Tuesday, May 27, 2008
239

A comparison of factors controlling periphyton in the engineered and forest sections and effects of light reduction

Y-K. Wang, Center of General Education and Graduate Institute of Environmental Management, Nan-Hua University, Chia-Yi County, 62248, Taiwan, Shih-Eng Dai, Department of Biological Resources, National Chia-Yi University, Chia-Yi County, 60004, Taiwan, and Ke-Ching Shiao, Graduate Institute of Environmental Management, Nan-Hua University, Chia-Yi County, 62248, Taiwan.

Stream engineered structures affect factors controlling periphyton and consequently periphyton. The study site is located in the Hopeikeng Creek of the Central Taiwan. The 1st goal of this study was to compare top-down and bottom-up effects in the engineered and forest sections. This experiment included 3 factors: grazer (access or block), nutrient (addition or ambient), and stream section. The 2nd goal was to understand the effects of nutrient, grazer, and light reduction on periphyton in the engineered section. Light reduction experiment was a 3-way factorial design and included nutrient treatment, grazer treatment, and 0, 30%, 60%, and 90% light reduction. Overall, stream sections had different algal biomass (the engineered section had higher algal biomass), grazer control had effects on algae, and the interaction effect was present between stream section and grazer control. On the 3rd sampling date, section effect was still significant but grazer effect was not present because tadpoles became frogs. In the light reduction experiment, nutrients, grazer, and light had significant effects on algae biomass. Despite light reduction, algal biomass was still higher than algae in the forest section.

 



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