Chapter 7 – Light

摘要: The quantity of light reaching the streambed is one most fundamental environmental factors that affect stream ecosystems. Solar radiation drives photosynthesis and has strong indirect effects on many lotic processes connected to primary production. incident streambeds highly variable both temporal spatial scales, an accurate assessment regime a relevant activity for research projects. Light measurements span at least dawn-to-dusk period (and preferably more than one) are essential characterizing daily any location. These can be made with quantum sensors directly measure photosynthetically active (PAR) (400–700 nm) or calibrated PAR. Data loggers recording intervals during day. Photosensitive dye-based integrate exposure over time may useful relatively inexpensive alternative electronic sensors. For study involving multiple sites stretches streams potentially environments, sensor-logger combinations should employed.