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Influence of predator odor on the rate of evacuation of the digestive tract of the invasive black-mouthed warbler (Neogobius melanostomus)
BRYLLOVÁ, Vendula
Over the past 30 years, the round goby (Neogobius melanostomus) has colonized a significant portion of the European river system and a similar trend can be observed in the Great Lakes of North America. In parallel, however, the round goby is coming under strong predation pressure from native predators at these sites, but this appears to be negligible in destabilising its populations. However, quantification of the indirect impact of these predators on the round goby is still lacking. The aim of the present thesis was to reveal the influence of chemical signals of the original, trophically higher predator (European eel - Anguilla anguilla) on the rate of gastric evacuation of the lower predator - round goby. In the experiment, round goby was tested in the following treatments: 1) without chemical signals (control group); 2) with chemical signals originating from the European eel fed by the round goby with enrichment of the water with the conspecific alarm cues from the skin of the round goby (conspecific treatment); 3) with chemical signals originating from the European eel fed by the earthworms (heterospecific treatment). The different treatments were tested on the evacuation rate of the larvae of Chironomus sp. in the digestive tract of the round goby. The rate of gastric evacuation of the round goby was not statistically significantly different among the treatments tested. Tested food was evacuated in all treatments within 9 hours from the start of the experiment. The results obtained show that the presence of chemical signals from a higher predator (European eel), with the simultaneous presence or absence of conspecific alarm cues originating from the food (of the lower predator), does not affect the rate of gastric evacuation of the round goby, which appears to be an additional advantage of this highly invasive aquatic species when colonizing new territories.
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Porovnání přežívání a růstu raka červeného a raka mramorovaného v teplotně suboptimálních podmínkách
DAVID, Jaroslav
Biological invasions are increasingly recognized as biological and economic threats. The numbers of these invasions continue to rise over time, disrupting the original biodiversity. In this experiment, we focused on two species of crayfish native to North America, the red swamp crayfish and the marbled crayfish, which are among the most important invasive crayfish worldwide. To determine which of these species should be dominant in permanently suboptimal temperature conditions (water temperature of 16 °C), we conducted an experiment evaluating growth, mortality, claws damage, and maturation in single-species and mixed stocks. It turned out that the faster-growing species was the red swamp crayfish, which grew the fastest in mixed stocks, at the expense of marbled crayfish, which, on the contrary, grew more slowly in these stocks than in single-species stocks. There were no large differences in survival in the individual groups, except single-species marbled crayfish stocks, for which the survival rate was about 15% higher than in other groups. The incidence of individuals with damaged claws was higher for red swamp crayfish, a large difference was recorded between marble crayfish groups, when in mixed stocks the damage was circa five times higher contrary to the single-species setup. At the end of the experiment (week 18), three mature males with gonopods and one female with glair glands were found in the red swamp crayfish.
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Zhodnocení přežívání a růstu dvou invazivních raků v teplotně suboptimálních podmínkách
MARKOVÁ, Kateřina
Biological invasions of non-native species are one of the most serious threats negatively impairing global biodiversity. The negative influence of these invasions is especially noticeable in freshwater ecosystems also exemplified by the populations of native crayfish species in Europe. Dominance of non-native species of crayfish over native ones is relatively well known and studied, but the interactions between individual non-native invasive species are significantly less explored. As the range expansion and numbers of non-native crayfish species constantly increases, it becomes apparent that the non-native species will dominate in European waters. However, it is not clear which of these invasive species, and under which conditions will perform better. The goal of this bachelor thesis was to create a literature review focusing on factors that negatively influence the population of the native species (mainly the issue of non-native species and crayfish plague which these species often transmit). Consideration was paid to the importance of the water temperature for the crayfish and to the focused species used in the experimental part the marbled crayfish Procambarus virginalis Lyko, 2017 and signal crayfish Pacifastacus leniusculus Dana, 1852. The experiment was focused on the evaluation of survival, growth, damage to the claws, and the maturation of these species at the water temperature of ~16 °C, which is in the optimal range for signal crayfish, but suboptimal for marbled crayfish (yet, within a range presumably allowing its successful reproduction). If these species should meet more frequently in the wild, it is important to understand their relationships.
