Aneta Spyra

Environmental factors influencing the occurrence of freshwater snails in woodland water bodies

Studies were carried out in eight woodland water bodies that are situated in an urbanised area of Southern Poland (Upper Silesia). The aim of this study was to determine the influence of auto- and allochthonous plant detritus and exposure to sunlight on the structure of snail communities in woodland ponds. Among some physico-chemical water parameters, pH influenced the occurrence of snails, whereas sunlight caused an increase in diversity of the snail communities. In the total snail collection, 72.1% of specimens were gathered in sun-exposed sites. By the same degree of insolation more preferred by snails were the sites with allochthonic detritus. The snail fauna of subsidence ponds located inside a forest area differs from those occurring in urban agglomerations. The most conspicuous difference is the high numbers in three woodland ponds of Hippeutis complanatus (L.), which is rare in this area.

Identifying factors linked to the occurrence of alien gastropods in isolated woodland water bodies.

Biological invasions are a significant component of human-caused global change and is widely regarded as one of the main threats to natural biodiversity. Isolated anthropogenic water bodies created in the areas that are deprived of natural freshwater habitats allow the survival and reproduction of alien species on newly settled sites. They are often small with water level fluctuations causing frequent environmental disturbances. The colonisation success may be the result of the rate of their degradation. The aims of the study were to determine the environmental conditions that affect the existence of alien species of gastropods in this type of aquatic environment and to examine whether the occurrence of non-native species affects the community structure of the native species. This study made it possible to group woodland ponds according to the occurrence of the three invasive species in snail communities and discuss the environmental conditions present in these pond types. Analysis of water properties emphasised the distinctiveness of the selected pond types. In ponds of the Potamopyrgus antipodarum type, we found the highest values of some parameters mainly hardness, conductivity, and content of calcium and chlorides, in contrast with the Physella acuta type, which were characterised by the lowest values except for phosphates and nitrites. In the Ferrissia fragilis type, we found the highest nitrate content. Data on the occurrence of alien species in different water environments play an important role in actions which are taken to prevent new invasions and spread of non-native species as well as to reduce future impacts of invaders.

Autochthonic and allochthonic plant detritus as zoobenthos habitat in anthropogenic woodland ponds

Regardless of origin, all water bodies situated inside forests form a unique habitat for many freshwater animals due to the allochthonous detritus covering the bottom, composed mostly of leaves from waterside trees. For many years these woodland ponds have been considered to be advantageous to regional biodiversity. Investigations were carried out in eight anthropogenic woodland ponds, formed as a consequence of coal mining activities, situated in forest complexes in Upper Silesia (Southern Poland), to evaluate the impact of allochthonic and autochthonic plant detritus on the formation of zoobenthic communities, together with insolation intensity. In sites covered by a layer of allochthonic plant matter, zoobenthos were more abundant compared to places covered by autochthonic detritus. The density of zoobenthos in sun-exposed sites was two to three times greater than in shaded sites.

The Importance of the Mining Subsidence Reservoirs Located Along the Trans-Regional Highway in the Conservation of the Biodiversity of Freshwater Molluscs in Industrial Areas (Upper Silesia, Poland).

The objectives of the survey were to analyse the structure of the mollusc communities in the mining subsidence reservoirs that were created as a result of land subsidence over exploited hard coal seams and to determine the most predictive environmental factors that influence the distribution of mollusc species. The reservoirs are located in urbanised and industrialised areas along the Trans-Regional Highway, which has a high volume of vehicular traffic. They all have the same sources of supply but differ in the physical and chemical parameters of the water. In total, 15 mollusc species were recorded including four bivalve species. Among them Anodonta cygnea is classified as Endangered according to the Polish Red Data Book of Animals and also as Near Threatened according to the European Red List of Non-marine Molluscs. Eleven of the 15 mollusc species are included on the European Red List of Non-marine Molluscs as Least Concern. Conductivity, pH and the concentration of calcium were the parameters most associated with the distribution of mollusc species. Canonical correspondence analysis showed that Potamopyrgus antipodarum, Radix balthica, Physella acuta, Gyraulus crista and Pisidium casertanum were associated with higher conductivity and lower pH values. A. cygnea, Anodonta anatina and Ferrissia fragilis were negatively influenced by these parameters of the water. The results of this survey showed that the mining subsidence reservoirs located in urbanised and industrialised areas provide refuges for rare and legally protected species and that they play an essential role in the dispersal of alien species as well.

