Environmental Drivers of Macroinvertebrate Assemblages within Peat Pool Habitat-Implication for Bioassessment

Macroinvertebrates are a crucial component of wetland trophic webs. Many taxa are used as bioindicators of ecosystem change. However, relationships between macroinvertebrates and the environmental factors in peat pool habitats are still not well recognized. The present study shows the results of long-term studies during the years 2010–2020, on the responses of macroinvertebrates to the changes of environmental variables in a peat pool habitat formed as a result of peat exploitation on continental raised bog. The RDA analysis significantly explained 87.3% of the variance in macroinvertebrates abundances. Assemblages of most taxa (Anisoptera, Chironomidae, Ceratopogonidae, Coleoptera, Hydrachnidia and Tabanidae) showed a strong relationship with N-NO3 and pH. Moreover, densities of Chaoboridae larvae were explained by chlorophyll-a concentrations. Dominant taxon, Chironomidae, constituted from 48% to 87% of total faunal density. The highest proportions showed larvae of Psectrocladius sp. (gr. sordidellus) and Chironomus sp. Changes in the composition of macroinvertebrate fauna over a period of 10 years reflect the eutrophication process of the peat pool and deterioration of habitat conditions

Submerged macrophytes as bioindicators of environmental conditions in shallow lakes in eastern Poland

We investigated the responses of submerged macrophytes to environmental conditions in shallow lakes to evaluate the role of macrophytes as bioindicators of water quality and anthropogenic disturbances (such as eutrophication) of shallow lake ecosystems. The studies were conducted on a group of ten shallow lakes situated on the area of Polesie Lubelskie (eastern Poland). The lakes represented five types of macrophyte communities, Chara- Stratiotes-, Myriophyllum-, Potamogeton- and Ceratophyllum-dominated. The total biomass of macrophytes and their distribution were significantly negatively correlated with the trophic status of the lake. Principal component analysis confirms the separation of the lakes with regard to trophic status and macrophyte species richness and biomass. The results of the Monte Carlo permutation test (RDA analysis) indicated the significant effect of Secchi disc depth, pH, conductivity, chlorophyll-a, Ptot, P-PO4, N-NO3 and N-NH4 on the biomass and distribution of submerged macrophytes in the lakes.Macrophyte assemblages showed visible negative changes of their species diversity and biomass through the human induced eutrophication process. Their diversity is the combined effect of environmental conditions specific for a lake ecosystem, thus macrophytes have a crucial role in biomonitoring studies of shallow lakes

Does Water Brownification Affect Duckweeds in Freshwaters? Results from a Laboratory Experiment

The influence of water brownification (an increase in water color) on floating-leaved macrophytes appears to be an important issue in predicting the consequences of climate change in freshwater ecosystems. To fill the gap in the knowledge in this area, we performed a laboratory experiment aiming to test the impact of humic acid (HA) on Lemna minor sampled from an oxbow lake. Plants were exposed over seven days to four different additions of pure HA (resulting in DOC concentrations between 5.0 ± 0.1 mg dm−3 and 36.5 ± 0.4 mg dm−3). Changes in duckweed total fresh biomass, leaf area and the root length were measured, as well as the concentrations of total phosphorus, phosphates and nitrates in the water. The study did not find any significant decrease in either the biomass or leaf area of L. minor under conditions of enhanced HA content. However, we found that a moderate increase in HA in water promoted the growth of duckweed roots, thus, increasing the biomass but not the leaf area. In contrast, a large increase in HA in the water suppressed the growth of roots in L. minor, which was also in coincidence with less nutrient depletion in the water

Distribution of planktonic crustaceans and its diurnal changes in a hypertrophic shallow lake: does the switch from turbid-water state to clear-water state matters?

The paper presents results of post hoc analysis of diurnal changes in the crustacean distribution along the horizontal transect in the shallow hypertrophic lake, which undergone a switch from turbid-water, phytoplankton-dominated state (chl-a: 257.8 ± 100.2 µg dm−3, Secchi depth: 0.17 ± 0.02 m) to clear-water plant-dominated state (chl-a: 26.8 ± 4.8 µg dm−3, Secchi depth: 1.03 ± 0.29 m). Changes in crustacean biomass were observed in two consecutive years during two July days (every sixth hour, starting with the noon) in three sampling sites (emergent macrophytes, submerged macrophytes and center), situated along the horizontal transect between the lake shore and the center of the lake. Analysis revealed that: (a) in turbid-water conditions crustaceans aggregated at night-time near the water surface, both in the littoral zone and the lake center; (b) in clear-water state a nocturnal increase in crustacean biomass was noted only in submerged macrophyte site, but concerned only cladocerans. In conclusion, we hypothesized that switch from phytoplankton-dominated to plant-dominated state effects in change of predator-avoidance strategy showed by planktonic crustaceans.The paper presents results of post hoc analysis of diurnal changes in the crustacean distribution along the horizontal transect in the shallow hypertrophic lake, which undergone a switch from turbid-water, phytoplankton-dominated state (chl-a: 257.8 ± 100.2 µg dm−3, Secchi depth: 0.17 ± 0.02 m) to clear-water plant-dominated state (chl-a: 26.8 ± 4.8 µg dm−3, Secchi depth: 1.03 ± 0.29 m). Changes in crustacean biomass were observed in two consecutive years during two July days (every sixth hour, starting with the noon) in three sampling sites (emergent macrophytes, submerged macrophytes and center), situated along the horizontal transect between the lake shore and the center of the lake. Analysis revealed that: (a) in turbid-water conditions crustaceans aggregated at night-time near the water surface, both in the littoral zone and the lake center; (b) in clear-water state a nocturnal increase in crustacean biomass was noted only in submerged macrophyte site, but concerned only cladocerans. In conclusion, we hypothesized that switch from phytoplankton-dominated to plant-dominated state effects in change of predator-avoidance strategy showed by planktonic crustaceans

