Neustonic distributions

In order to determine the effects of environmental parameters on neustonic population structure, correspondence analysis, a multivariate technique of ordination, was applied to data on 47 taxa of neustonic animals, collected at 149 stations between Fiji and the Bay of Biscay from August, 1979 to December, 1980. The positions of taxa and samples on the first 3 axes extracted from the similarity matrix were related to environmental variables. The 3 variables which exerted the greatest influence on neustonic distributions were the quantities of floating tar, plastic and pumice, time of day, and surface water temperature. Floating abiotic material provided settlement areas for epifauna, particularly in the Mediterranean (tar and plastic) and the western Pacific (pumice). Many taxa were more numerous in the surface waters at night. Only 3 of the neustonic taxa examined were most common in boreal waters, all others were primarily tropical or sub-tropical in distribution. The taxa formed 8 associations of fauna which had different distribution patterns.