Robert L. Cory

Epifauna of the Patuxent River Estuary, Maryland, for 1963 and 1964

Methods of collection and analysis of epifaunal communities from six stations in the Patuxent estuary are described. The stations were distributed from Solomons near the mouth of the estuary, upstream to Lower Marlboro, near the limit of salt water intrusion.

Thermal Additions and Epifaunal Organisms at Chalk Point, Maryland

Two sets of test panels, one in the intake and the other in the effluent canal of a steam-generating station, were submerged at montly intervals in 1967. The panels were analyzed for epifaunal species composition, abundance, seasonal attachment, and total biomass production. The average surface-water temperature rose 6.3 C above ambient on the effluent side, and the biomass production of the epifaunal organisms found there increased nearly three times that of the intake. An earlier and larger set of some attached organisms occurred in the effluent, but there was little change in species composition between the intake and effluent canals. During the summer when high surface-water temperatures prevailed, there seemed to be a reduced number and/or disappearance of flatworms and colonial hydroids, along with increased barnacle growth. *** DIRECT SUPPORT *** A00BY035 00006

The asiatic clam, Corbicula fluminea (Müller), in the tidal Potomac River, Maryland

The Asiatic clam,Corbicula fluminea (Müller), has extended its range to include the tidal fresh-water portion of the Potomac River, Maryland. Though patchily distributed, the clams have attained densities of 665 m−2. Size-class distributions indicate that the clams first appeared in 1975. About 90% of the population belong to year-class I and were less than 12 mm in length. Elsewhere, this species has created severe water quality problems; it should be closely watched in the Potomac.

Epifauna and thermal additions in the upper Patuxent River estuary

In the upper Patuxent Estuary environmental changes in temperature, salinity, and turbidity over a 5-year period are linked to changes in epifaunal production and species distribution. During 1967 a series of monthly panels showed dry weight production averaged 2.8 times greater in a steam electric station heated effluent than in the intake. A downriver shift in epifanual production in 1967 and changes in species abundance was noted and attributed to natural changes in salinity and turbidity and man-induced changes in temperature.

Changes in oxygen and primary production of the Patuxent estuary, Maryland, 1963 through 1969

From 1963 through 1969, the U.S. Geological Survey operated a water-quality monitor system in the upper-middle Patuxent estuary, near Benedict, Maryland. Over the period of record, a pronounced change occurred in the diel (24 hr.) oxygen measurement, particularly during the months of July, August, and September. Annual variations of dissolved oxygen ranged from 3.6 to 15.0 mg liter−1 in 1964 and from 2.3 to 16.5 mg liter−1 in 1969 with percentage saturation varying from 60 to 130 percent in 1964 and from 30 to 184 percent in 1969. The magnitude of diel summer oxygen variation changed from about 3 to 7 mg liter−1 day−1 over the same period.

Temperature and water-quality conditions of the Patuxent River estuary, Maryland, January 1966 through December 1967

The effect of power plant cooling water in raising natural water temperatures at a location near the power plant on the Patuxent River estuary is clearly evident from thermograph records. Surface temperature at a station 333 m (1,000 ft) downstream from the discharge canal was raised an average of about 4 C, and at times by as much as 8 C. Temperature rises were greatest during the winter. Infrared imagery showed that elevated surface temperatures could be detected about 5.5 km (3 nautical miles) upstream at flood tide. Temperature profiles obtained from airborne radiation equipment revealed a complicated surface temperature pattern and also showed the effects of density differences and wind action on the steam-electric station (S.E.S.) effluent plume. Mean annual salinity for a 5-year period (1963–1967) was highest in 1966, about 12.3 ‰, and lowest in 1967, about 9.9‰. Dissolved oxygen values for 1966–1967 ranged from 3.2 to 15.6 mg/l, and saturation ranged from 55 to 152%. Turbidity levels were inversely related to salinity, with the highest annual, mean of 28 JCU (Jackson Candle Units) occurring in 1967, the lowest salinity year. The extreme tide range was 2.1 m (6.7 ft); mean water levels at the Patuxent Bridge were highest in summer and lowest in winter. Water stages are more affected by wind speed and direction than by flow in the river.

A Tracer Simulation of Waste Transport in the Muddy Creek-Rhode River Estuary, Maryland

A small quantity of Rhodamine WT dye was injected at the headwater of the Muddy Creek estuary and concentration of the dispersed dye was measured with a uniform time interval at a number of fixed locations in the lower portion of the estuary. By the use of the superposition principle of a linear system, the built-up concentration of the dye is found to range from 8 ppb at 1,900 feet downstream from the confluence of the north and south forks of Muddy Creek to 2 ppb near the Smithsonian Institutions pier in the Rhode River, provided that the dye is continuously injected at the headwaters at the rate of one pound per two tidal cycles.