An attempt at modelling the periphyton dynamics with artificial neural networks exemplified by the oxbow lake reopening study (The Słupia River, Northern Poland)

An experiment was performed in the Osokowy Staw oxbow lake (the Słupia River, northern Poland). The old riverbed was reconnected with the riverine system and periphyton communities on nylon artificial substrate were surveyed before and after engineering works. Then, ANN (Artificial Neural Network) architectures were designed and trained in order to create models of interactions between 18 macrozooperiphyton, microzooperiphyton and phytoperiphyton taxa in the changing ecosystem. Calculations were performed using StatSoft Software Statistica 6.1 with the implemented neural network module.Neural network models allowed a quantitative insight into periphyton dynamics and indicated trophic relationships, both predatoryprey and competitive. Thus, we see ANN as a good technique for modelling multidimensional, nonlinear relations between epiphytic organisms and as a promising method for creating overall models

Influence of anthropogenic factors on microhabitats inhabited by riverine hydrobionts - assessment with MRT method

This study concerns the influence of urban area on vegetation and invertebrates inhabiting the Słupia River (northern Poland). Altogether, 10 plant communities and 37 macrozoobenthos taxa were determined during four seasonal samplings (October 2005, January, April and August 2006). In order to reveal how the city of Słupsk affects the vegetation and fauna, MRT (multivariate regression tree) models were created. On their basis the most important factors were determined from the following set of variables: season, water temperature, salinity, distance, water depth, bottom type, location in the river bed and degree of river bed transformations. Performed analyses showed that vegetation in the urban area was primarily influenced by distance (correlated with anthropogenic pressure), while for invertebrates season and temperature were the most important factors

Dam and reservoir removal projects : a mix of social‑ecological trends and cost-cutting attitudes

The removal of dams and reservoirs may seem to be an unforeseen and sometimes controversial step in water management. The removal of barriers may be different for each country or region, as each differs greatly in terms of politics, economy and social and cultural awareness. This paper addresses the complex problem of removing dams on rivers and their connected reservoirs. We demonstrate the scales of the changes, including their major ecological, economic, and social impacts. Arguments and approaches to this problem vary across states and regions, depending on the political system, economy and culture, as confirmed by the qualitative and quantitative intensities of the dam removal process and its global geographical variation. The results indicate that the removal of dams on rivers and their connected reservoirs applies predominantly to smaller structures (< 2.5 m). The existing examples provide an important conclusion that dams and reservoirs should be considered with regard to the interrelations between people and the environment. Decisions to deconstruct hydraulic engineering structures (or, likewise, to construct them) have to be applied with scrutiny. Furthermore, all decision-making processes have to be consistent and unified and thus developed to improve the lack of strategies currently implemented across world

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

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

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

Response of Benthic Fauna to Habitat Heterogeneity in a Shallow Temperate Lake

We investigated the response of benthic macroinvertebrates in the eulittoral, infralittoral, and sublittoral zones, in two segments of the freshwater Lake Wicko on the coast of the Baltic Sea. Our results showed that the morphometry of lakes plays a major role as a factor structuring the macroinvertebrates communities. Two parts of the lake, different in size and depth, show decreasing differences in the trophic state, abundance, diversity and number of indicator species of benthic fauna with the depth gradient. The most significant differences were observed between the littoral zones of both segments. Similar environmental conditions in the sublittoral zones corresponded to the simplified structure of the benthic macroinvertebrates communities. In the infralittoral zone, the most significant differences between the two segments, were recorded for mollusks and large crustaceans as well as the Oligochaeta/Chironomidae abundance ratio. In the sublittoral zone, the diversity of chironomids differed most strongly. Lower species diversity was found in the part of the lake with a slight depth decrease. Shredders reached significantly higher values in eulittoral and infralittoral of the deeper lake segment. Average Score Per Taxon increased with a depth gradient. We recommend testing benthic macroinvertebrates in lakes with different morphometrics individually for each depth zone

The Effect of Hydrological Connectivity on the Zooplankton Structure in Floodplain Lakes of a Regulated Large River (the Lower Vistula, Poland)

The zooplankton community structure and diversity were analysed against the gradient of floodplain lakes connectivity and water level under different flood-pulse dynamics in the Vistula River. The lakes differed in terms of hydrology, among others in the degree/type of their connection with the river (permanent, temporary and no connection). The study was conducted during the growing seasons in the years 2006&ndash;2013 and involved the lower Vistula River and three floodplain lakes: isolated, transitional and connected. Water samples were collected biweekly from April to September. Zooplankton was the most diverse and abundant in the transitional lake (the highest Shannon &alpha;-diversity index H&rsquo; and Pielou&rsquo;s evenness index J&rsquo;). The gentle washing of the lakes might have stimulated the development of zooplankton in accordance with the Intermediate Disturbance Hypothesis. The diversity and density of zooplankton were higher in the connected lake compared to the isolated one. We confirmed the hypothesis that zooplankton should be more abundant and diverse in floodplain lakes connected with the river (or transitional) than in isolated ones. Zooplankton analyses indicated that hydrological conditions (flood-pulse regime) contributed most substantially to zooplankton diversity and density in the floodplain lakes of the lower Vistula valley

Patterns of salinity regime in coastal lakes based on structure of benthic invertebrates.

The macrozoobenthic diversity patterns along a brackish-freshwater salinity gradient have been identified, considering effects of differences in the level of hydrological connection of coastal lakes with the sea on the structure of benthic invertebrate communities. The study is based on samples from six coastal lakes located along the southern coast of the Baltic Sea in Poland. The analysis of environmental and biological data confirmed the existence of stable phases (brackish water vs. freshwater), but as a result of periodical intrusion of seawater, adaptation of animal communities takes place, which was reflected in low values of the predictors describing them (number of taxa, density and diversity). Redundancy analysis indicates that values of conductivity and salinity are the major factors that determine the abundance of dominant groups of benthic fauna. The gradient of hydrological connection of the lakes with the sea accounted for 50% of the variance in biological data, physico-chemical variables for 25%, trophic variables for 15%, and only 9% of the variance was unexplained. The major implication of our results is that coastal lakes that differ only slightly in salinity can have alternative, regional patterns of diversity of structure of benthic fauna. Periodical inflow of brackish waters initiates adaptive cycles of benthic fauna, and their frequency is strongly linked with the hydrological regime. The rhythm of the inflow of seawater is variable, so that management and protection of coastal lakes are extremely complicated