Southern Ocean iron fertilization by baleen whales and Antarctic krill
By S. Nicol, A. Bowie, Simon N. Jarman, D. Lannuzel, K. Meiners, P. Merwe. 2010
173 citations recorded by the source corpus.
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 whale faeces contain significant quantities of iron. We analysed the iron content in 27 samples of faeces from four species of baleen whale. Faecal iron content (145.9 ± 133.7 mg kg )1 ) is approximately ten million times that of Antarctic seawater, suggesting that it could act as a fertilizer. Furthermore, we analysed the iron content of seven krill species and of muscle tissue of two species of baleen whales; all samples had high iron levels. Using these figures, together with recent estimates of the range and biomass of krill, we calculate that the Antarctic krill population contains 24% of the total iron in the surface waters in its range. Thus, krill can act as a long-term reservoir of iron in Antarctic surface waters, by storing the iron in their body tissue. Pre-exploitation populations of whales and krill must have stored larger quantities of iron and would have also recycled more iron in surface waters, enhancing overall ocean productivity through a positive feedback loop. Thus, allowing the great whales to recover might actually increase Southern Ocean productivity through enhancing iron levels in the surface layer.
Subfields: Ecology, Global and Planetary Change
View Paper: https://www.semanticscholar.org/paper/11a6cc3f92b92642bcbe871f2cccc75b992b1783
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Citations in the corpus
- Seabed foraging by Antarctic krill: Implications for stock assessment, bentho‐pelagic coupling, and the vertical transfer of iron (2011, background): “A role of krill in recycling iron within surface layers has been suggested before (Tovar-Sanchez et al. 2007; Nicol et al. 2010), but the fact that krill stomachs can contain up to 12 times more iron than the rest of the krill body points to krill as vector for ‘‘new’’ iron from the seabed.”
- Whales as marine ecosystem engineers (2014, background): “Deep carbon export from a Southern Ocean iron-fertilized diatom bloom.”
- Developing integrated models of Southern Ocean food webs: Including ecological complexity, accounting for uncertainty and the importance of scale (2012, unknown): “Linking biogeochemical and food web models can provide insights into top-down influences from upper trophic levels (e.g. faecal enrichment) on biogeochemical cycles that have recently been highlighted for Southern Ocean ecosystems (Nicol et al., 2010).”
- The Importance of Krill Predation in the Southern Ocean (2016, background): “Two contrasting ideas about the effects of this perturbation are that the removal of the great whales led to a possible “krill surplus” (Laws 1977, Ballance et al. 2006) or that it led to a possible reduction in krill (Nicol et al. 2010), (see below).”