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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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