Comparison of Phytoplankton and Autotrophic Picoplankton Populations Over a 24-Hour Period From a Pond\u27s Surface and Subsurface Waters

Phytoplankton abundance and composition relationships within the surface layer changed over short time periods (4-6 hours) in comparison with more constant associations at 2 cm below the surface. Both strata had a diverse algal flora (\u3e50 taxa), but no distinct neuston assemblage characterized the surface layer algal composition over the 24-hour study. The similarity between the two strata indicated the floral composition of the surface layer came from the water column algae below the surface. Chlorophytes, diatoms, cyanobacteria, and cryptophytes represented the most abundant algal categories for both strata with a total mean phytoplankton abundance of 3,566 cells ml-1 at the surface and 40,532 cells ml-1 at 2 cm over the 24 hours. The autotrophic picoplankton had generally similar levels of abundance over time. Their mean abundance for the 24 hours was 469 and 599 X 103 cells ml-1 at the surface and 2 cm respectively

Rotifer Diversity in the Acidic Pyrite Mine Pit Lakes in the Sudety Mountains (Poland)

The diversity of rotifers was studied in three artificial water bodies (Azure Lake, Yellow Lake, and Purple Lake), which were once pyrite mines. The physicochemical parameters and the zooplankton composition of the water were determined. Azure Lake had a pH of 3.4–6.9, conductivity values of 165–194 µS cm− 1, and low concentrations of sulphate, calcium, magnesium, copper, and iron, while the other lakes had a pH of 2.6–2.9, a conductivity of 1636–3400 µS cm− 1, and high concentrations of sulphate (up to 2863 mg dm− 3), Cu (up to 2650 µg dm− 3), and Fe (up to 178.3 mg dm− 3). The rotifer community in the lakes comprised 27 taxa (15 in Azure Lake, 13 in Purple Lake and 14 in Yellow Lake). We also found two species that are rarely observed in Poland (Aspelta cincinator and Elosa spinifera), and three species commonly found in acidic water (E. worallii, Cephalodella delicata, and C. hoodi). The types of rotifers in Azure Lake differed from those in the other two lakes. The Shannon–Weaver biodiversity index (H′) was the highest in Purple Lake (H′ = 1.255) and lowest in Azure Lake (H′ = 0.455). The effect of some of the physicochemical parameters on rotifer diversity is discussed

Phytoplankton production in relation to simulated hydro- and thermodynamics during a hydrological wet year – Goczałkowice reservoir (Poland) case study

Phytoplankton is one of the crucial components of water body ecosystems. Its presence and development depend on biological, physical and chemical factors and in consequence it is an important indicator of ecosystem condition. Monitoring of phytoplankton production, measured as chlorophyll a concentration, is a useful tool for assessing the status of dam reservoirs. Modeled chlorophyll a concentrations are used as water quality indicators in locations not included in monitoring systems, in situations when the temporal resolution of the monitoring is not enough, and in assessments of the impacts of future activities. Therefore, the aim of this study was to find correlations between hydro- and thermodynamics and the chlorophyll a concentration for possible application in reservoir monitoring and management, using an ELCOM-CAEDYM model. The analysis included summer and fall which are most prone to algal blooms, and four phytoplankton groups identified as dominant in the reservoir based on periodic observations. Comparisons of simulated water temperature and both observed and simulated chlorophyll a concentrations confirmed that these variables are significantly correlated (correlation of hourly chlorophyll a and water temperature was 0.70, ranging from 0.55 to 0.81 in the bottom and surface water layers, respectively, while for daily outputs it was 0.74, ranging from 0.60 to 0.83). This relation was stronger than that of chlorophyll a to nutrient (N, P and Si) concentrations. What is more, the method used allowed the assessment of a much more detailed spatial and temporal distribution of phytoplankton groups compared with conventional monitoring techniques. The study indicated that the phytoplankton community was dominated by Chlorophytes and Diatoms with a larger share of Chlorophytes in shallow parts of the reservoir. This domination was weaker after short water mixing events in summer and especially after the fall turnover. The increase in phytoplankton diversity was estimated to occur mainly near the surface and in shallow parts of the reservoir. Most of the observed concentrations of individual phytoplankton groups differed from simulation results by less than 25% and the model reflected accurately 74% of observed trends in concentrations. Calculated chlorophyll a concentration was well matched to hourly monitoring data (mean squared error = 5.6, Nash–Sutcliffe model efficiency coefficient = 0.51, Pearson correlation coefficient = 0.72 and p-value = 0.0007). High compatibility of the model to the values measured in the reservoir make it a promising tool for the prediction and planning of actions aimed at maintaining good functioning of the reservoir