Does Water Brownification Affect Duckweeds in Freshwaters? Results from a Laboratory Experiment

The influence of water brownification (an increase in water color) on floating-leaved macrophytes appears to be an important issue in predicting the consequences of climate change in freshwater ecosystems. To fill the gap in the knowledge in this area, we performed a laboratory experiment aiming to test the impact of humic acid (HA) on Lemna minor sampled from an oxbow lake. Plants were exposed over seven days to four different additions of pure HA (resulting in DOC concentrations between 5.0 ± 0.1 mg dm−3 and 36.5 ± 0.4 mg dm−3). Changes in duckweed total fresh biomass, leaf area and the root length were measured, as well as the concentrations of total phosphorus, phosphates and nitrates in the water. The study did not find any significant decrease in either the biomass or leaf area of L. minor under conditions of enhanced HA content. However, we found that a moderate increase in HA in water promoted the growth of duckweed roots, thus, increasing the biomass but not the leaf area. In contrast, a large increase in HA in the water suppressed the growth of roots in L. minor, which was also in coincidence with less nutrient depletion in the water

Hydrochemical and microbiological distinction and function of ombrotrophic peatland lagg as ecotone between

The testate amoeba, ciliate and rotifera communities living in interstitial waters in peatbog in eastern Poland were studied. Sampling was done on a monthly basis from April to November 2007–2008. Microbial communities were examined in a transect including three sites: (1) pine forest (site located 5 m from the lagg/forest contact zone), (2) lagg, (3) open peatbog (the centre of the peatbog). At each of the sites, interstitial water was sampled by means of piezometric wells placed to a depth of 1 m. The species richness and abundance of protozoa and rotifers significantly differed between the studied stations, with the lowest numbers in the pine forest and the highest in the lagg. These differences between macro-habitats may be due to differences in environmental conditions. The distribution of samples in ordination space led to conclude that studied habitats are distributed along the falling gradient of pH and rising gradient of total organic carbon, water table depth and nitrate nitrogen. Assemblages of all three groups showed a strong compositional gradient correlated with water-table depth, conductivity and total phosphorus. However, species composition of ciliates and rotifers was explained by nitrate nitrogen and/or phosphates concentrations. The results suggest that lagg zone of a raised bog can fulfil the function of an ecotone zone, distinguished by a significant increase in biodiversity, abundance and species specificity of micro-organisms. It can also be a place of very efficient matter and energy flow in a peat bog ecosystem

Changes in the Ecological Status of Rivers Caused by the Functioning of Natural Barriers

Introducing the European beaver to the catchment area, which adjusts the habitat to its own needs (by building dams), may have a positive impact on the ecology, geology, and hydromorphology of rivers and intensify the water self-purification process. In this study, a comparative assessment of the ecological status was made between the areas where the species Castor fiber L. occurs (habitat type A) and the areas unaffected by the influence (habitat type B). For this purpose, the Macrophyte River Index (MIR) and the Hydromorphological River Index (HIR) were calculated, along with the floristic indicators of biodiversity: species richness and Margalef, Shannon–Wiener, and Simpson indices. Only 35% of the sites met the standard of good ecological status. The presence of hypertrophic species and anthropogenic modifications of the river bed had a negative impact. The spread of beavers has a significant positive effect on changes in hydromorphological conditions and water levels in the river. The water levels in habitat types A and B were 0.504 and 0.253 m, respectively. There were statistically significant differences in the HIR values between habitat types A and B, which were 0.585 and 0.535, respectively. In habitats of type A, the heterogeneity of the current and bed material as well as the diversity of elements accompanying the tree stands increased. Research has shown greater species richness and greater biodiversity of macrophytes in the habitats of beaver dams. The research confirmed the significant influence of the European beaver on changes in the environment. The activity of beavers intensifies the processes of introducing wetland and rush species to forest areas

Changes in the Ecological Status of Rivers Caused by the Functioning of Natural Barriers

Introducing the European beaver to the catchment area, which adjusts the habitat to its own needs (by building dams), may have a positive impact on the ecology, geology, and hydromorphology of rivers and intensify the water self-purification process. In this study, a comparative assessment of the ecological status was made between the areas where the species Castor fiber L. occurs (habitat type A) and the areas unaffected by the influence (habitat type B). For this purpose, the Macrophyte River Index (MIR) and the Hydromorphological River Index (HIR) were calculated, along with the floristic indicators of biodiversity: species richness and Margalef, Shannon–Wiener, and Simpson indices. Only 35% of the sites met the standard of good ecological status. The presence of hypertrophic species and anthropogenic modifications of the river bed had a negative impact. The spread of beavers has a significant positive effect on changes in hydromorphological conditions and water levels in the river. The water levels in habitat types A and B were 0.504 and 0.253 m, respectively. There were statistically significant differences in the HIR values between habitat types A and B, which were 0.585 and 0.535, respectively. In habitats of type A, the heterogeneity of the current and bed material as well as the diversity of elements accompanying the tree stands increased. Research has shown greater species richness and greater biodiversity of macrophytes in the habitats of beaver dams. The research confirmed the significant influence of the European beaver on changes in the environment. The activity of beavers intensifies the processes of introducing wetland and rush species to forest areas