Józef Domagała

Similarities in zooplankton community between River Drawa and its two tributaries (Polish part of River Odra)

Zooplankton communities were studied in a river and its tributaries with different hydrological, biological and physico-chemical conditions. Small similarities were noted in the zooplankton community (mostly Rotifera) between a tributary characterised by a regular bed and the river. No influence of a tributary with an irregular bed and variable water flow was noted on the zooplankton of the river it joined. It was concluded that the tributaries had very little influence on the zooplankton community in the river which they joined. The most probable reasons for this were the predatory behaviour of fry, escape of zooplankton into the river vegetation and therefore not carried down by the river current, and reproduction of zooplankton in slack waters, small floodplains and densely vegetated riparian zones of the main river.

Post-thawed motility and fertility from Atlantic salmon (Salmo salar L.) sperm frozen with four cryodiluents in straws or pellets

The cryopreservation of salmonid sperm is a complex process involving the interplay of many factors. Although cryopreservation protocols can be evaluated through a range of responses at various stages in the process, the number of progeny is the ultimate indicator of success. We compared reproductive success from freezing Atlantic salmon (Salmo salar L.) sperm using the eight combinations of (1) the penetrating cryoprotectants, 10% dimethyl sulfoxide (DMSO) or methanol (MeOH); (2) the nonpenetrating cryoprotectants glucose (0.3 M) or sucrose (0.6 M), and freezing in 0.1 mL pellets or 0.25 mL straws. All cryodiluents were supplemented with 10% (v/v) of hens egg yolk. Response variables were the percentage and degree of motility of thawed and activated sperm using computer assisted sperm analysis (CASA), and rates of eyed embryos, hatch and egg sac larvae. Growth rates of alevins were assessed to two months post hatch. Atlantic salmon milt cryopreserved in straws had higher spermatozoa motility and fertilization success than milt cryopreserved in pellets (P < 0.05). Type of sugar tested did not significantly affect the response variables. In the MeOH treatment, thawed spermatozoa achieved higher speed and a higher fertilization rate evaluated at the eyed embryo stage than spermatozoa subjected to the DMSO treatment. Higher mortality rate (especially before hatching) of MeOH offspring than DMSO offspring led to equal numbers of progeny for the two treatments from the swimming stage to the end of the study. Moreover, during feeding fish from the MeOH group produced significantly lower weight larvae than the DMSO and control groups. Even so, the weight of the MeOH group was satisfactory. Length and the condition factors did not differ significantly among the larvae groups. Significant positive correlations were found between fertilization success (measured in number of eyed eggs) and both motility (rs = 0.81), and velocity (rs = 0.49). Freezing in straws gave betters results than freezing in pellets for cryopreservation of salmon milt; whereas type of sugar tested (glucose vs sucrose) did not have significant effects. Penetrating cryoprotectants DMSO and MeOH differed in their effect on post-thawed sperm velocity, fertilization rate and mortality rate of progeny, suggesting the need for further research on the influence of these cryoprotectants on frozen sperm and and post-fertilization devopmental processes.

Zooplankton communities of two lake outlets in relation to abiotic factors.

We examined the quantitative and qualitative zooplankton community structure in two small rivers flowing out from lakes differing in trophic conditions. Within each river, three sites were chosen for the collection of drifted zooplankton: one at the outflow, and two at distances of 0.2 km and 1 km from the outflow. The most significant difference in zooplankton community between the outflow and the lower course of the river occurred in the first section directly after the outflow. These differences in the zooplankton community were driven largely by crustaceans, which declined faster in the river flowing out from the mesotrophic lake. Physical parameters mainly impacted the zooplankton community found in the river flowing from the mesotrophic lake; however, chemical parameters also had an impact in the river discharging from the strongly eutrophic lake.

Potamozooplankton communities in three different outlets from mesotrophic lakes located in lake-river system

Qualitative and quantitative composition of potamozooplankton was studied in three outlets from mesotrophic lakes. The greatest taxonomic and quantitative similarity of zooplankton occurred between the outflows of the second and third lake, located in the lake-river system. The farther the lake was located in the lake-river system, the greater was the quantity of zooplankton in the outflow. Within a short distance between the outflow and the downstream section, there was a strong reduction of cladocerans’ communities, followed by copepods, while the communities of rotifers were reduced in relatively small quantities. The hydrological conditions and transparency had a strong impact on the rate of changes in the zooplankton community.

