Chlorinated hydrocarbon cycling in the benthic nepheloid layer of Lake Superior

1985 ◽  
Vol 19 (9) ◽  
pp. 854-861 ◽  
Author(s):  
Joel E. Qaker ◽  
Steven J. Eisenreich ◽  
Thomas C. Johnson ◽  
Barbara M. Halfman
Keyword(s):  
Lake Superior ◽  
Nepheloid Layer ◽  
Chlorinated Hydrocarbon ◽  
Benthic Nepheloid Layer

Bacterioplankton Density and Activity in Benthic Nepheloid Layers of Lake Michigan and Lake Superior

1991 ◽  
Vol 48 (5) ◽  
pp. 923-932 ◽  
Author(s):  
Randall E. Hicks ◽  
Christopher J. Owen
Keyword(s):  
Lake Michigan ◽  
Bacterial Abundance ◽  
Heterotrophic Bacteria ◽  
Lake Superior ◽  
Field Measurements ◽  
Depth Interval ◽  
Nepheloid Layer ◽  
Dividing Cells ◽  
Doubling Times ◽  
Benthic Nepheloid Layer

Benthic nepheloid layers were observed in Lake Michigan and Lake Superior during July 1988 using the Johnson-Sea-Link II submersible. A particularly well-defined benthic nepheloid layer was present in Whitefish Bay, Lake Superior, where particle concentrations increased 10 times over the bottom 30 m. Bacterial abundance, however, increased only 1.5 times in the same depth interval and a maximum of only 16% 1 m above the sediment in both lakes when the sediment boundary layer was deliberately resuspended. Bacterial abundance was greater in Lake Michigan than in Lake Superior. Bacterioplankton abundance and the frequency of dividing cells were both related to temperature and organic carbon concentrations. The range of individual cell volumes (0.024–0.042 μm3) was similar in both lakes, regardless of depth. Less than 5% of the heterotrophic bacteria were actively dividing and only 2.0–3.4% of the bacterioplankton in the epilimnion and hypolimnion were synthetically active in both lakes. Bacterioplankton doubling times, estimated from field measurements of the frequency of dividing cells, increased from 29 h at 5 m to > 230 h at 310 m in the Caribou Basin of Lake Superior. The abundance, cell size, and activity of heterotrophic bacterioplankton in the deep hypolimnia of Lake Michigan and Lake Superior were unaffected by the presence of a benthic nepheloid layer.

scholarly journals Scales of seafloor sediment resuspension in the northern Gulf of Mexico

Elem Sci Anth ◽  
2018 ◽  
Vol 6 ◽  
Author(s):  
Arne-R. Diercks ◽  
Clayton Dike ◽  
Vernon L. Asper ◽  
Steven F. DiMarco ◽  
Jeffrey P. Chanton ◽  
...  
Keyword(s):  
Time Series ◽  
Particle Size ◽  
Gulf Of Mexico ◽  
Sediment Resuspension ◽  
Small Scale ◽  
Nepheloid Layer ◽  
Northern Gulf Of Mexico ◽  
Flux Data ◽  
Seafloor Sediment ◽  
Benthic Nepheloid Layer

Seafloor sediment resuspension events of different scales and magnitudes and the resulting deep (>1,000 m) benthic nepheloid layers were investigated in the northern Gulf of Mexico during Fall 2012 to Summer 2013. Time-series data of size-specific in-situ settling speeds of marine snow in the benthic nepheloid layer (moored flux cameras), particle size distributions (profiling camera), currents (various current meters) and stacked time-series flux data (sediment traps) were combined to recognize resuspension events ranging from small-scale local, to small-scale far-field to hurricane-scale. One small-scale local resuspension event caused by inertial currents was identified based on local high current speeds (>10 cm s–1) and trap data. Low POC content combined with high lithogenic silica flux at 30 m above bottom (mab) compared to the flux at 120 mab, suggested local resuspension reaching 30 mab, but not 120 mab. Another similar event was detected by the changes in particle size distribution and settling speeds of particles in the benthic nepheloid layer. Flux data indicated two other small-scale events, which occurred at some distance, rather than locally. Inertia-driven resuspension of material in shallower areas surrounding the traps presumably transported this material downslope leaving a resuspension signal at 120 mab, but not at 30 mab. The passage of hurricane Isaac left a larger scale resuspension event that lasted a few days and was recorded in both traps. Although hurricanes cause large-scale events readily observable in sediment trap samples, resuspension events small in temporal and spatial scale are not easily recognizable in trapped material as they tend to provide less material and become part of the background signal in the long-term averaged trap samples. We suggest that these small-scale resuspension events, mostly unnoticed in conventional time-series sampling, play an important role in the redistribution and ultimate fate of sediment distribution on the seafloor.

Quantifying tidal signatures of the benthic nepheloid layer in Gaoping Submarine Canyon in Southern Taiwan

2010 ◽  
Vol 271 (1-2) ◽  
pp. 119-130 ◽  
Author(s):  
James T. Liu ◽  
Yu Huai Wang ◽  
I-Huan Lee ◽  
Ray T. Hsu
Keyword(s):  
Submarine Canyon ◽  
Nepheloid Layer ◽  
Southern Taiwan ◽  
Benthic Nepheloid Layer
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