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

An autoecological investigation of Desmodesmus: implications for ecology and taxonomy

Background and aims – Phenotypic plasticity is the morphological response of a single genotype to produce several different physiological and/or morphological types under changing environmental conditions. Desmodesmus, a green alga, has been well documented for its phenotypic responses (e.g. colony transformation to unicells, and spiny transformation to spineless). Two oxbow lakes (R1 and R2) and one artificial dam reservoir (R3) were used to evaluate the quantity and diversity range of Desmodesmus species occurring during four seasons of one-year. Methods – Water samples were quantified for Desmodesmus species and identified using the Scanning Electron Microscope (SEM). To better understand the morphological responses of Desmodesmus, an axenic culture of Desmodesmus abundans, CCAP 258/299, was cultured in sterile-filtered water from each water body collected from each season. Key results – Not surprisingly, different Desmodesmus species inhabited each water body and exhibited different densities of growth, contributing 77% of the total density in R1, 22% in R2 and only 1% in R3. Summer and autumn were the seasons when Desmodesmus showed the highest density in the shallow and polymictic oxbow lakes (R1 and R2). In the deep and dimictic reservoir (R3), the highest density of Desmodesmus was during autumn. Phenotypic plasticity was observed in the experiments, with unicells being formed from colonies, some with shorter spines. Desmodesmus grown in a high concentration of nitrogen (SE, Medium 7 +3N and BBM) had a higher percentage of unicells compared to the other culture conditions. Conclusions – Our studies are important from both taxonomical and ecological points of view, since our results showed that there may be new possibilities for using the phenotypic plasticity of Desmodesmus to assess water quality and as a potential bioindicator of nutrient availability in natural ecosystems

An autecological investigation of Desmodesmus:implications for ecology and taxonomy

Background and aims – Phenotypic plasticity is the morphological response of a single genotype to produce several different physiological and/or morphological types under changing environmental conditions. Desmodesmus, a green alga, has been well documented for its phenotypic responses (e.g. colony transformation to unicells, and spiny transformation to spineless). Two oxbow lakes (R1 and R2) and one artificial dam reservoir (R3) were used to evaluate the quantity and diversity range of Desmodesmus species occurring during four seasons of one-year. Methods – Water samples were quantified for Desmodesmus species and identified using the Scanning Electron Microscope (SEM). To better understand the morphological responses of Desmodesmus, an axenic culture of Desmodesmus abundans, CCAP 258/299, was cultured in sterile-filtered water from each water body collected from each season. Key results – Not surprisingly, different Desmodesmus species inhabited each water body and exhibited different densities of growth, contributing 77% of the total density in R1, 22% in R2 and only 1% in R3. Summer and autumn were the seasons when Desmodesmus showed the highest density in the shallow and polymictic oxbow lakes (R1 and R2). In the deep and dimictic reservoir (R3), the highest density of Desmodesmus was during autumn. Phenotypic plasticity was observed in the experiments, with unicells being formed from colonies, some with shorter spines. Desmodesmus grown in a high concentration of nitrogen (SE, Medium 7 +3N and BBM) had a higher percentage of unicells compared to the other culture conditions. Conclusions – Our studies are important from both taxonomical and ecological points of view, since our results showed that there may be new possibilities for using the phenotypic plasticity of Desmodesmus to assess water quality and as a potential bioindicator of nutrient availability in natural ecosystems

Small effects of a large sediment contamination with heavy metals on aquatic organisms in the vicinity of an abandoned lead and zinc mine

The effects of the long-term contamination of water reservoirs with mine effluents were investigated at an abandoned mine site in Upper Silesia, southern Poland. The studies covered metal content and mobility in bottom sediments as well as water chemistry in relation to the content of metals in selected macrophytes and their physiology and the composition of phyto- and zooplankton communities. Although it is 40 years since mining ceased, reservoir sediments are still heavily contaminated with cadmium, zinc and lead with concentrations (mg/kg), which vary roughly between 130–340, 10,000–50,000 and 4,000–12,000, respectively. About 50–80 % of these elements are associated with the reducible phase, and only a small percentage, <10 %, is present in the most mobile exchangeable phase. Despite the high total metal concentration in sediments, their content in the submerged plants Myriophyllum spicatum and the emerged plants Phragmites australis was low. The observed effects of heavy metal contamination on photosynthetic activity in the leaves of P. australis were negligible, whereas those in M. spicatum show up only as a difference in the distribution of photosynthetic activity in leaves of different ages, which seems to be related to the very good water quality and to the generally small concentrations of metals in pond water. The physicochemical properties of water also seem to control the presence of planktonic species more than does sediment contamination. However, a shift toward groups of species known to be more resistant to heavy metals (diatoms, green algae and Rotifera) indicates some adaptative changes related to the long-lasting contamination of ponds

