Floodplain Water Bodies Research Articles

Typification of Lymans of the North-Western Black Sea According to the Recommendations of the Eu Water Framework Directive

Purpose. Typification of limans in the north-western Black Sea coast (NWBS) (so called “marine lagoons”) according to the EU Water Framework Directive methodological approaches on hydrological, morphometric, hydrochemical and genesis characteristics. Methods. Comparative & geographical, generalization, cluster analysis. Results. Five groups of limans have been determined by analysis of their crucial parameters: mean annual salinity, depth fluctuation, fresh water influx, water bodies’ and their catchments’ genesis, which were taken from the historical sources and from researches of the Odessa I.I. Mechnikov National University. The selected groups comprised water bodies having similar properties in their water balance regime, origin and hydrochemical regime. Brief description of properties for the each group of water bodies has been formulated. A comparison of the typification results with the work of another team on these objects has been conducted. Conclusions. Five types of limans have been identified in the NWBS: 1) floodplain lagoons, oligogaline, shallow, without free connection to the sea; 2) polygaline shallow sea lagoons; 3) very elongated deep mesohaline floodplain water bodies; 4) estuaries of large rivers with permanent connection to the sea; 5) floodplain shallow hyperhaline water bodies, without a natural connection to the sea. The typification performed makes it possible to use modern monitoring programs for large groups of water bodies in NWBS taking into account the European experience.

Distribution of the Chinese Sleeper Perccottus glenii (Odontobutidae) in fish communities of floodplain waterbodies in the Samarskaya Luka National Park (Samara Region, Russia)

Distribution of the Chinese Sleeper Perccottus glenii (Odontobutidae) in fish communities of floodplain waterbodies in the Samarskaya Luka National Park (Samara Region, Russia)

The Daudkandi model of community floodplain aquaculture in Bangladesh: a case for Ostrom’s design principles

Floodplain water-bodies are major common-pool resources (CPRs) of Bangladesh and constitute more than fifty percent of inland open water bodies. Throughout the British colonial period, Pakistani rule and the first one and half decades of independent Bangladesh, a majority of inland water-bodies remained under direct government management, though the floodplains by getting heavily inundated during the monsoon turn into open access resource. In the mid-1980s co-management was introduced on a small scale with the help of NGOs as providers of management styles and credit to communities of fishers or villagers. NGOs also got involved in floodplain water-bodies and came up with different models of user-managed fishery bodies. This paper examines a specific management system of community-governed floodplain aquaculture (FPA) known as the Daudkandi model, developed by a local NGO in the Daudkandi sub-district of the Comilla district. Applying the design principles developed by Ostrom (1990) characterizing long surviving successful user-managed common-pool resource institutions, this paper explores the rules devised by partners in the management of a FPA under the Daudkandi model. Though the FPA management model is relatively new as it has been adopted in 1996, it has been found to follow the design principles in devising its management rules. However, because of its unique features in terms of seasonality, NGO-community partnership, exclusion of past users, and numerous replications, etc. the future of the model as a CPR governance system holds many challenges and deserves continuous research focus.

Aquatic methane dynamics in a human-impacted river-floodplain of the Danube.

River‐floodplain systems are characterized by changing hydrological connectivity and variability of resources delivered to floodplain water bodies. Although the importance of hydrological events has been recognized, the effect of flooding on CH4 concentrations and emissions from European, human‐impacted river‐floodplains is largely unknown. This study evaluates aquatic concentrations and emissions of CH4 from a highly modified, yet partly restored river‐floodplain system of the Danube near Vienna (Austria). We covered a broad range of hydrological conditions, including a 1‐yr flood event in 2012 and a 100‐yr flood in 2013. Our findings demonstrate that river‐floodplain waters were supersaturated with CH4, hence always serving as a source of CH4 to the atmosphere. Hydrologically isolated habitats in general have higher concentrations and produce higher fluxes despite lower physically defined velocities. During surface connection, however, CH4 is exported from the floodplain to the river, suggesting that the main channel serves as an “exhaust pipe” for the floodplain. This mechanism was especially important during the 100‐yr flood, when a clear pulse of CH4 was flushed from the floodplain with surface floodwaters. Our results emphasize the importance of floods differing in magnitude for methane evasion from river‐floodplains; 34% more CH4 was emitted from the entire system during the year with the 100‐yr flood compared to a hydrologically “normal” year. Compared to the main river channel, semi‐isolated floodplain waters were particularly strong sources of CH4. Our findings also imply that the predicted increased frequency of extreme flooding events will have significant consequences for methane emission from river‐floodplain systems.