Effect of pH and cation concentrations on spermatozoan motility of sea trout (Salmo trutta m. trutta L.).

Environmental conditions during external fertilization in fish have a significant effect on spermatozoan motility (MOT) and fertilization ability. Even in the same family of fish, spermatozoa might differ in sensitivity to ions present in the external medium. Elucidation of such differences within a species would help to understand spermatozoan biology and to determine external conditions that would optimize spermatozoan MOT and successful fertilization. Objectives of the current study were to determine the effects of pH and of sodium, potassium, and calcium ion concentrations in the activation solution on sea trout spermatozoan MOT. Six parameters characterizing MOT (MOT, curvilinear velocity [VCL], linearity, amplitude of lateral head displacement, beat cross frequency, and duration of MOT) in spermatozoa activated in prepared buffers were traced by computer-assisted sperm analysis. Sea trout spermatozoa were motile over a wide range of pH values, and increasing pH did influence MOT, VCL, linearity, amplitude of lateral head displacement, and MOT duration. The optimum pH for sperm MOT was established at approximately 10. Increasing K(+) ion concentration within the observed range caused a decrease in MOT and VCL. Spermatozoan movement ceased at 8 mM KCl concentrations. In Ca(2+) buffers, sperm were motile within the range of 0 to 70 mM CaCl(2) concentration; although beyond 8 mM concentration, VCL and MOT gradually declined. Spermatozoan aggregation was observed at the highest ion concentrations tested. Increasing CaCl(2) concentration affected MOT pattern from initiation to termination of spermatozoan movement in a similar manner as changes associated with increasing pH. At concentrations of CaCl(2) higher than 0.5 mM and in buffers with pH values 10 to 11, movement of spermatozoa was characterized by high initial linearity followed by its gradual reduction. In contrast to the effects of KCl and CaCl(2), increasing NaCl concentration up to 90 mM Na(+) concentration prolonged the duration of spermatozoan movement and, up to 60 mM Na(+) concentration, slightly increased sperm velocity as well. Above the concentration of 90 mM NaCl, these parameters decreased; and at 240 mM of Na(+), spermatozoa did not activate.

Reduction of zooplankton communities in small lake outlets in relation to abiotic and biotic factors

The aim of this study was to answer the following questions: (1) which environmental variables, biotic (fish predation) or abiotic factors, have a greater influence on the rate of zooplankton changes in lake outlet sections and (2) which plankters suffer the greatest reduction in the outlet section.Samples were collected in two locations at each of 18 lakes. The first site was right at the outflow; the second site was 0.2 km downstream from the outflow. At downstream sites the percentage contribution of Rotifera in zooplankton species number and abundance was higher than in the outflow, whilst the percentage contribution of Cladocera and Copepoda (except nauplii) in the zooplankton species number and abundance was lower at downstream sites than in outlets. The most important variables affecting the rate of zooplankton reduction in the lake outlets are the biomass of cyprinids and hydrological parameters along the outlet, such as discharge, current velocity, and depth.The most dramatic reductions involved daphnids, adult copepods, small cladocerans, and copepodites, while the reduction in the abundance of rotifers and nauplii was statistically insignificant.

Zooplankton communities of inter-connected sections of lower River Oder (NW Poland)

The aim of this study was the determination and comparative analysis of the zooplankton communities between the inter-connected sections of the lower Oder river in relation to physicochemical factors. The study was performed at five sites of Oder. Two sites were localized in the main channel of Oder (East Oder), other sites were localized in the west arm of Oder and at the beginning of the canal carrying the post-cooling water from the power plant, and the last site was below at the shallow channel joining the Western Oder with the Eastern Oder. At the channel site in which the two arms of the river are connected a significantly higher taxa number, abundance and biomass of crustaceans was observed than at the other sites. The taxonomic similarity index between all sites was at a rather low level. The Pearson’s coefficient, multiple regression analysis and CCA showed that temperature, conductivity and content of nitrates had the strongest impact on the abundance of zooplankton. Thus, in lower, slowly flowing section of River Oder the physico-chemical variables influenced zooplankton density. Post-cooling water from the power plant influenced the zooplankton communities only in the channel discharging the waters into the river, while its influence on the zooplankton in the Oder is insignificant.

