Life history of Talorchestia deshayesii (Amphipoda, Talitridae) in the Ionian sandy beach (southern Italy)

Abstract

The population structure and reproductive biology of Talorchestia deshayesii (Audouin, 1826) on an exposed sandy beach in Taranto (Italy) was examined during one year cycle. Monthly surveys were performed from September 2002 to August 2003. Individuals were subdivided into sex, measured and abundance were calculated for each sampling. Abundance varied during the study period, with a marked decrease in winter. T. deshayesii, was found in a relative narrow zone near the sea in winter and summer while in spring and autumn the animals were widespread along the supralittoral. Reproduction occurred from February to November. The minimum average CL at the moment of recovery ranged from 0.22 to 0.28 mm. The sex ratio was female biased. The females and males became distinguishable at 0.35 mm (corresponding to 4.5 mm of LT). The first time that females were observed ovigerous happened when they reached a size about 0.4 mm of CL. The males of T. deshayesii grew larger than the females. The males reached a maximum CL of 1.05 (corresponding to 13.2 mm of LT), while females reached a CL of 1 mm (corresponding to 12.6 mm of LT). Mean length was the lowest in the summer months. Maximum total length was 10.5 mm and the size at first reproduction for the females was 3.5 mm total length. T. deshayesii produced two generations per year. Fecundity varied from 3 to 20 eggs per female and mean fecundity varied through time.