Macroinvertebrate community composition and diversity in ephemeral and perennial ponds on unregulated floodplain meadows in the UK

Ponds are common and abundant landscape features in temperate environments, particularly on floodplains where lateral connectivity with riverine systems persists. Despite their widespread occurrence and importance to regional diversity, research on the ecology and hydrology of temperate ephemeral and perennial floodplain ponds lags behind that of other shallow waterbodies. This study examines the aquatic macroinvertebrate diversity of 34 ponds (20 perennial and 14 ephemeral) on two unregulated riverine floodplain meadows in Leicestershire, UK. Perennial ponds supported nearly twice the diversity of ephemeral ponds. Despite frequent inundation of floodwater and connectivity with other floodplain waterbodies, ephemeral ponds supported distinct invertebrate communities when compared to perennial ponds. When the relative importance of physical and chemical, biological and spatial characteristics was examined, physical and chemical characteristics were found to account for more variation in community composition than biological or spatial variables. The results suggest that niche characteristics rather than neutral colonisation processes dominate the structure of invertebrate communities of floodplain ponds. The maintenance of pond networks with varying hydroperiod lengths and environmental characteristics should be encouraged as part of conservation management strategies to provide heterogeneous environmental conditions to support and enhance aquatic biodiversity at a landscape scale.

Floodplain fish communities in river systems in Bolivia: Current knowledge and addressing future research challenges

Tropical freshwater fish communities are increasingly under threat from anthropogenic pressures, particularly alteration to the hydrological regime (e.g. via deforestation and mining within the watershed and in-stream impoundments) which defines the extent and characteristics of in-channel and floodplain habitats for fishes. The ecological consequences of altered hydrology for tropical floodplain ecosystems are likely to be major declines in fish abundance and diversity, lower food web connectivity, reduced microhabitat availability for reproduction and refuge, modified migration patterns and consequently reduced ecosystem services, e.g. fishery resource. Evidence of change is lacking and the current species inventory approaches of collecting fish-related data do not consider spatial (i.e. river-floodplain distances) and temporal (i.e. flood water levels) gradients that are known to largely influence fish communities present in floodplain waterbodies. In the context of increasing threats, fish diversity and community declines are real and require suitable methodological approaches to combine available information and an informed analysis of likely change before actions are irreversible. Bolivian rivers are relatively undisturbed compared to other tropical rivers, however, plans for hydropower and increased deforestation and mining in the region could have devastating effects on the hydrological patterns and the dependent biodiversity. This review aims to summarize the current knowledge of floodplain freshwater fishes using Bolivian rivers as the example, identify the gaps that exist in the science and to propose a landscape ecology approach to integrate pattern and process understanding of the river-floodplain mosaic to fill knowledge gaps in an appropriate way towards the conservation of fish resources.

Distribution and microhabitats of freshwater mussels in waterbodies in the terrestrialized floodplains of a lowland river

Even when anthropogenically altered, river floodplains continue to contribute to biodiversity. This study examined the distribution of freshwater mussels in relation to environmental factors in waterbodies in the terrestrialized floodplain of a lowland river. Mussels were captured, and environmental measurements were taken in November of 2013 and 2014 in quadrats established in three floodplain waterbodies (FWBs), which were isolated from the main river channel. Among the three FWBs, mussel abundance was highest in a shallow FWB (depth range 18–45 cm) that had intermediate conditions of mud depth and fine sediment rate. Mussel abundance showed a hump-shaped relationship with water depth (the peak 45–50 cm) and mud depth (the peak 8–12 cm). Mussel abundance was also negatively related to the abundance of benthic litter. Litter abundance was positively related to branch abundance and the presence of tree cover, and negatively related to the distance to tree cover, indicating that benthic litter was derived from riparian trees. Our results indicate that relatively shallow (≤ 50 cm) FWBs with moderately accumulated mud, which are not scoured even during flooding, appear to be suitable habitats for mussels. Moreover, it is possible that riparian trees negatively impact mussel distribution in FWBs. Possible short-term measures for improving mussel habitat in FWBs may include the elimination of riparian trees and benthic litter.

Diel variations in the assemblage structure and foraging ecology of larval and 0+ year juvenile fishes in a man-made floodplain waterbody.

