Impact of native and non-native aquatic plants on methane emission and phytoplankton growth

Grutters, B. M. C., R. C. H. Aben, S. Kosten, and E. S. Bakker. 2017. Impact of native and non-native aquatic plants on methane emission and phytoplankton growth. Aquatic Invasions 12:371–383. PDF.

Summary

While there is substantial evidence to show that increased CO2 favors invasive terrestrial plants, less is known about the impact of temperature and CO2 on aquatic species. There is even less known about how subsequent changes will impact freshwater ecosystem services, especially coupled with eutrophication. Grutters et al. (2017) conducted a mesocosm study to see how plant growth of native and non-native freshwater plant species under warm, eutrophic conditions would affect two freshwater ecosystem services: 1) the inhibition of phytoplankton dominance, and 2) the limiting of greenhouse gas emissions. They selected 4 species native to lakes in the Netherlands* and 4 non-natives** (Cabomba caroliniana, Carolina fanwort; Lagorosiphon major, oxygen weed; Myriophyllum aquaticum, parrot feather; Myriophyllum heterophyllum, Broadleaf water-milfoil). The authors found that plant growth (measured in biomass) was variable among plant species. The authors found that impact of the warmer, eutrophic conditions on growth and ecosystems services were species-specific. These results suggest that the impacts of climate change on freshwater invasive plants may be more difficult to predict that their terrestrial counterparts.  

Take home points

  • Parrot’s feather (Myriophyllum aquaticum) responded positively to warm, eutrophic conditions. However, the increase in biomass did not result in changes in ecosystem services (measured in phytoplankton mass and methane emissions). 

  • Overall, the differences in plant growth among the species of growing under warmer, eutrophic conditions was attributed to species-specific characteristics, rather than native vs. non-native characteristics.

  • The impact of altered plant growth on the inhibition of phytoplankton dominance and on limiting methane emissions was also species-specific. 

Management implications

  • The results of this study do not support the notion that non-native freshwater plants have a competitive advantage over natives, or that they will 

  • Overall, the impacts of climate change and eutrophication on biomass should be considered on a species by species by species basis. 

  • Myriophyllum aquaticum may become more invasive as temperatures increase under climate change. However, we caution that study was conducted in the Netherlands and under under eutrophic conditions. 

*Ceratophyllum demersum, Hottonia palustris, Myriophyllum spicatum, Ranunculus circinatus

**While the study was conducted in the Netherlands, all of the non-native species considered are also present in the Northeastern U.S, and 3 are ranked High or Very High by the NY DEC’s Species Status Assessments.  

Keywords

Impact Study; Experiment; Invasive Plant; Aquatic Habitat