Research About aquatic

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Changes in the lakes within the Mount St. Helens blast zone

We will study changes in two lakes (Meta and Ryan) since the blast. Analysis will consist of analyzing physical and chemical properties of soils and entering these data into a GIS to model the amount of runoff in each watershed. The other focus will look at nutrients and plankton within each lake and conducting experiments to determine the effects of different levels of nutrients and predation on the plankton.

 

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The herpetofauna of Mount St. Helens: survival and colonization following the 1980 eruption.

This study documents the survival and colonization of reptiles and amphibians in areas impacted by the 1980 eruption of Mount St. Helens. Surveys were conducted at 15 locations, with representative sites in three distinct volcanic impact zones, 1) ashfall, 2) blowdown, and 3) blast, during spring and summer from 1980 through 1991. Twelve species of herptiles (9 amphibians, 3 reptiles) are considered to have survived volcanic influences ranging from the directed blast to the accumulation of ash in otherwise unaltered habitats. These survivors represent most of a hypothetical list of 16 species considered to have occurred in the area before the eruption. Generally, surviving species were characterized by being more aquatic than those not found and this was attributed to the thermal buffering capacity of cool ice and snow covered aquatic systems where individuals were protected from the hot volcanic gases.

 

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Blast zone lakes and organic geochemistry

The objective of the research is to describe the processes controlling dissolved organic material in the lake water following the 1980 eruption of Mt. St. Helens. The concentrations of DOC (dissolved organic carbon) increased 50-fold after the eruption and these increases influenced the chemistry and biology of the lakes for several years. We have shown that most of this DOC was comprised of organic acids classified as either fulvic or hydrophilic acids, similar to those in typical natural waters. We found that between 1980 and 1983, these organic acid fractions underwent oxidative changes in their chemical characteristics. Similar changes may occur in more typical lakes.

 

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Microbiology of thermal vents

Our objectives are to observe, enrich, isolate, and identify bacteria from hot springs in the Mount St. Helens area. If any previously undescribed isolates are found, we will characterize them. In two trips to the area so far, we have observed the following: Cyanobacterial (blue-green algal) mats containing filamentous forms, some with heterocysts; filaments with the appearance of the sulfur oxidizer Beggiatoa or Thiothrix; and numerous rod shaped and coccus shaped bacteria. From anoxic sediment at 60oC, we obtained an enrichment of methanogenic bacteria that appeared similar to Methanobacterium thermoautotrophicum. We also obtained an enrichment of the green non-sulfur photosynthetic bacterium, Chloroflexus. We observed few organisms in a vent at 85oC.

 

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Post eruption studies of ecological recovery of lakes and rivers in the blast zone of Mount St. Helens

This study concentrates on the effects of the May 1980 eruption on Spirit Lake. During and subsequent to the eruption, Spirit Lake received debris avalanche material, timber and other forest vegetation, pyroclastic flows, mudflows, ashfall, and geothermal waters.

 

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Recovery of stream ecosystems following catastrophic disturbances

This study was conducted in the Clearwater basin of Mount St. Helens. Three projects within the study investigate recovery of trout and sculpin populations, tailed frog populations, and invertebrate populations. Trout were studied in the main channel of Clearwater Creek, and the effects of large woody debris in the stream on fish populations were examined. Trout populations were still low as of 1990, being one-tenth to 20% of that in undisturbed stream systems; this appears largely due to interruption of spawning in years following the blast and to continuing lack of spawning habitat. Trout densities were found to be higher in areas with lots of woody debris. The condition of trout was high throughout the stream in years since 1984 presumably due to rapid recovery of high abundance of invertebrate prey. By 1985 sculpin densities were as high as or higher than in undisturbed streams.

 

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Lakes and thermal environments in the blast zone of Mount St. Helens

Approximately 20 lakes exist in the blast zone of Mount St. Helens. The degree to which they were disturbed on May 18, 1980 ranges from slight to a complete physical, chemical, and biological restructuring. Initially, our research focused on the physical, chemical, and microbial conditions within the lakes. Heavily devastated lakes were markedly changed chemically and all plants and animals eliminated. Recovery took the form of dramatic physical and chemical changes within the lakes which were linked to microbial activity. Rapid recovery occurred the first two years. Once the physical and chemical conditions were ameliorated, further biological succession was possible. Presently, we continue to track these changes.

 

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Observations on the floating log raft in Spirit Lake.

Observations on Spirit Lake and its log raft have been conducted since 1982. At that time a significant number (close to 20%) of the stumps (not the broken flotsam) had settled into an upright position in the water. This number included some that had floated into shallow water and had grounded lightly on the bottom (Coffin, 1983).

 

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Recovery of aquatic insect communities in streams near Mount St. Helens

We have monitored stream insect communities from 1980 to 1988 in Clearwater Creek, Elk Creek, and Ape Canyon. Quantitative and qualitative samples indicate rapid colonization in 1981-82, and then a gradual increase in richness and diversity. Over 200 taxa have now been collected from Ape or Clearwater Creeks.

 

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Ecology of the tadpoles of the tailed frog (Ascaphus truei)

Data on the microhabitat parameters, especially pertaining to flow rate and substrate characteristics, of the stream-inhabiting tadpoles of the tailed frog (Ascaphus truei) were collected at two tributaries of Clearwater Creek at Mount St. Helens, Washington and at Parker Creek on Mary’s Peak, Benton County, Oregon. This is the only tadpole in North America that is highly specialized for maintaining position and feeding from algae while attached to rocks via an enlarged oral disc with many rows of labial teeth. Positions of tadpoles in the streams were correlated with oral morphology and associated anatomy. Because of the length of the larval period of Ascaphus, there are usually 2 to 3 yearly cohorts in the streams at one time. We hypothesized that the interaction of the abilities of the tadpoles to adhere to rocky substrates and the size of the tadpole would result in microhabitat segregation. Whether small or large tadpoles occupied fast versus slow water would depend on the growth pattern of the tadpole (drag) versus the changes of the adhesive abilities with size.

 

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