Seasonal observations for tidal periods of 12 or 24 h in, or near, Bay of Fundy salmonid mariculture sites were made. Variables measured included dissolved oxygen, salinity, temperature, chlorophyll a, current velocity, dissolved inorganic nitrogen, phosphate, and silicate. Circumstantial evidence suggests that the following processes were most important in controlling levels of dissolved oxygen: advection which supplies oxygen-saturated water and removes dissolved oxygen deficits; photosynthetic oxygen production which supersaturates seawater with dissolved oxygen during the spring and summer; and chemical and biological oxidation processes which could be dominant in removing dissolved oxygen during the night and in the late summer/fall when temperatures remain high but photosynthetic activity is low. Levels of nitrate, phosphate, and silicate were not increased by the salmonid mariculture industry above those typical of the oligotrophic Bay of Fundy, although ammonia levels were higher near the salmon net pens. During the summer, levels of silicate and dissolved inorganic nitrogen were diminished coincident with uptake by the microalgal bloom.

Fluorescence spectroscopy is demonstrated to be a valuable technique for estimating petroleum residue concentrations in sea water when large numbers of samples must be analyzed. A recommended procedure is presented, along with some concentrations observed in Bedford Basin, Nova Scotia, and along a section between Halifax and Bermuda.

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Effects of three oils accommodated in sea water upon the growth of unialgal cultures of marine phytoplankton were investigated. The oil concentrations used covered the range normally encountered in sea water subjected to oil pollution (< 1 mg/liter). In most experiments, minor stimulation or inhibition of growth was apparent but in only two experiments was the growth of oil-contaminated cultures statistically different from controls (in both instances stimulation). Extrapolation of the results to the natural environment is complicated by several factors, the most important of which appear to be variability in organism response and the observation that oil concentration and composition change during experiments. Oil concentrations encountered in polluted sea water can affect the growth of phytoplankton, but the effects seem to be minor and short-lived.

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The interactions between the polychaete Arenicola marina, a common deposit feeder in sandy intertidal areas, and sediment contaminated with the fresh API (American Petroleum Institute) reference oils and weathered Bunker C oil remaining from the 1970 Arrow spill were investigated in laboratory experiments. Worms can tolerate low concentrations of sediment-bound oil, although the sediment working rate is reduced depending upon oil type, concentration, and degree of weathering. Hydrocarbon concentrations, measured gravimetrically and by gas chromatography and fluorescence spectroscopy, were substantially lower (17–72%) in worm casts than in initial sediment. This loss can be accounted for by microbial degradation, which is stimulated by the worms' activity, uptake of hydrocarbons into worms, and perhaps dissolution. A large population (10–25/m2) of Arenicola is present at Black Duck Cove, N.S., living in sediment contaminated with weathered Bunker C oil remaining from the Arrow spill. These worms, which have spent their entire lives in oil-polluted sediment, do not have markedly elevated hydrocarbon concentrations and behaved no differently in experiments than worms collected from a clean environment. Calculations suggest that they are capable of removing the oil present in a square metre of sediment in 2–4 yr. After any oil spill, when concentrations reach tolerable levels, activities of deposit-feeding animals such as Arenicola can apparently accelerate the weathering rate of sediment-bound oil. Key words: sediment, Arenicola marina, polychaete, petroleum, weathering rate, pollution, hydrocarbon

Concentrations of oil accommodated in sea water under laboratory conditions are directly related to the amount added and the degree of turbulence, but inversely related to temperature. The major fraction (87–98%) of this oil is in particulate form ranging in size from about 1 to 30 μ, presumably small droplets. The exact ratio of the particulate to subparticulate fractions is directly related to the apparent viscosity of each individual oil. Of the total amount of oil initially added, 9–15% appeared in sea water at the end of the 7-days experiments. Except in the proximity of recent oil slicks, the oil concentrations observed in these experiments are one to two orders of magnitude greater than the concentrations generally observed in the marine environment off eastern Canada.

No abstract