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Title: Vertical migration of benthos in simulated dredged material overburdens : vol. 1 : marine benthos
Authors: Maurer, D. L.
Keck, R. T.
Tinsman, J. C.
Leathem, W. A.
Wethe, C. A.
Huntzinger, M.
Lord, C.
Church, T. M.
Keywords: Benthos
Animal migration
Benthic ecology
Dredging spoil
Dredged material
Publisher: U.S. Army Engineer Waterways Experiment Station
Series/Report no.: Technical Report (Dredged Material Research Program (U.S.)) ; no. D-78-35; Volume I
Abstract: This research was conducted to determine the effect of simulated dredged material disposal on the vertical migration ability and survival of benthic invertebrates (Mercenaria mercenaria, Nucula proxima, Ilyanassa obsoleta, Scoloplos fragilis, Nereis succinea, Parahaustorius longimerus, and Neopanope sayi).Depending on the sediment type, .sediment measurements of particle size, void ratio, water content, percent silt-clay, and total organic carbon content varied significantly with time and sediment depth. The concentration of dissolved oxygen in the pore water decreased rapidly throughout the experiment; sulfide and ammonia concentrations in the pore water increased the first week and then remained fairly constant throughout the second week; pH and Eh remained essentially unchanged over the same period. Since the surface water chemistry appeared more conducive to the survival of benthic organisms than the pore water chemistry, the organisms may have needed to reestablish direct or indirect contact with the surface waters via siphons, tubes, burrows, etc., through the dredged material overburden. One basic pattern of vertical migration or burrowing response occurred when the majority of animals migrated from substratum zero and established an even distribution, normal distribution, normal distribution skewed to either upper or lower sediment layers, bimodal distribution, or polymodal distribution in the overlying sediment. The other pattern occurred when the majority of animals remained in substratum zero or in the bottommost layers. Mortalities generally increased with increased sediment depth, with increased burial time, and with overlying sediments whose particle size distribution differed from that of the animals’ preferred habitat. Temperature affected mortalities under certain conditions, but percent migration was more responsive than mortality to temperature. In addition, mortality and percent migration were influenced by synergistic effects of experimental variables. Because physiological conditions of animals differ widely from area to area, unqualified extrapolation of these results to other areas and animals with morphology similar to those tested here should be done with caution. However, the morphological and habitat approach was considered a viable means to develop a dependable method for prediction. Many of the species tested showed a surprising ability to vertically migrate and successfully survive in relatively thick deposits of native and exotic sediments. Assuming worst-case laboratory conditions, vertical migration may be an important factor in the recovery of benthic communities in dredging and dredged material disposal areas.
Description: Technical Report
Gov't Doc #: Technical Report D-78-35; Volume I
Rights: Approved for Public Release; Distribution is Unlimited
Appears in Collections:Technical Report

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