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

Fraser River Action Plan 3rd Research Workshop
Assessing the Relative Bio-Recovery of Select Invertebrate Fauna on
an Ecologically Important Tidal Flat, Sturgeon and Roberts Banks, B.C.
J.L. Arvai and P.J. Harrison
Department of Oceanography
University of British Columbia
Abstract
As part of a project to better understand the ecology of Sturgeon and Roberts Banks and the responses of benthic
invertebrates to the diversion of sewage effluent, density and secondary production analyses are currently being
conducted on two ecologically important indicator species (Corophium salmonis [Amphipoda], Macoma
balthica [Bivalvia]).
Preliminary density data indicated an increase in abundance of these two species at two contaminated sites —
one located at the northern tip of Sturgeon Bank adjacent to the Iona Island Sewage Treatment Plant (STP) and
the other near the mouth of the South Arm of the Fraser on Roberts Bank. These increases in abundance were in
sharp contrast to density measurements taken at two control sites (essentially unaffected by effluent
contaminants) located on Sturgeon Bank. In addition, these density analyses clearly indicated that significant
benthic recovery has taken place immediately adjacent to the Iona Island STP (a site that was reported to be
entirely azoic prior to 1988).
This observation of recovery on Sturgeon Bank is further supported by preliminary data which seems to indicate
that additional winter cohorts of Corophium salmonis are being supported adjacent to the Iona Island STP and
on Roberts Bank, whereas they do not seem to exist at any of the control stations. It is hypothesized that this may
be the result of anthropogenic organic loading occurring during the winter months at these two sites. However, it
should be noted that these observations are preliminary in nature and will be further examined in extensive
cohort analyses.
It is expected that a completed presentation of the results of this project will be available by the summer of 1997.
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