The influence of the disturbed continuity of the river and the invasive species - Potamopyrgus antipodarum (Gray, 1843), Gammarus tigrinus (Sexton, 1939) on benthos fauna: a case study on urban area in the River Ruda (Poland).

Abstract The progressive degradation of aquatic ecosystems and ecohydrological role of rivers is one of the most important global environmental issues. The loss of the ability of rivers to self-purify waters due to the disturbances of river continuity cause a lack of biological life in parts of rivers or even in an entire river. The appearance of alien species in degraded aquatic environments is an increasingly common phenomenon and constitutes one of the threats to biodiversity. The aim of the study was to evaluate the possible impact of alien species Potamopyrgus antipodarum (Gray, 1843) and Gammarus tigrinus (Sexton, 1939) on native invertebrates as well as the influence of environmental factors on the occurrence benthos fauna including also alien species. The study conducted in industrial area, in the River Ruda (Poland), showed that at the sites at which the occurrence of the two alien species was observed, the density of native benthos and diversity decreased significantly. CCA analysis showed that non-native species occurred in fast water velocity and that their presence was associated with high values of conductivity, hardness, and a high chloride content. The arrival of new species from other geographical areas is one of the factors that influences the species balance in native aquatic fauna. The number of alien species in freshwater ecosystems probably will increase in the future as new aliens are moved outside of their native ranges.

Occurrence and morphological variability of Gyraulus crista (Gastropoda: Pulmonata: Planorbidae) on different types of substratum in woodland ponds

Gyraulus crista is often a dominant component of lentic freshwater snail communities because it may occur in densities of hundreds of individuals/m2 across continents and in lentic water types. A study on the occurrence and conchological variability of the shell of G. crista was carried out on five different types of substrates in the anthropogenic woodland ponds at thirteen study sites. In order to answer the question of whether the existence of this species in different forms is affected by the quality of the inhabited substrates, various physico-chemical properties of the water, different bottom sediments and water level fluctuations, we examined the variation of forms across 5990 specimens of G. crista in woodland ponds. This research, which was supported by Redundancy Analysis (RDA), showed a highly significant association of G. c. spinulosus with leaf deposits and G. c. cristatus for T. latifolia remains. G. crista nautileus was mainly associated with T. latifolia and also with G. aquatica remains. They also showed no statistically significant relationship between the occurrence of particular conchological G. crista forms and different physico-chemical properties of water.

New data on the biology and habitat preferences of the oligochaete species Ripistes parasita (Annelida: Clitellata: Naididae): a case study in a temporary woodland pond

Abstract Studies carried out in woodland ponds located in an industrial area of southern Poland revealed the occurrence of a large population of Ripistes parasita (Schmidt, 1847) in one of them. This is a naidid species that is not usually abundant in oligochaete communities. Its ecology and biology is poorly known and thus the aim of this study was to characterise the environmental conditions influencing the occurrence of R. parasita and to assess its population dynamics and life history pattern. R. parasita occurred in a pond with soft water and a low level of mineralisation, a pH ranging from 6.1 to 7.0, and a high content of nitrogen and phosphorus. During our investigation, considerable seasonal changes in the occurrence and population density were detected. Specimens of this species inhabited alder leaf deposits in winter and early spring while in summer and autumn they occupied in large number floating Nuphar lutea leaves. A stepwise regression analysis showed a relationship between the temperature and dissolved oxygen content in the water and the density of R. parasita. The R. parasita reproduced asexually by paratomy (between May and November). The mean doubling time (days) for the population was 22.4. Only a few individuals (less than 1% of the population) matured in September and October.

