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Trophic structure of fish communities in the tributaries upstream of the Lipno Reservoir
Kofentová, Nikola ; Horká, Petra (advisor) ; Slavík, Ondřej (referee)
River obstacles, especially dams, are known to alter the natural environment in streams, which significantly impacts fish communities. The cyprinid species migrate from the reservoirs upstream to the reservoir's tributaries, where they may cause changes in the trophic structure of native fish communities. The aim of this study was to evaluate the trophic structure of the fish community composed mainly of cyprinid and salmonid species throughout seven localities in the Vltava River upstream of the Lipno reservoir. Stable isotope analysis was used to identify trophic positions, trophic niche width and trophic niche overlap between species. Trophic relationships of individual species were then evaluated to assess the potential for food competition. The trophic niche width of the salmonid species was significantly higher than that of the cyprinid species. Trophic niche overlap between salmonids and cyprinids was observed, with the most significant overlap being with both common dace Leuciscus Leuciscus and common roach Rutilus rutilus, suggesting a potential competition for food. The effect of the presence of cyprinids on the trophic niche width of salmonids was shown not to be statistically significant. From the perspective of protecting native salmonid species, there should be special attention paid...
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The impact of eutrophication and turbidity on riverine fishes
Jeníšová, Karolína ; Horká, Petra (advisor) ; Frouzová, Jaroslava (referee)
There is currently a rapid decline in the amount in freshwater species and they face extinction. The risk of extinction of freshwater organisms is much greater than that of terrestrial ones, and almost 40 % of freshwater fish are currently facing extinction. In addition to the overexploitation of freshwater ecosystems and their degradation, eutrophication is one of the most significant threats to river ecosystems, leading to significant changes in biodiversity. Eutrophication causes severe changes in river ecosystems, which have a positive effect on some fish species but an adverse effect on other fish species. Due to eutrophication, water becomes turbid due to the development of cyanobacteria and algae, changes in the oxygen concentration in the water, pH level fluctuation, the presence of toxic substances and clogging of the bottom with fine sediment. The aim of this master thesis was to describe the influence of environmental factors related to eutrophication on the number of selected fish species caught in the Czech Republic, in the Vltava and Ohře river basins, in a total of 47 locations. Individual environmental factors (14), which describe changes in the ecosystem caused by eutrophication, were tested for the caught fish using generalised linear mixed models (GLMM). The results of my work...
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Factors influencing movement and behaviour of animals in riverine environment
Horká, Petra
Animals living in riverine environments are influenced by various abiotic and biotic factors which shape their behaviour. Among the most distinctive behavioural traits by which animals react and adapt to environmental variability is movement behaviour. In my study I focused on movement and distribution of several species and their response to environmental and anthropogenic factors. The thesis consists of two parts: the first part synthesizes studies on behaviour of European grayling Thymallus thymallus, Ide Leuciscus idus and an invasive crustacean Hemimysis anomala; the objectives of individual projects were to determine which environmental factors influence the species' behaviour and how. The first two chapters present extensive radio-telemetry studies which examined diel movements and migration of ide (one year observation in the River Elbe) and European grayling (study conducted in autumn-winter periods of three consecutive years in the River Blanice, focusing on differences between juveniles of wild and hatchery origin). The third study was also conducted in the Elbe and evaluated the diurnal behavioural patterns and spread of the Pontocaspian mysid shrimp Hemimysis anomala. The second part of the thesis consists of two chapters focusing on young-of-the-year (YOY) fish assemblages: the first...
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Fish community trophic structure and interaction in riverine environment
Dalecká, Kateřina ; Horká, Petra (advisor) ; Jandová, Kateřina (referee)
In anthropogenically influenced rivers, fishes with lower environmental requirements are supposed to have an advantage over more specialised fish species. Such features include, for example, limited migration and habitat requirements, unspecialised breeding requirements or use of food resources. Guilds of sensitive species that share life history strategies that are highly adapted to specific riverine conditions have declined far more than generalist species that can survive in a wide range of habitats that are not characteristic of natural river ecosystems. In European lowland rivers, several species belong to eurytopic ecological group of fish which are often omnivorous feeders and have lower habitat requirements. It is suggested that these species are favoured by feeding omnivory in contrast to more specialised, rheophilic fishes among whose more specialised feeding can be found. The aim of our study was to evaluate the trophic niche use and interactions among eurytopic and rheophilic fish species. We hypothesized that eurytopic, omnivorous fish will exhibit a broader isotopic niche area (SEAc, TA) and higher trophic position (TP) then specialized rheophilic fish species. Isotopic niche area of species, between species niche overlap and trophic position of species in community were evaluated...
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Using of stable isotopes for studies of fish otoliths
Mavrogeni, Josefína ; Frouzová, Jaroslava (advisor) ; Horká, Petra (referee)
In this work, I try to approach some general concepts related to the study of stable isotopes. The processes through which isotopes go through. Stable isotopes of some elements are suitable for ecological studies. This is due to fractionation and discrimination processes that occur during their movement through ecosystems. These movements happen due to natural cycles, which the elements undergo in one of their forms. Thanks to these cycles, isotopes enter the bodies of organisms. I especifically focus on fish tissues, primarly on otoliths. To determine the usefulness of otoliths in ecological studies, it is necessary to know their appropriate use, and the appropriate use of other tissues. The aim of this work was to gather information about the possible link between stable isotope analysis and the study of otoliths. Their composition and the information that we can obtain by examining this composition, especially the isotope composition, can be helpeful in studying the course of the fish's life and the environment in which the fish has lived in.
