The influence of the landscape structure within buffer zones, catchment land use and instream environmental variables on mollusc communities in a medium-sized lowland river

The world’s freshwater molluscan fauna is facing unprecedented threats from habitat loss and degradation. Declines in native populations are mostly attributed to the human impact, which results in reduced water quality. The objectives of our survey were to analyse the structure of the mollusc communities in a medium-sized lowland river and to determine the most important environmental variables at different spatial scales, including landscape structure, catchment land use and instream environmental factors that influence their structure. Our survey showed that a medium-sized river, that flows through areas included in the European Ecological Natura 2000 Network Programme of protected sites, provides diverse instream habitats and niches that support 47 mollusc species including Unio crassus, a bivalve of Community interest, whose conservation requires the designation of a special conservation area under the Habitats Directive Natura 2000. This survey showed that mollusc communities are impacted by several environmental variables that act together at multiple scales. The landscape structure within buffer zones, catchment land use and instream environmental variables were all important and influenced the structure of mollusc communities. Therefore, they should all be taken into consideration in the future restoration of the river, future management projects and programmes for the conservation of biodiversity in running waters. The results of this study may be directly applicable for the rehabilitation of river ecosystems and are recommended to stakeholders in their future decision concerning landscape planning, monitoring species and their habitats, conservation plans and management in accordance with the requirements of sustainable development

A faunistic and ecological characterization of the water mites (Acari: Hydrachnidia) of the Branew River (central-eastern Poland)

A characteristic feature of the Hydrachnidia communities of the Branew River, distinguishing its fauna from that of other Polish rivers, was the very high abundance of species of the genus Lebertia. Species of this genus accounted for as much as 53.1% of the collected material. The most numerous was Lebertia rivulorum, which was caught in numbers not found in other Polish rivers. Lebertia inaequalis and L. oblonga were also abundant. The largest synecologi-cal groups were rheophiles and rheobionts (94.9% combined). More individuals (1494) and species (27) were caught in the lentic zone of the river than in the lotic zone (1291 ind., 25 sp.). The species most associated with the lotic zone was L. rivulorum. This species was caught mainly on a substrate of gravel and stones with a small amount of sandy sediments, sparsely covered with Elodea canadensis. The species most associated with the lentic zone was Forelia variegator. The most abundant species in the Branew River, Hygrobates setosus, was caught in much higher numbers in the littoral zone than in the central part of the river. The high similarity of fauna was observed between the lotic and lentic zones, and much lower similarity between sites. The results indicate intensive species migration in the transverse profile of the river and low migration in the longitudinal profile. Higher species diversity was recorded in the lentic zone than in the lotic zone of the river – both in the river as a whole and at the individual sites. In the anthropogenically transformed stretch of the river (straightened riverbed, concrete dam, and concrete bottom), species diversity was significantly lower (H’ = 1.83) than in the natural stretch (H’ = 2.37). The results confirm literature data describing the negative impact of such transformations on Hydrachnidia communities. Despite anthropogenic transformations in parts of the river, the structure of the fauna (a very large proportion of rheobionts and rheophiles), as well as the physicochemical parameters of the water, is indicative of the good ecological condition of the river.Cechą specyficzną zgrupowań Hydrachnidia rzeki Branew, odróżniającą jej faunę od innych rzek Polski, była bardzo duża liczebność gatunków z rodzaju Lebertia. Gatunki z tego rodzaju stanowiły aż 53.1% zebranego materiału. Najliczniejsza była Lebertia rivulorum, którą łowiono w liczebnościach niespotykanych w innych rzekach Polski. Ponadto, w dużych liczebnościach łowiono L. inaequalis i L. oblonga. Najliczniejszymi grupami synekologicznymi były reofile i reobionty (łącznie 94.9%). Więcej osobników (1494) i gatunków (27) złowiono w strefie lenitycznej rzeki niż w strefie lotycznej (1291 osobn., 25 gat.). Gatunkiem najbardziej zwią-zanym ze strefą lotyczną była L. rivulorum. Lebertia rivulorum łowiono przede wszystkim na dnie żwirowo-kamienistym z niewielkim udziałem osadów piaszczystych, skąpo poro-śniętym Elodea canadensis. Gatunkiem najbardziej związanym ze strefą lenityczną była Forelia variegator. Najliczniejszy gatunek w rzece Branew – Hygrobates setosus, łowiono zdecydowanie liczniej w strefie przybrzeżnej, niż w centralnej części rzeki. Stwierdzono duże podobieństwa faun między strefą lotyczną i lenityczną i znacznie mniejsze podobieństwa fau-nistyczne między stanowiskami. Uzyskane wyniki świadczą o intensywnej migracji gatunków w profilu poprzecznym rzeki i słabej migracji w profilu podłużnym. Większą różnorodność gatunkową notowano w strefie lenitycznej, niż lotycznej rzeki – zarówno w skali całej rzeki, jak i na poszczególnych stanowiskach. Na przekształconym antropogenicznie odcinku rzeki (wyprostowane koryto, betonowa zapora, wybetonowane dno) stwierdzono znacznie niższą różnorodność gatunkową (H’ = 1.83) niż na odcinku naturalnym (H’ = 2.37). Uzyskane wyniki potwierdzają dane literaturowe opisujące negatywny wpływ takich przekształceń na zgrupowania Hydrachnidia. Mimo lokalnych przekształceń antropogenicznych, struktura fauny (bardzo duży udział ilościowy reobiontów i reofili), a także wartości wskaźników fizyczno--chemicznych wody, świadczą o dobrym stanie ekologicznym rzeki

