Effects of mine tailing on benthic infaunal composition in a British Columbia inlet; with special reference to sampling, instrumentation, and the biology of Ammotrypane aulogaster (Polychaeta, Opheliidae)
Date
1974
Authors
Jones, Adrián Alejandro
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Abstract
Preliminary results from a Government-required program monitoring the discharge of tailing into the Rupert-Holberg Inlet trough indicated localized smothering of the deep benthic infauna. The sub-obliterative effects of the tailing on the infauna, and the sampling efficiencies of the 0.052 m² Ponar grab and the 0.1 m² Van Veen grab were investigated by sampling seven environmentally similar stations at increasing distances from the outfall. The Inlet infauna was found to be very reduced, apparently naturally, and was similar to Thorson's (1957) arctic foraminiferan community. Stations up to a distance of 4.5 kilometers from the outfall and with more than 40 cm of tailing were very depauperate. Stations as close as 5 .5 kilometers from the outfall and with less than 28 cm of tailing appeared to be able to support a relatively diverse infauna, though biomass and densities were reduced. Natural seasonal fluctuations and decrease of fauna as a function of distance from the open sea made it impossible to distinguish any tailing-derived differences between the other four stations. Species associational analysis (Cluster and modified Zürich-Montpellier) also showed no differences between the non-depauperate stations. Bivalves and possibly Maldanid polychaetes appear to be very sensitive to the tailing and the first to disappear. Slumping of tailing deposits from shallower areas is postulated as playing a significant role in the deep benthic infaunal obliteration. An exploratory production study on a benthic polychaete (Armotrypane aulogaster Rathke, 1843) showed that crops and worm lengths decreased with increasing tailing. Some inc1J.cation of reduced production rates can be deduced from the results.
Comparisons between the Ponar and Van Veen grabs showed that the former collected more planktonic and light interface benthic organisms and gave crop estimates considerably greater than the Van Veen grab. A randomizing effect by the smaller Ponar sample is suggested as the cause of its larger crop estimates.