Orconectes limosus; Czech Republic; biometry; ecology; populations

We selected three types of localities: 1.Large rivers, residential (Labe, Vltava); 2. Brooks (small and shallow running waters), marginal; 3. Isolated standing waters ? residential (old sandpits or flooded quarries). No significant differences in the total body length of crayfish were found between running and standing water localities as a whole, or between marginal and residential populations from running waters. There was, however, a low but distinct difference in the body weight between crayfish from brooks and other waters. Larger specimens (up to 117 mm in body length) were found only in isolated standing waters, whereas no crayfish longer than 100 mm were found in the rivers. The sex ratio of the crayfish was almost equal in rivers and isolated waters; males were more numerous in brooks. There was a significant difference between male and female body weight-length relations.

We selected three types of localities: 1.Large rivers, residential (Labe, Vltava); 2. Brooks (small and shallow running waters), marginal; 3. Isolated standing waters ? residential (old sandpits or flooded quarries). No significant differences in the total body length of crayfish were found between running and standing water localities as a whole, or between marginal and residential populations from running waters. There was, however, a low but distinct difference in the body weight between crayfish from brooks and other waters. Larger specimens (up to 117 mm in body length) were found only in isolated standing waters, whereas no crayfish longer than 100 mm were found in the rivers. The sex ratio of the crayfish was almost equal in rivers and isolated waters; males were more numerous in brooks. There was a significant difference between male and female body weight-length relations.