Climate change and intensifying human resource use are causing massive changes to Subantarctic coastal systems and carbon cycling. At the same time, these systems house benthic communities of highest biomass and biodiversity, which sustain important ecosystem services and require strategic observation and management plans. Although they are just beginning to be appreciated by scientists and public, natural (climate mitigation) and cultural ecosystem services (e.g. local fisheries, tourism, sustainable aquaculture) are already jeopardized by the massive scale and velocity of the regional change in Southern Patagonia (SP) and at the West Antarctic Peninsula (WAP). The multidisciplinary network CoastCarb joins experts in Subantarctic coastal system ecology and ecological modelling to create a knowledge information system with open access data portal and produce dynamic ecosystem models for fjordic and estuarine environments. Using data on carbon budgets and flow (including benthic and pelagic food webs, microbes to megafauna) from across the network, specialists will analyse the relationships between ecosystem services, local stakeholders and communities, to identify barriers and enablers of the sustainable use of marine resources. Study areas along the fragmented SP/WAP coastline are intensively investigated. Data sets from more than 10 recent interdisciplinary research projects of CoastCarb participants, and from the scientific core programmes at coastal stations (ARG-GER Carlini-Dallmann, US Palmer, UK Rothera, PL Arctowski) will be used for knowledge compilation. The established network is based on German, Belgian, Dutch, British, Argentine, Chilean and US participants with new Polish and Canadian partners included. CoastCarb secondments foster capacity building in research and observation for a better understanding of complex ecosystem processes and major hazard scenarios (e.g. harmful algal blooms), and in targeted science stakeholder interaction events.