This study investigated diel variations in zooplankton composition and abundance, and the species composition, density, size structure, feeding activity, diet composition and prey selection of larval and 0+ year juvenile fishes in the littoral of a man-made floodplain waterbody over five 24 h periods within a 57 day period. There was a significant difference in the species composition of diurnal and nocturnal catches, with most species consistently peaking in abundance either during daylight or at night, reflecting their main activity period. There were no consistent diel patterns in assemblage structure or the abundance of some species, however, most likely, respectively, due to the phenology of fish hatching and ontogenetic shifts in diel behaviour or habitat use. There were few clear diel patterns in the diet composition or prey selection of larval and 0+ year juvenile roach Rutilus rutilus and perch Perca fluviatilis, with most taxa consistently selected or avoided irrespective of the time of day or night, and no obvious shift between planktonic and benthic food sources, but dietary overlap suggested that interspecific interactions were probably strongest at night. It is essential that sampling programmes account for the diel ecology of the target species, as diurnal surveys alone could produce inaccurate assessments of resource use. The relative lack of consistent diel patterns in this study suggests that multiple 24 h surveys are required in late spring and early summer to provide accurate assessments of 0+ year fish assemblage structure and foraging ecology.

The risk of river pollution due to washout from contaminated floodplain water bodies during periods of high magnitude floods

Summary The risk of river pollution due to washout (removal of pollutants) from contaminated floodplain water bodies (floodplain lakes and quarries whose origin is related to the large-scale mining of nonmetallic building materials in the floodplain zone) during high magnitude flood periods is analyzed using a combination of one-, two- and three-dimensional hydrodynamic modeling and in situ measurements. The modeling performed for the floodplain water bodies contaminated by N compounds shows that during large magnitude floods washout occurs. The washout process consists of two stages: an initial rapid stage lasting about two hours during which the upper (3–4 m thick) layer is washed out, followed by a second stage when the concentration of NH4-N in the floodplain water body remains nearly constant. The maximum contaminant concentration in the river in the vicinity of a water intake for drinking water located 21 km downstream is attained about 9 h from the beginning of the flood; concentration of NH4-N can reach values several times larger than acceptable concentration guidelines. The initial primary peak in contaminant concentration at the water intake is followed by a slight decrease in contaminant concentration; a second peak related to the contaminant transport through the inundated floodplain subsequently occurs, after which the concentration slowly decreases, reaching acceptable values after 30–40 h. Contaminated floodplain water bodies located near drinking water supply systems are not significant sources of contamination during small and moderate floods, but during high magnitude floods, they can become sources of water pollution. Operational measures that can decrease potential health risks are discussed.

Dynamics of fish dispersal during river-floodplain connectivity and its implications for community assembly

In river-floodplain ecosystems, overbank flows interact with floodplain geomorphology to generate a network of transient inter-waterbody connections. Heterogeneity in the characteristics of these connections may interact with species-specific dispersal capacity to affect the maintenance of diversity and community assembly on the floodplain. We modelled the immigration and emigration rates of nine species of fish entering and leaving a large floodplain lake during a hydrological connection with the parent river. Dispersal rates were modelled as a continuous function of time-since-connection over 3 months, with the aim of testing for species-specific patterns in (a) the timing and magnitudes of lateral dispersal, and (b) the balance between total immigration into, and emigration from, the lake. Significant interspecific variation in the timing and magnitude of lateral dispersal was evident. Magnitude of lateral dispersal was not a function of local abundance for all species. Further, the balance between immigration to, and emigration from, the lake varied significantly across species, and over time within species. The immigration–emigration balance of a species was not related to its magnitude of lateral dispersal, but may be related to its behavioural and life-history traits. Spatial heterogeneity in the duration of inter-waterbody connections may interact with species-specific dispersal functions to shape assembly of floodplain communities. Accordingly, habitat heterogeneity among floodplain waterbodies is not strictly necessary for heterogeneity in fish community composition. These dynamics have implications for the maintenance of diversity in river-floodplain fish metacommunities under both natural and managed connectivity regimes.

Ecohydrology, floodplain water bodies, European legal provisions and the future

Using the ecohydrology concept for mitigating or resolving pressures on the natural environment caused by human activities is a successful way to find low-technology solutions which comprise the use of ecosystem services provided by dedicated ecosystems. Today this approach faces constraints by lack of area in highly developed countries, or related to legal tools established by the European Community. Even more important are climate change effects and the inevitable response of ecological systems, which interfere with their present resilience. Science is called on providing new strategies and tools to better predict the future of ecosystem services and how climate change effects can be mitigated or transformation activities can be initiated.

