SGER: Estimating Effects of Ultraviolet Irradiance on Periphyton Primary Production in Streams

9411380底栖藻类(底栖藻类和相关的异养生物)是许多浅水水生系统固定碳的最重要来源。藻类组合的上层暴露在高水平的辐射下，因此可能容易受到紫外线辐射增加的抑制。有关入射紫外线辐射预期增加对附生植物光合作用速率影响的数据极其有限；如果这种影响很严重，可能会损害生态系统功能。将建造设备，使用O2微电极来原位估计光合作用速率，以探索完整的附生植物组合中高紫外线辐射和光抑制之间的关系，并将开发光微探针来评估紫外线暴露和光衰减。紫外线将由被动式太阳紫外线聚光器补充。聚光器将使用抛物面反射镜来聚集太阳光，并用滤光器去除光谱中除紫外线以外的所有区域，并通过光纤将光引导到围生植物组合。这项提议将允许建造和测试太阳能紫外线聚光器。该系统将通过对康扎草原研究自然区溪流中的附生植物进行为期数周的实验进行测试。这项拟议的研究是独一无二的，因为长期(几周)的紫外线补充天然集合体的实验还没有发生。开发的技术将使评估全球紫外线辐射增加的长期影响成为可能。

9411380 Dodds Periphyton (benthic algae and associated heterotrophs) is the most important source of fixed carbon in many shallow aquatic systems. The upper layer of the algal assemblage is exposed to high levels of irradiance, and thus may be susceptible to inhibition from increased UV radiation. Data on the effect of expected increases in incident UV radiation on photosynthetic rates of periphyton are extremely limited; if such effects are severe, they could impair ecosystem function. Equipment will be constructed to explore the relationships between high UV irradiance and photoinhibition in intact periphyton assemblages using O2 microelectrodes to estimate in situ photosynthetic rates, and light microprobes will be developed to assess UV exposure and light attenuation. UV will be supplemented with a passive solar UV concentrator. The concentrator will use parabolic mirrors to concentrate sunlight, and remove all but the ultra-violet regions of the spectrum with filters, and guide the light to periphyton assemblages with fiber optics. This proposal will allow construction and testing of the solar UV concentrator. The system will be tested with experiments of several weeks duration on periphyton inhabiting the streams of Konza Prairie Research Natural Area. The proposed research is unique because long term (weeks) UV supplementation experiments of natural assemblages have not occurred. The techniques developed will allow assessment of long term effects of global increases of UV irradiance.