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Localization of double and triple donds positions in fatty acids methylesters by HPLC/APCI-MS2
Horká, Petra ; Vrkoslav, Vladimír ; Cvačka, Josef
Poloha a počet dvojných vazeb v alifatickém řetězci ovlivňuje fyzikální, chemické a biologické vlastnosti lipidů, avšak jednoznačné určení poloh těchto násobných vazeb je problematické. V roce 2012 byla publikována metoda kapalinové chromatografie s chemickou ionizací za atmosférického tlaku s hmotnostní detekcí (HPLC/APCI-MS) [1] vhodná pro analýzu polohy dvojných vazeb využívající tvorby molekulových aduktů [M + C3H5N]+. při APCI za přítomnosti acetonitrilu. Methylestery mastných kyselin (FAMEs) byly analyzovány HPLC/APCI-MS2 se 100% acetonitrilem jako mobilní fází. Při APCI docházelo v plynné fázi k tvorbě reaktivních částic, vznikajících ze složek mobilní fáze, které se vázaly na násobné vazby v alifatickém řetězci FAMEs za vzniku aduktu [M + C3H5N]+.. Kolizně indukovanou disociací (CID) aduktu [M + C3H5N]+., se získaly diagnostické fragmenty určující polohu (polohy) násobných vazeb. Zmíněná metoda byla evaluována pro běžně analyzované polynenasycené FAMEs s tradiční polohu dvojných vazeb (methylene-interrupted).
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Structural characterization of fatty acids with triple bond and unusual double bond positions by HPLC/APCI-MS2
Horká, Petra ; Vrkoslav, Vladimír ; Cvačka, Josef
Fatty acid methyl esters (FAMEs) were analyzed by reversed-phase HPLC coupled to atmospheric pressure chemical ionization (APCI) mass spectrometry. Acetonitrile was used as mobile phase. The gas-phase reactions of acetonitrile and unsaturated FAMEs in the APCI source provided [M + C3H5N]+• adducts. Subsequent MS/MS analysis of these ions gave diagnostic fragments. The formation and fragmentation of the acetonitrile-related adducts were utilized for the structural characterization of FAME with isolated double bonds in (Z)-9,19-hexacosadienoic acid methyl ester, FAME with conjugated double bonds in (Z)-9,11-octadecadienoic acid methyl ester and FAME with a triple bond in 9-octadecynoic acid methyl ester.
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Diel activity of common bleak Alburnus alburnus in response to prey availability
Josefovičová, Anna ; Horká, Petra (advisor) ; Slavík, Ondřej (referee)
Fish behaviour and the structure of fish communities in rivers are known to be affected by various environmental factors. Turbidity imposes a considerable environmental constraint by influencing visibility and reducing the distance at which a predator detects prey. Previous studies have shown that fish become more active and extend their diurnal movements and home range size during the high turbidity period. However, this effect may also be associated with a lower food availability in turbid water and various other environmental factors like are day time, water temperature, discharge or oxygen concentration may also have an effect. This thesis present radio-telemetry study which examined factors influencing diurnal activity and home range size in common bleak Alburnus alburnus in riverine environment. The aim was to assess the response of bleak behaviour to various abiotic factors and prey availability, to establish the extent diurnal movements and home range size of bleak and to evaluate feeding strategy of fish. Four individuals of bleak were radio-tracked in the River Elbe during July - September 2007.The position of an individual fish was determined every three hours during one diurnal cycle, in total 10 diurnal cycles were recorded. During the same intervals, turbidity, water temperature,...
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The effect of barriers on riverine fish communities
Kofentová, Nikola ; Horká, Petra (advisor) ; Čech, Martin (referee)
The construction of river obstacles is considered one of the major threat to freshwater ecosystems worldwide, with a greater impact upon riverine fish than any other human activity. River obstacles, especially dams and weirs, affect the natural environment in streams and rivers, causing changes in physical, chemical and biological processes and disrupting connectivity of rivers via alternating series of lotic and lentic reaches. The effect of obstacles is further magnified by associated habitat alterations like are channelization, flow regulation, fortification and deepening of a riverbed. Orga- nisms and especially fish that live in rivers are highly sensitive to these changes, which affects them at the level of individuals, species and the whole populations. The most pronounced is the barrier-effect to upstream and downstream migration and loss of habitats. Diadromous and rheophilic species of fish are the most sensitive ones as they have complex migration strategies and habitat requirements. Fish are further affected by obstacles via many other mechanisms, such as the effect on reproduction success, growth and development, changes in the composition and trophic structure of communities and restricted response to further environmental constraints including water pollution or predicted climate...
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Fish community trophic structure in antrhopogenically perturbed rivers
Dostál, David ; Horká, Petra (advisor) ; Jandová, Kateřina (referee)
Využití stabilních izotopů pro hodnocení trofické struktury společenstev nabývá v posledních dekádách na popularitě a stává se tak stále více používaným nástrojem užívaným k výzkumu trofických pozic a potravních nik. V této práci jsou shrnuty základní principy, které se při práci se stabilními izotopy využívají, představeny mechanismy výměny tkání, izotopového routingu a diskriminačního faktoru, jejichž zanedbání může vést až ke znehodnocení nabytých poznatků. Dále jsou v práci představeny základní metody využití stabilních izotopů, jejich výhody a nevýhody, matematické modely zpracování dat a jejich uvedení do praxe pomocí praktické části, ve kterém bylo zkoumáno trofické postavení a niky kaprovitých ryb v antropogenně ovlivněných řekách.
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