Title

Control Of Algal Standing Crop By P And N In The Clark Fork River

Abstract

In the mid and late 1980' s, attached algae levels in the Clark Fork of the Columbia River varied from unnoticeable to extreme nuisance levels. Thi.5 study addressed the question: are P and N levels low enough long enough to limit algal growth and standing crop in this river? If so, river reaches with nuisance levels may improve if nutrient levels are lowered, and high quality reache.5 may worsen if nutrient levels are allowed to increase. Because the Clark Fork often exhibits N and P levels thought to saturate algal growth, there was doubt that nutrient management would affect algal levels. Through the use of artificial stream fertilization experiments, this study showed that the standing crop of these attached algal communities saturate at much higher nutrient levels than does growth. At most river sites from Sept.1987 to 1989, dissolved P and N were almost always below levels that saturate algal standing crop. The ratio of dissolved N:P in the water suggested that N limitation, P limitation or a balance between the two existed for significant periods of time at almost all sites. Hence management of both N and P may reduce nuisance levels (when other factors are not limiting) and are important to protecting high quality areas.

Note: This presentation was both an oral presentation as well as a poster.

Start Date

20-4-1990 1:00 PM

End Date

20-4-1990 3:00 PM

Document Type

Poster

 
Apr 20th, 1:00 PM Apr 20th, 3:00 PM

Control Of Algal Standing Crop By P And N In The Clark Fork River

In the mid and late 1980' s, attached algae levels in the Clark Fork of the Columbia River varied from unnoticeable to extreme nuisance levels. Thi.5 study addressed the question: are P and N levels low enough long enough to limit algal growth and standing crop in this river? If so, river reaches with nuisance levels may improve if nutrient levels are lowered, and high quality reache.5 may worsen if nutrient levels are allowed to increase. Because the Clark Fork often exhibits N and P levels thought to saturate algal growth, there was doubt that nutrient management would affect algal levels. Through the use of artificial stream fertilization experiments, this study showed that the standing crop of these attached algal communities saturate at much higher nutrient levels than does growth. At most river sites from Sept.1987 to 1989, dissolved P and N were almost always below levels that saturate algal standing crop. The ratio of dissolved N:P in the water suggested that N limitation, P limitation or a balance between the two existed for significant periods of time at almost all sites. Hence management of both N and P may reduce nuisance levels (when other factors are not limiting) and are important to protecting high quality areas.

Note: This presentation was both an oral presentation as well as a poster.