Mediterranean Shallow Lakes Research Articles

The impact of salinization on benthic macro-crustacean assemblages in a Mediterranean shallow lake

The impact of salinization on benthic macro-crustacean assemblages in a Mediterranean shallow lake

Is salinity a driving factor for the phytoplankton community structure of a brackish shallow Mediterranean lake?

Is salinity a driving factor for the phytoplankton community structure of a brackish shallow Mediterranean lake?

Modelling Microcystis Cell Density in a Mediterranean Shallow Lake of Northeast Algeria (Oubeira Lake), Using Evolutionary and Classic Programming

Caused by excess levels of nutrients and increased temperatures, freshwater cyanobacterial blooms have become a serious global issue. However, with the development of artificial intelligence and extreme learning machine methods, the forecasting of cyanobacteria blooms has become more feasible. We explored the use of multiple techniques, including both statistical [Multiple Regression Model (MLR) and Support Vector Machine (SVM)] and evolutionary [Particle Swarm Optimization (PSO), Genetic Algorithm (GA), and Bird Swarm Algorithm (BSA)], to approximate models for the prediction of Microcystis density. The data set was collected from Oubeira Lake, a natural shallow Mediterranean lake in the northeast of Algeria. From the correlation analysis of ten water variables monitored, six potential factors including temperature, ammonium, nitrate, and ortho-phosphate were selected. The performance indices showed; MLR and PSO provided the best results. PSO gave the best fitness but all techniques performed well. BSA had better fitness but was very slow across generations. PSO was faster than the other techniques and at generation 20 it passed BSA. GA passed BSA a little further, at generation 50. The major contributions of our work not only focus on the modelling process itself, but also take into consideration the main factors affecting Microcystis blooms, by incorporating them in all applied models.

Microbial marker for seawater intrusion in a coastal Mediterranean shallow Lake, Lake Vrana, Croatia

Climate change-induced rising sea levels and prolonged dry periods impose a global threat to the freshwater scarcity on the coastline: salinization. Lake Vrana is the largest surface freshwater resource in mid-Dalmatia, while the local springs are heavily used in agriculture. The karstified carbonate ridge that separates this shallow lake from the Adriatic Sea enables seawater intrusion if the lakes' precipitation-evaporation balance is disturbed. In this study, the impact of anthropogenic activities and drought exuberated salinization on microbial communities was tracked in Lake Vrana and its inlets, using 16S rRNA gene sequencing. The lack of precipitation and high water temperatures in summer months introduced an imbalance in the water regime of the lake, allowing for seawater intrusion, mainly via the karst conduit Jugovir. The determined microbial community spatial differences in the lake itself and the main drainage canals were driven by salinity, drought, and nutrient loading. Particle-associated and free-living microorganisms both strongly responded to the ecosystem perturbations, and their co-occurrence was driven by the salinization event. Notably, a bloom of halotolerant taxa, predominant the sulfur-oxidizing genus Sulfurovum, emerged with increased salinity and sulfate concentrations, having the potential to be used as an indicator for salinization of shallow coastal lakes. Following summer salinization, lake water column homogenization took from a couple of weeks up to a few months, while the entire system displayed increased salinity despite increased precipitation. This study represents a valuable contribution to understanding the impact of the Freshwater Salinization Syndrome on Mediterranean lakes' microbial communities and the ecosystem resilience.

The effects of inter-annual fluctuations in precipitation, lake surface area, and wind speed on phytoplankton structure in three shallow Mediterranean lakes (Sakarya, Turkey)

The effects of inter-annual fluctuations in precipitation, lake surface area, and wind speed on phytoplankton structure in three shallow Mediterranean lakes (Sakarya, Turkey)

Variables' classification via equivalence relations for the trophic state of a Mediterranean ecosystem.

