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Prediction of invasive marbled crayfish (Procambarus fallax f. virginalis) global spread
Nováková, Pavla ; Patoka, Jiří (advisor) ; Antonín, Antonín (referee)
Biological invasions are currently a global problem. They often cause a loss of biodiversity and severely disrupt the balance of entire ecosystems. One of the most dangerous among the many species of crayfish known to be invasive is the marbled crayfish or Marmorkrebs (Procambarus fallax f. virginalis Martin et al., 2010).
The marbled crayfish is a major ornamental crayfish species. It is a known vector of infectious crayfish plague, which is lethal for crayfish species of non-North American origin. Marbled crayfish is also very tolerant to different water temperatures. The most important feature making it an especially dangerous invasive species, is the way of its reproduction. Marbled crayfish reproduces via apomictic parthenogenesis. Therefore, only females are able to reproduce and males of this taxon has not been recorded. This crayfish is characterised by a very quick maturation and extremely rapid growth.
Even though some established populations of this taxon in the wild have already been recorded, and probability of the establishment in selected regions was evaluated, no predictions for expansion on a global scale have been conducted.
The program CLIMATCH was used in this thesis to match the climate conditions between the source area (distribution of established populations of marbled crayfish in the wild) and target areas (all continents excluding Antarctica) based on temperatures during the coldest and warmest quarters of the year.
The results showed that marbled crayfish can probably survive and reproduce in even colder regions of the temperate zone. The presented findings additionally indicate that temperate zones contain slightly higher potentially suitable regions than in the case of tropics. There are temperature conditions most suitable for the survival and reproduction of the marbled crayfish within Europe in comparison of the rest of the world; and the least favourable temperature conditions are within Australia.
The marbled crayfish introduction and ability to survive and reproduce in the wild is a potential threat to native biota and entire ecosystems on all continents assessed. Therefore, it is strongly recommended that the breeding of and the pet trade with this crayfish should be regulated by policymakers and wildlife managers by improvement of legislative restrictions (such as in the EU) and intensive future education of general public. It is obvious that the monitoring of invasive crayfish species might be continuous. Nevertheless, the most important step is to make producers and hobbyists aware of the risks related with marbled crayfish.
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Environmental risk assessment of ornamental aquaculture
Patoka, Jiří ; Kalous, Lukáš (advisor) ; Antonín, Antonín (referee)
The ornamental aquaculture comprises both outdoor and indoor keeping of aquatic animals and plants for ornamental purpose which is a very popular hobby with many followers worldwide. It is also commercially profitable for specialized producers and vendors. Associated environmental risks include particularly introduction of non-native species, biological invasions and intensive field capture of exploited and marketed species. Since subsequent regulation, mitigation and eradication of naturalised alien species is very difficult and ineffective in many cases, the most important above all is to prevent new introductions. This trend is accented with a short delay in European legislature. The European Union (EU) currently initiates formation of list of the most invasive alien species. Although invasive potential of certain ornamental species such as red-eared slider (Trachemys scripta elegans) is well known, the vast majority of traded species has never been tested and analysed from this point of view. Publications attached to this thesis are focused on monitoring and survey of market with ornamental animals, such as fishes and crayfishes, with special emphasis on list of advertised species, size classes, prices, origin and availability on market. With use of predictive models the probability of naturalisation and potential invasiveness of mentioned ornamental species were estimated. These information are supported by analysis of hobbyist behaviour. Results in present thesis highlight known environmental risks associated with ornamental aquaculture and also show detailed information about overlooked risks from the Czech Republic's as well as from EU perspective. Therefore this thesis should to help formation of aforementioned list of the undesirable species.
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