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The aim of this study was to compare survival and growth of juvenile narrow-clawed crayfish (Astacus leptodactylus) and signal crayfish (Pacifastacus leniusculus) fed only with experimental pellets (45% of proteins, 6% of fat, 20% crude fibre) under controlled conditions. The animals were reared in 12 (50 l) circular plastic tanks, the narrow-clawed crayfish set-ups being designated A1 and A2, the signal crayfish set-ups P1 and P2. The initial stocking densities for each species were 600 (A1, P1) and 1,200 (A2, P2) juveniles stage 2 per square metre for each set-up in three replicates. The experiment lasted 92 days under continuous photoperiod (L:D 24:0; 100 LUX) conditions at a temperature of 22.0 ± 0.1°C and an oxygen saturation > 90%. One shelter (plastic tube) was provided for 2 crayfish in each set-up. The highest survival rate was obtained for signal crayfish from set-up P1 (47.5%), the lowest for narrow-clawed crayfish from set-up A2 (22.8%). Crayfish survival evidently depends on the stocking density: in set-ups A1 and P1 it was about 16% higher than in set-ups A2 and P2 (P < 0.05). Mortality was significantly higher (P < 0.05) in both species during the first 30 days of the experiment (48-77% of the total mortality) than during the subsequent two months of the experiment (< 20% of the total mortality). The final body size was the largest in narrow-clawed crayfish from set-up A1 (799 mg, 29.2 mm) and the smallest in signal crayfish from set-up P2 (534 mg, 26.5 mm). Specimens of narrow-clawed crayfish were larger than signal crayfish, and the specimens of both species in set-ups A1 and P1 were larger than those in set-ups A2 and P2. During the first 30 days of the experiment the specific growth rate (SGR) of both species in all set-ups was twice the value reported during the subsequent two months (P < 0.05).

The taxonomic classification of European crayfish is neither fully examined nor generally accepted as a unifying scheme. At present, one of the most obvious differences exists between astacologists from Western and Eastern Europe. In the present paper, an analysis of the information published on the systematics of European crayfish over the last decades was conducted against the background of own observations on features with importance for the systematics of narrow-clawed crayfish (Astacus (Pontastacus) leptodactylus) from Poland. The objective of this analysis was to standardize the nomenclature of European crayfish at the level of genera. The presented proposal for a taxonomy recognizes three genera within the family Astacidae in Europe: Austropotamobius, Astacus, and Pontastacus. The main (morphological, zoogeographical and ecological) criteria for considering the genus Pontastacus a separate genus are of a discriminatory strength similar to the widely accepted criteria for the separation of the genus Austropotamobius. Further studies on the taxonomy and ecology of crayfish from eastern Europe using modern techniques such as molecular genetics are strongly recommended.

The potential of artificial hideouts, outfitted with magnets or their imitations (control), to attract spinycheek crayfish Orconectes limosus was studied. The experiments were carried out within 1999-2002 in an 80-hectar natural lake. There were three parallel setups, with three experimental treatments (hideouts) each. The presently acquired results suggest explicitly that the magnetic field generated at the entrance to the hideouts (made of ceramic pipes), affects the movement direction of crayfish. This was evident from statistically significant differences between the numbers of crayfish attracted to the pipes equipped with magnets and to the control ones.

The genetic variability between individuals from five crayfish (Astacus astacus L.) populations was determined. The analysis was based on sequences variations of mitochondrial DNA (cytochrome oxidase subunit I (COI) and 16S ribosomal DNA. Mitochondrial DNA sequences are widely used to detect genetic variation within and between populations. Data analysis revealed the existence of two COI haplotypes – most common haplotype Hap01 and one new haplotype, differed only in one substitution. Analysis of the 16S rDNA sequences obtained showed no differences in nucleotide composition. The results of the analysis are important part of project “Active protection of noble crayfish in lakes of Pomeranian Complex Landscape Parks” financed by Financial Mechanism of the European Economic Area 2014–2016.

Trematode infestation of Mallards (Anas platyrhynchos) varies between northern Poland and the Czech Republic. We determined the trematode fauna of juvenile and adult Mallards from Poland in 2010–16 (n=79 Mallards) and from the Czech Republic in 1964–2001 (n=296). Infracommunity diversity of trematodes from juvenile Mallards, defined by the Brillouin index and mean number of species, was significantly greater in Poland than it was in the Czech Republic. There were more species and greater biodiversity in the trematode communities of Mallards from Poland, where the environment is more natural and less altered by human activity than it is in the Czech Republic. In the trematode community of juvenile Mallards, the Simpson's index of biodiversity was higher in the Czech Republic than it was in Poland. The Berger-Parker dominance index was comparable in both countries. In terms of prevalence, the structure of the trematode fauna was hierarchic, and trematode species had different positions in this hierarchy in the two countries. Statistically significant differences in the epidemiologic indices between infection of juvenile Mallards from Poland and the Czech Republic were noted for Bilharziella polonica, Echinostoma miyagawai, Echinostoma revolutum, Prosthogonimus cuneatus, Prosthogonimus ovatus, Notocotylus attenuatus, Echinoparyphium recurvatum, Australapatemon minor, Apatemon gracilis, Cyathocotyle prussica, Hypoderaeum conoideum, Metorchis xanthosomus, Psilochasmus oxyurus, and Cotylurus cornutus. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Nano- and ultrafiltration processes were used to obtain acid whey concentrate. • The effect of acid whey concentrates on physiological response of rats was study. • Concentrate after ultrafiltration was more beneficial for the rat's body. Abstract The effects of acid whey concentrates after nano- or ultrafiltration on the nutritional and physiological indices of rats were analysed. The ultrafiltration concentrate was characterized by a higher protein and lactoferrin content, and lower lactose content compared to the nanofiltration concentrate. In vivo , a diet incorporating the ultrafiltration concentrate instead of the nanofiltration concentrate seemed to be more beneficial to rats in terms of a good growth rate and utilization of the diet, higher concentration of butyric acid and lower concentration of putrefactive short chain fatty acids in the caecum, increased bacterial enzyme activities in the caecum, lower blood glucose levels and reduced levels of triglycerides, and greater antioxidant capacity of blood serum. Both acid whey concentrates fulfilled the recommendations for powder intended for direct consumption or further processing in food production and showed potential health benefits. [ABSTRACT FROM AUTHOR]

The paper presents an effect of fiber bending on sensitivity of long-period gratings (LPGs) to temperature and to surrounding refractive index (RI). The LPGs were manufactured by UV-exposure of hydrogen-loaded Corning SMF28 fibers and their annealing was followed by wet etching in hydrofluoric acid up to dispersion turning point (DTP) where the LPG shows the highest sensitivity. The LPGs were subjected to curvatures in range 0.8 to 4.8 m -1 when their temperature (T=20-100 °C) and refractive index (RI) responses (n D =1 to 1.47) were measured. Bending sensitivity reaching 54 nm/m -1 has been obtained. It has been found that as a result of bending, coupling to asymmetrical cladding modes takes place. It results in the resonances increasing their depth and shifting towards longer wavelengths with bending. The bending effect also allows for post-fabrication tuning of the LPGs working at DTP. The LPGs with bending-modified temperature sensitivity up to 0.54 nm/°C have been shown. The method can also be applied for tuning of RI sensitivity of the LPGs. [ABSTRACT FROM AUTHOR]