The trophic state of an aquatic body is influenced by many biotic and abiotic factors. When lots of parameters affect a phenomenon, such as eutrophication, it is difficult to distinguish which are the ones that affect the ecosystem the most. In this paper, we propose an alternative way for data analysis, in order to avoid complex systems with many variables. For the examined Mediterranean shallow lake, the studied parameters are water temperature (°C), ammonia (NH4 -N) (mg/L), dissolved oxygen (mg/L), turbidity (NTU), pH, conductivity (mS/cm), and chlorophyll-a (μg/L). We formed groups with the variables above based on fuzzy equivalence relations and from each group we chose the parameter influence the studied phenomenon the most. Numerical results of fuzzy linear regression showed strong agreement with the proposed method above and pH, NH4 -N, and dissolved oxygen are the variables influence this ecosystem more than the others. PRACTITIONER POINTS: When having many parameters in a studied ecosystem, we propose a way we can distinguish the most representative ones, the parameters that influence more the phenomenon we study each time. Formation of groups in variables can be applied to many case studies in order to have a clear idea of our data and the relevance of each of them in our dependent one. Fuzzy linear regression can be used in order to check the final results and ensure that the equivalence relations are a such a good method used in the data analysis while the researchers save time in long procedures of analyzing parameters not very close involved to the phenomenon investigated every time.

Updated Distribution of Rare Stonewort Chara kokeilii A.Braun (Charophyta) in Southeast Europe with Environmental Notes

A new site for stonewort Chara kokeilii A.Braun was recorded in a Mediterranean shallow lake Prološko Blato Retention, Croatia, SE Europe. The species was associated with the vegetation alliance Potamogetonion graminei Westhoff & Den Held. This record has been compared with four other sites (Albania, Bulgaria, Greece and Montenegro) from which the species was recorded in SE Europe, regarding the species morphological traits, environmental parameters and vegetation types. It is possible that the main distribution area of this species is in Southeast Europe, a statement that is supported by previous micropaleontological research. This research provides new data on distribution and ecological affiliation of the critically endangered C. kokeilii (IUCN Red List Categories and Criteria).

How historical land use/land cover changes affected ecosystem services in lake Pamvotis, Greece

Historic land changes reflect human pressure in aquatic ecosystems. The value of littoral and riparian zones for lakes is of outmost importance for their hydrology, ecology and support of ecosystem services. The last 75 years altered the landscape mosaic of Lake Pamvotis affecting those habitats. In such an ancient, urban, Mediterranean shallow lake, historic black and white aerial photographs and satellite images were screened in 25 years timestep, from 1945 for extracting land use/land cover changes. The classification took place in two buffer zones (50 m and 500 m). The changes are assessed with respect to their possible impact in water-related ecosystem services. Ecosystem services values were further calculated historically along with landscape ecology indices. The research revealed an extreme landscape makeover until 1995 with detrimental effects in the riparian habitats, with augmented pressure in the 0-50 m buffer. Artificial areas covered 21% in 1995 when in 1945 they occupied only 9%. Total area ecosystem services values rised at the expense of some provisioning and regulating services. As for landscape homogenization and fragmentation, it was already affected by human. Through this research, new ways of studying water bodies can be developed, by following the pressures’ and alterations’ evolution, aiming at better urban and management planning.

The impact of climate change on a Mediterranean shallow lake: insights based on catchment and lake modelling

Shallow lakes in the semi-arid climate zone of the Mediterranean are sensitive to drought due to the low annual precipitation and high evaporation. Changes in precipitation and temperature as projected by climate change scenarios will have an effect on the hydrology of these shallow lakes with secondary effects on nutrient dynamics and ecological state. In this study, we used a combined modelling approach that included the catchment model Soil and Water Assessment Tool (SWAT) and the lake model PCLake to study the possible effects of several climate scenarios on a shallow lake in semi-arid central Anatolia, Turkey. Our results show that lower precipitation and higher temperatures may reduce inflow rates and water levels drastically. Diffuse nutrient loading depended highly on precipitation and thus decreased as well. The lake model predicts an interaction between external nutrient loading and water levels. Low water levels benefited submerged macrophytes if nutrient concentrations were low, but low inflow rates and high evaporation during dry periods increased in-lake nutrient concentrations and chlorophyll-a. Cyanobacteria biomass was also higher in the drier and warmer scenarios. Overall, the results show that lower hydraulic loads and reduced flushing rates as a result of drier and warmer conditions lead to lower water levels and higher in-lake nutrient concentrations unless nutrient loading decreased as well. This implies that catchment-scale nutrient management is essential to maintain low nutrient concentrations in the lakes with increasing temperature and decreasing precipitation in a dry climate.

