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Společenstvo bentických organismů na dolním toku Ohře, Labe a jejich přítocích
MUSIL, Martin
The purpose of this work was to describe the current status of benthic communities on the main stream of Elbe River and Ohře River and their tributaries affected and non-affected by biological invasions - especially by round goby (Neogobius melanostomus) and spiny - cheek crayfish (Faxonius limosus). Sampling for this research took place from April 2018 to August 2018, while morphiologic survey of waterbodies was done in November 2017. Two tributaries of the Elbe River (Milešovský brook and Ploučnice River) and one tributary of the Ohře River (Čepel) were selected for this research. Two 100 m long sections (lower stretch potentially affected by invaders and upper stretch as referential) were monitored at each tributary. At the same time a 100 m long main flow section was monitored near the mouth of the tributaries. The following parameters were monitored: morphology of the stream and basic physical and chemical parameters of water, zoobenthos community, crayfish occurrence, and fish community. The benthic communities of the upper streams were less affected by biological invasions. The biodiversity of the benthic communities in the upper sections was richer compared to the lower sections. The occurrence of the round goby seemed to be factor affecting benthic and fish communities at the sites concerned. It was an eudominant species in the Elbe section in Děčín and becoming dominant in the lower section of Ploučnice River.
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Monitoring of invasive spiny-cheek crayfish in Lipno dam and the evaluation of its predation on chosen fish species.
SALON, František
Astacologic survey took place in ÚN Lipno and was conducted in time from 2012 till 2013. For the actual mapping of the occurrence of spiny-cheek crayfish, the locations of total 17 places were detected. These monitoring areas were carried out in two ways for collecting the samples. The trapping of all individuals was achieved with special instruments, like pots or traps by hands or with the help of nets. For the caught specimens of spiny-cheek crayfish, which were determined by sex, the length of carapace was measured and as well if possible, the postorbital carapace length was taken. Throughout the whole monitoring, 228 individuals of spiny-cheek crayfish were caught in the amount of 107 (47%) females (CL = 21.5 ? 7.3 mm) and 121 (53%) males (CL = 20.1 ? 5 mm). Another aim of this work was to demonstrate that crayfish figure in fish food menu. Catches of fish were carried out in two ways, using fishing rods or into the clutches. The stomachs and intestines contents were analyzed at caught fish samples. If the condition of the contents of stomachs or intestines were allowed, it was also identified, what kind of food it was. For our annual issues, were included mainly species of piscivor fish. Spiny-cheek crayfish were identified in the stomachs of two species of fish, namely perch and pike.
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Toxicity of selected substances for spiny-cheek crayfish
MAHOVSKÁ, Ivana
The thesis examined the toxicity of selected compounds for spiny-cheek crayfish (Orconectes limosus) in laboratory conditions. Tested the acute toxicity of the insecticide Diazinon 60 EC and herbicide Roundup Biaktiv. Tests were chosen to juveniles spiny-cheek crayfish (Orconectes limosus), and juvenile and adult specimens of signal crayfish (Pacifastacus leniusculus).These species of crayfish have been selected as an easily accessible model organism. Both species of crayfish spreading and in Europe they are unoriginal. Work focused on the observed toxicity of these substances on spiny-cheek crayfish and signal crayfish and the demands on the quality of the environment.
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