A faunistic and ecological characterization of the water mites (Acari: Hydrachnidia) of the Bukowa River (central-eastern Poland)

The water mite communities of the Bukowa River were found to be similar to those of other lowland rivers in Poland. An element specific to the Bukowa River was a much higher abundance of Lebertia inaequalis than in other Polish rivers. Another distinctive element was the very high numbers of Arrenurus crassicaudatus, but this taxon should be considered allochthonous – its presence in the river was due to the periodic inflow of water from fish ponds. The largest synecological group was rheophiles and rheobionts, which together accounted for 80% of the fauna. The very large quantitative share of rheobionts and rheophiles is indicative of the natural character of the river, and the physicochemical parameters confirm its good water quality. More individuals (1,764) and species (47) were caught in the lentic zone of the river than in the lotic zone (1,027 individuals, 32 species). The species most associated with the lotic zone and fast water flow were Sperchon clupeifer and Hygrobates calliger. Data from the Bukowa River, as well as other rivers of the Janów Forests Landscape Park, indicate that the most characteristic habitat for Lebertia inaequalis is the lentic zone, with abundant water vegetation. The typical habitats of Hygrobates setosus are marginal pools and zones with slower water flow. Mideopsis crassipes and Torrenticola amplexa were associated with the upper course of the river. Sperchon clupeifer was associated with lotic habitats of the middle and lower course of the river, and Hygrobates setosus and Forelia variegator were associated with habitats with slower flow in the middle and lower stretches of the river.Uznano, że zbiorowiska wodopójek z rzeki Bukowej są podobne do innych zbiorowisk z rzek nizinnych w Polsce. Elementem charakterystycznym dla rzeki Bukowej była znacznie większa liczebność Lebertia inaequalis niż w innych polskich rzekach. Innym wyróżniającym ją elementem była bardzo wysoka liczba Arrenurus crassicaudatus, ale ten takson powinien być uważany za allochtoniczny – jego obecność w rzece była spowodowana okresowym napływem wody ze stawów rybnych. Największą grupą synekologiczną były reofile i reobionty, które łącznie stanowiły 80% fauny. Bardzo duży ilościowy udział reobionów i reofili świadczy o naturalnym charakterze rzeki, a parametry fizykochemiczne potwierdzają jej dobrą jakość wody. Więcej osobników (1764) i gatunków (47) zostało złowionych w strefie lenitycznej rzeki niż w strefie lotycznej (1027 osobników, 32 gatunki). Gatunkiem najbardziej związanym ze strefą lotyczną i szybkim przepływem wody były Sperchon clupeifer i Hygrobates calliger. Dane z rzeki Bukowej, a także z innych rzek Parku Krajobrazowego Lasy Janowskie wskazują, że najbardziej charakterystycznym siedliskiem dla Lebertia inaequalis jest strefa lenityczna z obfitą roślinnością wodną. Typowe siedliska Hygrobates setosus to zastoiska i strefy o wolniejszym przepływie wody. Mideopsis crassipes i Torrenticola amplexa były związane z górnym biegiem rzeki. Sperchon clupeifer był związany z siedliskami lotycznymi środkowego i dolnego biegu rzeki, a Hygrobates setosus i Forelia variegator były związane z siedliskami o wolniejszym przepływie w środkowych i dolnych odcinkach rzeki

