The role of three-dimensional eddies in the Baltic Sea – a ten year perspective of physical and biological implications

• Applicant: Dr. Rahel Vortmeyer-Kley
• Subject Area: Oceanography
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 428841213

This project will deal with the impact of three-dimensional eddies on the distribution of plankton and nutrients in the Baltic Sea. It is of crucial interest to investigate if and how these eddies enhance or suppress planktonic growth, since large algal - partly harmful cyanobacteria - blooms are a recurring problem in the Baltic Sea.This research question requires an investigation of eddies’ different impact factors which all influence planktonic growth. Therefore, I divided the problem into four sub-questions (SQ):SQ1. How many and which types of three-dimensional eddies can be found in the western and central Baltic Sea? An answer to this question will lead to a general overview of the properties of our research topic. To this day, neither a long term study of three-dimensional eddies has been conducted nor any knowledge about seasonal and regional distribution of eddies in the entire Baltic Sea exists.SQ2. What is the horizontal volume transport by these three-dimensional eddies? Investigating into this matter helps us to evaluate the transport properties of eddies and to examine whether eddies provide nutrient or plankton pathways or not.SQ3. How distinct is the vertical transport inside these three-dimensional eddies? Insights regarding this question will help us to evaluate the impact of vertical nutrient transport, vertical transport of warmer/colder or saltier/less salty water inside the eddy on biomass increase or decrease of different plankton groups inside the eddy.SQ4. Which influence do three-dimensional eddies have on biological processes? A deeper understanding related to the foodweb-dynamics of different plankton groups inside the eddy will be generated. Therefore, we will investigate changes of biomass of different functional plankton groups inside the eddy. The study will be based on model data (velocity, salinity, temperature, nutrients and plankton concentration fields) from the GETM-ERGOM model for the western and central Baltic Sea for the years 2006-2016 (www.getm.eu, www.ergom.net).

• DFG Programme: Research Grants