The aim of this study was to determine the ability of crustacean zooplankton outflowing from the dam reservoir to colonize new habitats of a river valley. Siemianówka Reservoir is a huge source of crustaceans for the outflowing Narew River and results in a 33- to 307-fold increase in summer biomass of potamozooplankton. Zooplankton samples were collected from a permanently connected oxbow lake located directly behind the reservoir and from 18 oxbow lakes 10 to 180 km from the dam. The results of our study showed that crustacean zooplankton of oxbow lakes generally showed low similarity to Siemianówka Reservoir. However, a high level of zooplankton similarity was observed among oxbow lakes themselves. This could suggest that the crustacean zooplankton of the oxbow lakes in the river valley show a metacommunity structure.
Introduction. Training of children and young people is one of the most important stages and subsystems in coaching and determines future achievements of adult athletes. Level of physical fitness determines effectiveness of coaching and development of technical skills, influences the effectiveness of tactical actions and has an impact on current psychical disposition of a person. Aim of Study. The research presented herein focused on establishing trends in the changes of young fencers’ motor effects (their structure and level) in the period of 2006-2013 with reference to tasks aimed to comprehensively shape functional, fitness and technical foundations that take account of requirements set by a desired specialisation and regarded as typical for an oriented stage of sport training. Material and Methods. The study was based on the findings of research carried out 2006-2013 among young fencers – members of the Junior Team of the Greater Poland region (KWJ). The analysis involved a total of 200 boys aged 15 to 16. Measurements – designed to determine the level and structure of the fencers’ motor effects – were conducted by means of the International Physical Fitness Test. The test was also to assess basic somatic parameters, such as body height and weight, and to calculate the BMI. Results. The research found out that the general physical fitness of young fencers established on the basis of the International Physical Fitness Test – decreases in subsequent age groups. It may be a consequence of a regressive trend in intergenerational motor changes generally observed in the population, or relate to a change in height-and-weight proportions leading to an increase in body corpulence. Conclusions. A significant drop in strength related to overcoming one’s body resistance is most likely an outcome of the above-mentioned changes in the body structure. Therefore, as it appears, this fact should not be regarded as confirming a view that the so-called strong types of physical fitness are now more seldom among young people. A rise in endurance abilities in the period under research is a positive phenomenon from the point of view of fencing requirements, but also or even mainly – in the context of reversing the negative trend as regards lower general fitness of the young generation.
An aim of the research was to test a hypothesis that impact of a shallow hypertrophic reservoir on riverine zooplankton is limited to a short section of the outflowing river because of a rapid conversion of the lentic habitat into the lotic one. The second hypothesis assumed that species richness of zooplankton is increasing along the river due to washing out littoral and benthic species. The study was carried out in the years 2009–2010, during summer-autumn strong dominance of toxic filamentous Cyanobacteria in a shallow hypertrophic humic Siemianówka Dam Reservoir (northeast Poland) and the outflowing Narew River. During research samples were collected on three consecutive days because water requires approximately as much time to cover the distance from the dam down to 118 km of the river. Results of two-year studies confirmed both hypotheses. The hypertrophic reservoir was the huge source of rotifers and crustaceans for the outflowing river. However, a rapid decline was observed in zooplankton abundance below the dam at the distance of 9.1 km. With decreasing share of reservoir dominants along river, an increasing importance of littoral and benthic rotifers constituted ca 0.8% at the dam and 37.5% at 118 km of the river and crustacean ca 4% and 60% respectively. The dam reservoirs similar as fluvial lakes disrupt river continuity by changing the conditions of the zooplankton development. The strongest influence of reservoir on potamozooplankton communities is observed below outlets.