Global Change Sharpens the Double-Edged Sword Effect of Aquatic Alien Plants in China and Beyond.

Hao Wu,Jianqing Ding

doi:10.3389/fpls.2019.00787

Hao Wu, Jianqing Ding

Open Access

https://doi.org/10.3389/fpls.2019.00787

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Abstract

Many alien aquatic plants are deliberately introduced because they have economic, ornamental, or environmental values; however, they may also negatively affect aquatic ecosystems, by blocking rivers, restricting aquatic animals and plants by decreasing dissolved oxygen, and reducing native biodiversity. These positive and/or negative ecological effects may be enhanced under global change. Here, we examine the impacts of global change on aquatic alien plant introduction and/or invasions by reviewing their introduction pathways, distributions, and ecological effects. We focus on how climate change, aquatic environmental pollution, and China’s rapid economic growth in recent decades affect their uses and invasiveness in China. Among 55 species of alien aquatic plants in China, 10 species are invasive, such as Eichhornia crassipes, Alternanthera philoxeroides, and Pistia stratiotes. Most of these invaders were intentionally introduced and dispersed across the country but are now widely distributed and invasive. Under climate warming, many species have expanded their distributions to areas where it was originally too cold for their survival. Thus, these species are (and will be) considered to be beneficial plants in aquaculture and for the restoration of aquatic ecosystems (for water purification) across larger areas. However, for potential invasive species, climate warming is (and will be) increasing their invasion risk in more areas. In addition, nitrogen deposition and phosphorus inputs may also alter the status of some alien species. Furthermore, climate warming has shifted the interactions between alien aquatic plants and herbivores, thus impacting their future spreads. Under climate change, more precipitation in North China and more frequent flooding in South China will increase the uncertainties of ecological effects of alien aquatic plants in these regions. We also predict that, under the continuing booming economy in China, more and more alien aquatic plants will be used for aquatic landscaping and water purification. In conclusion, our study indicates that both human activities under rapid economic growth and climate change can either increase the potential uses of alien aquatic plants or make the aquatic invaders worse in China and other areas in the world. These findings are critical for future risk assessment of aquatic plant introduction and aquatic ecosystem restoration.

Highlights

Global change includes climate change, nitrogen deposition, changes in land-use patterns, and biological invasions (Lin et al, 2010; Pyšek et al, 2010; Lu et al, 2013)
Most of studies on climatic warming, eutrophication and elevated rainfall reported negative impacts and a few addressed positive impacts, while studies for global trade only dealt with the negative impacts, i.e., ecological effects of aquatic alien plants (Figure 3)
In China, eutrophication increases biomass accumulation, asexual reproduction, compensatory growth, and photosynthetic leaf areas of A. philoxeroides (Shen et al, 2007; Jiang et al, 2010; Zuo et al, 2012; Ding et al, 2014); promotes the growth rate, clonal propagation, nitrate reductase, and glutamine synthetase activities of E. crassipes (Li et al, 2008, Li and Wang, 2011); and increases the biomass, shoot length, and nutrient uptake of M. aquaticum (You et al, 2013; Liu S.B. et al, 2017), which intensify the interspecific competition of these three aquatic invaders with respect to native plants

Summary

Introduction

Global change includes climate change, nitrogen deposition, changes in land-use patterns, and biological invasions (Lin et al, 2010; Pyšek et al, 2010; Lu et al, 2013). The negative impacts of warming include the reduction in native species diversity through increased interspecific competition, accelerated water pollution through increased alien plant litter decay rates, and aggravated aquatic alien plant invasions through an increase in their biomass and overwintering (Figure 4).

Results

Conclusion