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Title: Aquatic disposal field investigations, Columbia River disposal site, Oregon. Appendix C, The effects of dredged material disposal on benthic assemblages
Authors: Richardson, M. D. (Michael D.)
Carey, Andrew G.
Colgate, William A.
Keywords: Aquatic ecology
Sedimentation and deposition
Sediment transport
Dredging spoil
Dredged material
Columbia River
Dredged Material Research Program (U.S.)
Publisher: U.S. Army Engineer Waterways Experiment Station
Series/Report no.: Technical Report (Dredged Material Research Program (U.S.)) ; no. Technical Report D-77-30; Appendix C
Abstract: The objectives of this study were to identify and determine the significance of physical, chemical, and biological factors that govern the rate at which open-water dredged material disposal sites are colonized by benthic assemblages. In the macrobenthic areal baseline, 5 assemblages and 13 species groups were found. The distribution, community structure, and seasonal constancy of these assemblages were related to the distribution of sediments and organic matter, the stability of sediments, and changes in sediment characteristics due to the deposition of fine-grained material from the Columbia River. The deposition of dredged material significantly increased diversity and evenness values and reduced the density of macrofauna. Of the 33 most abundant species, 11 species had significantly lower abundances at stations exposed to direct dredged material deposition. The effects of dredged material disposal on benthos were probably related to direct burial of benthos and changes in sediment characteristics and not increased turbidity from the disposal operation or introduction of pollutants or organic matter. Repopulation of benthos into the affected area was probably accomplished primarily by benthos burrowing up through the dredged material or benthos migrating into the area and, to a lesser extent, reproduction and recruitment of benthos from outside the area. There was very little evidence for transportation of benthos to the experimental disposal site via dredged material.
Description: Technical Report
Gov't Doc #: Technical Report D-77-30; Appendix C
Rights: Approved for Public Release; Distribution is Unlimited
Appears in Collections:Technical Report

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