P-Campus Lecture Series 2023

The lecture has to be cancelled at short notice on 20.04.2023 due to illness.
New date: 27.04.2023

Abstract
Coastal ecosystems are exposed to multiple stressors due to their use and transboundary position between the sea and terrestrial realm, which can decrease ecosystem integrity and subsequent ecosystem services. For example, the catchment area of rivers transports large amounts of nitrogen and phosphorus into coastal waters, which subsequently suffer from eutrophication. Countermeasures have had limited success to date, as decreased nutrient inputs have also altered phytoplankton communities. The altered community, often consisting of picophytoplankton, is able to maintain a high biomass and turbidity despite little freely available phosphorus, which prevents the establishment of e.g. macrophytes. In this talk, ecological aspects of the phytoplankton communities of the southern Baltic Sea in relation to phosphorus will be examined in more detail. Results will be presented on seasonal, long-term, and spatial data of phosphorus, physiological, population biology and biomanipulation studies using mesocosms. It will be discussed what other management options could be pursued (or not) to reach again a clear water state in German coastal waters.

Date/Time
20.04.2023 / 15:00 - ca. 15:45 h (excl. questions)

Location
online via Webex

Lecturer
Dr. Maximilian Berthold (Phytoplankton Ecophysiology, Mount Allison University, Canada)

Language
German / slides of the presentation in English

Participation Fee
free of charge

Abstract
The availability and cycling of phosphorus in soils are significantly influenced by soil aggregates, which range in their size from large macroaggregates to smallest nanoparticles. The assembly of aggregates of different sizes creates a 3D structure with interconnected voids and pores of different shapes, sizes, and geometries. This network of pores acts as a dynamic biogeochemical interface that facilitates the movement of gases and water within the soil. The architecture and stability of soil aggregates, and thus their ability to provide niches for water storage and microbial nutrient metabolism, depend largely on the spatial arrangement of the individual structural units, their elemental composition, and the distribution of metal oxides and organic matter. In particular, soil colloids (particles smaller than 1000 nanometers) are increasingly recognized as important nutrient carriers in ecosystems because of their unique composition and large specific surface area. They are highly mobile in soils, and the transport of elements facilitated by colloids is closely linked to water movement in the soil. As a result, loss of P and other nutrients through particulate transport has become a growing concern. In this talk, we will take a closer look at the composition and stability of soil aggregates and their controls on phosphorus turnover by organisms. We will discuss the impact of land use change on the phosphorus turnover and examine analytical techniques for characterizing nanoparticles and colloids in soil, including their size and elemental composition. By means of a case study, we specifically examine subsurface transport of particulate phosphorus to adjacent surface waters. By understanding the complex interactions between soil aggregate architecture, elemental composition, and biogeochemical processes, we can control nutrient cycling in ecosystems and mitigate the loss of phosphorus and other nutrients through particulate transport.

Date/Time
01.06.2023 / 15:00 - ca. 15:45 h (excl. questions)

Location
online via Webex

Lecturer
Dr. Nina Siebers (Forschungszentrum Jülich)

Language
English

Participation Fee
free of charge