The use of molecular techniques in the taxonomy of water mites (Hydrachnidia, Acari)

The Hydrachnidia (water mites) are a robust component of aquatic communities in terms of both abundance and species richness. They have colonized all types of freshwater habitats and are highly diversified in both lotic and lentic habitats. Over 6,000 species of Hydrachnidia have been described worldwide, representing eight superfamilies, 57 families, 81 subfamilies and more than 420 genera. Water mite systematics is continually subject to change and various modifications. Performing systematic revisions can lead to numerous misunderstandings and difficulties in comparing research results, as the same species can have different systematic names in different publications. The development of molecular biology techniques has popularized the use of genomic traits in taxonomic identification. Among various markers used to identify species, the most important is the gene encoding cytochrome c oxidase I (COI). Species identification based on this gene is known as ‘DNA barcoding’. The use of DNA barcoding was a breakthrough in molecular methods of species identification and has dominated research on invertebrates. It has become possible to identify not only new species, but also species that are difficult to distinguish using traditional methods. Water mites are organisms on which molecular analysis is still rarely performed, as compared to other groups of invertebrates. Fortunately, recent years have seen increasing use of molecular techniques to clarify the intricacies of Hydrachnidia taxonomy. Using DNA markers in the taxonomy of water mites enables definitive resolution of ambiguities in the case of numerous questionable taxa, which is of great importance in all other types of research on these organisms.Wodopójki (Hydrachnidia) są istotnym komponentem zgrupowań bezkręgowców wodnych zarówno pod względem liczebności, jak i bogactwa gatunkowego. Organizmy te skolonizowały wszelkie rodzaje siedlisk wodnych. Zróżnicowana fauna Hydrachnidia występuje zarówno w wodach stojących, jak i płynących. Dotychczas opisano na świecie ponad 6 tys. gatunków, reprezentujących dziewięć nadrodzin, 57 rodzin, 81 podrodzin i ponad 420 rodzajów. Systematyka wodopójek ulega ciągłym zmianom i różnym modyfikacjom. Przeprowadzanie częstych rewizji w systematyce Hydrachnidia może prowadzić do wielu nieporozumień i trudności przy porównywaniu wyników, ponieważ te same gatunki mogą występować w różnych publikacjach pod różnymi nazwami. Rozwój technik molekularnych spopularyzował wykorzystanie cech genomu przy identyfikacji gatunków. Spośród różnych markerów stosowanych przy identyfikacji poszczególnych gatunków największe znaczenie ma gen oksydazy I cytochromu c (COI). Identyfikacja gatunkowa w oparciu o ten gen nazywa się “DNA barcoding”. Zastosowanie tzw. metkowania genetycznego (DNA barcoding) stanowiło przełom w molekularnych metodach identyfikacji gatunków i zdominowało badania bezkręgowców. Możliwa stała się nie tylko identyfikacja nowych gatunków, ale także gatunków, które trudno rozróżnić metodami tradycyjnymi. Wodopójki są organizmami, u których wciąż rzadko przeprowadza się analizy molekularne. Jednak w ostatnich latach można zauważyć coraz częstsze zastosowanie tych technik w taksonomii Hydrachnidia. Wykorzystanie markerów DNA w taksonomii wodopójek pozwala na ostateczne wyjaśnienie przynależności taksonomicznej wątpliwych gatunków, co ma ogromne znaczenie we wszelkich badaniach nad tymi organizmami

Environmental heterogeneity at different scales: key factors affecting caddisfly larvae assemblages in standing waters within a lowland river catchment

We examined the importance of environmental parameters at different spatial scales influencing the occurrence of caddisfly larvae at different levels of their organization (species, faunistic metrics and functional groups) in lentic floodplain waters, in order to gain information on the ecological status and management of a small lowland river catchment. At the lowest spatial level – pH, sediment grain size, insolation and the presence of aquatic macrophytes proved significant for caddisfly larvae, at higher and the highest level (including buffer zones and the catchment) – the surface areas of watercourses and the river, distance from standing waters and distance from broadleaf forests, respectively. Rheophilous hydropsychids accounted for 17% of the whole fauna of the examined water bodies. They spread from the river via water during flood in the spring. We also detected some significant correlations between functional groups of caddisfly larvae and parameters describing buffer zones and the river catchment against the sub-catchment type use. Information provided by the Caddisfly Habitat Index showed an overall  good ecological status of the river-floodplain. Caddisfly larvae may be good indicators of numerous factors and processes, but they should be studied comprehensively, at different levels of organization. Our results can be useful for preservation of biodiversity and management of river valleys. We suggest: 1) maintaining the varied structure of aquatic macrophytes in water bodies, 2) securing the long-term presence of broadleaf trees in buffer zones in order to provide detritus input, varied insolation and shelter for caddisflies, 3) limiting drainage activities in the river valley in order to save varied habitats, especially temporary ones, 4) providing heterogeneous landscape in the river catchment (homogenous land use is inappropriate). </p

