Does Dredging of Floodplain Lakes Affects The Structure of The Macrophytes and Epiphytic Fauna Inhabiting Stratiotes Aloides

Hydrotechnical activities on the Słupia river above the town of Słupsk (northern Poland) were performed against floods in the valley. The results based on the data on fauna and flora gathered before (in 2003, T+0) and after (in T+2, T+6 and T+11) the reclamation showed that the river canalization and oxbow lake dredging can significantly disturb the ecology of water bodies adjacent to the river. Observations of the oxbow lake (OLS5), showed the decrease in the number of macrophyte phytocenoses from 11 before the dredging to 6 very valuable Potametea phytocenoses, after wards. The development of common pleustonic phytocenoses of Lemnetea minoris and the massive development of green algae resulted from the bottom sediment removal. In the case of population, Stratiotes aloides was rebuilt after elimination during dredging already in T+2. Before hydrotechnical works, the oxbow lake was characterized by 12 invertebrate taxa inhabiting S.aloides, whereas only 9 were found first period after the dredging, 15 taxa in second period and 23 in a recent study. During both observation periods, dominated by Chironomidae larvae (T+0), Trichoptera larvae (T+2 and T+6) and again Chironomidae larvae (T+11). The hydrotechnical activities significantly altered in the first period the structure of fauna and flora inhabiting the water body. Such radical interference in natural values of oxbow lakes is un-suitable for the preservation of ecosystems due to the significant decrease in their biodiversity. Achieved on a similar or higher level of macrophytes diversity and epiphytic invertebrates was noticeable ten years after the dredging of a water body

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

Wpływ ładunków fosforu na strukturę makrofitów i status troficzny zbiornika zaporowego na małej rzece nizinnej

The main objective of the study was to evaluate if macrophytes structure and trophic status of dam reservoir Kraśnik on a small lowland river Wyżnica are determined by phosphorous loadings. Studies were conducted seasonally in May, July and October during the years 2008-2009. Samples were taken at four sites: Site 1 - inflow of the Wyżnica River to pre-dam, Site 2 − pre-dam, Site 3 − dam reservoir and Site 4 - outflow of the Wyżnica River from dam reservoir. Physical and chemical parameters (temperature, Secchi disc depth, dissolved oxygen, pH, conductivity, total suspension, chlorophyll-a, TP and P-PO4) were measured in water samples. Together with water parameters there were estimated biomass of phytoplankton and species composition and biomass of emergent, floating-leaved and submerged macrophytes. Concentrations of TP, chlorophyll-a and Secchi disc depth were used to calculate trophic state index of Carlsson for dam reservoir and its pre-dam. Based on mean water current, mean residence time of water in dam reservoir and concentrations of TP and P-PO4 loadings (g m-2) flowing into dam reservoir with the Wyżnica River were calculated. The results showed visible negative effect of phosphorous loadings on both macrophytes composition and trophic state of the reservoir. The marked changes concerned soft vegetation. High P loadings (7.74 g m-2 of TP and 6.03 g m-2 P-PO4) during the spring of 2008 caused the disappearance of characeans meadows. In 2009, the presence of rigid hornwort (Ceratophyllum demersum L.), the species typical for eutrophic lakes was noted. This unrooted submerged plant uptakes dissolved orthophosphates directly from the water column. Values of Carlsson index (51.4 ≤ TSI ≤ 68.2) indicate the eutrophic state of dam reservoir Kraśnik. During summer season in dam reservoir there were observed algal blooms (biomass of phytoplankton exceed 10 mg WW dm-3) and low water transparency (Secchi disc depth ranged from 0.4 to 0.65 m). During the two-year studies in dam reservoir Kraśnik a high reduction of P loadings, mostly dissolved orthophosphates was observed. Dependently on season, reduction of P-PO4 loadings ranged from 52% (July 2008) up to 91% (May 2009). The reduction of TP was lower and reached values from 15% (May 2008) to 48% (July 2009).Celem badań była ocena czy ładunki fosforu dopływające z wodami rzeki Wyżnicy mogą mieć istotny wpływ na strukturę makrofi tów i status trofi czny zbiornika zaporowego w Kraśniku. Badania prowadzono w trzech sezonach, maj, lipiec i październik w latach 2008-2009. Próby pobierano na czterech stanowiskach; stanowisko 1 - wpływ rzeki Wyżnicy do zbiornika wstępnego; stanowisko 2 - zbiornik wstępny; stanowisko 3 - zbiornik zaporowy; stanowisko 4 - odpływ rzeki Wyżnicy ze zbiornika zaporowego. W wodzie oznaczano parametry fi zyczne i chemiczne (temperatura, widzialność krążka Secchiego, tlen rozpuszczony, pH, przewodnictwo, zawiesina ogólna, chlorofi l-a, fosfor ogólny, fosfor fosforanowy). Ponadto analizowano biomasę fi toplanktonu oraz skład gatunkowy i biomasę makrofi tów wynurzonych, zanurzonych i o liściach pływających. Na podstawie stężenia fosforu ogólnego, chlorofi lu-a oraz widzialności krążka Secchiego obliczono wskaźnik trofi i Carlssona (TSI) dla zbiorników zaporowego i wstępnego. Na podstawie średnich przepływów, czasu retencji wody w zbiorniku oraz stężeń fosforu ogólnego i fosforanowego obliczono ładunki (g m-2), które dopływają do zbiornika z wodami rzeki Wyżnicy. Uzyskane wyniki wskazują, że ładunki fosforu dopływające do zbiornika zaporowego oddziałują negatywnie zarówno na strukturę roślinności zbiornika, jak i jego stan trofi czny. Najbardziej widoczne zmiany dotyczą składu gatunkowego roślinności miękkiej. W 2008 roku na skutek wysokich ładunków fosforu, zwłaszcza fosforanowego (6.03 g P-PO4 m-2), ze zbiornika ustąpiły ramienice. W 2009 roku odnotowano występowanie rogatka sztywnego, gatunku typowego dla wód żyznych, posiadającego zdolności wiązania fosforu fosforanowego bezpośrednio z toni wodnej. Wartości wskaźnika Carlssona (51.4 ≤ TSI ≤ 68.2), wskazują na eutrofi czny charakter wód zbiornika Kraśnik. W sezonie letnim zbiornik charakteryzuje się zakwitami glonów (biomasa fi toplanktonu przekracza wówczas 10 mg MM dm-3) oraz małą przezroczystością wody (widzialność krążka Secchiego waha się w granicach 0.4-0.65 m). W zbiorniku zaporowym Kraśnik następuje znaczna redukcja ładunków fosforu, przede wszystkim fosforanowego. W zależności od sezonu, redukcja fosforanowego wahała się w przedziale od 52% (lipiec 2008) aż do 91% (maj 2009). Redukcja ładunku fosforu ogólnego była znacznie niższa, osiągała wartości od 15% (maj 2008) do 48% (lipiec 2009)

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