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Canadian Science Advisory Secretariat
Research Document - 2005/035
The suitability of DEPOMOD for use in the management of finfish aquaculture sites, with particular reference to Pacific Region
By Chamberlain, J., D. Stucchi, L. Lu, C. Levings
Abstract
We have applied the Scottish aquaculture waste model DEPOMOD to one British
Columbia finfish farm as part of a project to test and validate this model for
use in the Pacific Region. The site modeled had an extensive suite of field
observations at multiple time points during a growth cycle. Detailed farm
productions and configuration information were complete for the corresponding
period. Since several parameter settings used in the model are not well known,
we explored the effect of this uncertainty on the predicted carbon flux by
running a series of simulations using a range of values representing best- to
worse-case estimates. The resulting model predictions covered a broad range of
outputs whose extremes represented the most optimistic and pessimistic scenarios
in terms of benthic loading.
The simulation of resuspension processes within the model resulted in
predictions where virtually all of the applied material was exported from the
model domain and precluded meaningful comparisons of model fluxes with field
data. Model predictions, with no resuspension, showed the expected steep
gradient in carbon flux with distance from the edge of the net cages.
Significant relationships were demonstrated between predicted carbon flux (no
resuspension) and several measures of benthic impact, namely sediment sulphide
concentration, species diversity, infaunal trophic index (ITI) and faunal
abundance. The sediment chemistry and biology showed a clear effect from the
deposition of wastes from the finfish farm.
We discuss key limitations of the model, uncertainty surrounding model parameter
settings and simulation of resuspension processes, and make several
recommendations for further research and testing of the model.
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(57 pages; 1220K)
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