Tagoro Submarine Volcano as a Natural Source of Significant Dissolved Inorganic Nutrients

The shallow submarine volcano Tagoro releases high amounts of inorganic nutrients (N, P, Si, Fe) into the surrounding waters. These emissions have been intensely monitored during both the eruptive stage (October 2011–March 2012) and the post-eruptive hydrothermal stage (March 2012—ongoing). The obtained seven-years dataset comprises over 3300 water samples analysed for concentrations of silicate (Si(OH)4), phosphate (PO4), nitrate + nitrate(NO3− + NO2−), ammonium (NH4+), and iron (Fe(II)) in the area affected by the volcanic emissions (> 250 km2) as well as outside of this area for reference. This chapter provides an overview on the main results obtained from this comprehensive dataset, as well as contextualizing these results by comparison with other volcanic and hydrothermal nutrient sources in the world. The results show that the hydrothermal emissions from Tagoro volcano cause nutrient enrichments both in the vicinities of the vents (88–130 m depth) and the water column up to 50 m above the seabed. The emissions can occasionally also be injected into the mixed layer and might even reach the surface. The transport of these emissions presents a flux of comparable magnitude to other important nutrient fluxes in the region, such as those related to the NW-African coastal upwelling, when compared per unit of area. We highlight the importance of accounting for shallow hydrothermal and volcanic inputs worldwide as significant nutrient sources that can exert an important influence on the ecosystems of superficial nutrient-poor waters.