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

9411380 Dodds Periphyton（底栖藻类和相关的异养生物）是许多浅水系统中固定碳的最重要来源。 藻类聚集体的上层暴露于高水平的辐照度，因此可能容易受到增加的紫外线辐射的抑制。 关于入射紫外线辐射预期增加对附着生物光合速率的影响的数据极为有限;如果这种影响严重，则可能损害生态系统功能。 将建造设备，以探讨高紫外线照射和光抑制在完整的附着生物组合之间的关系，使用O2微电极估计在原位光合速率，和光微探针将开发，以评估紫外线照射和光衰减。 紫外线将补充被动太阳能紫外线集中器。 聚光器将使用抛物面镜来集中阳光，并使用滤光器去除光谱中除紫外线以外的所有区域，并使用光纤将光引导到附着生物集合体。 该提案将允许建造和测试太阳能紫外线集中器。 该系统将进行测试，为期几周的实验，对栖息在康扎草原研究自然区的溪流的附着生物。 拟议的研究是独一无二的，因为长期（数周）的紫外线补充实验的自然组合还没有发生。 所开发的技术将能够评估全球紫外线辐照度增加的长期影响。

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.