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

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Abstract

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.

Detaljer

Författare
  • Maidul I. Choudhury
  • Pablo Urrutia-Cordero
  • Huan Zhang
  • Mattias K. Ekvall
  • Leonardo Rafael Medeiros
  • Lars Anders Hansson
Enheter & grupper
Externa organisationer
  • Swedish University of Agricultural Sciences
  • Uppsala universitet
  • Carl von Ossietzky University of Oldenburg
  • Region Skåne
  • Helmholtz Institute for Functional Marine Biodiversity
  • Institute of Hydrobiology, Chinese Academy of Sciences
  • Instituto Federal de Educação, Ciência e Tecnologia do Rio Grande do Norte
  • Lund University
Forskningsområden

Ämnesklassifikation (UKÄ) – OBLIGATORISK

  • Ekologi

Nyckelord

Originalspråkengelska
Sidor (från-till)148-154
Antal sidor7
TidskriftScience of the Total Environment
Volym661
StatusPublished - 2019
PublikationskategoriForskning
Peer review utfördJa