Short-term changes in phytoplankton assemblages and their potential for heavy metal bioaccumulation – a laboratory study

This study focused on phytoplankton changes in polluted waters of Lake Manzala and the assessment of heavy metal bioaccumulation capacity during the 15-day laboratory experiment. Phytoplankton samples were analyzed every day and the concentration of zinc, iron and lead in water, in phytoplankton and in filtrate – every fifth day of the experiment. Significantly higher phytoplankton abundance was recorded in water from the El-Boom station (basin I) compared to the New Bahr El-Baqar drain (basin II), followed by distinct differences in its composition and chlorophyll content. However, the most abundant species were the same in both basins, i.e. Chroococcus minor, Microcystis aeruginosa, Actinoptychus octonarius, Aulacoseira granulata, Pantocsekiella ocellata, Kirchneriella obesa and Nephrocytium limneticum. Water in basin I was more polluted with heavy metals compared to basin II. Basin I was characterized by the dominance of cyanobacteria and high relative abundance of chlorophytes compared to basin II, where either cyanobacteria and/or diatoms dominated in the phytoplankton. In the former basin, the highest uptake factors (UFs) were recorded for iron and zinc and the lowest UF for lead. In basin II, the highest UF was determined for zinc, but relatively high UFs were recorded also for iron and lead. The presented results suggest that phytoplankton can contribute to natural biosorbents of heavy metals in Egyptian lakes.This study focused on phytoplankton changes in polluted waters of Lake Manzala and the assessment of heavy metal bioaccumulation capacity during the 15-day laboratory experiment. Phytoplankton samples were analyzed every day and the concentration of zinc, iron and lead in water, in phytoplankton and in filtrate – every fifth day of the experiment. Significantly higher phytoplankton abundance was recorded in water from the El-Boom station (basin I) compared to the New Bahr El-Baqar drain (basin II), followed by distinct differences in its composition and chlorophyll content. However, the most abundant species were the same in both basins, i.e. Chroococcus minor, Microcystis aeruginosa, Actinoptychus octonarius, Aulacoseira granulata, Pantocsekiella ocellata, Kirchneriella obesa and Nephrocytium limneticum. Water in basin I was more polluted with heavy metals compared to basin II. Basin I was characterized by the dominance of cyanobacteria and high relative abundance of chlorophytes compared to basin II, where either cyanobacteria and/or diatoms dominated in the phytoplankton. In the former basin, the highest uptake factors (UFs) were recorded for iron and zinc and the lowest UF for lead. In basin II, the highest UF was determined for zinc, but relatively high UFs were recorded also for iron and lead. The presented results suggest that phytoplankton can contribute to natural biosorbents of heavy metals in Egyptian lakes

Microbial and classic food web components under ice cover in eutrophic lakes of different morphometry and fisheries management

The thickness and duration of ice cover are strongly influenced by global warming. The aim of this study was to determine chemical (organic carbon, total nitrogen and phosphorus concentrations) and biological (nanoflagellates, ciliates, phytoplankton, rotifers, crustaceans) parameters under the ice cover in three eutrophic lakes (Masurian Lake District, Poland), differing in their morphometry and fisheries management. All the studied groups of organisms showed high variability over a short time. Taxonomic composition of planktonic communities, except for rotifers and phytoplankton, was similar in all lakes. Nanoflagellates were dominated by autotrophic forms, while ciliates were primarily composed of small oligotrichs and prostomatids. Nano-sized diatoms and mixotrophic cryptophytes were the most important components of phytoplankton and they formed an under-ice bloom in one lake only. Rotifers were mainly represented by Keratella cochlearis, Polyarthra dolichoptera and Asplanchna priodonta. Among crustaceans, copepods clearly dominated over cladocerans. Our research suggests that winter was a very dynamic period. In the under-ice conditions, pelagic organisms were strongly dependent on each other. The shallow lake and the deeper, small lake differed significantly in nutrient and chlorophyll concentrations, ciliate and phytoplankton biomass and the ratio of autotrophic to heterotrophic biomass. These results suggest that morphometric parameters may affect planktonic organisms during the ice-covered period.The thickness and duration of ice cover are strongly influenced by global warming. The aim of this study was to determine chemical (organic carbon, total nitrogen and phosphorus concentrations) and biological (nanoflagellates, ciliates, phytoplankton, rotifers, crustaceans) parameters under the ice cover in three eutrophic lakes (Masurian Lake District, Poland), differing in their morphometry and fisheries management. All the studied groups of organisms showed high variability over a short time. Taxonomic composition of planktonic communities, except for rotifers and phytoplankton, was similar in all lakes. Nanoflagellates were dominated by autotrophic forms, while ciliates were primarily composed of small oligotrichs and prostomatids. Nano-sized diatoms and mixotrophic cryptophytes were the most important components of phytoplankton and they formed an under-ice bloom in one lake only. Rotifers were mainly represented by Keratella cochlearis, Polyarthra dolichoptera and Asplanchna priodonta. Among crustaceans, copepods clearly dominated over cladocerans. Our research suggests that winter was a very dynamic period. In the under-ice conditions, pelagic organisms were strongly dependent on each other. The shallow lake and the deeper, small lake differed significantly in nutrient and chlorophyll concentrations, ciliate and phytoplankton biomass and the ratio of autotrophic to heterotrophic biomass. These results suggest that morphometric parameters may affect planktonic organisms during the ice-covered period