Activity of beavers as an ecological factor that affects the benthos of small rivers - a case study in the Żylica River (Poland)

The Eurasian beaver (Castor fiber) has a greater impact on local ecosystems than other herbivores, and the affected area exceeds the range of its presence. Its activity may change or create new habitats by modifying the availability of the biotic and abiotic resources available not only to beavers, but also to other groups of animals. Our aim was to study how beaver activity affects the benthos composition in a small river and in a beaver pond. The way in which beavers function in the case of small rivers has received little attention. The study showed a lower density of benthos above the dam (beaver pond - 1467 ind./m2) compared to the river (3147 ind./m2). Below the dam, the diversity of Trichoptera and Coleoptera was greater, while Diptera were more abundant in the beaver pond. Betidae were a constant component in the benthos assemblages and were most abundant in the beaver pond. Collectors-gatherers and predators were the most numerous in the beaver pond. Decreasing percentages of collectors-gatherers were observed with an increased abundance of collectors-filterers and shredders in the river. All of the ratio values except the P/T FFG (Predators to total of all other groups) were lower in the beaver pond compared to the river. The % EPT (Ephemeroptera Plecoptera and Trichoptera) was also greater in the beaver pond. Small differences in the physicochemical properties of the water and organic matter content in the bottom sediments were found both above and below the beaver dam.

The Use of Biological Indices for the Assessment of the River Quality (Ruda River, Poland)

Abstract Recognition of the deteriorating conditions of rivers worldwide has called for increased efforts to improve the ecological quality of impacted river systems. This is particularly important in areas that have suffered from a significant impact of human pressure on the ecological status of water. Field studies were conducted in the Ruda River in an area that had undergone anthropogenic disturbances. The objectives of our survey were to test the biological metrics based on benthic macroinvertebrates at four study sites. Spring and autumn surveys of benthic invertebrates indicated that based on the BMWP and BMWP(PL) indices, water quality was higher in comparison with the value of Multimetric index at all of the sites that were studied. Our results revealed that the water quality was higher at the study sites that are located above the dam reservoir based on both the chemical and biological parameters. This study also indicated that both spring and autumn constitute appropriate periods for carrying out monitoring studies. The values of multimeric index indicated the same water quality (except for site 1) in both sampling periods. Anthropogenic transformations of a riverbed influence the flora and fauna and affect the ecological status of rivers.

Assessing the diversity of the benthic oligochaete communities in urban and woodland ponds in an industrial landscape (Upper Silesia, southern Poland)

Studies were carried out in two mining pond complexes in an industrial landscape. The first complex (consisting of six ponds) was located in an urban area and the second one (consisting of six ponds) in a woodland area. The aims of the study were to assess the diversity of benthic oligochaetes and to evaluate which environmental variables are most important in determining variations in the community structure in ponds of varying location. In total, 21 oligochaete species were recorded (7–11 in the urban ponds, 11–15 in the woodland ponds). Aulodrilus pluriseta, Aulodrilus japonicus and Ophidonais serpentina were only found in the woodland ponds, while Potamothrix bavaricus only occurred in the urban ponds. Limnodrilus hoffmeisteri, Limnodrilus claparedeanus, Chaetogaster diaphanus and Ophidonais serpentina dominated in the woodland ponds, whereas Limnodrilus hoffmeisteri, Limnodrilus claparedeanus, Potamothrix bavaricus and Tubifex tubifex prevailed in the urban ponds. The total density of oligochaetes was higher in the urban ponds thought the values of the diversity indices were higher in the woodland ponds. The local diversity of the ponds was high, while the among-site diversity made only a small contribution to the regional diversity. Nonetheless, a cluster analysis divided all of the ponds into two distinct groups depending on their location. CCA analysis showed that conductivity, pH, total hardness, alkalinity, the concentration of chlorides and the content of organic matter in the bottom sediments were most associated with the distribution of some oligochaete species among the ponds studied.