Does flooding mitigation measures affect cladoceran and copepod communities in floodplain water bodies?

We investigated the relative importance of flood defenses and other environmental variables for the cladoceran and copepod communities in floodplain water bodies in Southeastern Norway. The water bodies covered gradients of size, distance to the river and water chemistry, and half of them were located behind flood defenses. The effects of environmental variables on the communities were analyzed using redundancy analysis. The set of environmental variables accounted for more of the explained variation in the cladoceran community than in the copepod community. Water quality was much more important than flooding-related variables for both communities. Although cladoceran species richness was slightly higher in water bodies outside flood defenses, total nitrogen, total organic carbon (TOC), and water body area were the most important factors for the cladocerans. Macrophyte coverage was the most important variable for both species richness and community structure of copepods. Although our results show that water quality and spatial/structural variables are more important than flood defenses in structuring the communities, the effect of TOC on the cladoceran community could likely be mediated through effects of flood defense on TOC. Prospects for a continued anthropogenic pressure on river floodplains raise concern for the future of these unique ecosystems.

Realised and predicted changes in the invertebrate benthos after restoration of connectivity to the floodplain of a large river

Summary River–floodplain interactions (i.e. lateral connectivity) are a major driver of the structure and function of the biota in floodplain waterbodies. Therefore, the enhancement of lateral connectivity is a key focus of large river restoration. The Rhône River restoration project in France includes an array of floodplain habitats and restoration measures, offering opportunities to test the predictability of changes in taxon abundance after connectivity restoration. Quantitative samples of benthic macroinvertebrates taken before restoration were used to derive generalised additive models (GAMs) relating the density of taxa to an index of lateral connectivity. The index combined the diversity of sediment grain size, its organic content, vegetation cover and the water's electrical conductivity. GAMs were used to predict changes in taxon density and between‐site (i.e. beta) diversity 2 and 4 years after restoration at 34 sites (14 unrestored, eight reconnected to the river, six dredged, six restored by increasing river flow). Observed post‐restoration changes included an increase in the density of rheophilous taxa and an increase of beta‐diversity among restored sites. Fifty‐four GAMs (27% of the taxa) were selected for post‐restoration predictions. Predictions from these models matched observations for a set of Trichoptera and other taxa with large density changes after restoration. The quality of predictions of density changes was poor on average among sites, but higher for sites where large changes in lateral connectivity occurred. Taxon‐level predictions partly explained increased beta‐diversity in restored sites, suggesting that predictions based on a subset of individual taxa can be used to predict community‐level changes. Our models can guide restoration measures in the Rhône and other rivers. Our results also show the benefit of diversifying restoration actions at the scale of entire floodplains. Post‐restoration trajectories should be monitored over long periods to improve the identification of the key environmental predictors of biotic changes, especially at the less connected floodplain sites.

Environmental drivers of aquatic macrophyte communities in southern tropical African rivers: Zambia as a case study

The first-ever extensive macrophyte survey of Zambian rivers and associated floodplain waterbodies, conducted during 2006–2012, collected 271 samples from 228 sites, mainly located in five freshwater ecoregions of the world primarily represented in Zambia. The results supported the hypothesis that variation in macrophyte community structure (measured as species composition and diversity) in southern tropical African river systems, using Zambia as a case study area, is driven primarily by geographical variation in water physico-chemical conditions. In total, 335 macrophyte taxa were recorded, and a chronological cumulative species records curve for the dataset showed no sign of asymptoting: clearly many additional macrophyte species remain to be found in Zambian rivers. Emergent macrophytes were predominant (236 taxa), together with 26 floating and 73 submerged taxa. Several species were rare in a regional or international context, including two IUCN Red Data List species: Aponogeton rehmanii and Nymphaea divaricata. Ordination and classification analysis of the data found little evidence for temporal change in vegetation, at repeatedly-sampled sites, but strong evidence for the existence of seven groups of samples from geographically-varied study sites. These supported differing sets of vegetation (with eight species assemblages present in the sample-groups) and showed substantial inter-group differences in both macrophyte alpha-diversity, and geographically-varying physico-chemical parameters. The evidence suggested that the main environmental drivers of macrophyte community composition and diversity were altitude, stream order, shade, pH, alkalinity, NO3-N, and underwater light availability, while PO4-P showed slightly lower, but still significant variation between sample-groups.

