Proceedings - Teaching and Learning Centre - Simon Fraser ...

Fraser River Action Plan 3rd Research Workshop
Intertidal Primary Productivity Following the
Diversion of Sewage Effluent on Sturgeon Bank, near Iona Island
L. Ross and P.J. Harrison
Department of Oceanography
University of British Columbia
Abstract
This study looks at the rate of primary productivity in the intertidal area on Sturgeon Bank near Iona Island, as
well as the environmental factors that influence it:
• nutrient concentrations;
• solar irradiance;
• water turbidity;
• sewage effluent pollutants; and,
• the abundance and diversity of primary producers.
The rate of primary production serves as an indicator of recovery of the phycological populations, namely
benthic diatoms and phytoplankton. The net difference of nutrient (ammonium and nitrate) concentrations
provide a rate of consumption or production that reiterate the conclusion from the primary productivity results.
Benthic chambers were employed for up to 22 hours to create a self-contained, yet natural environment in which
the change in the oxygen concentration was measured over the incubation period. Water inside the chambers was
stirred with bilge pumps to maintain natural water movement and avoid unnatural stratification. Both
photosynthesis and respiration were measured in light chambers and benthic respiration alone from the dark
chambers which allowed for the isolation of benthic animal respiration. Sampling was conducted from July to
November, 1995, and is planned to continue March to September, 1996. Variability was found between the
sampling stations revealing a greater abundance of chlorophyll a at the polluted station than the control.
However, the control station showed a greater concentration of nitrate in November and ammonium in August.
Productivity was also generally higher at the control site than the polluted site near Iona Island. Results from this
project will establish a reference for future studies to use in primary production measurements, as well as
determine the change in algal and phytoplankton productivity over a two-year period.
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