Kelps are important foundation species in coastal cold-water ecosystems, and loss of these organisms are a threat to global biodiversity. The kelp Saccharina latissima is widely abundant on the northern hemisphere, however severe reduction in the abundance of the kelp has been observed in Northern Europe during recent decades. S. latissima is adapted to cold waters and the decline of the kelp is likely caused by increased frequency and intensity of extreme summer heat events as a result of climate change. We assessed the physiological stress response of S. latissima when exposed to 4 simulated heat wave scenarios of maximum 15°C, 18°C, 21°C and 24°C. Mortality was only significant for S. latissima exposed to the 24°C heat wave where >90% died after 8 days of exposure to maximum temperature. Furthermore, growth rate and photosynthetic efficiency decreased significantly, while production of reactive oxygen species (ROS) increased significantly for S. latissima exposed to 21°C and 24°C compared to 15°C. Our results indicate that the reduced photosynthetic efficiency at high temperatures may partly have been caused by photoinhibition of PSII and low chlorophyll a content due to photooxidation. The concentration of carotenoid pigments increased at high temperatures which was likely an antioxidant response to thermal increased production of ROS. Contrary to our expectations yield of regulated heat dissipation (ΦNPQ) decreased with increasing temperatures indication a lack of photoprotective capacity during heat stress. Our findings indicate that thermal stress caused by extreme events, like the 21˚C and 24˚C heat waves pose a serious threat to Danish populations of S. latissima.
|Uddannelser||Miljørisiko, (Bachelor/kandidatuddannelse) Kandidat|
|Udgivelsesdato||10 nov. 2015|
|Vejledere||Morten Foldager Pedersen|
- Macroalgae Physiology
- Global warming
- Saccharina latissima