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Full-Text Articles in Life Sciences
Zooplankton Community Structure In Lakes Near Mt. St. Helens, Wa, Larry Duane Scharnberg
Zooplankton Community Structure In Lakes Near Mt. St. Helens, Wa, Larry Duane Scharnberg
Dissertations and Theses
Eighteen lakes around Mt. St. Helens (MSH) were sampled for zooplankton from September '92 until September '94. Samples were enumerated and identified to the species level in most cases. Standard deviation and t-tests were performed to determine the precision of enumeration methods and replication of duplicate tows. Palatability indexes based upon predator preferences were developed and coupled with length-frequency analyses as indicators of predation pressure. The weighted means of the summer samples were then subjected to cluster analysis in an attempt to categorize lakes with respect to zooplankton community structure. Lastly, the community compositions and abundances of MSH lakes were …
The Biogeochemistry Of Lakes In The Mount St. Helens Blast Zone, Victor Lee Menting
The Biogeochemistry Of Lakes In The Mount St. Helens Blast Zone, Victor Lee Menting
Dissertations and Theses
Dilution and ash weathering are the most important processes controlling the ion chemistry of lakes in the Mount St. Helens blast zone. Gibbs' models indicated total dissolved solids were decreasing as a result of dilution from high precipitation and runoff and the lakes plot in the rock weathering dominated region. Plots of theoretical dilution curves indicated a decline in ion concentrations as a result of dilution. Ion concentrations followed the exponential decline predicted by the dilution curve, although concentrations were higher than predicted by the curve. Increased concentrations were a result of the rapid weathering of ash in basins and …
Indicators Of Nutrient Limited Plankton Growth In Lakes Near Mount Saint Helens, Washington, Kurt Davis Carpenter
Indicators Of Nutrient Limited Plankton Growth In Lakes Near Mount Saint Helens, Washington, Kurt Davis Carpenter
Dissertations and Theses
Several lakes located in the blast zone of the 1980 eruption of Mount St. Helens were studied to determine if the plankton in the lakes were limited in their growth by nitrogen or phosphorus availability. Long term nutrient enrichment experiments were performed on lake water from five lakes and measures of chlorophyll-a, carbon fixation, and nutrient uptake were used to evaluate the extent of limitation. Nutrient concentrations, ratios, and uptake from 14 lakes provided additional evidence for limitation by nitrogen and/or phosphorus. The physical, chemical, and biological characteristics of the lakes were also examined to monitor the return of these …