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Study of ecosystem impact of giant hogweed (Heracleum mantegazzianum) invasion
Hladík, Marek ; Pergl, Jan (advisor) ; Hadincová, Věroslava (referee)
The present study deals with ecological impact of giant hogweed (Heracleum mantegazzianum) invasion in Slavkovský les area. Being one of the prominent invasive species with significant impact on human health it has been subjected to a wide research. In spite of that little is known about its impact on the invaded ecosystem. My research was therefore focused on analysis of the ecosystem impact, particulary 1) microclimatic measurements of temperature and soil moisture and their comparisons between invaded and noninvaded vegetation, 2) comparison of germination and survival of model plant species sowed into invaded and noninvaded plots and 3) study of the effect of H. mantegazzianum presence on model species seed production. Results have shown significant alteration of microclimate due to H. mantegazzianum invasion. Further research is needed to resolve what impact it may pose to species in invaded communities. The effect of Heracleum mantegazzianum presence on germination and survival of model species was not significant. Similarly, seed production of model plants was not significantly affected.
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Alien species of plants and biotic resistence of invaded communities
Kubátová, Michaela ; Dostál, Petr (advisor) ; Frouz, Jan (referee)
Michaela Kubátová Alien species of plants and biotic resistence of invaded communities This study is about problems and questions of alien plants and their relation to native communities in their new range. Ecologists are increasingly aware that soil organisms may affect plant communities because they are part of the processes that affect them. The soil organisms may affect the success of alien species invasion. Each species of plants differ in interaction with soil organisms, these interactions can result in specific feedback that will influence the future growth of other plants. According to Darwin's naturalization hypothesis related species should have similar enemies. This implies less successful invasion of alien plants at home with relatives. The practical part consists of two experiments. Using plant-soil feedback I studied under controlled conditions the importance of kinship of native plants and their soil organisms on the growth of three species of alien plants Impatiens, Parviflora, Stenactis annua and Epilobium ciliatum. There were used soil samples from localities with related and unrelated species; the soil was used as inoculums for growing first-generation plants, where there were original related, unrelated and alien plants. In the second phase only alien species were grown. Part of...
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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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Porovnání raka mramorovaného a raka pruhovaného: přímá interakce a kompetice o zdroje
MAN, Milan
Biological invasions of non-native species are one of the most serious factors threatening global biodiversity. Their negative impacts are particularly evident in the case of freshwater ecosystems and native crayfish populations that live there. Generally, the higher dominance of non-native crayfish species over the native species is relatively well known, but the interactions between non-native crayfish species are significantly less investigated. Although their distribution is increasingly more important and it is obvious that non-native crayfish species will dominate in European waters. However, it is not yet clear which of these crayfish will be more successful. The aim of this diploma thesis was to create a literature review on the topic of interspecific interactions in crayfish with emphasis on native and non-native crayfish species occurring in Europe. The experimental part of the thesis was focused on the comparison of direct interactions and competition for shelter between the widespread spiny-cheek crayfish Faxonius limosus (Rafinesque, 1817) and the newly increasingly occurring marbled crayfish Procambarus virginalis Lyko, 2017. These species are becoming increasingly common in the European wild, but about their mutual direct interactions and competition is largely unknown. During agonistic interactions the marbled crayfish won in significantly more fights than the spiny-cheek crayfish in the absence as well as presence of the shelter. The marbled crayfish established a significantly greater dominance over the females of the spiny-cheek crayfish in the absence and in the presence of shelter, but not over the males. It is also important to say that the presence of the shelter reduces the number of fights and their total duration. There was no significant difference in dominance established by occupation of shelter between the marbled crayfish and the spiny-cheek crayfish. Still, thanks to its aggressiveness, marbled crayfish is able to compete with other non-native species or displace them from freshwater ecosystems.