Annual development cycle of gonads of Eurasian ruffe (Gymnocephalus cernuus L.) females from lower Odra River sections differing in the influence of cooling water

The subject of this study was gonadal development of Eurasian ruffe females collected at three sites: the Regalica River carrying natural waters of the Odra River, Warm Canal to which cooling water from a power plant is discharged, and Lake Dąbie in which the waters from East Odra and Warm Canal are mixed. According to histological analysis, under the natural conditions in the lower Odra River, ruffes spawning season usually begins in April and lasts till the end of May. The fish from Lake Dąbie started their spawning season in a similar period, while the fish from Warm Canal started their spawning season in March, a month earlier, and also finished their spawning season earlier. The size of oocytes from the ruffe collected in the Warm Canal at the beginning stage of vitellogenesis was smaller (mean diameter of 184.3 μm) and at the end of vitellogenesis larger (755.3 μm) than the size of oocytes from the fish collected at the other two sites (p < 0.05), although their sizes were within the typical range. In the gonads of the fish caught from June to September at all the sites, the presence of degenerating oocytes was confirmed. Folliculi atresia at the beginning of summer was observed in the last not-laid portion of oocytes, while the degeneration of a part of newly produced vitellogenic September oocytes was caused by a high temperature of the lower Odra River water, of over 20°C at that time. Both types of oocyte degeneration are the natural adaptations to the conditions of a changing natural environment.

Analysis of benthic macroinvertebrate communities from the Lower sections of Large river in relation to different environmental factors

The aim of this study was to make a comparative analysis of macrozoobenthos composition at different sites at selected sections of lower the Odra River with relation to different physicochemical factors. The observations were made on the lower section of Odra River at five study sites: two of them were localized in the main channel, one in the left branch of river, another one in the channel carrying post-cooling water from Dolna Odra power plant, and the last one was in the channel connecting both branches of Odra River. At all sites, 26 taxa were found representing by: Bivalvia, Gastropoda, Oligochaeta, Hirudinea, Malacostraca and Insecta. The greatest biodiversity and the highest abundance of zoobenthos organisms were noted in the channel joining the two branches of the river, site 5, characterised by the lowest water flow rates and the densest coverage of the macrophytes at the bottom. Temperature was the sole parameter to be studied that affected the composition of benthic invertebrates. A clearly negative impact of temperature on the diversity of invertebrates was observed only in the channel with post-cooling water discharged from the power plant.

ANNUAL DEVELOPMENT OF GONADS OF PUMPKINSEED, LEPOMIS GIBBOSUS (ACTINOPTERYGII: PERCIFORMES: CENTRARCHIDAE) FROM A HEATED-WATER DISCHARGE CANAL OF A POWER PLANT IN THE LOWER STRETCH OF THE ODER RIVER, POLAND

The pumpkinseed, Lepomis gibbosus (Linnaeus, 1758), known also as pumpkinseed sunfish, is native to eastern and central North America (Tomeček et al. 2007). Because of its attractive appearance, the species was introduced to Europe in the 19th century as an ornamental fish for aquaria or park ponds, or a prospective sport fish (Vooren 1972, Witkowski and Grabowska 2012). Natural escapes and intentional introduction of the fish into open waters has resulted in fast spreading of the species over Europe and a successful colonisation. The pumpkinseed has been already found in at least 28 European countries and in Asia Minor (Coop and Fox 2007). The fish are found in shallow, weedy, quiet reservoirs, lakes, river inlets, tributaries, and canals, in cool to moderately warm waters (Miller 1963, Tomeček et al. 2007). The range of the species is limited by the water temperature. The optimum temperature for pumpkinseed growth is 20–30oC (Mischke and Morris 2002). For reproduction, they need the critical temperature range of 14–16.5oC (Burns 1976). ACTA ICHTHYOLOGICA ET PISCATORIA (2014) 44 (2): 131–143 DOI: 10.3750/AIP2014.44.2.07