The Use of Fuzzy Estimators for the Construction of a Prediction Model Concerning an Environmental Ecosystem

As a variable system, the Lake of Kastoria is a good example regarding the pattern of the Mediterranean shallow lakes. The focus of this study is on the investigation of this lake’s eutrophication, analyzing the relation of the basic factors that affect this phenomenon using fuzzy logic. In the method we suggest, while there are many fuzzy implications that can be used since the proposition can take values in the close interval [0,1], we investigate the most appropriate implication for the studied water body. We propose a method evaluating fuzzy implications by constructing triangular non-asymptotic fuzzy numbers for each of the studied parameters coming from experimental data. This is achieved with the use of fuzzy estimators and fuzzy linear regression. In this way, we achieve a better understanding of the mechanisms and functions that regulate this ecosystem.

Zooplankton is more strongly controlled by nutrients than predation in a vegetation-free Mediterranean shallow lake: a mesocosm experiment

ABSTRACTWe conducted a mesocosm experiment in a Mediterranean shallow lake dominated by Myriophyllum alterniflorum to assess the effects of nutrient enrichment and fish addition on the composition and functional structure of zooplankton assemblages when macrophytes are absent. Fish (Achondrostoma arcasii) and nutrients were added in 9 combinations: 3 fish densities (fresh mass: 0, 4, and 20 g m−2) and 3 nutrient loading (nitrogen–phosphorus final concentration increases of 0–0, 1–0.1, and 5–0.5 mg L−1). After 5 weeks, macrophytes were cut and removed. The results suggest that the response of zooplankton to increased nutrient loading and fish densities was modulated by the presence or absence of vegetation. Small cladocerans were the most important group to differentiate between vegetated and nonvegetated phases, and their biomass significantly decreased after vegetation removal. Throughout the phase without macrophytes, the biomass of cyclopoids and Daphnia longispina increased in the most fertilized mesocosms while phytoplankton biovolume decreased along the nutrient gradient, mainly as a result of the decline of cyanobacteria; therefore, the bottom-up effect was transferred to zooplankton. The effect of fish on total zooplankton biomass was negligible; however, the response of D. longispina to fish densities was modulated by nutrient concentration. Zooplankton:phytoplankton biomass (ZB:PB) and Daphnia:phytoplankton biomass (DB:PB) ratios showed that the trophic cascade was strengthened in the most eutrophic conditions. We suggest that, in vegetation-free Mediterranean shallow lakes, eutrophication management strategies based on the control of phytoplankton production could be achieved even when a moderate fish population is maintained.

Nitrogen loading and natural pressures on the water quality of a shallow Mediterranean lake

The water quality of Koumoundourou Lake, a heavily modified, peri-urban, brackish and shallow lake near Athens, Greece, is under multiple stressors due to the industrial activities in the catchment area and natural pollution pressures. Although the broader area has undergone significant land use changes since the beginning of the 20th century converting it from rural to heavily industrialized, Koumoundourou Lake remained as one of the few habitats in Attica Region, for large numbers of aquatic birds. The water quality of the lake has been recently improved, which contributed to the increase of aquatic birds' population in the area and to the higher, in relation to the past, nitrogen inputs from natural sources. Therefore, a monitoring program has been implemented to assess the pollution pressure factors in the lake. A water quality model has been also used to simulate the lake's processes and estimate the nutrient mass budget focusing on the various nitrogen loading mechanisms (natural and anthropogenic). Based on the model output, the main polluting factor of the lake is the groundwater inflows. Aquatic birds affect slightly the lake's water quality, while the dry and wet atmospheric deposition contributes insignificantly to the total nitrogen loading.

