engleski

Seasonal changes of the condition indices and haemocyte counts of the Austropotamobius torrentium population in Kraljevec Stream, Croatia

The stone crayfish, Austropotamobius torrentium is one of the four native European crayfish living in Croatian freshwaters. Kraljevec Stream is situated on the southern slopes of Medvednica Mountain (north-west Croatia) at 400m above the sea level. Our research was conducted during one year, from May 2003 to April 2004. Temperature varied between 2 to 17, 2 oC, medium oxygen concentration was 12, 12 mg/L, medium pH was 8, 27 and alkalinity was between 100 and 200 mg CaCO3/L. Crayfish were trapped by baited hand made traps which were secured in a stream current with the stones and roots of the surrounding trees. We caught 100 crayfishes, 68 males and 32 females. Hemolymph was sampled 10 to 15 min after catch. EDTA anticoagulant was used to prevent hemolymph coagulation and 10% formaline was used to fix haemocyte for differential counts. Each month five to six animals were sacrificed and hepatosomatic, gonadosomatic and muscle indices were measured. We found statistically significant differences in hepatosomatic and gonadosomatic indices between months and between sexes. Muscle indices were significantlly different between males and females. Average total haemocyte count for males was 7, 6 x 105 cells/ml hemolymph and for females was 6, 5 x 105 cells/ml. Average hyalinocyte, granulocyte and semigranulocyte ratio was 77:14, 5:8, 5%, respectively. There were no statisticaly significant differences in total and differential counts between months and between sexes.

austropotamobius torrentium; condition indices; haemocyte counts; Croatia

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