US EPA

3289231 

Journal Article 

Effects of N and P additions to water column on growth of Vallisneria natans 

Mei, X; Zhang, X 

2015 

Yes 

Journal of Aquatic Plant Management
ISSN: 0146-6623 

Aquatic Plant Management Society, Inc., US Army Engineer Waterways Experiment Station Vicksburg MS 39180 United States 

53 

36-43 

WOS:000367964700006 

We examined the effects of adding nitrogen (N) and phosphorus (P) to the water column of aquatic mesocosms in which the freshwater eelgrass Vallisneria natans was growing. Total nitrogen (TN) and total phosphorus (TP) concentrations in the water column, biomasses (measured as Chl a) of phytoplankton and periphyton, light intensity, and dry biomasses of plant material were measured. Ramet count, biomass/ramet, and ratio of belowground/aboveground biomass were calculated. Compared to controls, mesocosms with added N exhibited increased TN, periphyton Chl a, and biomass ratio, but showed reductions in ramet counts, biomass, total biomass/ramet, and aboveground biomass/ramet of V. natans. The addition of P resulted in increased ramet counts, biomass, and biomass ratio compared to controls, but reduced total biomass/ramet and aboveground biomass/ramet. The addition of combined N + P resulted in higher concentrations of TP and Chl a of phytoplankton, but lower light intensity, ramet counts, and biomasses compared with controls. Biomass (total and aboveground)/ramet and biomass ratio remained unaltered after N + P addition. Our study demonstrates that growth of V. natans is significantly affected by addition of N and P in the water column, which has important implications for plant management in aquatic ecosystems because decline or enhancement of the growth of submersed plants can markedly alter many aspects of aquatic ecosystem. In light of our findings, both N and P loading to aquatic ecosystems should be controlled to restore the degraded aquatic ecosystem or protect aquatic ecosystems with submerged plants. 

nutrient; growth; submerged plant; aquatic ecosystem