Plant macrofossil assemblages from surface sediment represent contemporary species and growth forms of aquatic vegetation in a shallow Mediterranean lake

Macrofossils are known as a useful tool in reconstructing their original plant communities. However, most studies have been focused on comparing the composition and distribution of living plant communities and their remains in temperate lakes. Mediterranean shallow lakes have been historically far less studied and little is known about the relationships between Mediterranean macrophyte communities and their remains. The aim of our study is to assess how contemporary aquatic macrophyte communities are represented by their sedimentary remains in terms of composition, distribution and concordance between the contemporary and the subfossil assemblages in a procrustean superimposition space, and to determine which surface sediment cores, collected along a depth gradient, may represent best the whole-lake macrofossil assemblage. These analyses were carried out for both species and macrophyte growth forms (submerged hydrophytes, floating-leaved hydrophytes, helophytes and charophytes) in order to check which of the two (species and growth forms) were represented best by their macro-remains. The most abundant present-day species (Myriophyllum alterniflorum DC. and Potamogeton trichoides L.) were under-represented while Characeae and some floating-leaved hydrophytes (Polygonum amphibium L. and Ranunculus peltatus Schrank) were over-represented in sedimentary samples. Additionally, macro-remains of submerged hydrophytes and helophytes were generally found in the central areas and in close proximity to contemporary vegetation, whereas floating-leaved hydrophytes distributed close to the near-shore. Notwithstanding some disparities between contemporary vegetation and their macrofossil assemblages, we found a good agreement between present-day and sedimentary datasets for both species and macrophyte growth forms. Furthermore, our study suggests that sediment cores from deep areas are more likely to represent best the whole-lake macrofossil assemblage because of their high diversity, equitability and heterogeneity. We conclude that aquatic macrophyte subfossils from the central areas of the basin can be a very useful tool in tracking the species composition and structure of the original macrophyte communities in shallow Mediterranean lakes. Additionally, when considering the use of macro-remains to reconstruct the composition and structure of macrophyte growth forms, we recommend a multicore approach that uses transects running from the shore to the lake center.

Predation by Acanthocyclops americanus (Copepoda: Cyclopoida) in the hypertrophic shallow waterbody, Lake Albufera (Spain): field and laboratory observations

We quantified the predation of Acanthocyclops americanus from the shallow Mediterranean lake Albufera, using gut contents from field collections and laboratory feeding tests. For functional response studies, we used Brachionus plicatilis (at 6 concentrations, 400–4000 ind. 40 ml−1) and Diaphanosoma mongolianum (at 2–20 ind. 40 ml−1). Copepod feeding rates were also estimated using different proportions of rotifer prey and lake seston (0–67.5% of seston + 40 individuals of B. plicatilis). Prey selection studies were conducted using five zooplankton species: Brachionus angularis, Brachionus plicatilis, Keratella tropica, Daphnia magna and Diaphanosoma mongolianum. Gut contents of field-collected adult Acanthocyclops contained filamentous algae and cyanobacteria and 16 zooplankton species (Keratella cochlearis, unspined and spined forms, K. tropica, Brachionus plicatilis, Brachionus calyciflorus, Brachionus angularis, Brachionus variabilis, Asplanchna girodi, Polyarthra vulgaris, Synchaeta pectinata, Lepadella rhomboides, unidentified bdelloids, Alona rectangula, Chydorus sphaericus, Bosmina longirostris, D. magna, Ceriodaphnia dubia and copepod nauplii). When fed B. plicatilis or D. mongolianum, female A. americanus had higher prey consumption rates than males. Increased proportion of lake seston caused reduced consumption of brachionid prey. Our data suggest that A. americanus is omnivorous in nature.

