Hydrothermal iron supply contributes to the Southern Ocean carbon cycle via the regulation of regional export production. However, as hydrothermal iron input estimates are coupled to helium, which are uncertain depending on whether helium inputs are based on ridge spreading rates or inverse modelling, questions remain regarding the magnitude of the export production impacts. A particular challenge is the limited observations o...

As marine microorganisms and environmental conditions coevolved over geological timescales, metals have been incorporated into all essential metabolic processes. In the modern ocean, metals are present from trace amounts limiting microbial growth to toxic concentrations. Dissolved trace metals are a major bioavailable reservoir. However, the acquisition of metals from marine particles remains largely unexplored. Here, we combi...

Manganese (Mn) is an abundant element in the Earth's crust. However, its concentrations in open ocean seawater are low, where external inputs are scarce. In this study, we report the dissolved Mn and particulate Mn distributions in the Southern Ocean, measured along the GEOTRACES—SR3 transect, from Tasmania (Australia) to Antarctica in the Southern Ocean, during the austral summer 2018. Both dissolved Mn and particulate Mn con...

Iron is the limiting micronutrient in the Southern Ocean and experiments have demonstrated that addition of soluble iron to surface waters results in phytoplankton blooms, particularly by large diatoms. Antarctic krill ( Euphausia superba ) eat diatoms and recycle iron in surface waters when feeding. Baleen whales eat krill, and, historically, defecation by baleen whales could have been a major mechanism for recycling iron, if...