The section Bentho-Pelagic Processes (BPP) unites marine scientists and staff for an in situ Observational Ecology approach. We combine traditional sampling methods with novel instrumentation to explore the structure and dynamics of polar animal communities in their natural environment and in response to climate change. Our scientific focus is on makrofauna – large corals and sponges providing three-dimensional habitat supporting a rich biodiversity – and the roles of bottom-up (environmental) versus top-down (predation by fish and seals) control in structuring communities and processes. With a regional focus on the Weddell Sea, we contrast the rapid climate-induced changes in the Antarctic Peninsula region with the more gradual changes along the eastern Weddell Sea shelf in response to warming. Furthermore, we do research in the Patagonian fjords of Chile, since the origin of many organisms, such as cold-water corals in the deep sea, allows us to find these animals both in the Antarctic and north of the Drake Passage. Studies on organisms in the Patagonian fjords therefore allow conclusions to be drawn about their relatives in Antarctica.