The impact of dredging of a small lowland river on water beetle fauna (Coleoptera)

Using the example of a regulated stretch of the Krąpiel River (NW Poland), an analysis of the impact of dredging on the aquatic beetle (Coleoptera) fauna was made. After dredging the beetle fauna became markedly poorer quantitatively and had lower species diversity. Moreover, the qualitative composition and dominance structure were highly transformed. However, species number and diversity increased rapidly and were restored within just half a year. The structure of the restored fauna was most strongly influenced by vegetation, flow velocity and bottom sediment composition. The first to colonize the river were eurytopic beetles and species typical of small water bodies, which had significant refuges in the form of fish ponds bordering on the river; these species dominated the assemblage throughout the study period. Rheophiles with less dispersal power appeared later, and finally rheobionts, in low numbers but occupying an increasing number of sampling sites. </p

Water mites (Acari, Hydrachnidia) of riparian springs in a small lowland river valley: what are the key factors for species distribution?

This paper examines the impact of disturbance factors—flooding and intermittency—on the distribution of water mites in the riparian springs situated in the valley of a small lowland river, the Krąpiel. The landscape factors and physicochemical parameters of the water were analysed in order to gain an understanding of the pattern of water mite assemblages in the riparian springs. Three limnological types of springs were examined (helocrenes, limnocrenes and rheocrenes) along the whole course of the river and a total of 35 water mite species were found. Our study shows that flooding influences spring assemblages, causing a decrease in crenobiontic water mites in flooded springs. The impact of intermittency resulted in a high percentage of species typical of temporary water bodies. Surprisingly, the study revealed the positive impact of the anthropogenic transformation of the river valley: preventing the riparian springs from flooding enhances the diversity of crenobiontic species in non-flooded springs. In the conclusion, our study revealed that further conservation strategies for the protection of the riparian springs along large rivers would take into account ongoing climatic changes and possible the positive impact of the anthropogenic transformation of river valleys

Early recolonization of a dredged lowland river by dragonflies (Insecta: Odonata)

The influence of dredging on the dragonfly assemblages of the small regulated lowland River Krąpiel (north-western Poland) was analyzed a short time after the dredging. Dragonfly assemblages were destroyed, but they began to recover rapidly. Many biocoenotic indices reached high values at just six months after the dredging. The recolonization first occurred as a result of larval drift, and then, via dispersion of adult dragonflies. This process took place in conditions different from the prevailing conditions in the period before dredging, in terms of microhabitat availability and physico-chemical conditions. Compared to the previous assemblage, the emerging assemblage was more typical of assemblages found in small, natural running waters. Therefore, dredging (carried out for economic reasons) could be regarded as a process that unintentionally had a positive influence on odonate assemblages. Currently, when most small watercourses are regulated, dredging that is properly planned and controlled has proven to protect the natural fauna. It is worthwhile to apply lessons learned from examples of active fauna protection to what is currently known as “the rotational model” for dredging

Early recolonization of a dredged lowland river by dragonflies (Insecta: Odonata)

The influence of dredging on the dragonfly assemblages of the small regulated lowland River Krąpiel (north-western Poland) was analyzed a short time after the dredging. Dragonfly assemblages were destroyed, but they began to recover rapidly. Many biocoenotic indices reached high values at just six months after the dredging. The recolonization first occurred as a result of larval drift, and then, via dispersion of adult dragonflies. This process took place in conditions different from the prevailing conditions in the period before dredging, in terms of microhabitat availability and physico-chemical conditions. Compared to the previous assemblage, the emerging assemblage was more typical of assemblages found in small, natural running waters. Therefore, dredging (carried out for economic reasons) could be regarded as a process that unintentionally had a positive influence on odonate assemblages. Currently, when most small watercourses are regulated, dredging that is properly planned and controlled has proven to protect the natural fauna. It is worthwhile to apply lessons learned from examples of active fauna protection to what is currently known as “the rotational model” for dredging