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Vliv různých teplot na konkurenceschopnost raka mramorovaného v agresivních interakcích
KREJČÍ, Miloslav
Crayfish are an important aquatic ecosystems engeneers. Non-indigenous crayfish often decrease the abundance of native species and they affect ecosystem balance. Changes in freshwater ecosystems are usually caused by invasive species of crayfish, especially North American species. These species transmit crayfish plague (Aphanomyces astaci) too. One of these species is marbled crayfish (Procambarus virginalis).Aim of the thesis was an experimental comparison of the competitiveness of marbled crayfish in interspecies interactions with red swamp crayfish (Procambarus clarkii), signal crayfish (Pacifastacus leniusculus) and spiny-cheek crayfish (Faxonius limosus) depending on water temperature. The experiment included 20 runs of interspecific interactions at 16 °C, 18 runs of interspecific interactions at 20 °C and 19 runs of interspecific interactions at 24 °C. Interactions occurred in individual plastic tanks with tempered water. Interactions in tanks were recorded by camera. Subsequently, the agonistic interactions of crayfish were evaluated from 30 minutes of recordings. In conclusion, marbled crayfish is competitive opponent for psychrophilic and thermophilic crayfish species, especially at higher temperatures. The global warming could increase the success of spreading to new areas for marbled crayfish, as well as the survival of winter. In new areas, marbled crayfish could cause negative impacts for native organisms, especially native crayfish species.
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Hosts and transmission of the crayfish plague pathogen Aphanomyces astaci
Svoboda, Jiří
The crayfish plague pathogen, the oomycete Aphanomyces astaci, has been decimating populations of European crayfish species for more than 150 years, and is therefore considered one of the 100 worst world's invasive species. A. astaci is highly specialised for a parasitic life, but it can be isolated from moribund crayfish and grown on synthetic media, as it is the case also for several other oomycetes (chapter 7). The life of A. astaci includes three basic forms: mycelium in host's tissues, and the infective units occurring in water, zoospores and cysts. All North American crayfish species tested so far have shown some resistance to A. astaci, i.e., they could carry the infection for long, serving as vectors of the pathogen. Massive sporulation from infected North American crayfish starts when the host is moulting, stressed, or dying (chapter 4). However, I could show in my experiments that some sporulation occurs even from apparently healthy and non-moulting American crayfish hosting A. astaci, so infected North American crayfish must be considered a permanent source of the infection (chapter 4). Five genotype groups of A. astaci have already been distinguished. Strains from a particular genotype group probably share the same original host crayfish species of North American origin. Nevertheless, they can...
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Hosts and transmission of the crayfish plague pathogen Aphanomyces astaci
Svoboda, Jiří
The crayfish plague pathogen, the oomycete Aphanomyces astaci, has been decimating populations of European crayfish species for more than 150 years, and is therefore considered one of the 100 worst world's invasive species. A. astaci is highly specialised for a parasitic life, but it can be isolated from moribund crayfish and grown on synthetic media, as it is the case also for several other oomycetes (chapter 7). The life of A. astaci includes three basic forms: mycelium in host's tissues, and the infective units occurring in water, zoospores and cysts. All North American crayfish species tested so far have shown some resistance to A. astaci, i.e., they could carry the infection for long, serving as vectors of the pathogen. Massive sporulation from infected North American crayfish starts when the host is moulting, stressed, or dying (chapter 4). However, I could show in my experiments that some sporulation occurs even from apparently healthy and non-moulting American crayfish hosting A. astaci, so infected North American crayfish must be considered a permanent source of the infection (chapter 4). Five genotype groups of A. astaci have already been distinguished. Strains from a particular genotype group probably share the same original host crayfish species of North American origin. Nevertheless, they can...
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Genetic variation in North American crayfish species introduced to Europe and the prevalence of the crayfish plague pathogen in their populations
Filipová, Lenka ; Petrusek, Adam (advisor) ; Diéguez-Uribeondo, Javier (referee) ; Trontejl, Peter (referee)
- ABSTRACT (IN ENGLISH) - Biological invasions by crustaceans represent a serious threat for native species in Europe. In my thesis I focus on non-indigenous freshwater crayfish introduced to Europe and their parasite Aphanomyces astaci, the pathogen of the crayfish plague. The thesis consists of four already published first-author papers (chapters I, II, IV and V), two first-author manuscripts (chapters III and VI), and one paper which I co-authored (chapter VII). The first part (chapters I-V) focuses on genetic variation in North American crayfish introduced to Europe. We showed that in two crayfish species, both successful invaders in Europe, genetic variation differs significantly, reflecting their different colonization histories on the continent. The spiny-cheek crayfish Orconectes limosus was likely introduced to Europe just once, in small numbers (90 individuals). Variation at the mitochondrial DNA (mtDNA) level in the spiny-cheek crayfish in Europe is much lower compared to North America (chapter I), although some variation was revealed by nuclear markers in its Central European populations (chapter II). In contrast, the signal crayfish Pacifastacus leniusculus was introduced to Europe several times, in large numbers. Its European populations are highly diverse genetically and belong to a single...
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Hosts and transmission of the crayfish plague pathogen Aphanomyces astaci
Svoboda, Jiří ; Petrusek, Adam (advisor) ; Maguire, Ivana (referee) ; Jussila, Japo (referee)
The crayfish plague pathogen, the oomycete Aphanomyces astaci, has been decimating populations of European crayfish species for more than 150 years, and is therefore considered one of the 100 worst world's invasive species. A. astaci is highly specialised for a parasitic life, but it can be isolated from moribund crayfish and grown on synthetic media, as it is the case also for several other oomycetes (chapter 7). The life of A. astaci includes three basic forms: mycelium in host's tissues, and the infective units occurring in water, zoospores and cysts. All North American crayfish species tested so far have shown some resistance to A. astaci, i.e., they could carry the infection for long, serving as vectors of the pathogen. Massive sporulation from infected North American crayfish starts when the host is moulting, stressed, or dying (chapter 4). However, I could show in my experiments that some sporulation occurs even from apparently healthy and non-moulting American crayfish hosting A. astaci, so infected North American crayfish must be considered a permanent source of the infection (chapter 4). Five genotype groups of A. astaci have already been distinguished. Strains from a particular genotype group probably share the same original host crayfish species of North American origin. Nevertheless, they can...
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