Klug, J. L.. University of Wisconsin, email@example.com
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POSITIVE AND NEGATIVE EFFECTS OF DISSOLVED ORGANIC MATTER ON PHYTOPLANKTON GROWTH
Dissolved organic matter (DOM) may affect phytoplankton growth in several ways. A major negative effect is the limitation of phytoplankton growth by shading from absorbance of light by colored DOC. However, DOM may also change the availability of inorganic nutrients directly via chelation or indirectly via bacterial processes. These effects may be either positive or negative. I conducted short-term cubitainer experiments to explore these contrasting effects of DOM on phytoplankton in West Long Lake located in Upper Michigan. When the experiments were performed at high or medium light, additions of DOM (extracted from sphagnum peat moss) alone, or in combination with inorganic nitrogen and phosphorus, stimulated phytoplankton growth. At low light, DOM did not stimulate growth presumably because phytoplankton were light limited. Possible explanations for the stimulatory effect include addition of trace elements with the DOM and changes in the availability of inorganic nutrients. These results suggest that in addition to the negative shading effects of DOM on phytoplankton growth, positive effects exist which may stimulate algal growth under certain conditions.
Day: Thursday, Feb. 4
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