Resistance of Eurytemora hirundoides Nordquist, a Brackish Water Copepod, to Oxygen Depletion

Abstract

THE River Tyne estuary is polluted by crude sewage and manufacturing effluents to such an extent as to cause a serious depletion in dissolved oxygen. It is not unusual to find a complete absence of dissolved oxygen on isolated occasions during the summer months. The number of normal estuarine organisms able to withstand these adverse conditions is very limited.¹ Of these, Eurytemora hirundoides is the most abundant and the most hardy. Its region of maximum abundance lies between 9 miles and 13 miles from the river mouth, in the area of heaviest pollution and most noticeable oxygen depletion. At a survey held on July 22, 1925, it occurred plentifully in regions where the dissolved oxygen was nil, as determined by the Winkler method.^{1. 2} During 1929 I obtained it freely in the water sampler on occasions when the oxygen content was again nil (these remarks apply to the sampling depth of 6 ft.).