Seasonal kelp primary production at a rocky shore site: Integrating physiology and biochemistry into ecological modelling

• Applicant: Professor Dr. Ulf Karsten, since 4/2019
• Subject Area: Ecology and Biodiversity of Plants and Ecosystems ; Plant Physiology
• Term: from 2018 to 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 407670545

Coastal hard bottom zones of temperate regions are dominated by dense underwater kelp forests as key primary producers, thereby generating high amounts of biomass and carbon, which represent a major trophic contribution to these marine ecosystems. Kelp forests provide three-dimensional, heterogeneously structured habitats, providing food and shelter for the associated rich marine flora and fauna. However, these underwater forests are under risk due to global warming as kelp needs low water temperatures. Surface waters in the North Sea around Helgoland have already warmed by more than 1°C since the 1960s and this trend is predicted to reach into the next century. Despite the ecological importance of kelps in coastal ecosystems, only very few data exist worldwide on standing biomass, distribution and crude primary production estimates. The study area Helgoland in the North Sea is an exceptional region with a reasonable database on kelp biomass, growth and vertical distribution. However, for an accurate calculation of kelp primary production, two main missing gaps remain: (1) the exact conversion of photosynthetic oxygen production into carbon fixation units and (2) the impact of increasing temperatures on seasonal kelp photosynthetic performance for a dynamic assessment of primary production. Both processes are not only unknown for kelps in the temperate region, but also for all other kelp communities worldwide. Therefore, the main goal of this project is to determine for the first time the seasonal changing primary production and carbon budget in these macroalgae. This will be achieved by using a combination of different approaches (O2- and 14C-method) as well as physiological and biochemical measurements of the actual carbon fixation with state-of-the-art methods such as chromatography and mass spectrometry. The impact of the forecasted global warming will be also investigated on the seasonal primary production rates. These results, together with the existing database on kelps around Helgoland, will be used to develop for the first time an ecological model for kelp primary production, i.e. a dynamic physiological box model. This will serve as a tool to simulate various global change scenarios and to identify biological sensitivities and possible thresholds. Such a broad approach has never been applied before to kelps worldwide and hence represents one of the key innovations of this proposal.

• DFG Programme: Research Grants
• International Connection: Spain
• Co-Investigators: Dr. Inka Bartsch; Dr. Katharina Zacher-Aued
• Cooperation Partner: Professor Dr. Francisco Gordillo
• Ehemalige Antragstellerin: Dr. Angelika Graiff, until 3/2019