Primary Productivity in a Polymictic Lake – Temporal Dynamics, Controlling Factors and Trophic State

✍ Scribed by Frank Gervais; Horst Behrendt

• Publisher: John Wiley and Sons
• Year: 2003
• Tongue: English
• Weight: 220 KB
• Volume: 88
• Category: Article
• ISSN: 1434-2944
• DOI: 10.1002/iroh.200390001

✦ Synopsis

Abstract

The seasonal and interannual dynamics of phytoplankton biomass, underwater light climate and primary productivity were studied in a phytoplankton‐dominated, polymictic lake (Müggelsee, Berlin, Germany) from 1994 to 1998. Turbidity was relatively high (k~0~ between 0.4 and 2.5 m^–1^) and the mixing depth often exceeded the euphotic depth. Therefore light was the most important factor limiting primary productivity. 82% of the observed variability in photosynthetic carbon uptake could be explained by a linear regression of carbon uptake against the product of chlorophyll a concentration and mean underwater irradiance. Annual productivity showed a rather large interannual variability (carbon uptake: 233–358 g C m^–2^ y^–1^; net oxygen productivity: 730–1150 g O~2~ m^–2^ y^–1^) that was clearly related to algal biomass and global radiation. Compared to the 1980s, the mean annual primary productivity has decreased by 33%.