Department of Biological Sciences, Kent State University Kent, OH 44242

*Corresponding author: ttrzebuc@kent.edu

Summary

   The effects of labile dissolved organic carbon (LDOC) on phosphorus dynamics of plankton were studied at diverse stations during synoptic surveys of Lake Erie aboard the CCGS Limnos in August of 2003 and June, July, and August of 2004. The sites represented diverse LDOC regimes, trophic states, and basin locations. LDOC values ranged from 13.7 to 126.5 µM. At higher LDOC concentrations, a greater portion of the phosphorus pool was distributed to algae, and at lower LDOC concentrations, a greater portion of the phosphorus pool is distributed to bacteria. Bacterial P-quota was greatest at stations with the lowest LDOC concentrations. Phosphate uptake by bacteria was greater at lower LDOC sites and lower at higher LDOC sites. LDOC concentration was not related to trophic state index (TSI), calculated based on chlorophyll a concentrations. These observations support the microbial shunt hypothesis (MSH). Phosphate apportionment to bacteria was consistent and independent of LDOC concentrations. This observation varies from the MSH.