The marbled crayfish, (Marmorkrebs) Procambarus sp., inhabits freshwater habitats in Germany and the Netherlands, and it is the only known parthenogenic crayfish species. It is widely available in pet stores. The goal of this study was to better understand some aspects of embryogenesis of the marbled crayfish, specifically, morphomechanical properties of the egg. We found that 1.) the duration of marbled crayfish embryogenesis is 462 degree days (D°) at 22ºC, 2.) the volume of eggs at 100 D° is 2.11 ± 0.12 mm³ and it increases to 2.39 ± 0.12 mm³ shortly before juveniles hatch, 3.) egg membrane resistance at 100 D° is 173 ± 0.65 g, but declines to 1229 ± 0.78 g shortly before hatching, 4.) the nauplius stage appears at 132 D°, and 5.) heart activity is observed after 240 D°. This species parthenogenic ability, high fecundity, possibility of multiple clutches during the year, and high tolerance to potentially harmful environmental factors make this species a serious threat to the native European crayfish fauna. Therefore, it is important to understand and to educate people about the potential hazard that marbled crayfish pose once released into the environment. It is especially important to inform amateur aquarists, who maintain these crayfish in decorative home aquaria, about the threats they pose.
Keywords: diseases • embryogenesis • marbled crayfish • parthenogenesis
No comments:
Post a Comment