A preliminary biological study of the effects of pollution on Farmer's Creek and Cox's River,New South Wales

Summary Biological means were used to assess the effect of organic pollution from sewage effluent and mill-washings in Farmer's Creek and Cox's River (New South Wales). The work was largely qualitative and based on monthly collections of plants and animals for a period of a year. Some additional evidence was produced by a quantitative analysis of the growth of algae on immersed slides, numbers of Protozoa, and numerical counts of the macro-fauna on stones, from a single series of observations. It was found that the association of oligochaetes, chironomids, snails, sewage fungus and small growths of Stigeoclonium and diatoms immediately below the outfall was rapidly succeeded by extensive growths of Stigeoclonium, high counts of Protozoa, and an increase in the number of snails. Recovery from the effects of pollution in Farmer's Creek before the confluence of the two streams was marked by the appearance of stoneflies, dragonflies, mayflies, caddis, and riffle beetles, although snails, limpets, and chironomids were the dominant organisms. In the lower reaches of Cox's River most of the wide range of species found in the clean water above the confluence was recorded, and variations between the fauna at the two stations were regarded as habitat differences. It was found however that the nutrients produced by mineralization of the sewage had induced a more extensive growth of algae in Cox's River. No indicator species of pollution was found. The results are compared with chemical analyses and show biological associations provide a means of assessing pollution.Present adress: Department of Zoology, University of Glasgow.