Biomass, growth, and secondary production of Arcitalitrus dorrieni (Crustacea: Amphipoda: Talitridae) at two sites in Co. Galway, IrelandS

Growth rates, podomere addition, and secondary production of Arcilalitrus dorrieni (Hunt, 1925) populations inhabiting two neighbouring woodland sites at Kylemore, Co. Galway, Ireland, were investigated. One site 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 sites. In both years of the study, maximum biomass was recorded in September. Females had a higher growth rate than males, but growth rates of both males and females were higher at the mixed deciduous site. The number of podomeres on the second antenna was correlated with the size of the animal. The average length of A. dorrieni at each podomere number appeared to change seasonally. Comparisons of mean spring values with mean summer values showed a statistically significant decrease in mean amphipod length for a given podomere number, though this was more marked at the mixed deciduous site. Annual secondary production rates ranged from 5.06 g dry wt m^-2 year^-1at 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 crustacean species.