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| Effects of elevated nitrogen loading on the growth of Vallisneria natans and Myriophyllum spicatum |
| Received:December 17, 2018 |
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| KeyWord:nitrogen loading;submerged macrophytes;shallow lake;Vallisneria natans;Myriophyllum spicatum |
| Author Name | Affiliation | E-mail | | LI Qi-sheng | National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China
Centre for Research on Environmental Ecology and Fish Nutrion(CREEFN) of the Ministry of Agriculture, Shanghai Ocean University, Shanghai 201306, China
Shanghai Engineering Research Center of Aquaculture, Shanghai Ocean University, Shanghai 201306, China
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China | | | HU Zhong-jun | National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China
Centre for Research on Environmental Ecology and Fish Nutrion(CREEFN) of the Ministry of Agriculture, Shanghai Ocean University, Shanghai 201306, China
Shanghai Engineering Research Center of Aquaculture, Shanghai Ocean University, Shanghai 201306, China | | | LI Yong-ji | Yueyang Institute of Aquaculture, Yueyang 414001, China | | | HE Hu | State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China | | | HAN Yan-qing | State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China | | | JIN Hui | State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China | | | LI Kuan-yi | National Demonstration Center for Experimental Fisheries Science Education, Shanghai Ocean University, Shanghai 201306, China
Centre for Research on Environmental Ecology and Fish Nutrion(CREEFN) of the Ministry of Agriculture, Shanghai Ocean University, Shanghai 201306, China
Shanghai Engineering Research Center of Aquaculture, Shanghai Ocean University, Shanghai 201306, China
State Key Laboratory of Lake Science and Environment, Nanjing Institute of Geography and Limnology, Chinese Academy of Sciences, Nanjing 210008, China
Sino-Danish College, University of Chinese Academy of Sciences, Beijing 100049, China | kyli@niglas.as.cn |
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| Abstract: |
| N and P are key factors that limit phytoplankton growth in freshwater lakes. Controlling external P loading is a widely recognized measure for lake restoration, but the necessity of limiting N inputs remains under debate. Here, we conducted a mesocosm experiment with a duration of 28 d to explore the effects of external N loading on the growth of submerged macrophytes with contrasting growth types of rosette(Vallisneria natans)and canopy(Myriophyllum spicatum). There were mixed plantings of both macrophytes(density ratio:1:1)in each mesocosm. Our experiment design included one treatment with two levels of N inputs(high N group:N:P=100:1; low N group:N:P=5:1). The results showed that high N inputs greatly inhibited the growth of V. natans, which had a significantly lower relative growth rate, biomass, root length, and number of plants and leaves in the high N group compared with those in the low N group. However, there were no significant differences in the relative growth rate, biomass, internodal length, total height, and number of plants of M. spicatum between the two N loading treatments, thereby indicating that N loading did not have a significant effect on the growth of M. spicatum. Overall, the total biomass of the two submerged macrophytes in the high N group(115.86 g·m-2)was only 36.0% of that in the low N group(321.98 g·m-2), thereby indicating that high external N loading had a significant negative effect on submerged macrophytes. Our study suggested that high N inputs can greatly reduce submerged macrophytes in shallow lakes, but the effects are species-specific. From the perspective of lake management and restoration, our study supported the view that both N and P should be controlled. |
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