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Charophytes collapse beyond a critical warming and brownification threshold in shallow lake systems

Author:
  • Maidul I. Choudhury
  • Pablo Urrutia-Cordero
  • Huan Zhang
  • Mattias K. Ekvall
  • Leonardo Rafael Medeiros
  • Lars Anders Hansson
Publishing year: 2019
Language: English
Pages: 148-154
Publication/Series: Science of the Total Environment
Volume: 661
Document type: Journal article
Publisher: Elsevier

Abstract english

Charophytes play a critical role for the functioning of shallow lake ecosystems. Although growth of charophytes can be limited by many factors, such as temperature, nutrients and light availability, our understanding about concomitant effects of climate warming and other large-scale environmental perturbations, e.g. increases in humic matter content (‘brownification’) is still limited. Here we conducted an outdoor mesocosm experiment during 71 days with a common charophyte species, Chara vulgaris, along an increasing gradient of temperature and brownification. We hypothesized the growth of C. vulgaris to increase with temperature, but to level off along the combined temperature and brownification gradient when reaching a critical threshold for light limitation via brownification. We show that C. vulgaris increases the relative growth rate (RGR), main and total shoot elongation, as well as number of lateral shoots when temperature and brownification increased by +2 °C and + 100%, respectively above today's levels. However, the RGR, shoot elongation and number of lateral shoots declined at further increment of temperature and brownification. Macrophyte weight-length ratio decreased with increased temperature and brownification, indicating that C. vulgaris allocate more resources or energy for shoot elongation instead of biomass increase at warmer temperatures and higher brownification. Our study shows that C. vulgaris will initially benefit from warming and brownification but will then decline as a future scenario of increased warming and brownification reaches a certain threshold level, in case of our experiment at +4 °C and a 2-fold increase in brownification above today's levels.

Keywords

  • Ecology
  • Chara vulgaris
  • Climate change
  • Freshwater
  • Growth rate
  • Humic substances
  • Mesocosm
  • Morphology
  • Submerged macrophyte

Other

Published
  • ISSN: 0048-9697
Lars-Anders Hansson
E-mail: lars-anders [dot] hansson [at] biol [dot] lu [dot] se

Professor

Aquatic ecology

+46 46 222 41 69

E-C140

50

Professor

NanoLund

14

Research group

Aquatic Ecology

Other projects I´m involved in

Doctoral students and postdocs

PhD students, main supervisor

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