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Odhad ekologického vlivu hlaváče černoústého (Neogobius melanostomus) na makrozoobentos dolního Labe pomocí funkční odpovědi potravního chování: vliv velikosti predátora
RYTÍŘ, Jan
The round goby Neogobius melanostomus (Pallas, 1814) originally from the Ponto - Caspian region, has remarkably expanded in recent decades in areas of the North American Great Lakes and European river systems. This small benthic fish represents for the invaded aquatic ecosystems a serious threat, through both competition for food sources, habitats, and direct predation on benthic organisms. The aim of the B. Sc. thesis was to summarize the available information in the field of biological invasions and non-native species, with a special emphasis on the round goby and issue of the functional response. In the practical part, a potential impact of the round goby as the predator and its size (3 size cohorts: small individuals = 3.0 - 3.5 g; medium individuals = 5 - 5.5 g; large individuals = 8.0 - 8.5 g) on the waterlouse, Asellus aquaticus (Linnaeus, 1758) (tested in 6 concentrations: 2, 8, 20, 35, 60, 90 individuals.box-1) as a selected representative of macrozoobenthos forming an important food component of the round goby diet was evaluated using a series of "functional response" experiments. All size cohorts of the round goby exhibited a functional response type 2. The highest efficiency in prey search (search rate) was found in the large individuals. Statistically significantly lower values were achieved in this parameter in medium and small individuals (p 0.001). The smallest individuals processed a food for the longest time. Statistically significantly lower values were reached in case of handling time in medium and large individuals (p 0.001). In large individuals, a curve of the functional response showed a steeper slope and faster attainment of the limit value (curve asymptote). Per capita impact of the medium and large individuals (based on the value of the asymptote of a functional response) did not differ. However, small individuals have reached a lower value. In summary, it can be concluded that a size cohort of the large individuals of the round goby could represent the highest potential impact upon macrozoobenthos communities. Nevertheless, for a more accurate estimation and evaluation of the real impact of this fish predator on benthic invertebrate communities of the Elbe river, it is necessary to combine the results of the B.Sc. thesis with the field data on the total size of the predator population, the size composition and seasonal variability.
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Alien species of plants and biotic resistence of invaded communities
Kubátová, Michaela ; Dostál, Petr (advisor) ; Frouz, Jan (referee)
Michaela Kubátová Alien species of plants and biotic resistence of invaded communities This study is about problems and questions of alien plants and their relation to native communities in their new range. Ecologists are increasingly aware that soil organisms may affect plant communities because they are part of the processes that affect them. The soil organisms may affect the success of alien species invasion. Each species of plants differ in interaction with soil organisms, these interactions can result in specific feedback that will influence the future growth of other plants. According to Darwin's naturalization hypothesis related species should have similar enemies. This implies less successful invasion of alien plants at home with relatives. The practical part consists of two experiments. Using plant-soil feedback I studied under controlled conditions the importance of kinship of native plants and their soil organisms on the growth of three species of alien plants Impatiens, Parviflora, Stenactis annua and Epilobium ciliatum. There were used soil samples from localities with related and unrelated species; the soil was used as inoculums for growing first-generation plants, where there were original related, unrelated and alien plants. In the second phase only alien species were grown. Part of...
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Study of ecosystem impact of giant hogweed (Heracleum mantegazzianum) invasion
Hladík, Marek ; Pergl, Jan (advisor) ; Hadincová, Věroslava (referee)
The present study deals with ecological impact of giant hogweed (Heracleum mantegazzianum) invasion in Slavkovský les area. Being one of the prominent invasive species with significant impact on human health it has been subjected to a wide research. In spite of that little is known about its impact on the invaded ecosystem. My research was therefore focused on analysis of the ecosystem impact, particulary 1) microclimatic measurements of temperature and soil moisture and their comparisons between invaded and noninvaded vegetation, 2) comparison of germination and survival of model plant species sowed into invaded and noninvaded plots and 3) study of the effect of H. mantegazzianum presence on model species seed production. Results have shown significant alteration of microclimate due to H. mantegazzianum invasion. Further research is needed to resolve what impact it may pose to species in invaded communities. The effect of Heracleum mantegazzianum presence on germination and survival of model species was not significant. Similarly, seed production of model plants was not significantly affected.
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