Influence of Floodplain Area on Fish Species Richness in Waterbodies of the Chao Phraya River Basin, Thailand

River-floodplain ecosystems are in delicate balance and are impacted by even minor changes in water availability. In this study, we surveyed fish assemblages and investigated environmental and landscape parameters in a total of 135 floodplain waterbodies (rivers, diversion canals, ponds, irrigation ditches, paddy fields, and wetlands) in the Chao Phraya River Basin in rainy (September 2014) and dry (March 2015) seasons. Factors affecting fish species richness in each type of waterbody were analyzed using generalized linear mixed models. Floodplain area around each surveyed waterbody was a major factor determining fish species richness in rivers, diversion canals, and ponds in the region. The contribution of floodplain area was equivalent to that of hydrology (current velocity, water depth) and water quality (dissolved oxygen, turbidity) in the waterbodies. The population of juvenile fishes was increased in temporarily connected floodplain waterbodies to main rivers compared with isolated waterbodies, and fluvial and lacustrine fishes were observed in the temporary inundated floodplain waterbodies during the rainy season. The high dependence of fish species richness on floodplain area in the region appeared to be a result of the use of inundated floodplains by fish species to forage and breed. Our results highlight the impact of flood control measures that reduces floodplain area. These measures must be reviewed to ensure the conservation of fish biodiversity in the Chao Phraya River Basin, one of the world’s most threatened floodplain systems.

揖斐川高水敷掘削後の微地形形成過程

Flood-channel excavation is not only countermeasure against river flooding but also effective operation for floodplain restoration. In the Ibi River, 14 excavation sites varying in relative height to water level were investigated to examine process of microtopgraphy formation after the flood-channel excavation. Deposit rate was lower in the sites with lower relative height. The proportion of water area (i.e. floodplain waterbodies) in the excavation sites was 10-20%. Sediment profiles were also surveyed at 10 locations in two representative sites and were elaborated in relation to microtopographies that were classified into four types: natural-levee, low land behind natural-levee and isolated and connected waterbodies. Moreover, the microtopography formation process and factors were estimated based on the results of the field survey.

The hydrochemical response of small and shallow floodplain water bodies to temporary surface water connections with the main river

Summary We investigated the effects of temporary surface water connections with the main river on the water chemistry of large and small waterbodies in a Danube floodplain by comparing hydrochemical data before, during and after water exchange with the Danube during two large floods in 2009 and 2013. In addition, we studied the effects of an increased frequency of flood pulses on the water chemistry of the floodplain via long‐term monitoring data. We used conservative (i.e. biologically non‐reactive) parameters (alkalinity, Ca, Cl, K, Mg, Na, SO4, conductivity) to identify hydrochemical changes due to the mixing with river water. Changes in non‐conservative parameters (PO4‐P, NO3‐N, NO2‐N, NH4‐N, total phosphorus, dissolved organic carbon, dissolved oxygen, chlorophyll‐a), which deviated from pure mixing effects, were ascribed to alterations of biogeochemical processes induced by the imported river water. In large floodplain waterbodies, both conservative and non‐conservative parameters changed towards Danube water concentrations during the connection with the main river and returned to pre‐connection levels after the water exchange ended. Only chlorophyll‐a concentrations were almost twice as high in the post‐connection phase than before the connection. In small floodplain waterbodies, conservative and non‐conservative parameters showed similar changes during the connection with the main river. However, the concentrations of PO4‐P, total phosphorus and chlorophyll‐a did not return to pre‐connection levels, but increased further in the post‐connection phase, exceeding even Danube water concentrations. We attribute these changes to phosphorus releases from the sediments and enhanced primary and bacterial production induced by the river water. In years with an increased flooding frequency, both conservative and non‐conservative parameters approached Danube water concentrations in large floodplain waterbodies due to the increased surface water exchange. In small floodplain waterbodies, conservative parameters remained unaffected by the increased connection with the river, while nitrate, ammonium, phosphate, total phosphorus and chlorophyll‐a concentrations were considerably higher in wet years than in dry years. We conclude that the temporary input of oxygen‐ and nutrient‐rich river water to small, mainly isolated backwaters can induce changes in benthic biogeochemical processes, which may provoke an internal eutrophication of these waterbodies.