Changes in climate, land use and local conditions drive macrophyte assemblages in a Mediterranean shallow lake

espanolLas lagunas mediterraneas sufren procesos de deterioro derivados de la eutrofizacion, los cambios en los usos del suelo de su cuenca de drenaje y el cambio climatico. Es esperable que las plantas acuaticas respondan a los cambios ecologicos al encontrarse en estrecho contacto con los factores ambientales. En este estudio se evalua la influencia del clima, los usos del suelo y las caracteristicas locales en los cambios experimentados por la comunidad de macrofitos de la laguna Sentiz, un medio lenitico y de caracter estepario situado en el noroeste de Espana. Para ello, se han utilizado datos de las caracteristicas locales, imagenes de satelite, ortofotografias y series climaticas. El estudio revelo la existencia de importantes cambios en los factores ecologicos determinantes de las comunidades de macrofitos, destacando los cambios sufridos en la profundidad media, la superficie del medio palustre, la vegetacion higrofila, la temperatura media anual y la cobertura de pastizal. Asimismo, se ha encontrado que la evolucion temporal de la cobertura de los hidrofitos sumergidos y con hojas flotantes estuvo determinada por las caracteristicas locales, mientras que la cobertura de los grandes y pequenos helofitos estuvo definida por los cambios en los usos del suelo y en las condiciones climaticas, respectivamente. Nuestro estudio sugiere que las estrategias de conservacion de las comunidades de macrofitos en lagunas someras mediterraneas deben enfocarse no solamente en la gestion de las caracteristicas locales de cada laguna, sino tambien en la gestion de sus cuencas de drenaje y teniendo en cuenta la evolucion climatica. En este sentido, nuestros resultados mejoran el conocimiento de los factores ambientales de las comunidades de macrofitos de lagunas someras mediterraneas, incorporando series historicas tanto de las caracteristicas fisico-qui- micas del ecosistema como de sus comunidades biologicas. Finalmente, se pretende aportar informacion relevante de los factores determinantes de las comunidades de macrofitos a la hora de implementar estrategias de gestion y conservacion de estos y de otros ecosistemas leniticos similares. EnglishMediterranean shallow lakes are affected by many deterioration processes like eutrophication, land-use changes along its drainage basin and climate change. Aquatic plants are expected to reflect the ecological changes of shallow lakes since they are in close contact with the environmental factors. We assessed the influence of climate, land use and local conditions on macrophyte community changes in Sentiz Lake, a steppe water body located in the northwest of Spain, using long term data of local conditions, satellite imagery, orthophotography and climatic series. We found important changes in the environmental drivers of aquatic macrophyte assemblages (e.g. mean depth, water surface area, shore vegetation, mean annual temperature and grassland coverage). Similarly, we found that aquatic macrophyte growth forms responded to different environmental controlling factors: submerged and floating-leaved hydrophytes responded to local conditions, while big helophytes and small helophytes responded to land use and climate, respectively. Overall, our study suggests that management efforts aimed at preserving aquatic macrophyte assemblages of shallow Mediterranean lakes should focus not only on local conditions of each lake but also on their watersheds and climate. Therefore, this study improves the knowledge of the environmental drivers of aquatic macrophyte assemblages of shallow Mediterranean lakes, incorporating long term data of both physical and biological parameters and providing a basic framework for applying management and conservation strategies in these and other similar ecosystems

Biogeochemical characterization of a Mediterranean shallow lake using stable isotopes: Laguna del Cristo (NW Iberian Peninsula)

The present multi-isotopic study (δ18O–δDwater, δ34S–δ18Odissolved-sulphate, δ13Cdissolved-inorganic-carbon, δ13C–δ18Oshells-modern-gastropods, δ13Cplants, and δ13Csedimentary-organic-matter) is aimed at assessing the hydrogeochemical changes and biogeochemical dynamics in a Mediterranean shallow lake fed by a Quaternary–Tertiary aquifer, the “Laguna del Cristo” (NW Iberian Peninsula), a system sensitive to climate fluctuations, between 2010 and 2011. Lake water is of the bicarbonate type, and there are no major pollutants. δ18O-δDwater values plot on a local evaporation line (δD=5.29δ18O–12.29) indicating that evaporative enrichment had a significant impact on lake water isotopic features. Periods of high water levels are characterized by lower δ34S–δ18Odissolved-sulphate and δ13Cdissolved-inorganic-carbon values and suggest sulphate derived from weathering of sulphides in the catchment area, delivered to the lake by surface run-off or via groundwater, and in situ decay of organic matter. During lower water levels, sulphate reduction and enhanced primary productivity lead to higher δ34Sdissolved-sulphate and δ13Cdissolved-inorganic-carbon values. Evaporation induced enrichment in 18Osulphate, 13Cdissolved-inorganic-carbon and 13C–18Oshells-Galba-Gyraulus. δ13Cplant confirms the C3 photosynthetic pathway. Enrichment in 13C submerged aquatic plants indicates that HCO3− is the main carbon source, except for 13C-depleted Potamogeton. The TOC, δ13Corg values, and TC/TN ratios in sediments all confirm the autochthonous character of organic matter contribution. This study provides a baseline for isotopic research into shallow, flow-through lakes fed by siliciclastic aquifers, and stresses the importance of evaporation and refilling (direct precipitation and groundwater discharge) in controlling the solute chemistry and stable isotopic composition in temperate regions with contrasting seasonal climates. The results also provide a snapshot of modern lake isotope variability that can be applied to paleoenvironmental reconstructions.

