TRAFFIC
The overall objective of the research project TRAFFIC (Trophic TRAnsfer eFFICiency in the Benguela Current) is to broaden our knowledge on processes driving the trophic systems of the northern and southern Benguela upwelling sub-systems (nBUS, sBUS) and associated feedbacks to fisheries and climate. Despite similar primary production (PP), significant differences are found in composition and biomass in fish stocks and top predators and in contrast to the nBUS, which is a significant source of CO2 to the atmosphere the sBUS acts as CO2 sink. The aim of the project is to study the food-web structure and functional links, to analyse the trophic transfer efficiency, and the associated effect of the biologically mediated CO2 uptake. A more efficient trophic transfer efficiency probably increases fishery yields and the CO2 uptake in the southern BUS, and human induced changes in the pelagic food web structure lowered fishery yields and favored the CO2 emission in the nBUS. The results will be used to develop a conceptual model of the BUS explaining how changes in ecosystems structure effects fisheries and the biologically mediated CO2 uptake as seen in the two subsystems.
The Working Group Biogeochemistry of the Universität Hamburg together with the Leibniz-Centre for Marine Tropical Ecosystem Research in Bremen and the regional partner institutions in Namibia and South Africa aims to study changes in the trophic transfer efficiency and thus changes in the recycling efficiency of nutrients as well as the uptake of CO2 through the biological pump. Even small changes in the Redfield ratio (C/N/P) may significantly affect the efficiency of the biological pump and thus the uptake or release of CO2 in the Benguela region. In 2019 and 2020, two research expeditions with RV Meteor will be conducted where bottom-tethered moorings will be deployed in order to study the export of elements out of the Benguela Upwelling System. Moreover, planktonic and nutrient samples will be taken and the transfer of the gases at the water-atmosphere interface studied.
Project Leader:
PD Dr. Tim Rixen
Dr. Niko Lahajnar