Multiple stressors

Mille Anna Lilja & Steffanie Düring Hansen

Studenteropgave: Fagmodulprojekt


Marine macroalgae play a major ecological role in many coastal marine systems, where some seaweeds function as foundation species. Ongoing climate changes are predicted to increase the sea temperature and lower salinity in coastal areas due to heavier and more intense precipitation during summer. These abiotic factors often come hand in hand with each other and may have interacting effects on the organisms. In order to study how reduced salinity and increased temperature affect macroalgae, and how the two stressors interact, we selected the intertidal species of brown algae, Fucus serratus, which is often used as a model organism due to its ecological importance and high prevalence. Furthermore, this project also aims to explore what F. serratus potential to acclimate to constantly changing environments is.
To answer these questions, we exposed F. serratus to 13 and 25 PSU salinity levels combined with temperatures ranging across 15, 23 and 28°C over a 6 weeks period. We chose the following end-point as proxies for the performance of F. serratus; growth, survival, PAM fluorescence (Fv/Fm and ETRmax), photosynthesis performance (dark respiration and photosynthetic rate), and changes in the pigmentation (amount and composition). These measurements are expected to provide a scientific basis for determining the level of stress induced to the algae.
From the results we concluded that F. serratus could not survive prolonged exposures to high 28°C temperatures. Exposure to 23°C temperature is harmful to the algae, but it was not deadly, and F. serratus acclimated. The lower salinity concentration of 13 PSU did not severely harm the algae and it was able to acclimate to it too. Finally, the overall combined effects from the two factors on F. serratus appeared to be additive over 6 weeks period.

UddannelserMiljøbiologi, (Bachelor/kandidatuddannelse) Bachelor
Udgivelsesdato18 dec. 2018
Antal sider27
VejledereMorten Foldager Pedersen


  • Fucus serratus
  • multiple stressors
  • high temperature
  • low salinity