The core research theme of the RTG 2530 is biota-mediated effects on estuarine C cycling under current environmental conditions and with respect to global change scenarios. Whereas the role of basic physiological processes of biota for C cycling is generally acknowledged, biotic interactions and their mediating role on C cycling have been largely ignored. In estuaries, plant-microbe interactions in the rhizosphere of tidal marshes, microphytobenthos-microbe interactions on sediment surfaces and phytoplankton-microbe interactions on organic matter (OM) aggregates in estuarine channels are key for C cycling. These biotic interactions and their effects on C cycling are, in turn, controlled by animals through their role in estuarine food webs, which also impact the reciprocal C fluxes between marshes and estuarine channels.
The RTG 2530 aims at a systematic analysis of these biota-mediated effects on estuarine C cycling. By an innovative combination of ecological, biochemical, molecular and modeling approaches in an interdisciplinary consortium, key processes in rhizospheres in estuarine marshes, on biofilms at sediment surfaces of intertidal flats and on OM aggregates (‘phycospheres’) in estuarine channels will be studied. Furthermore, their interactions with herbivory and estuarine food webs and resulting C fluxes between estuarine marshes, intertidal flats and subtidal channels will be studied. Based on the knowledge gathered in the RTG, processes of biota-mediated effects on estuarine C cycling will be parameterized in estuarine ecosystem models (EMs). Our long-term vision is to develop robust, mechanistic and biologically reasonable model approaches that capture the essential processes of biota-mediated estuarine C cycling and are suitable for implementation in Earth System Models (ESMs).
The RTG 2530 aims at addressing three overarching research questions:
- How do biotic interactions mediate C cycling in estuaries?
- Which interactions are relevant from the micro- to the landscape scale?
- How is biota-mediated C cycling in estuaries affected by global change?
This figure shows the tidal high water situation.
Abbreviations: DIC = Dissolved inorganic carbon, DOC = Dissolved organic carbon, POC = Particulate organic carbon, SPM = Suspended particulate matter, MThw = Mean tidal high water, MTlw = Mean tidal low water
This figure shows the tidal low water situation.
Abbreviations: DIC = Dissolved inorganic carbon, DOC = Dissolved organic carbon, POC = Particulate organic carbon, SPM = Suspended particulate matter, MThw = Mean tidal high water, MTlw = Mean tidal low water.
The initial research programme is structured by the following three Research Themes (RTs):
- RT A: Biota-mediated C cycling in estuarine marshes: Rhizosphere processes and effects of herbivory
- RT B: Biota-mediated C cycling in estuarine channels: Phycosphere processes on and effects of trophic interactions
- RT C: Biota-mediated C fluxes across marsh-water boundaries