Project Details
Projekt
Whale, seal and seabird feces: Promotors of Southern Ocean phytoplankton productivity and carbon export?
Applicants
Professor Dr. Morten Iversen; Dr. Scarlett Trimborn
Subject Area
Oceanography
Term
since 2025
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 562074043
The Southern Ocean (SO) influences global water circulation and acts as atmospheric CO2 sink, thus affecting our climate at a global scale. In this region, the input of the trace metal iron (Fe) is the primary control of phytoplankton growth and CO2 fixation, thus affecting the biological CO2 uptake of the SO and ultimately global CO2 fluxes. Externally sourced contributions of new Fe to SO surface waters are thought to be low, which suggests that recycling within the system is an important mechanism for supplying Fe to Antarctic phytoplankton. Animals recycle Fe through their diet and subsequent defecation. However, Fe recycling by these animals represents an important, but not well quantified pathway to supply Fe to pelagic phytoplankton. Currently, there are no investigations that looked at the bioavailability of the released Fe by whales, seals and flying seabirds and that directly measured their influence on SO phytoplankton productivity and the potential for carbon export. Hence, an evaluation of the impact of these Antarctic animals to act as potential Fe fertilizers is urgently required. In this project, we will concentrate on whales, seals and flying seabirds, for which currently no information on their role as Fe fertilizers of the remote Fe-poor SO waters exist. Covering a broad range of food preferences, from krill feeders and more opportunistic consumers of higher trophic levels, which differently affect the Fe turnover rate, we chose humpback and fin whales, crabeater, Weddell and fur seals as well as Antarctic, Wilson’s storm and snow petrels as model organisms for our project. The main research objectives in the proposed research project will be to investigate the fertilization effect of their feces on SO phytoplankton productivity in laboratory experiments under well constrained environmental conditions. In this project we will investigate (1) how much Fe is released by the defecation products of baleen whales, seals and flying seabirds into seawater and estimate their Fe bioavailability to Antarctic key phytoplankton species. We will assess the (2) fertilizing effect of each fecal material on growth and carbon fixation on Antarctic phytoplankton and will determine (3) the carbon export potential of phytoplankton after fecal Fe fertilization. This will allow to obtain a better understanding on the importance of whales, seals, and flying seabirds in sustaining SO productivity and carbon export and will give more insights on their impact on the biological carbon pump.
DFG Programme
Infrastructure Priority Programmes
