Setting the Phosphorus Boundaries for Greek Natural Shallow and Deep Lakes for Water Framework Directive Compliance

Kagalou I, C. Ntislidou, D. Latinopoulos, D. Kemitzoglou, V. Tsiaoussi, and DC Bobori. 2021. Setting the Phosphorus Boundaries for Greek Natural Shallow and Deep Lakes for Water Framework Directive Compliance. Water 13(5):739. https://doi.org/10.3390/w13050739Eutrophication caused by nutrient enrichment is a predominant stressor leading to lake degradation and, thus, the set-up of boundaries that support good ecological status, the Water Framework Directive’s main target, is a necessity. Greece is one of the Member States that have recorded delays in complying with the coherent management goals of European legislation. A wide range of different statistical approaches has been proposed in the Best Practice Guide for determining appropriate nutrient thresholds. To determine the nutrient thresholds supporting the good status of natural Greek lakes, the phytoplankton dataset gathered from the national monitoring programme (2015–2020) was used for shallow and deep natural lakes. The regression analyses were sufficient and robust in order to derive total phosphorus thresholds that ranged from 20 to 41 μg/L in shallow and 15–32 μg/L in deep natural lake types. Nutrient boundaries that encompass the stressors these lakes are subject to, are essential in proper lake management design

Classification and management issues of Greek lakes under the European Water Framework Directive: a DPSIR approach

The European Water Framework Directive (WFD) establishes a framework for the protection of water bodies. The aim of the Water Framework Directive (WFD) is to ensure sustainable management of groundwater, freshwater and marine water in the European Union, such that a minimum "good ecological status" will be obtained by 2015. We used background morphometric, hydrologic, physicochemical and biological data, in order to highlight the ecological status of the natural Greek lakes using also the Driving-Pressure-State-Impact-Response (DPSIR) approach in order to link the driving forces and further the pressures with the present state of the lakes' ecosystems. In addition detailed biodiversity and habitat typology data are provided. The assessment of the DPSIR approach under the view of WFD provided a quite clear identification of pressures and the subsequent impacts of the qualitative status of the Greek lake

The DPSIR Approach for an Integrated River Management Framework. A Preliminary Application on a Mediterranean Site (Kalamas River -NW Greece)

The European Water Policy introduced the necessity to apply new methodological approaches for the sustainable management of water resources. In the present paper the Driving-Pressure-State-Impact-Response (DPSIR) framework was developed as a methodological tool for the case study of Kalamas River basin (NW Greece). According to the DPSIR approach, it was revealed that the main driving forces, leading to pressures, were the agriculture, the livestock and the numerous point-pollution sources located at the catchment area. Elevated nutrients concentrations (NO3-N:0.1-2.6 mg/L, NH4-N:0.01-1.29 mg/L, SRP: 0.03-5.76 mg/L) along with high chlorophyll-a values (0.54-6.14 mg/m(3)) highlight river eutrophication. Response actions include elimination of diffuse pollution as well as reduction of the organic load through the optimization of the existed treatment plants. Since several parts of Kalamas River are designated as protected areas, specific measures for protecting biodiversity should be undertaken

Assessment of pressures and impacts on surface water bodies of the Mediterranean. Case study: Pamvotis Lake, Greece

The aim of the study presented in this article is to assess the ecological status of a surface water body in the Mediterranean using the methodological approach of Driver-Pressure-State-Impact-Response. Based on this approach for the case study analyzed (Pamvotis Lake, Greece), it is concluded that the main drivers, which lead to pressures in the study area are: intensive agricultural activities, alteration of hydrological regime, contamination from point sources and changes in the land-use and fish stocking. The ecological status is assessed by analysing data series of physical, chemical and biological elements that are available from early '80s. Findings suggest elevated nutrient concentrations sufficient for maintaining eutrophic conditions while their seasonal variability is mostly driven by factors as water level fluctuation, catchment runoff and in-lake biological processes. Subsequently, concerning biotic factors, the poor biodiversity mainly represented by the dominance of the most tolerant species, confirm the previous profile. Since, reference conditions have only recently been established in Greece, the ECOFRAME scheme and the guidelines proposed by the "Intercalibration Group for Mediterranean Lakes" were applied. In terms of the above elements; the water quality status could be characterized as "High", "High to Good" and "High to Bad", respectively, whereas the overall ecological status tends to shift in poor conditions. Finally, the major response actions needed should be in the direction of reduced application of fertilizers and chemicals in the cultivated land of the catchment, removal of the point-contamination sources from the catchment, appropriate land-use management and biomanipulation

Oxidative stress in Cyprinus carpio to analyze microcystin impact in eutrophic shallow lakes: a preliminary study

