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Srdeční a pohybová aktivita raků jako nástroj ke studiu vlivu farmaceuticky aktivních látek
LOŽEK, Filip
Aquatic ecosystems face to anthropogenic pollution worldwide. One of the currently investigated pollutants entering the aquatic environment due to the insufficient efficiency of wastewater treatment plants are pharmaceutically active compounds (PhACs), such as psychoactive pharmaceuticals or illegal drugs. Although the target organism is human, PhACs target evolutionarily old receptors, so their presence in the environment affects organisms across the animal kingdom. The first part of the dissertation summarizes the current knowledge about the impact of psychoactive substances on the biological parameters of aquatic invertebrates including mollusc and arthropods. Some animals, such as crayfish, are sensitive indicators of the quality of the water to which they respond by ethophysiological changes. Consecutive parts of thesis are composite from scientific publications starting with subscription of novel robust method of non-invasive measuring of crayfish cardiac activity. The method was validated in second publication where the natural (scent of food, predator, conspecific and injured conspecific) and chemical (water disinfectant chloramineT) stimuli were distinguished by crayfish in order to be able to study changes in responses to stress when exposed to environmentally relevant concentration of PhACs i.e. analgesic tramadol what is covered in the third paper. Fourth and final publication describes the alterations in the heart rate and behaviour while stress response of crayfish during long term exposure to 1 ?g.l-1 of illicit drug methamphetamine. The discussion critically compares the advantages and disadvantages of individual approaches used in the detection of changes in biological parameters of organisms exposed to psychoactive substances and suggested future ways of progress in study area. From the results obtained we concluded that the crayfish organism with its biological functions is sensitive to detect selected psychoactive compounds in the relatively low concentrations that were found in the aquatic environment. In addition, ethophysiological alterations highlight possible impacts of these compounds on the ecology of aquatic invertebrates. The recorded effects on crayfish cardiac physiology could present a new area of research in relation not only to residual PhACs, but to a wide range of contaminants with possible impacts on the aquatic environment.
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Branchiobdellidan population on alien species of crayfish in the Czech Republic
LOŽEK, Filip
The thesis summarizes the current knowledge about the class Branchiobdellae including their anatomy, ecology and geographic distribution with respect to the presence of introduced species in Europe. Using samples of Branchiobdellidan obtained from two introduced species of crayfish caught in a pond near Čáslavice u Moravských Budějovic (signal crayfish, Pacifastacus leniusculus) and in Černíský stream (eastern crayfish, Orconectes limosus), two out of seven European species of Branchiobdellidan were identified, namely B. parasita with 100% presence in the eastern crayfish and 58.7% presence in the signal crayfish, and B. pentodonta with 41.3% presence. Based on data collected from the caught crayfish and samples of Branchiobdellidan, the individual weight of eastern crayfish was proved to influence the quantity and biomass of Branchiobdellidan on the body of crayfish (p<0.001), i.e. increased quantity and biomass of Branchiobdellidan was found on more robust specimens of crayfish, however the effect of gender was not statistically significant. With respect to the signal crayfish, a significant difference was observed in the quantity and biomass of Branchiobdellidan depending on the weight of the crayfish (p<0.001), and the influence of the gender of the crayfish was detected (p<0.001), i.e. the quantity and biomass of Branchiobdellidan was higher on the surface of male specimens of crayfish. The presence of eggs in some female signal crayfish had no significant effect on the quantity and biomass of Branchiobdellidan (p=0.052), however in combination with the weight, the influence of the presence or absence of eggs was proved (p=0.011), more robust females showed increased quantity and biomass of Branchiobdellidan.
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Damages caused by predation of invertebrates on the earliest development stages of fish
LOŽEK, Filip
Cílem bakalářské práce bude zjistit do jaké míry je přítomnost bezobratlých predátorů pro raná stádia ryb nebezpečná a má vliv na míru jejich přežívání. Většina hospodářsky chovaných druhů ryb se do rybníků nasazuje ve stádiu váčkového plůdku a nedochází k předchozímu rozkrmování na vacích či jiných odchovných zařízeních s pozdějším vysazením již silnějšího rozkrmeného plůdku. V prvních dnech po nasazení dochází také k největším ztrátám, které mohou být způsobeny ať už nedostatečnou potravní nabídkou nebo zejména predací bezobratlými predátory. Mezi ně mohou patřit tzv. "dravé" buchanky, larvy vážek nebo vodních brouků, a i některé druhy vodních ploštic. Student v průběhu bakalářské práce uskuteční několik laboratorních pokusů na rozplavaném plůdku kaprovitých, případně i okounovitých ryb, které bude konfrontovat s dravci, tedy dravými larvami hmyzu, vodními plošticemi či buchankami. Na základě pokusů vyhodnotí potenciální nebezpečnost jednotlivých dravců vzhledem k plůdku ryb.
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