BIOMASS, GROWTH, AND SECONDARY PRODUCTION OF ARCITALITRUS-DORRIENI (CRUSTACEA, AMPHIPODA, TALITRIDAE) AT 2 SITES IN CO GALWAY, IRELAND

Growth rates, podomere addition, and secondary production of Arcitalit rus dorrieni (Hunt, 1925) populations inhabiting two neighbouring wood land sites at Kylemore, Co. Galway, Ireland, were investigated. One si te was a mixed deciduous woodland infested with Rhododendron ponticum. The Other a pure coniferous stand of Pinus contorta var. latifolia S. Wats. Seasonal changes in biomass were recorded at the two sires. In both years of the study, maximum biomass was recorded in September. Fe males had a higher growth rate than males, but growth rates of both ma les and females were higher at the mixed deciduous site. The number of podomeres on the second antenna was correlated with the size of the a nimal. The average length of A. dorrieni at each podomere number appea red to change seasonally. Comparisons of mean spring values with mean summer values showed a statistically significant decrease in mean amph ipod length for a given podomere number, though this was more marked a t the mixed deciduous site. Annual secondary production rates ranged f rom 5.06 g dry wt m(-2)year(-1) at the coniferous site to 14.55 g dry wt m(-2)year(-1) at the mixed deciduous site-P:B values ranged from 2. 41 at the coniferous site to 3.01 at the mixed deciduous site. Results are compared between sites and with data from other relevant crustace an species.