Diel oxygen variations in the Rhode River Estuary, Maryland, 1970-1978

Water-Resources Investigations Report 81-10



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Since April 1970 the U.S. Geological Survey has operated an estuarine water quality monitor in the upper reach of Rhode River, a small embayment on the northwestern shore of Chesapeake Bay. This report analyzes variations in diel oxygen over the period April 1970 through January 1979. The diel oxygen range is used as an indicator of open-water metabolism. Polygons of temperature versus salinity portray the monthly variations of the two dominant environmental factors which influence biological metabolism and reveal effects of events such as a cool versus a warm spring or salinity reduction due to tropical storm freshwater runoff. Seasonally the average daily oxygen pulse range increased from a winter low of 1.6 mg/L to summer high of 5.3 mg/L. Annually highest daily ranges occurred the summer of 1972 when nutrient laden runoff from tropical storm Agnes stimulated open-water metabolism to produce an average diel range of 6.3 mg/L. Spearman 's ranked correlation coefficients were used to compare seasonal and annual variations in temperature and salinity versus diel oxygen range. There was high agreement between annual variations in spring temperatures and diel oxygen ranges and an inverse correlation between summer and autumn salinity and diel oxygen range. (USGS)

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USGS Numbered Series
Diel oxygen variations in the Rhode River Estuary, Maryland, 1970-1978
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Water-Resources Investigations Report
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U.S. Geological Survey,
iv, 14 p. :ill., maps ;26 cm.