Temperature Effects Explain Continental Scale Distribution of Cyanobacterial Toxins

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains.Peer reviewe

Cyanobacterial Blooms and Zooplankton Structure in Lake Ecosystem under Limited Human Impact

Cyanobacterial blooms are tightly related to increasing trophic conditions of lakes and climate warming. Abiotic and biotic parameters were studied in a shallow lake, in which the island with the largest cormorants colony in north-eastern Poland is situated. We hypothesized that the strongest cyanobacterial blooms will persist near the cormorant’s island and will decrease with an increasing distance from it. Filamentous cyanobacteria (Pseudanabaena, Planktolyngbya, Limnothrix, Planktothrix) were the main phytoplankton components during summer and autumn. Their strongest blooms (up to 66 mg L−1) were recorded near the roosting area. The content of nutrients and chlorophyll a, and the biomass of phytoplankton (primarily cyanobacteria) and zooplankton, decreased gradually with the increasing distance from the island. The changes from hypertrophic to eutrophic conditions were confirmed by a decrease in values of the trophic state index from 72 (site 1) to 58 (site 5). This all suggests that cormorants might have a significant impact on the deterioration of water quality (at distance to 1.6 km) and can contribute to faster water eutrophication. Our results suggest that protection of breeding sites for many waterbirds, such as cormorants, becomes a real threat for the functioning of aquatic ecosystems due to a large load of nutrients

Phytoplankton response to fish-induced environmental changes in a temperate shallow pond-type lake

Since 1967, the temperate, shallow, pond-type Lake Warniak has been subjected to different biomanipulation methods including the introduction of common carp, Cyprinus carpio L., grass carp, Ctenopharyngodon idella (Val.), silver carp, Hypophthalmichthys molitrix (Val.), and bighead carp, Hypophthalmichthys nobilis (Richardson) and then their removal in an effort to control macrophytes and phytoplankton. Recently, pilot stocking with predatory fish, particularly pike, Esox lucius L., has also been conducted. Hence, an examination of the long-term response patterns of phytoplankton to multiple fish-induced stressors was undertaken. In recent years, Chara domination (2000-2004) has helped to stabilize a clear-water state, high/good ecological status, and meso-eutrophic conditions. After the disappearance of Charales in 2004, the rapid, unstable changes in phytoplankton biomass, structure, and biodiversity suggested a shift toward a turbid-water state. As a result, the phytoplankton assemblages changed from those dominated by cryptophytes Y+X2+X1+LO (2000-2004) through those dominated by cyanobacteria K (2005-2008), dinoflagellates LO+Y (2009-2011), and cryptophytes Y+LO+F+X2 (2012), to those dominated by diatoms D+K+P+A (2013-2014) with representative taxa that occur in nutrient-rich and/or nutrient-poor water bodies. The 1967-2014 changes indicated that four periods, two with clear-water state and two with turbid-water state, alternately, one after the other, resulted from different fish pressure. Higher autochthonous fish biomass was usually accompanied by lower phytoplankton biomass. In contrast, the introduction of Cyprinidae fish had a stimulating effect on summer phytoplankton dominated by cyanobateria. Among the nutrients, only phosphorus played an important role

Legal and remedial actions against the damage to the aquatic environment. A case study of an ecological disaster on the Odra River

The subject of this article are the legal consequences of the ecological disaster that occurred on the Odra River, as well as legal instruments and corrective actions in the field of liquidation of damage in the water environment. In order to improve the effectiveness of the water management and protection system, especially in the event of a natural disaster in water reservoirs, as exemplified by the ecological disaster on the Odra River, changes are required with regard to water law in the field of monitoring, control, information system and duties of competent authorities. It is also necessary to work out appropriate procedures, which will contribute to a faster response in such cases and more effective preventive and corrective actions

Rozwój przepisów prawnych w zakresie bioindykacji środowiskowej a stan jakości wód jeziorowych

This article shows the genesis of legal regulations in the range of environmental bioindication in national legislation as a result of the implementation of EU solutions. The most important legal act in EU is the FrameworkWater Directive while the Water Law of 2017 in Poland. The main purposeof these legal acts is to maintain a good status, especially ecological status orpotential of water bodies based on bioindication. Changes in this area contributed to detailing and standardizing of the biological indicators of waters,which allow for a more detailed examination of the status of waters and defning the directions of their protection. The assessment of water quality inWarmian-Mazurian Voivodship indicates that approximately 30% of the lakes studied in 2010–2017, had at least good ecological status or potential. In70% of the lakes, primarily phytoplankton (the most sensitive bioindicator)decided on lowering to below good ecological status/potential. Recently, thefnal assessment of the status (ecological plus chemical) of water bodies hasbeen more rigorous due to chemical status based on exceeded content of priority substances in fsh (i.e. in another important bioindicator)</jats:p