摘要:

The eruption of Mount St. Helens resulted in a gray, dense, pasty layer, 3–4 cm thick, on the bottom of Moses Lake, Washington. The ashlayer was easily recognizable in sediment cores either visually or chemically by its low calcium and water content. The layer fractured and sunk through the existing uncompacted sediment; apparent sinking rates were greater at 5 m than at 10 m depth. Sinking may not be the explanation for displacement at the shallowest (3 m) station. Although variable, the ashlayer had stabilized at the 10 m and 3 m stations after two years at average sediment depths of 5.6±1.1 and 7.9±4.4 cm, respectively. The relatively rapid sinking of the ashlayer through the sediment column at the 10 m and 5 m depths was probably due to its greater density (60–70% solid) than normal lake sediment (20–30% solid). Displacement at the 3 m depth may have resulted from a combination of greater rates of ash input and resuspension. Use of an ashlayer as an accurate marker for sedimentation rate calculations must include a consideration of such displacement.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665096

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Tissue aluminum levels in channel catfish, gizzard shad and largemouth bass were compared between a lake receiving water treatment plant effluent containing alum (aluminum sulfate) and a control lake. Statistical analysis indicated few significant differences in aluminum levels between lakes and between species, but significant differences did exist between tissues. Liver and brain tissues were found to have higher tissue aluminum concentrations than muscle and gill tissues.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665097

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Physical habitat data (velocity and depth of water, and percentage substrate composition) for several southwestern fishes collected by point and transect methodologies were similar. Velocity estimates showed less agreement and greatest variation. Choice of direct observation or capture by electrofishing as methods to locate fishes for habitat evaluation is problematic. Fish location techniques may induce more error in measurement of habitat than do different habitat evaluation techniques.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665098

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

摘要:

Trap net samples of white crappie were collected in the spring from Rend Lake, Illinois, from 1978 through 1983. Analyses of age, growth, length-frequency, and diet reveal a dominant, slower-growing 1978 year class and two sub-populations, separated by growth rate and feeding behavior. At ages II–VI crappie feeding on fish have back-calculated total lengths 10.1, 27.6, 42.6, 58.9, and 63.2 mm greater than those of crappie of the same age feeding on an invertebrate diet.

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665099

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665100

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor

ISSN:0270-5060    

DOI:10.1080/02705060.1985.9665085

出版商:Taylor & Francis Group    

年代:1985

数据来源: Taylor