Abstract A study was undertaken in the New York Bight in an effort to understand small scale variations of single species populations and coastal zooplankton communities as they relate to the disposal of acid wastes. Two grids of eight locations each, one day and one night station per location, were placed so that one covered the acid grounds and the other a similar area functioning as a control 9 km to the northeast. Thirty-nine taxonomic categories of zooplankton were counted from oblique net tow samples collected at the 32 stations. Biomass was determined from length measurements of individuals of 24 taxa. Species composition of the samples was typical of neritic waters of the north-east Atlantic coast. The spatial distribution of the majority of the species was markedly aggregated, but no trend was observed which would suggest that the acid wastes were an important factor in shaping the distributions. Species did not show collective agreement as to the area in which a higher average abundance for each occurred; and no significant trends in percent similarity or diversity (Simpson's D and the information theory H′) were evident. Although Vaccaro et al. (1972) found zooplankton biomass to be approximately 30% higher from the control area than from the acid grounds, comparison of the biomass difference between the two areas on a species by species basis showed that 95% of the overall difference was accounted for by only three species, Pseudocalanus sp. and its copepodids, Calanus finmarchicus copepodids and Temora longicornis. The acid-iron wastes appeared to be a minor factor affecting the distribution and abundance of zooplankton species during the time of this investigation. The laboratory data reported in the preceding paper (Grice et al., (1973)) support this conclusion. Empirical measures of the variability of single species populations and community indices presented in the text may be useful guides for future surveys or monitoring studies.