Global patterns of light saturation and photo-inhibition of lake primary production

Staehr, Peter A. and Brighenti, Ludmilla S. and Honti, Márk and Christensen, Jesper and Rose, Kevin C. (2015) Global patterns of light saturation and photo-inhibition of lake primary production. INLAND WATERS. ISSN 2044-2041 (Submitted)

Text Peter Ludmilla cikk.pdf - Submitted Version Restricted to Repository staff only Download (2MB) | Request a copy

Abstract

The importance of light availability on lake gross primary production (GPP) depends on the physical setting and meteorological and chemical conditions characterizing the lake. While it has long been recognized that complex interactions between external and in-lake conditions affect whole lake GPP, few studies have evaluated the importance of different drivers of daily and seasonal variability in lake GPP for a diverse set of lake types. Here we use a unique dataset covering a wide spectrum of lakes in terms of size, nutrient loading and phytoplankton density combined with high-frequency meteorology, dissolved oxygen (DO), and light data to determine the GPP of lakes and investigate the degree of light limitation and photo-inhibition of GPP over multiple time scales. We used a Bayesian modeling approach to model diel changes in DO as a non- linear function of light and temperature, making it possible to determine the parameters describing the light dependency of hourly GPP rates under in situ conditions. 52% of the 1641 analyzed days had moderate to strongly light saturated GPP during midday summer conditions, and photo- inhibition occurred on at least 48% of the days. GPP became increasingly light limited with increasing nutrient and phytoplankton concentrations, conditions which also reduced the likelihood of photo-inhibition. The highest summer rates of GPP were found in the light limited, non-photo-inhibited, nutrient and phytoplankton rich lakes although annual rates were much lower her. This shows the strong interacting effects of light and nutrients for the magnitude and temporal variability in GPP of lake ecosystems.

Actions (login required)

Edit Item