engleski

LIFE HISTORY OF ASTACUS LEPTODACTYLUS IN TWO CROATIAN RIVERS

As little is known about Astacus leptodactylus life cycle, the aim of our research was to gather data on narrow-clawed activity throughout one year. The research was conducted on the Dobra and Mrežnica rivers (continental Croatia) from October 2006 to October 2007. Crayfish sampling was carried out twice a month with baited LiNi traps. Different physiological crayfish functions and morphometrical characteristics were recorded, as well as the physico-chemical parameters of the water. Altogether 311 crayfish were trapped (180 males, 131 females). Sex ratio fluctuated throughout the year, depending on crayfish physiological cycle. The heaviest male was 113 g, and female 125 g, whilst the longest male was 14.78 cm, and female 16.71 cm. Animals were active all the year round, with the peak of activity in April and July in the Dobra River, and without an apparent peak of activity for the crayfish from the Mrežnica River. Preparation for mating started in September (developed glair glands), spawned eggs were recorded in December, and juveniles hatched in the second half of May. Freshly moulted animals were found from May until September. Main injuries were claw and limb loss, and there were no signs of diseases or epibionts within the studied populations.

Astacus leptodactylus; year cycle

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