Abstracts (Water column part, week 2)

Boat excursion: Hydrographic measurements, plankton and water sampling (Thomas Badewien)

Lecture: Marine technology (Thomas Badewien)

The lecture will provide an overview of modern technology used for coastal oceanographic research and discusses the hydrodynamic processes governing the Wadden Sea area close to Spiekeroog Island. A special emphasis lies on the instrumentation (e.g. ADCP, CTD) that will be used during the field excursion to this area on the following day. In addition, an introduction will be given to long-term measurements using the ICBM-run Spiekeroog time series station as an example.

Lecture: Basics about the logarithmic ocean bottom boundary layer (Karsten Lettmann)

The lecture provides an introduction to the well known logarithmic velocity profile in coastal oceanic waters. Furthermore, it explains how to extract information on the sea bottom roughness from measured current velocity profiles.

Lecture: High resolution modelling of hydro- and sediment-dynamics with structured and unstructured grids (Jörg Wolff)

Over the last decade the area-specific hydrodynamics and the suspended particulate matter (SPM) dynamics in the East-Frisian Wadden Sea have been extensively investigated under the umbrella of the DFG Research Group on BioGeoChemistry of Tidal Flats at the University of Oldenburg. High-resolution modelling efforts in combination with high-resolution measurements at the Wadden Sea time series station and novel theoretical approaches have revealed various new and exciting insights into this complex system thus significantly contributing to the current state of research. The available suite of numerical models integrates worldwide experience with innovative concepts in numerical modelling such as state-of-the-art parameterizations of physical processes and novel concepts of suspended particulate matter transport. These models have been widely used for various research applications in the Wadden Sea and the German Bight in different horizontal resolutions. Combined with sophisticated measurements using ADCP and satellite data these models enable a reliable state estimate for hydrodynamics and sediment dynamics. The response of the Wadden Sea system to atmospheric and hydrological impacts (storms and sea-level rise) will be highlighted in this lecture along with the basic underlying physics and model details. A new model approach using a finite-volume method on unstructured grids is discussed in a descriptive manner, showing the underlying ideas, the model characteristics, the necessary grid generation and some results from benchmarking the model on various computer architectures. Scientific results from an application to the waste water dispersal close to the city of Wilhelmshaven give first insights into the model performance in the area of the East Frisian coast.

Lab work: Analysis and discussion of hydrography data (Thomas Badewien)

Lecture Phytoplankton Ecology (Helmut Hillebrand)

The lecture starts with a presentation of a functional and taxonomic overview of phytoplankton groups in the Wadden Sea/Southern North Sea. Furthermore, we will present the major growth constraints and mortality sources for phytoplankton. The final part of the lecture focuses on resource limitation under changing biogeochemical cycles.

Lab exercise: Multiple resource limitation (Helmut Hillebrand)

The exercise aims at testing the concept of limiting resources or multiple resource limitation in phytoplankton. The experiment is based on field samples spiked with nutrients (N, P, Si) during the cruise on Monday. Eight treatment combinations are added (N, P, Si, NP, NSi, PSi, NPSi, Control) in triplicate (= 24 flasks in total) and stored under common conditions. On Wednesday, each group microscopically analyses one replicate of each treatment in order to analyze the total and the group specific response to nutrient additions. Literature: Elser et al. 2007, Ecology Letters

Lecture: Trace metals and nutrients in the Wadden Sea system - emphasis on the water column
Lab exercise: Nutrient analysis (Philipp Böning)

The sediments of the Wadden Sea produce dissolved constituents like metals and nutrients, which once released to the overlying bottom waters fuel biogeochemical reactions in the water column. Hence, sources and sinks for dissolved constituents will be discussed in theory (Mn, Mo, nutrients) and in practice (nutrients). During the planned cruise sea water samples will be taken and analysed later in the lab for nutrients via optical means.

Lecture: Introduction to Population Dynamics (Ulrike Feudel)

Population dynamics is a branch of mathematical biology that models important aspects of ecological communities: population growth and decline, competition and predation, immigration and emigration, biodiversity and the risk of extinction to mention but a few. In the lecture I will restrict to systems of ordinary differential equations modelling these aspects in continuous time and through the use of continuous species concentrations. In 90 minutes I will take participants on a tour starting with single species dynamics, leading across predator-prey and two-competitor models, finally culminating in the dynamics of complex food webs.

Lecture and tutorial: Complex ecosystem modelling (Cora Kohlmeier)

The complex ecosystem model ERSEM describing the North Sea and the Langrangian model EcoTiM describing the back barrier area of the island Spiekeroog will be introduced. Both models describe the cycling of carbon and macro nutrients in the water column and in the sediment. The tutorial will give the opportunity to look inside the model, to run different simulation scenarios, for example eutrophication or sea level rise and to compare model results with data from the time series station.

Lecture: Bioinvasion into the North Sea (Bernd Blasius)

Bioinvasion refers to the geographical expansion of species into a new range, in which they proliferate, spread and persist. An important case is given by the increasing number of aquatic non-indigenous species in marine environments. The North Sea with its enormous maritime traffic is particularly affected by introductions of exotic species. One dramatic example is the spread of the Pacific oyster Crassostrea gigas in the Wadden Sea. The lecture will present an overview of the current state of bioinvasion into the North Sea and will discuss perspectives to model, describe and possibly manage bioinvasion processes.

Seminar and discussion: Lessons learned (all lecturers)

At the end we will have a seminar at ICBM in Oldenburg aiming at a synopsis of the summer school activities. The results of the practical exercises and tutorials performed during summer school will be summarized and presented by small groups of the participants. Finally, we like to get a feedback from the attendees about the summer school. Departure is possible in the afternoon from Oldenburg.