Size‐based interactions across trophic levels in food webs of shallow Mediterranean lakes

Abstract Body size is a key trait of an organism which determines the dynamics of predator–prey interactions. Most empirical studies on the individual size distribution of the aquatic community have focused on the variations in body size of a single trophic level as a response to certain environmental variables or biotic factors. Few studies, however, have evaluated how individual size structure is altered simultaneously across interacting trophic levels and locations. Such comparative examinations of the size distribution in predator and prey communities may bring insight into the strength of the interactions between adjacent trophic levels. We assessed the potential predation effect of size‐structured predators (i.e. predation by individuals of different sizes) on prey size structure using data from 30 shallow Turkish lakes spanning over five latitudinal degrees. We correlated size diversity and size evenness of predator and prey assemblages across the planktonic food web after accounting for the confounding effects of temperature and resource availability which may also affect size structure. We expected to find a negative relationship between size diversity of predators and prey due to the enhanced strength of top‐down control with increasing predator size diversity. We also hypothesised that competitive interactions for resources in less productive systems would promote a higher size diversity. We further expected a shift towards reduced size diversity and evenness at high temperatures. In contrast to our hypothesis, we found a positive correlation between size structures of two interacting trophic levels of the planktonic food web; thus, highly size‐diverse fish assemblages were associated with highly size‐diverse zooplankton assemblages. The size evenness of fish and phytoplankton assemblages was negatively and positively related to temperature, respectively. Phytoplankton size diversity was only weakly predicted by the resource availability. Our results suggest that size structure within a trophic group may be controlled by the size structure at adjacent trophic levels, as well as by temperature and resource availability. The positive relationship between the size diversity of fish and zooplankton suggests that higher diversity of the resources drives a higher size diversity of consumers or vice versa, and these effects are beyond those mediated by taxonomic diversity. In contrast, the size diversity and size evenness of phytoplankton are mainly influenced by physical factors in this region and perhaps in warm shallow lakes in general.

Patterns of microbial food webs in Mediterranean shallow lakes with contrasting nutrient levels and predation pressures

To elucidate the specific and combined effects of bottom-up and top-down control on the microbial community in warm lakes, we sampled microbial community along with physical–chemical and biological variables and performed in situ food web experiments, in 14 Turkish shallow lakes with contrasting nutrient levels and predation pressures. Our field results revealed that differences in microbial communities correlated with differences in zooplankton community structure, temperature (increasing nutrient concentrations, change in zooplankton composition), nutrient concentrations (increasing bacteria and heterotrophic nanoflagellate abundances with increasing nitrogen concentrations and temperature) and macrophyte coverage (ciliates as potential consumers of bacteria and HNF was strongest in macrophyte-dominated lakes). Our in situ experimental study revealed that the zooplankton not only affect the biomass and composition of microbial communities but also alter the microbial structure and trophic relationships. Our results therefore indicate that both bottom-up factors and top-down effects were important for the efficiency of the carbon transfer from bacteria to higher trophic levels in the study lakes. Due to an anticipated increase in eutrophication, temperature and alteration of the classical food web with climate warming, major changes in the microbial community of lakes are, therefore, expected in a warmer future in semi-arid Mediterranean climatic regions.