Ecological validity of river-floodplain system assessment by planktonic crustacean survey (Branchiata: Branchiopoda)

Studies of the Slovakian Danube have indicated profound changes in the structures of several invertebrate assemblages in the section of the river bypassed by the Gabčíkovo hydroelectric project in 1992 and in adjacent floodplain water bodies. The present study investigates the relationship between hydrological connectivity and species diversity in the old main channel and adjacent left-bank water bodies, using resident cladocerans as indicators of the ecological integrity of the river-floodplain system. The work aimed to quantify cladoceran habitat preferences using habitat values (HV) and indication weights (IW) calculated from data accumulated during long-term monitoring of planktonic communities of the Danube floodplain (1,840.5-1,804rkm) and supplemented with data from the literature. Although not listed as an indicator group in the European Union Water Framework Directive, cladocerans are shown to be highly apposite in the ecological assessment of river-floodplain systems. Of 71 recorded cladoceran species, 19 taxa showed a preference for eupotamal habitats, 24 species preferred eupotamal B/parapotamal waters, and 28 cladocerans were found to prefer the plesiopotamal/paleopotamal habitat type. Identified habitat types follow a gradient of hydrological connectivity with the main river channel, ranging from the eupotamal to more or less isolated floodplain water bodies. A secondary aim was to use the calculated values to assess the ecological integrity of the river-floodplain system. The key element of this procedure is the calculation of the Floodplain Index (FI) (Chovanec et al. Large Rivers, 15(1-4), 169-185 2005) from the summation of the habitat values and indication weights of all species present at the sampling sites. Calculated index values indicate the extent of disruption to lateral connectivity in the floodplain area.

Sampling intensity in biodiversity assessment: malacofauna of selected floodplain water bodies

The assessment of completeness of mollusc species lists in selected permanent and temporary floodplain water bodies located within the lower Bug River valley, as well as estimation of the minimum number of samples required to obtain an acceptable efficiency of inventory in individual water bodies, was carried out using sample-based rarefaction curves and non-parametric estimator Chao2. The effect of sampling effort on different measures of species diversity (species richness, Shannon diversity exp(H’)) was examined. Dependence of sampling effort, inventories completeness and diversity measures on habitat stability was analysed by comparing permanent and temporary water bodies. Mollusc assemblages of the investigated water bodies showed high temporal and spatial variability, as well as inter-habitat differences (relatively low Jaccard’s similarity coefficient, J). Significant differences in diversity and composition of mollusc assemblages were found between permanent and temporary habitats, whereas species richness was similar in both permanence groups. In general, both species richness and diversity increased similarly with growing sampling effort. Total richness accuracy reached at least 90% of the predicted value (calculated with Chao2) with 5 to 14 random samples, depending on the water body (10–14 samples in permanent habitats and 5–10 samples in temporary ones). kEy words: aquatic molluscs, species richness, diversity, sampling effort, data set completeness

Wild boar’s (Sus scrofa) role in the vegetation dynamics of water bodies of Oksky state reserve

Wild boar (Sus scrofa) is a native inhabitant of the southeastern Meshchera lowland. However, as a result of human activity, biotic communities evolved for a long time in the absence this species. When, after a long absence, wild boars reappeared in the Oksky reserve nearly 50 years ago and began to restore its population quickly, the activity of these animals became a new factor of disturbances. Rooting by wild boar can strongly affect wetland and aquatic vegetation, although the effect of wild boar on freshwater ecosystems has seldom been studied. We characterized the use of different types of water bodies by wild boars and assessed long-term and short-term changes in vegetation of water reservoirs under the influence of a wild boar by the example of the Oksky Reserve. Sagittaria sagittifolia was a species that was most attractive for wild boars of any water and wetland vegetation. Vegetation is most intensely disturbed by the animal at floodplain water bodies without significant muddy sediments and at the Pra and Oka rivers. However, the vegetation dynamics begins to be influenced by wild boar activity only in the waters of the high floodplain that are not regularly flooded by spring waters. This influence is expressed as a reduction and thinning of Sagittaria sagittifolia patches, an increase in heterogeneity and patchiness of vegetation on disturbed plots, and formation of naked sites lacking vegetation (in wallows made by the animals). Comparison of our data with initial descriptions of vegetation in ten oxbows of the Pra that were made before wild boar introduction showed an increase in the occurrence of Sagittaria sagittifolia at the level of plant associations and water bodies. This is probably due to the fact that a disturbance of dense thickets of dominant plants of the coastal zone by boars provides favorable conditions for the invasion of species such as Sagittaria sagittifolia.