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Title: Aquatic disposal field investigations, Columbia River disposal site, Oregon. Appendix D, zooplankton and ichthyoplankton studies
Authors: Holton, Robert L.
Small, Lawrence F. (Lawrence Frederick)
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 D
Abstract: A zooplankton and ichthyoplankton field research study was conducted in the vicinity of the mouth of the Columbia River to establish baseline planktonic conditions and to estimate the effect of open-water disposal of dredged material on the zooplankton and ichthyoplankton in the region. During the 1-1/2-year study, a total of 304 plankton samples were taken from bottom, oblique, and surface tows using 1-m (571 micron mesh) and 1/2-m (200 or 110 micron mesh) nets. All ichthyoplankton samples collected were sorted and identified; however, due to time and funding constraints, only 50 percent of the zooplankton samples collected were sorted and identified. The second objective, i.e., evaluation of the impact of dredged material on the local zooplankton population, was not achieved since the disposal of dredged material basically did not occur at the scheduled times. However, the data presented do provide new information on the zooplankton and ichthyoplankton seasonal distributions at the mouth of the Columbia River and there-fore should provide useful information for further research in this region. Larval and juvenile fish (6320 total) from eighteen families were taken during the study, with smelt being the most abundant group followed by anchovies, righteye flounders (pleuronectidae), codfishes (gadidae), and sculpins (cottidae). Ichthyoplankton abundances were highest in the winter-spring periods and lowest in August. Calunus spp. dominated the copepod numbers throughout the year as did Atylus tridens among gammaridean amphipoda with 79.7 and 93.6 percent, respectively, of the totals. Hyperoche medusarum was the most abundant hyperid amphipod while Diastylopsis dawsoni. was the most abundant cumacean. Decapod numbers were dominated by Cancer magister, pinnotheridae, crangonidae zoea, and miscellaneous natantia. Both ichthyoplankton and zooplankton catch data suggest that summer disposal operations would minimize any dredged material disposal effects.
Description: Technical Report
Gov't Doc #: Technical Report D-77-30; Appendix D
Rights: Approved for Public Release; Distribution is Unlimited
Appears in Collections:Technical Report

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