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

Acidic, neutral and alkaline forest ponds as a landscape element affecting the biodiversity of freshwater snails

In recent years, the number of areas remaining under the influence of acidity has increased. At all levels of ecosystems, biodiversity decreases with acidification, due to the elimination of species that are most sensitive to low pH. Forest ponds belong to a specific group that varied in location, a huge amount of leaf litter, and isolation from other aquatic environments. They are crucial in the industrial landscape with well-developed industry and human activity. The aim was to investigate the relative importance of water chemistry in explaining snail assemblage compositions and species richness in forest ponds of contrasting pH. Patterns in gastropod communities were determined from an analysis in 26 forest ponds with multivariate gradient analysis. Ponds ranged in a base mean pH from 3.0 to 9.0. pH has been found to be an important factor influencing gastropod fauna. Neutral ponds support diverse communities, typical of small water bodies. In two acidic pond types, snail fauna was different. Among the species characteristic for acidic ponds (pH < 6) were Anisus spirorbis and Aplexa hypnorum. The greatest distinct characterised alkaline ponds with the numerous appearance of alien Physa acuta. The most diverse gastropod fauna was found in neutral ponds, whereas the lowest degree of diversity was found in ponds with the lowest pH. Current knowledge of pH-associated changes in aquatic ecosystems is still incomplete because anthropogenic acidification is a recent phenomenon. It is extremely important in forest habitats, since they react more intensively to climatic factors and are often used in landscape management and planning

Contribution to the biology of Hippeutis complanatus (Linnaeus, 1758) (Gastropoda:Planorbidae): life cycle in Silesian woodland ponds (Southern Poland)

In spite of the common occurrence of Hippeutis complanatus (L.) in some regions of Poland, it is considered to be a rare species with scattered sites. A study on its life cycle and shell growth in various conditions was possible due to the existence of very abundant populations in several woodland ponds of Silesia. The snails breed twice in a lifetime, and two generations reproduce in one year. The main breeding period is July/August. Some individuals breed also in the spring of the next year. The first appearance of the smallest individuals is clearly related to the water temperature

Woodland Ponds as an Important Habitat of Hippeutis Complanatus (Linnaeus 1758) Occurrence - Effect of Environmental Factors and Habitat Preferences

In industrial areas, woodland ponds are refuges of biological diversity. The impact of environmental factors such as the physico-chemical properties of water, organic matter content in bottom sediments and various types of substratum on the occurrence of Hippeutis complanatus were assessed. In Poland, it is considered to be a species with an established but unspecified risk, deserving the status of endangered species due to the decline of wetland environments. A Canonical Correspondence Analysis (CCA) revealed associations between the distribution patterns of freshwater snails species and the concentration of nitrates (NO3) and calcium (Ca) as well as pH and the organic matter content in the bottom sediments. Based on statistical relationships, results of study suggest that the kind of substratum (Typha latifolia remains, Phragmites australis remains, fallen leaves of waterside trees) has an impact on the occurrence of freshwater snails including Hippeutis complanatus for which the preferred substratum is the fallen leaves of waterside trees and sites with a high content of organic matter in bottom sediments. The study has shown that isolated water bodies located in forest complexes can be refuges for species that occur in small numbers in other types of aquatic environments

Identifying factors linked to the occurrence of alien gastropod 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

Małgorzata Strzelec (1955-2019) - obituary

"Professor Małgorzata Strzelec passed away prematurely on May 3rd, 2019, as a result of severe illness. She was a well-known and respected scientist, whose achievements place her among the prominent Polish malacologists. At the same time, she was a person of great modesty, with a high level of personal culture, and with an urge to help other people. She was always ready to give good advice and had a warm word for everyone. Being a person of great sense of humour, cheerful and very kind, she was friendly to everyone. She had very firm opinions and a righteous character. In recent time she has struggled with a severe and painful illness which she endured with dignity and immense humility." (fragm.

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

The implications of the impact of the recreational use of forest mining ponds on benthic invertebrates with special emphasis on gastropods

The relationships between the distribution and diversity patterns of benthic invertebrates in forest ponds used for different recreational activities were examined in this study. The study was based on sampling of benthic invertebrates, plant coverage, physical and chemical analysis of water samples and multivariate species analysis. Mining ponds varied in their solution chemistry and plant cover, with those used for recreation having significantly lower invertebrate occurrences (755 ind. m−2) compared to ponds with no recreational use (2629 ind. m−2). Statistically significant differences were also observed in the density of Oligochaeta, Hirudinea, Coleoptera, Trichoptera and Diptera between the two types of ponds. Overall, gastropods were more diverse and abundant in ponds not used for recreation. This appeared to relate strongly to plant cover, since cover was greatly reduced in recreational ponds, although plant diversity was enhanced. Density and diversity of benthic invertebrates was also observed to differ in relation to the kind of recreational use involved (recreational angling, swimming, power boating) although this was not quantified. The occurrence of freshwater snails primarily depended on the Ca concentration, the conductivity of the water and plant cover, but recreational disturbance appeared to reduce abundance where it occurred and was related to a reduction in overall plant cover

Wykorzystanie indeksów biologicznych w ocenie jakości wód rzecznych (rzeka Ruda, Polska)

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

Molluscs of extremely artificial, small temporary water bodies in a city park

The Pole Mokotowskie Park in Warsaw contains small, artificial and temporary water bodies created in the 1970s and supplied with water from waterworks. In them, molluscs constituted the dominant group of macroinvertebrates. They were represented by eight gastropod and one bivalve species. Both Prosobranchia (mainly Bithynia tentaculata and Valvata piscinalis), and Pulmonata (mainly Radix balthica, Planorbis planorbis and Bathyomphalus contortus) occurred abundantly. The bivalve Musculium lacustre, listed in The Red List of Threatened and Endangered Species in Poland, was also numerous. A large spatial diversity of species composition and abundance of molluscs was observed in a small and relatively homogenous area. The role of this type of water bodies in the creation of mollusc habitats as well as the possibility of colonisation of man-made and artificially drained water bodies by these animals are discussed