Microcystins (MCYSTs) are toxins produced by cyanobacteria in aquatic environment and are of high potential risk to aquatic organisms. The physiological responses and pathobiological developments that they elicit in fish have been extensively studied, mainly through acute toxicity experiments. This study was designed to examine the seasonal fluctuation of biochemical markers of oxidative stress in different tissues of a natural population of Cyprinus carpio inhabiting a shallow Mediterranean lake, along with the respective MCYSTs concentrations in blood and tissues at environmentally relevant MCYSTs values. MCYSTs content was assessed in liver, kidney, intestine, brain and muscle along with the MCYSTs in lake water and scum applying ELISA technique. Catalase activity, GSH/GSSH relative concentrations and lipid peroxidation were used as biochemical markers. Our results suggest that common carp of Lake Pamvotis exposed to naturally fluctuating concentrations of MCYST in water and scum contained stably high MCYST concentrations in all tissues that might pose a threat to public health. Liver and kidney were the primary target organs. Tissue concentrations did not correlate with the response of any of the elements of the antioxidant defence system. Hepatic catalase, GSH content and TBARS in all tissues tested followed the fluctuations of major limnological parameters, i.e. water temperature and oxygen concentration, chlorophyll-a, MCYST in water and scum, suggesting that they should be cautiously used to monitor exposure to MCYSTS in natural freshwater ecosystems

Brain and liver histopathological examination of carassius gibelio from a newly reconstructed lake with toxic cyanobacteria

Lake Karla, Greece, is a partially reconstructed lake. The lake's water filling process started in September 2009. Existing evidence based on the prevailing microorganisms and cyanotoxin levels in the lake in 2010 suggested that the lake could have a negative effect on its biota. By investigating whether Carassius gibelio individuals bear brain and liver histopathological findings, this study complements the data now available from the first year of L. Karla's reconstruction. Based on the 16S rRNA gene diversity, the potentially toxic cyanobacteria Anabaenopsis sp. and Planktothrix were shown to be present in the lake's water in May 2011. C. gibelio specimens were collected a month later. Histopathological alterations in the liver of the individuals, namely picnotic nuclei, loss of structure and hemorrhagic regions, were detected by microscopic examination. Picnotic nuclei, loss of the liver structure and hemorrhagic regions were detected. These alterations may be associated with the occurrence of cyanobacterial toxins possibly produced by the potentially toxic cyanobacterial species found in the water column. No alterations were found in the brain, probably due to the existence of the blood-brain barrier. © Published by Central Fisheries Research Institute (CFRI) Trabzon, Turkey

Detection of microcystins in Pamvotis lake water and assessment of cyanobacterial bloom toxicity

Lake Pamvotis is a shallow, eutrophic Mediterranean lake with ecological significance. This paper deals with the evaluation of cyanobacterial toxicity in Lake Pamvotis. ELISA and HPLC revealed the presence of significant amounts of MCYST-LR. Danio rerio bioassay confirmed the toxic nature of the bloom. Cyanobacterial extracts had adverse toxic effects on development of D. rerio. Also, it was shown that cyanobacterial extracts containing environmentally detected concentrations of MCYST can cause reduced survival rate of fish species. The results clearly indicate that cyanobacterial blooms in Lake Pamvotis may be regarded as human and fish health hazard. Continuous monitoring of the lake is suggested, in order to prevent future possible intoxications

The presence of microcystins in fish Cyprinus carpio tissues: a histopathological study

The occurrence of heavy cyanobacterial blooms has become a worldwide problem, as a consequence of eutrophication of the aquatic ecosystems; furthermore, 60% to 75% of these blooms have been found to be toxic. Microcystins (MCYSTs), the predominant toxins of cyanobacterial blooms, are associated with mortality and illness in both animals and humans. Laboratory-controlled experiments studying the effects of different microcystins on the common carp (Cyprinus carpio) have revealed various histopathological alterations. The aim of the present study is to investigate the effect of chronic or subchronic exposure of fish to microcystins under natural environmental conditions by examining the possible histopathological changes associated with a dense cyanobacterial bloom and determining the microcystin contents of fish tissues. Common carps (C. carpio) were caught from Lake Karla (Greece), during a dense cyanobacterial bloom. The concentration of MCYSTs in the fish liver, kidney and muscle tissues was measured by enzyme-linked immunosorbent assay. The pseudogaster contents were analysed, and a histopathological examination was performed using light and electron microscopy. Severe alterations were detected in the liver and the kidney, suggesting that the toxic effects were caused by various pollutants that were particularly associated with microcystins. The histopathological findings are also discussed, taking into consideration the health conditions of the common carp as a commercial fish species. The mechanisms of expansion of the microcystins and the poisoning of aquatic organisms (e.g. fish) are not yet known in the Lake Karla ecosystem. Future research may focus on identifying the changes caused by microcystins and other factors that exert similar effects on fish tissues, as well as on establishing the overall combined effect of all these factors on fish health. © 2013, Mitsoura et al.; licensee Springer