Dramatic impact of alien carp Cyprinus carpio on globally threatened diving ducks and other waterbirds in Mediterranean shallow lakes

Mediterranean shallow lakes support high biodiversity but suffer many anthropogenic threats, including introductions of alien fish. We studied the impact of introduction of common carp (Cyprinus carpio) to Medina and Zoñar lakes in SW Spain. Both lakes were protected as Ramsar sites because of their importance for waterbirds, particularly the globally threatened white-headed duck (Oxyura leucocephala IUCN Endangered) and common pochard (Aythya ferina IUCN Vulnerable). Two carp introduction events in Medina lake, with total eradication of carp in between, provided a unique opportunity to study the impacts of carp on the waterbird community (counted monthly from 2001 to 2013, with up to 69 species) and submerged macrophyte cover (quantified with satellite images). A comparison of waterbird abundance before and after carp eradication in the smaller Zoñar lake supported the results from Medina lake. Carp consistently led to the destruction of macrophyte beds and a radical change in the waterbird community. After controlling for the influence of depth fluctuations, the numbers and species richness of diving ducks were significantly reduced by carp, whilst the opposite effect was observed for piscivores such as herons. Negative impacts on O. leucocephala, A. ferina, red-crested pochard (Netta rufina) and herbivorous coots (Fulica spp.) were particularly pronounced. A significant negative impact of carp was also recorded on greater flamingos (Phoenicopterus ruber), black-necked grebes (Podiceps nigricollis), little grebes (Tachybaptus ruficollis) and gadwall (Anas strepera). In contrast, carp presence had a positive impact on grey herons (Ardea cinerea). The ongoing expansion of alien cyprinids in the Mediterranean region constitutes a major threat for waterbirds and particularly for sedentary, threatened taxa such as the white-headed duck and red-knobbed coot (F. cristata). Of 22 key sites for the isolated Iberian population of white-headed duck identified in a European action plan in 1996, at least 14 have since suffered carp invasions. Further development of successful control methods for carp populations is urgently required to support the conservation of waterbirds in the Mediterranean region.

Monitoring a newly re-born patient: water quality and cyanotoxin occurrence in a reconstructed shallow Mediterranean lake

Lake Karla (Central Greece) is a unique example - at European scale - of a shallow lake ecosystem that was dried in the 1960s and in 2009 started to be restored. The lake is listed in the network of the Greek protected areas as it is considered a vital aquatic ecosystem, in terms of biodiversity. It has, however, already been adversely affected by both agricultural and industrial land uses in the surrounding area, leading to eutrophication and shifting algal community towards bloom-forming toxic cyanobacterial species. After repeated heavy-blooms, cyanotoxin occurrence and mass fish kills, the local ecosystem management authority has implemented a water quality monitoring program (July 2013 - July 2015) to assess environmental pressures and the response of aquatic biota in the lake. Microscopic, immunological, and molecular techniques combined with physico-chemical parameters, complemented by liquid chromatography tandem mass spectrometry (LC-MS/MS), were used to monitor cyanobacteria blooms and the associated cyanotoxin production from three different sites in Lake Karla and from the adjacent Kalamaki Reservoir. Water quality was also assessed by the structure of benthic invertebrate community on the sediment. Cyanobacteria were the main phytoplankton component, representing more than 70% of the total phytoplankton abundance; dominant taxa belonged to Cylindrospermopsis raciborskii, Limnothrix redekei, Anabaenopsis elenkinii, and Microcystis spp. Euglenophytes (Euglena), diatoms (Nitzschia), and chlorophytes (Scenedesmus) were also important phytoplankton constituents. LC-MS/MS confirmed the co-occurrence of microcystins, cylindrospermopsin, saxitoxin, neo-saxitoxin and anatoxin-a. The occurrence of cyanotoxins in relation to the persistent and dominant cyanobacteria and the impact of cyanobacterial harmful algal blooms on the newly constructed lake along with the land uses and the emergent mitigation measures are discussed.