Submerged vegetation removal promotes shift of dominant phytoplankton functional groups in a eutrophic lake
Dong Jing
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DOI:
Received October 30, 2013,Revised February 16, 2014, Accepted February 19, 2014, Available online 2014-04-10
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Abstract: Historical data indicate that the dominance of submerged plants in Dianchi Lake in the 1960s was characterized by low algal density with dominance of non-toxic group J (Scenedesmus, Pediastrum, etc.). The removal of submerged plants, which began in the 1970s, resulted in the expansion of bloom-forming Microcystis (group M). Laboratory experiments suggested that Microcystis aeruginosa was inclined to grow and develop at elevated temperatures. The growth of Scenedesmus obiquus was slower than that of co-cultivated M. aeruginosa in the absence of C. demersum, especially at higher temperatures. The existence of submerged plant Ceratophyllum demersum could inhibit the growth of the harmful algae M. aeruginosa. And this inhibitory effect by C. demersum was enhanced with an increase in temperature. Instead, with C. demersum, the growth of S. obliquus was not inhibited, but the co-cultivated M. aeruginosa was eliminated in short time. Combined with the historical data and laboratory experiments, it was indicated that the submerged plants might play important roles in the dominance of the non-toxic group J in the historical succession. Consequently, the introduction of the submerged plant such as C. demersum might alter the dominant phytoplankton functional groups from M to J and benefit the restoration of the eutrophic lake.
