Arthropod Communities in a Maritime Antarctic Moss-Turf Habitat: Effects of the Physical and Chemical Environment

Abstract

SUMMARY (1) 384 samples of moss and peat were cut from a moss-turf habitat on Signy Island in the maritime Antarctic. For each sample, the arthropods were extracted and counted, and the following environmental variables were measured: dry weight, percentage water content, Polytrichum cover, pH, and the concentrations of sodium, potassium, calcium, phosphorus and nitrogen. (2) Sample dry weight, percentage water content and calcium were most regularly correlated with the number of arthropods in samples. Nitrogen, phosphorus and pH were least important. (3) In step-wise multiple regression analyses, calcium, potassium and percentage water content were consistently important, whereas sodium and Polytrichum cover were only sometimes important. (4) The three largest principal components of the environmental data were related to the physical, chemical and biological-chemical characteristics of the habitat. Relationships between these components and the arthropod data were weak in the green moss zone, but were stronger in the dead moss zone. (5) Canonical correlation analysis showed that only sodium, potassium, calcium and phosphorus amongst the environmental variables contributed to the correlations, whereas all arthropod species were included. (6) A weak relationship between Polytrichum cover and the arthropods was suggested in the green moss zone, but this relationship was not found in the dead moss zone. (7) A study of the correlation coefficients suggested that there is an optimum water content for Cryptopygus and Eupodes and an optimum calcium concentration for Eupodes and Ereynetes. (8) Although some physical environmental variables affected the arthropod distribution in the green moss zone, overall it was the chemical characteristics of the environment which most influenced the distribution of the arthropods.