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Plankton tows were taken at 55 stations over Newport Submarine Canyon, along with temperature, salinity, and transparency measurements. Two factors modify prevailing conditions: upwelling of water in the canyon, and effluent flow from the Orange County sewer outfall.
Colder isotherms penetrate warm nearshore water during times of upwelling. Under such conditions, planktonic foraminiferal numbers increase fourfold in areas of previously low concentrations. High values are found in the canyon axis, whereas planktonic frequency decreases both north and south of the axis. However, an anomalous situation exists over the sewer outfall, where in relatively warm water, large quantities of Foraminifera are present. Increase in quantity of these forms appears to be caused by a supply of fresh nutrients provided by upwelling in the canyon and organic matter discharged from the sewer. These factors make it possible for a larger population to persist.
Foraminifera range in size from 60 to 250 microns, the lower limit being determined by the mesh size of the plankton net. Size distribution is significant because many programs employ nets larger than 250 microns. Globigerina bulloides composes 90 per cent or more of the samples. Scattered specimens of Globigerina pachyderma occur in deep tows along with G. quinqueloba. Some benthonic forms, species of Bolivina, were found in the tows, presumably because of either transport by upwelling bottom currents or float mechanisms.
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