Light dependency of lake primary production

The main goal of the project is to investigate the overall light dependency of net ecosystem production during daytime. This includes light utilization efficiency (α), NEPmax, minimum light requirements (Ic) and the amount of light at which NEP starts to saturate (Ik). For that, we are using the light at which NEP starts to saturate (Ik) and compare this with the actual available light during the day. This will provide use with a quantitative measure of the percentage of days (using mid-day) in a given lake where available light is either below or above Ik. A couple of testable hypotheses that we expect to achieve would be that primary production in lakes: 1) is generally light limited, especially during spring and fall 2) nutrient limitation dominates during summer in temperate systems, but all year round in the tropics 3) shallow clear water systems, dominated by macrophytes will often be light saturated compared to deeper more turbid waters Furthermore, Ik Ic and α will be influenced by chemical and meteorological drivers, which in turn will be strongly influenced by lake meta-parameters (area, depth, lake area relative to watershed area, latitude)