Title

Seasonal Nutrient Limitation in Taneum Creek, Washington

Presenter Information

Tyler Alling
Desiree Clark
Samara Awan

Document Type

Oral Presentation

Location

SURC Ballroom B/C/D

Start Date

21-5-2015

End Date

21-5-2015

Keywords

Productivity, Autotrophic, Heterotrophic

Abstract

Two key determinants of stream ecosystem productivity are algal activity, the source of primary production of energy in a food web from solar radiation via photosynthesis, and heterotrophic activity, the bacterial and fungal consumers of this primary ecosystem production. Nitrogen (N) and phosphorus (P) concentrations often determine ecosystem productivity, and varying nutrient levels exist within an ecosystem seasonally. For example, during the fall, leaf input decomposes, possibly leading to different nutrient levels compared to winter, when few leaves remain in the stream. This variation can be applied to higher trophic levels via bottom up ecosystem production whereby increased primary production increases production at higher trophic levels such as fish. We used nutrient diffusing substrata to measure seasonal changes in ecosystem nutrient limitation in two sites in Taneum Creek, which has been of interest to the Yakama Nation due to their active migratory fish repopulation efforts. In the fall, we found that heterotrophic activity in Taneum Creek was co-limited by N and P at both study sites, p=0.006 upstream and p<0.001 downstream, whereas autotrophic activity was not nutrient limited. In the winter, upstream heterotrophic and downstream autotrophic production were co-limited by N and P, p=0.007 and p=0.019, respectively, but autotrophic productivity upstream and heterotrophic activity downstream were not nutrient limited. This study will continue in spring and summer for a comprehensive analysis of limiting factors to autotrophic and heterotrophic activity, which will form a better understanding of ecosystem productivity to support fisheries reintroduction.

Poster Number

40

Faculty Mentor(s)

Clay Arango

Department/Program

Biological Sciences

Additional Mentoring Department

Biological Sciences

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May 21st, 8:30 AM May 21st, 11:00 AM

Seasonal Nutrient Limitation in Taneum Creek, Washington

SURC Ballroom B/C/D

Two key determinants of stream ecosystem productivity are algal activity, the source of primary production of energy in a food web from solar radiation via photosynthesis, and heterotrophic activity, the bacterial and fungal consumers of this primary ecosystem production. Nitrogen (N) and phosphorus (P) concentrations often determine ecosystem productivity, and varying nutrient levels exist within an ecosystem seasonally. For example, during the fall, leaf input decomposes, possibly leading to different nutrient levels compared to winter, when few leaves remain in the stream. This variation can be applied to higher trophic levels via bottom up ecosystem production whereby increased primary production increases production at higher trophic levels such as fish. We used nutrient diffusing substrata to measure seasonal changes in ecosystem nutrient limitation in two sites in Taneum Creek, which has been of interest to the Yakama Nation due to their active migratory fish repopulation efforts. In the fall, we found that heterotrophic activity in Taneum Creek was co-limited by N and P at both study sites, p=0.006 upstream and p<0.001 downstream, whereas autotrophic activity was not nutrient limited. In the winter, upstream heterotrophic and downstream autotrophic production were co-limited by N and P, p=0.007 and p=0.019, respectively, but autotrophic productivity upstream and heterotrophic activity downstream were not nutrient limited. This study will continue in spring and summer for a comprehensive analysis of limiting factors to autotrophic and heterotrophic activity, which will form a better understanding of ecosystem productivity to support fisheries reintroduction.