Responses of the submerged macrophyte Vallisneria natans to elevated CO2 and temperature

Abstract

Inorganic carbon and temperature are 2 important factors that regulate the growth of submerged macrophytes. However, experimental evidence regarding the eco-physiological changes that occur in submerged macrophytes in response to elevated CO 2 and temperature is still limited. To investigate how the submerged macrophyte Vallisneria natans (Hydrocharitaceae), a common species in the waters of the middle and lower reaches of the Yangtze River, responds to these factors, we conducted a mesocosm experiment using simulated CO 2 elevation (by bubbling CO 2 into experimental water) and ambient temperature warming systems. During the 60 d experiment, CO 2 elevation significantly increased the inorganic carbon concentration in the water column. The warming systems elevated average water temperature by approximately 3°C. The elevation of CO 2 levels significantly enhanced the photosynthetic performance, growth and clonal propagation of V. natans. When combined with an increase in CO 2 , elevated temperatures also promoted photosynthesis and growth. The individual ramet biomass of V. natans decreased with increasing temperature, but only significantly under ambient CO 2 levels. CO 2 elevation increased both stolon elongation and bud number. At elevated CO 2 concentration, more biomass was allocated to the stolons, roots and buds, while less biomass was allocated to the leaves. These results indicate that the eco-physiological responses of V. natans should increase its stress tolerance in aquatic plant communities under future spatial and temporal variation in CO 2 levels, however, further research is required.

Response of Submerged Macrophyte Growth, Morphology, Chlorophyll Content and Nutrient Stoichiometry to Increased Flow Velocity and Elevated CO2 and Dissolved Organic Carbon Concentrations

“…In this study CO 2 , DOC and, to a smaller extent, flow velocity (all potential effects of climate change) had strong effects on the growth and development of B. erecta, which is consistent with what was found in literature (Steinberg et al, 2006;McElarney et al, 2010;Cao and Ruan, 2015;Reitsema et al, 2020). Macrophytes that grew in the wet climate change scenario with increased heavy precipitation intensity (HD-HC-HF) had a higher RGR, more biomass, shorter stems, a higher root:shoot ratio, lower N content and higher P content than the plants growing in the no climate change scenario.…”

Effects of salinity and temperature on tuber sprouting and growth of Schoenoplectus nipponicus

“…In the present study, the ramet number was increased at 25/15°C and then diminished with the temperature rose in non‐saline conditions. Similar to our results, an appropriate increase in temperature will increase the ramet number of submerged macrophyte Vallisneria natans (Cao and Ruan 2015). For one thing, temperature elevation can increase the activity of photosynthetic, enzymes, and carbonic anhydrase, which likely caused the increases in ramet number in our experiment (Olesen and Madsen 2000).…”

“…The influence of salinity on plant growth generally showed that seedling growth is inhibited with the increase in salinity, which is mainly manifested by the reduction in growth traits and biomass accumulation (Pompeiano et al 2016, MacTavish and Cohen 2017). Meanwhile, the biomass accumulation and clonal reproductive capacity of salt marsh plants would increase with the rising temperature (Johnson and Thornley 1985, Cao and Ruan, 2015, Zhang et al 2018). Higher temperature may also enlarge or reduce the influence of salinity on plant growth, but the relevant evidence is still insufficient.…”

Freshwater biota and rising pCO2?

“…), increase growth (Yan et al . ; Cao & Ruan ), and alter allocation of biomass (Cao & Ruan ). Of note, however, macrophytes have been found to self‐limit based on daily fluctuations in pH (i.e.…”