Chemoattraction to dimethyl sulfide links the sulfur, iron, and carbon cycles in high-latitude oceans

Large marine regions, including the exceptionally productive Southern Ocean, are iron-limited. As a result, there has been substantial interest in iron-fertilizing high nutrient low chlorophyll (HNLC) areas in an effort to sequester atmospheric carbon dioxide. More recently, research has shifted to quantifying the beneficial effects of iron recycling by marine biota. Marine top predators such as whales and seabirds have been examined specifically in this regard as they have high biomass, form dense aggregations, and excrete bioavailable iron in concentrations seven orders of magnitude higher than ambient seawater. Despite it being well established that marine fauna link the iron and carbon cycles, the connection of this process to the sulfur cycle has rarely been considered. The chemoattraction of specific marine fauna to algal-derived dimethyl sulfide (DMS) is key in triggering dense, multi-species foraging aggregations that induce iron recycling, augmenting carbon assimilation. The goal of this paper is twofold; first, to highlight DMS chemoattraction as a behavior that catalyzes carbon sequestration via natural iron fertilization, and second, to identify knowledge gaps that recent biogeochemical advances can address. Fostering this interdisciplinary research will enhance our understanding of global climate regulation, ecosystem services provided by marine top predators, and the biogeochemical cycles of carbon, iron, and sulfur in HNLC waters.