This contribution presents new observations of the red swamp crayfish, Procambarus clarkii in Poland. The species was detected in Żerań Canal and Krasiński Garden in Warsaw (central Poland) where 5 and 2 individuals were collected respectively as well as in Dąbie Pond in Krakow (southern Poland) with total of 4 crayfish observed. These new sites are located approximately 500 km eastward (Warsaw) and 240-260 km northward (Krakow) from the nearest European sites where this species has been previously recognised (near Berlin, Germany, Egerszalók and Budapest, Hungary), thus are the furthest north-east records of the species in European open waters. It is likely that the examined stock originates from single introductions, however, presence of the juveniles caught in Warsaw suggests that the population found there may be breeding. The findings are discussed with available literature describing possible ways P. clarkii may use to colonize new habitats as well as the impact it has on the invaded ecosystems in general and native crayfish in particular.Keywords: Alien species / freshwater crustacean / ornamental pet trade / inland waters / Central Europe Résumé -Nouveaux signalements de l'écrevisse de Louisiane envahissante Procambarus clarkii (Girard, 1852) (Decapoda : Cambaridae) en Pologne. Cette contribution présente de nouvelles observations de l'écrevisse de Louisiane, Procambarus clarkii en Pologne. L'espèce a été détectée sur le Canal Żerań et le jardin Krasiński à Varsovie (centre de la Pologne) où 5 et 2 individus ont été prélevés respectivement ainsi que dans l'étang Dąbie à Cracovie (sud de la Pologne) avec au total 4 écrevisses observées. Ces nouveaux sites sont situés à environ 500 km à l'est (Varsovie) et 240-260 km au nord (Cracovie) des sites européens les plus proches où cette espèce a été précédemment reconnue (près de Berlin, Allemagne, et Budapest, Hongrie), ce qui en fait les plus au nord-est de l'Europe en eaux libres. Il est probable que le stock examiné provient d'introductions uniques, mais la présence de juvéniles capturés à Varsovie suggère que la population qui s'y trouve pourrait s'y reproduire. Les résultats sont discutés avec la littérature disponible décrivant les façons que P. clarkii peut utiliser pour coloniser de nouveaux habitats ainsi que l'impact qu'il a sur les écosystèmes envahis en général et les écrevisses indigènes en particulier.

An ornamental freshwater shrimp, Neocaridina davidi, is popular as an aquarium hobby and, therefore, a potentially invasive species. There is a growing need for proper management of this species to determine not only their optimum breeding conditions, but also their ability to colonise novel environments. We tested habitat preferences of colour morphs (brown, red, white) of N. davidi for substratum colour (black, white, grey shades, red) and fine or coarse chess-board patterns to recognise their suitable captivity conditions and predict their distribution after potential release into nature. We conducted laboratory choice experiments (n = 8) with three individuals of the same morph exposed for two hours to a range of backgrounds. Shrimp preferred dark backgrounds over light ones irrespective of their own colouration and its match with the background colour. Moreover, the brown and red morphs, in contrast to the white morph, preferred the coarse background pattern over the finer pattern. This suggests that the presence of dark, uniform substrata (e.g., rocks, macrophytes) will favour N. davidi. Nevertheless, the polymorphism of the species has little effect on its total niche breadth, and thus its invasive potential.

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This contribution presents the first record of ornamental shrimp epibiont, Scutariella japonica (Platyhelminthes: Temnocephalida) in European waters. The species lives on freshwater Atyidae shrimp from temperate, subtropical and tropical zones of South-East Asia. In total, 120 individuals of Neocaridina davidi shrimp were caught in thermally polluted canal of Oder river, near the city of Gryfino, in the northwest part of Poland. In that group, 5.83% were infected with scutariellids. Among shrimp, females were mostly infected (85.71%). Since ornamental shrimp released into thermally polluted water bodies have been also noticed in surrounding waters of natural temperature regime in Europe, S. japonica may spread further following potential expansion of the Neocaridina shrimp in Oder river. It is possible that other crustaceans, both native and alien which are present at this location, may also become vectors of this epibiont.

In recent years, ornamental shrimps gained increasing popularity in the aquarium trade. Unfortunately, they are potential vectors of epibionts, which may be unintentionally introduced to aquaria with imported shrimps. This contribution presents the first report of the occurrence of Holtodrilus truncatus on aquarium freshwater shrimp Caridina formosae. A total of 120 shrimp imported from Taiwan as aquarium pets were examined for the presence of epibionts. Holtodrilus truncatus occurred in 23.3% of shrimps. A total of 29.6% of crustaceans showed signs of damages as a result of H. truncatus activity. The shrimp is not common in the ornamental trade and is not subject to selective breeding. Therefore C. formosae populations available on the market, if not wild-caught, are most likely very similar to those occurring in Taiwanese natural water bodies, where H. truncatus occurs in Neocaridina shrimp. Neocaridina spp. are a known host for this epibiont, and transmission between species might occur in nature as well as in the aquarium trade were densities of animals are often high. The ability of H. truncatus to infect also highly invasive crayfish Procambarus clarkii, might also pose concern for regions where this crustacean is widespread. The actual lack of preventive measures for shrimp epibionts as well as confirmed releases of ornamental crustaceans into new aquatic ecosystems may result in further spread of H. truncatus, a potential new threat to native crustaceans and other epibionts.

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The paper presents quantitative results of mass wear of plough chisels working in soil made of various steel types and subjected to pad welding. The research was carried out in real field conditions on soils with similar physical and chemical parameters during routine field work in autumn. The scope of the research included the quantitative determination of wear values depending on the type of steel used and the surface treatment carried out. The photographs also show the surface profiles of plough chisels exposed directly to the impact of abrasives.