Workpackage 2
Research Objective: The coastal zone is a highly dynamic transit space for matter and organisms, characterized by significantly varying exchange processes. The goal of AP2 is to develop a harmonized sampling system that links core physical data (e.g., salinity, temperature) with turbulence measurements, biogeochemistry, and biodiversity. This approach aims to capture the complex interactions between hydrodynamics and biology at the relevant scales.
Methodology: The approach combines high-resolution time series at fixed stations via automated measurements with spatially flexible data collection using innovative autonomous systems. This enables a precise analysis of the ecological impacts of short-term extreme events ("hot moments"), such as algal blooms or storms, on the coastal ecosystem. The results are validated and further specified through laboratory experiments.
Automated Measurements
The Imaging FlowCytobot (IFCB) is an automated, submersible cytometer that captures in-situ phytoplankton images, identifying them using AI-algorithms. Recently acquired for the Shore-to-Basin program, it is deployed at the Heiligendamm pier to complement the IOW’s long-term monitoring. This setup provides continuous, real-time data on how phytoplankton communities in coastal waters of the Baltic Sea respond to stressors like storms and heatwaves.
Environmental DNA Oceanic Thresher (eDOT): The eDOT enables the seamless monitoring of biological diversity (biodiversity) in water bodies over long periods using eDNA samples, without the need for constant on-site personnel. Within the S2B project, this is utilized to record continuous measurements and assess the impacts of extreme weather events in shallow waters.
Innovative Autonomous Measuring Systems
Drone-Based Remote Sensing: Regular hyperspectral flights are conducted in coastal areas to record marine parameters. Image data acquisition is performed specifically over water surfaces, with data validation ensured through accompanying in-situ environmental measurements.
Uncrewed Surface Vehicle (USV): The BlueBoat is a versatile USV designed for automated surveys in shallow water areas. This modular platform can integrate a variety of sensors—including underwater cameras, ADCPs, multibeam echosounders, side-scan sonars, profiling winches, and the eDOT.
The eddy covariance system measures turbulent flux by capturing high-resolution flow and concentration data. Our system also integrates an Acoustic Doppler Velocimeter with multiple sensors (currently oxygen and temperature) to simultaneously record complex biogeochemical exchange processes.
Laboratory Experiments
Shallow coastal waters are frequently characterized by storm-induced sediment resuspension. Since anoxic conditions in the sediment inhibit the germination of plankton resting stages, this mechanism could potentially facilitate the process. In a laboratory experiment, sediment cores were observed over four months at increasing temperatures, either left undisturbed or subjected to regular resuspension events.t.
The results show that the composition of the protist community was primarily determined by a temperature-dependent species succession. While the total number of species remained unaffected by the mixing, the community structure changed due to the germination of resting stages.
For zooplankton, the focus is on life cycles and spring recruitment. In incubation experiments, we investigate under in-situ conditions how seasonal environmental factors—specifically temperature and resuspension—influence the activation of resting eggs in the sediment. Furthermore, we are researching the conditions for the production of these stages in the context of climate change.