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.
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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