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

J Cao,H Ruan

doi:10.3354/ab00605

Abstract

AB Aquatic Biology Contact the journal Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections AB 23:119-127 (2015) - DOI: https://doi.org/10.3354/ab00605 Responses of the submerged macrophyte Vallisneria natans to elevated CO2 and temperature Jiajie Cao1, Honghua Ruan2,* 1College of Landscape Architecture, Nanjing Forestry University, Nanjing 210037, PR China 2College of Biology and the Environment, Joint Center for Sustainable Forestry Studies, Nanjing Forestry University, Nanjing 210037, PR China *Corresponding author: hhruan@njfu.edu.cn 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 CO2 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 CO2 elevation (by bubbling CO2 into experimental water) and ambient temperature warming systems. During the 60 d experiment, CO2 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 CO2 levels significantly enhanced the photosynthetic performance, growth and clonal propagation of V. natans. When combined with an increase in CO2, elevated temperatures also promoted photosynthesis and growth. The individual ramet biomass of V. natans decreased with increasing temperature, but only significantly under ambient CO2 levels. CO2 elevation increased both stolon elongation and bud number. At elevated CO2 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 CO2 levels, however, further research is required. KEY WORDS: CO2 elevation · Biomass allocation · Photosynthetic performance · Submerged macrophyte · Warming Full text in pdf format PreviousNextCite this article as: Cao J, Ruan H (2015) Responses of the submerged macrophyte Vallisneria natans to elevated CO2 and temperature. Aquat Biol 23:119-127. https://doi.org/10.3354/ab00605 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in AB Vol. 23, No. 2. Online publication date: January 22, 2015 Print ISSN: 1864-7782; Online ISSN: 1864-7790 Copyright © 2015 Inter-Research.

Highlights

Since the first records in 1958, the concentration of CO2 in the atmosphere has increased at an annual rate of 0.45%, and the present atmospheric CO2 concentration is > 360 ppm (Parry et al 2007)
Other studies have shown that utilization of bicarbonate increases when plants are grown under conditions of low CO2 availability (SandJensen & Gordon 1986, Jones 2005). These results indicate that the inorganic carbon content of water is an important resource for submerged macrophytes, and that macrophytes vary in their ability to exploit carbon sources under inorganic carbon enrichment (Lacoul & Freedman 2006, Bornette & Puijalon 2011, Wang et al 2012)
Elevated CO2 concentration (1000 ppm) was obtained by bubbling ambient air (CO2 concentration: 370 ppm) mixed with CO2 stored in gas cylinders (99.99% purity) (Yan et al 2006) into a semi-enclosed system; the control treatment was obtained by bubbling ambient air into the system

Summary

Introduction

Since the first records in 1958, the concentration of CO2 in the atmosphere has increased at an annual rate of 0.45%, and the present atmospheric CO2 concentration is > 360 ppm (Parry et al 2007). According to the IPCC (2001, 2007), the greenhouse effect caused by such high CO2 concentrations will increase the global average temperature by 1.4 to 5.8°C. Aquat Biol 23: 119–127, 2015 between these 2 factors on submerged macrophytes are rare. Submerged macrophytes are important to aquatic ecosystems and play an important role in regulating the structure and function of these systems (Cook 1990, Bornette & Puijalon 2011). The effect of temperature on submerged macrophytes is well known (Madsen & Brix 1997, Rooney & Kalff 2000). Barko & Smart (1981) studied 3 common submerged macrophytes and demonstrated that they increased production of aboveground biomass as temperature increased, increasing their total biomass. Potamogeton crispus begins turion production at temperatures above 20°C (Rogers & Breen 1980). You et al (2013b) found that as temperatures increase, the invasive ability (i.e. production of large stem bases) of Eichhornia crassipes increases, with its distribution spreading from southern China into central and northern China

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