Tunisia and that these patterns may greatly vary on a regional basis. [ABSTRACT FROM AUTHOR]

Phytoplankton assemblages in two Sicilian water bodies were compared to test the hypothesis that colonization events and the successful establishment of a new species in an aquatic ecosystem may depend on the number of water bodies in a given area and on their relative distance. The two ecosystems are both natural, shallow lakes and they are protected sites hosting a rich avifauna. Lake Biviere di Gela is located in an area with a high density of ponds, whereas Lake Pergusa is an isolated waterbody without other aquatic ecosystems in its surroundings. Both lakes had almost disappeared about 10 years ago because of the over-exploitation of their main inflows. They were therefore re-filled using water from other catchments and their phytoplankton has been sampled since their re-filling. The results show that Lake Pergusa has maintained a species-poor phytoplankton assemblage since its re-filling, whereas Lake Biviere di Gela has been showing progressively richer phytoplankton assemblages during time. The composition of samples collected in nearby located temporary ponds suggests that phytoplankton in this area belongs to a species-rich metacommunity which favored its re-establishment in the lake. Aquatic ecosystems conservation plans cannot thus neglect the role of small waters located in the catchments. [ABSTRACT FROM AUTHOR]

The selected theme of the 17th Workshop of the International Association for Phytoplankton Taxonomy and Ecology (IAP), 'Biogeography and Spatial Patterns of Biodiversity of Freshwater Phytoplankton,' offered the opportunity to explore one neglected aspect of phytoplankton ecology: the distribution of species in the geographic space. This paper summarizes the outcomes of 20 selected contributions among those presented at the workshop. The articles report the results from studies carried out in five continents (only Oceania is not represented) and on a wide array of aquatic ecosystems (deep and shallow natural lakes, man-made lakes, temporary and permanent ponds, rivers). The topics analyzed by the contributors are related to Island Biogeography paradigms, dispersal vectors, survival strategies, environmental filters, dispersal distances, vertical and horizontal spatial variability of phytoplankton between and within water bodies, and of course, invasive algae. The overall analysis of the results presented clearly demonstrates that, as for many others organisms, there are 'rules' governing freshwater phytoplankton spatial patterns and that these organisms also have a true biogeography, as nowadays is quite evident for several other groups in the same range of size. We can definitively conclude that the statement 'Everything is everywhere' is obsolete, even though human activities tend to homogenize species distribution in the biosphere. [ABSTRACT FROM AUTHOR]

Water quality improvement and suppression of cyanobacterial blooms were planned in a eutrophic reservoir in southern China through ecological engineering measures from 2006 to 2011. This consisted in (i) a hydraulic resetting of inflows and outflows to increase the distance between inlet and outlet and the water residence time in the reservoir, and in (ii) the installation of floating frames hosting wetland vegetation to promote an alteration in phytoplankton composition. The environmental changes were therefore followed through the analysis of biotic responses in phytoplankton assemblages. Ecological engineering was effective in reducing phytoplankton total biomass, in re-establishing more diversified phytoplankton assemblages and in avoiding cyanobacterial blooms. These changes may be considered as an improvement of the reservoir water quality. However, trophic state parameters and the dynamics of dominant species were not sensitive enough in describing the environmental changes that had occurred when the eco-engineering measures were implemented. These were more effectively tracked by the dynamics followed by phytoplankton Morpho-Functional-Groups and by their classification based on Competitors, Stress tolerants and Ruderals strategies. Although providing immediate positive effects, the eco-engineering was temporally limited, highlighting the importance of constant management in the context of long-term oriented remediation techniques. [ABSTRACT FROM AUTHOR]

An introduction is presented in which the editors discuss the theme of the issue biology and ecology of aquatic organisms.

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. [ABSTRACT FROM AUTHOR]

Lakes and ponds are scattered on Earth's surface as islands in the ocean. The organisms inhabiting these ecosystems have thus developed strategies to pass the barrier represented by the surrounding land, to disperse and to colonize new environments. The evidences of a high potential for passive long-range dispersal of organisms producing resting stages inspired the idea that there were no real barriers to their actual dispersal, and that their distribution was only limited by the ecological characteristics of the available habitats. The development of genetic techniques allowed to criticize this view and revealed the existence of a more complex and diverse biological scenario governed by an assortment of historical and ecological factors. In this paper, we review the literature related to the passive dispersal of organisms producing resting stages among inland lentic ecosystems, with special emphasis to temporary ponds, which represent 'isolated' ecosystems both in space and in time, and are characterized by high levels of biological diversity. The existence of a sharp decoupling between 'dispersal potential' and 'actual establishment rates' is stressed, thus urging a definitive overcome of the so-called 'Everything is Everywhere' hypothesis in order to gain a proper understanding of the biogeography and ecology of inland water organisms. [ABSTRACT FROM AUTHOR]

