Jiri Machacek

Learn More
Both the size of Daphnia galeata primiparae and the average egg volume were smaller in individuals reared from neonata in water inhabited for the preceding 24 hours by Y-O-Y roach when compared with control animals reared in the same water with the exclusion of fish. The smaller size of experimental primiparae resulted from smaller increments in some(More)
The relative homogeneity of pelagic environments has been regarded as the reason for the absence of hybrid zones for hybridizing planktonic Daphnia (Crustacea: Cladocera); occasional dominance of interspecific hybrids over parental species was explained by their temporal superiority in fluctuating environments. However, water bodies with spatially varying(More)
Daphnia galeata is traditionally regarded to be a non-migratory species, which lives in warm epilimnetic waters. Depth segregation or vertical migration is usually attributed to other Daphnia species such as D. hyalina or D. longispina. In a two-year study, we found that in a deep, dammed-valley reservoir (Římov Reservoir, Czechia) the majority of the(More)
Laboratory cultivation experiments were carried out in order to determine the response of D. galeata to food conditions and dissolved chemicals in the water collected in three contrasting sites of the Rímov Reservoir. There were two types of cultivation media: (1) lake water with natural seston, filtered through a 40 μm mesh size sieve, (2) lake water(More)
Growth and reproduction were studied in the laboratory in a cross-designed experimental set-up in four Daphnia galeata subpopulations collected from different locations (with respect to water characteristics) in a reservoir (epilimnion, metalimnion and hypolimnion in the deepest part of the reservoir near the dam and epilimnion of the upstream part of the(More)
Long-term persistence of a Daphnia population is allowed by the production of dormant stages, produced mostly through sexual reproduction. We investigated the spatio-temporal dynamics of male production in a spring population of Daphnia galeata in the reservoir, and compared the genetic structure of three groups within this population: male-,(More)
Control of the interacting multivariable systems can be in the simplest way realized by single input single output PID/PI controllers (so called decentralized control). When model of the process is not a priori known, basic information about system can be obtained by relay autotuner. Controllers tuning is then realized in a few iterations, e.g. by(More)
Environmental gradients influence the distribution and taxonomic composition of planktonic taxa, including Daphnia. In canyon-shaped reservoirs with pronounced horizontal gradients of food supply, predation pressure and other factors, not only species and interspecific hybrids but also clones within these taxa are non-randomly distributed. Using a long-term(More)
  • 1