Interactions between ciliate species and Aphanizomenon flos-aquae vary depending on the morphological form and biomass of the diazotrophic cyanobacterium

Aphanizomenon flos-aquae can form extensive blooms from freshwater to the brackish environment and, being a diazotrophic species, contribute significantly to the nitrogen and carbon cycle. It occurs as single filaments or aggregates and could be used as an alternative nutrients source for bacteria and ciliates. Ciliates are a group of organisms playing a crucial role in the transfer of nitrogen from primary producers to higher trophic levels in aquatic food webs. The aim of the experiment was to study the effects of the cyanobacterium A. flos-aquae on the community of five ciliate species (Spirostomum minus, Euplotes aediculatus, Strobilidium sp., Vorticella sp. and Paramecium tetraurelia). The response of each species to the presence of a low/high cyanobacterial biomass and to the different morphological forms of A. flos-aquae (single filaments or aggregates) was demonstrated. The results of the experiment showed the variability of interactions between the cyanobacterium A. flos-aquae and ciliates and pointed out the possible benefits that A. flos-aquae provides to the ciliates (e.g., a substrate for the development of bacteria as food for ciliates or as a source of nitrogen and carbon)

The influence of climate factors on the presence of microcystins in freshwaters – a case study from Poland

Climate changes are expressed as increase of temperature and the frequency and intensity of severe weather conditions. Furthermore, climate change promotes development of bloom-forming cyanobacteria and the increase the intensity and toxicity of the blooms. According to European Environmental Agency (EEA), Europe is the fastest warming continent and particularly high warming is found over eastern Europe. The last six years were recognized as the warmest on record. However, the greatest changes will be possible to identify locally. We conducted the short-term surveys of concentrations of microcystins, which are recognised as the most often produced cyanotoxins, in two shallow and small water bodies in southern Poland. Data was collected during four years of monitoring: 2017, 2019-2021. We hypothesised that microcystin concentration is related to weather conditions. The pattern of microcystins distribution during the seasons were similar in both of them: toxins were present from July to October. Statistical analyses showed that significant factor correlated with concentration of microcystins was rainfall higher than 2.2 mm. Besides, stepwise regression demonstrated that rainfalls and air temperatures were significant contributors for dimensions PCAI and PCAII, which cumulatively explained 53% of varianc

Conservation status of the Natura 2000 habitat 3110 in Poland: Monitoring, classification and trends

Soft water lakes, or so-called lobelia lakes, which are inhabited by a specific vegetation composed of isoetids, have been subjected to intense research aimed at evaluating their condition and conservation status for many years in Poland. At the time of Poland’s accession to the European Union and the implementation of the EU Habitats Directive, these lakes were classified as natural habitat 3110. In accordance with the provision of the Habitat Directive a comprehensive methodology for monitoring and classification of the state of this habitat has been developed. Using this methodology, two monitoring trials (in 2009–2010 and again in 2016–2017) were carried out at 45 and 43 sites of the 3110 natural habitat, respectively. These studies confirm the high sensitivity of these poorly buffered aquatic ecosystems to all external influences, both natural and anthropogenic. The overall conservation status of the 3110 habitat in Poland showed a relatively high stability, with similar proportions of sites classified as favourable (FV), unfavourable inadequate (U1) and unfavourable bad (U2) between 2009–2010 (35%, 49% and 16%, respectively) and 2016–2017 (33%, 56% and 11%, respectively). Out of 43 sites examined in 2016–2017, 29 remained unchanged compared with the results of the previous survey concerning their overall status. Results of the monitoring research also allow for the observation and evaluation of mechanisms and directions of changes in the functioning of these ecosystems. Based on the experiences from two series of monitoring conducted so far, the methodology has been assessed as appropriate for the assessment of the conservation status of the 3110 natural habitat, however, some modifications and additions have been suggested