The use of ecological classification systems is becoming more and more widely used when studying phytoplankton. Grouping phytoplankton species into ecologically coherent groups allow to reduce redundancy and in this way, to handle a minor number of biological variables when investigating the ecological status of aquatic ecosystems. Three ecological classifications are mostly used when freshwater phytoplankton is studied: functional groups or coda, morpho-functional groups (MFGs) and morphology-based functional groups (MBFGs). In this study, these three ecological classifications were comparatively used along with two taxonomic classifications based on species and genera to analyse phytoplankton response to environmental variability in three sub-tropical Chinese reservoirs. Canonical correspondence analysis was performed to compare the five mentioned biological classifications. When ecological classifications were used, the percentage of variance explained in the biological groups-environmental variables was higher than that explained by the taxonomic classifications. Coda and MFGs showed a very high degree of overlapping, but since coda are associated to very detailed environmental templates, this method was more helpful in explaining phytoplankton variability in relation to environmental factors. [ABSTRACT FROM AUTHOR]

The hypothesis that physical constraints may be as important, if not more important, than biological ones in shaping the structure of phytoplankton assemblage was tested by analyzing long-term (11–29 years) phytoplankton series in eight lakes and nine sites located along a latitudinal gradient in the Northern hemisphere. Phytoplankton biomass was used and similarity of assemblages in same months of the annual data sets was then calculated by subtracting the Bray–Curtis dissimilarity index from 1. The extent of biological and physical forcing was partly based on “expert evaluation”: the importance of four physical (light availability, temperature, conductivity, and sediment stirring up) and five biological variables (basic nutrients [SRP-, DIN-, SRSi-availability] as estimators of competition straight, importance of grazing, and importance of parasitism) was evaluated month by month by arbitrarily scaling from 1 to 5 the intensity of each variable and then summing them in the appropriate subgroup. Since the number of physical variables is less than that of the biological ones, the latter was rescaled to reach the same maximum attainable value of physical variables. The results showed an extremely high variability, making evident that each lake, although showing the same metabolic processes, behaves as an individual with regard to its phytoplankton structure. More generally, it was possible to highlight a largely more important role of physical constraints in shaping both biomass and composition of phytoplankton. This is especially true in winter. In addition, the results were compared to the outcomes of the PEG model, since a plasticity in the structure of phytoplankton much greater than that reported in this widely acknowledged model has been recorded in the data set used. This high variability found in this study in relation to physical constraints might also explain the different patterns of phytoplankton growth observed from Northern temperate to Mediterranean lakes as well as those occurring in shallow and deep lakes. [ABSTRACT FROM AUTHOR]

A foreword to the February 2010 issue of the journal "Hydrobiologia" is presented.

The hypothesis that climate changes may strongly interfere with the peculiar hydrological patterns in the Mediterranean basin and alter the structure of the aquatic biota was tested in a shallow Sicilian lake. A phytoplankton survey, carried out monthly in the brackish and shallow Biviere di Gela, in 2005–2007, revealed a transformation in the structure of its phytoplankton assemblage as compared with similar data collected in 1987–1988. An analysis of the trends followed by precipitation and temperature over the last 40 years, showed reduced water inflows, due to increased air temperature and evapotranspiration rather than to a decrease in the amount of precipitation. A consequent reduction in water level occurred, which almost caused the disappearing of the lake at the beginning of the century. This reduction in water level disrupted the littoral zone of the lake and transformed it from a clear, macrophyte-dominated environment to a turbid one characterized by huge summer blooms of the cyanobacteria Aphanizomenon ovalisporum, Cylindrospermopsis raciborskii, and Pseudanabaena limnetica. The addition of freshwater from a nearby dam reservoir, to restore water levels, likely opened the way to another alga, Prymnesium parvum, whose allelopathic and toxic glycosides further contributed to the transformation of the lake biota. On the whole, the Biviere di Gela is an example of how climate changes, coupled with inadequate management procedures, may negatively impact Mediterranean aquatic ecosystems. [ABSTRACT FROM AUTHOR]

This article summarizes the outcomes of the 15th Workshop of the International Association for Phytoplankton Taxonomy and Ecology. Four major issues dealing with the role of physical factors in phytoplankton ecology were addressed in the articles of this special volume: global change and its likely impacts on phytoplankton, the role of physical factors in the autecology of particular species, impacts on the inocula for the following years, and the role of light in shaping phytoplankton dynamics. Case studies from different types of aquatic environments (rivers, deep and shallow lakes, floodplain lakes, wetlands, oxbows, and even the deep ocean) and from diverse geographical locations (not only from the Mediterranean and temperate regions, but also from subtropical and tropical ones) have shown that physical forcing exerts a variety of selective pressures with impacts ranging from molding shape and size of organisms to modifying, through cascade effects, the structure of whole ecosystems. [ABSTRACT FROM AUTHOR]