Effects of cleaning a tidal river of sewage on gull numbers: a before-and-after study of the River Tyne, northeast England

Autor:	S.J. Raven, J. C. Coulson
Rok vydání:	2001
Předmět:	Hydrology geography geography.body_of_water Ecology business.industry Environmental science Sewage Before and after study Sewage treatment Tidal river business Ecology Evolution Behavior and Systematics Nature and Landscape Conservation
Zdroj:	Bird Study. 48:48-58
ISSN:	1944-6705 0006-3657
DOI:	10.1080/00063650109461202
Popis:	For most of the 20th century, the tidal reaches of the River Tyne in northeast England were used as an open sewer for organic wastes from almost a million people. This produced anaerobic conditions in the river, but supplied an appreciable source of food for five species of gulls. Observations on the number of gulls using the river were made in 1969/70 to establish the situation before a sewage treatment scheme was implemented. By 1994, the volume of untreated sewage discharged into the river had been reduced by 97% and by 86% in the study area, and a second survey was carried out to evaluate the effect of the clean-up on gull numbers. Overall, gull numbers showed a significant decrease of 37% between the two study periods. The decrease in winter was 38% and was also significant, while the decline in summer was 33%, but not significant. Considering individual species, numbers of Common and Great Black-backed Gulls declined by 93% and 91% respectively. In both these cases this is presumed to be due to the ...
Databáze:	OpenAIRE
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