Micro mug shotThe exoskeleton of a toxin-producing diatom Pseudonitzschia turgidula. The phytoplankton species proliferates when fed dissolved iron, a finding that reveals a potential downside of attempts to sequester carbon by fertilizing the ocean.Brian Bill, NOAA/SFSU
A plan to combat global warming by fertilizing the ocean may backfire by triggering toxic algal blooms, a new study suggests.
Scientists have known for decades that dumping iron in the ocean, especially in areas where that nutrient is in short supply, stimulates the growth of algae and other phytoplankton. These tiny organisms pull carbon dioxide from the atmosphere as they grow, prompting research on the potential of iron fertilization to pull the greenhouse gas from the atmosphere and scuttle it in the deep sea as sunken algae.
But some researchers, besides wondering about the long-term effectiveness of such efforts, have questioned whether such schemes might have unintended side effects, says Charles Trick, a biological oceanographer at the University of Western Ontario in London, Canada. Now, Trick and his colleagues report online the week of March 15 in Proceedings of the National Academy of Sciences that fertilizing the ocean with iron can stimulate algae that make a neurotoxin called domoic acid.