Tanja Stratmann is a sea-going deep-sea ecologist who works at the interface of biogeochemistry and benthic ecology. She studies benthic ecosystem functions and ecosystem health. To be more precise, she aims to decipher the underlying processes and interactions within an ecosystem (i.e., its functions) to better understand and predict the stability, the resilience to natural and anthropogenic disturbances, and the recovery potential of the ecosystem (i.e., its health). Afterwards, measures may be taken to improve the health status of the system, for example by applying nature-based solutions.
Research approaches/ methodologies
For her studies, Tanja Stratmann combines observational studies using still-photo and video transects with towed camera systems and remotely operated vehicles (ROV) with in-situ sampling of physical specimens by ROVs. Afterwards, in shore-based laboratories she analyzes the natural abundance stable isotopic composition (未13C, 未15N, 未2H) of these specimens and of sediment samples; she determines the fatty acid (i.e., total fatty acids, phospholipid-derived fatty acids, neutral fatty acids) and amino acid composition using compound-specific stable isotope analyses.
Additionally, she performs ex-situ and in-situ (pulse-chase) labelling experiments with 13C and/ 15N-enriched food sources (e.g., phytodetritus, bacteria) that she combines with 1 鈥� 2.5% deuterium oxide (2H2O) enrichments. In-situ experiments are conducted with fully automated benthic chamber landers or semi-automated incubation chambers that are deployed by ROVs in the deep sea and by hand/ divers in shallow waters. In comparison, ex-situ experiments with sediments or individual faunal organisms are conducted in core incubations and incubation chambers in temperature-controlled climate rooms.
Often, she implements data gained during field campaigns and research cruises in carbon-based linear inverse food-web models. This modelling type is particularly suitable for data-poor sites, and it allows to quantify the carbon cycle through the different food-web compartments ranging from bacteria to fish.
To estimate the importance of specific substrate types (e.g., polymetallic nodules) or taxa (e.g., Astrophorina sponges), she uses interaction-web models that link all trophic and non-trophic interactions in a specific study area. In this way, she can determine which taxon is the so-called 鈥榟ighest impact taxon鈥�, i.e., the taxon whose removal has the largest impact on food-web properties.
Links