Ocean Iron Fertilization Could Stimulate Toxic Algae Blooms in Open Ocean  

TreeHugger has a post on a potential drawback of one proposed geoengineering strategy - Ocean Iron Fertilization Could Stimulate Toxic Algae Blooms in Open Ocean.

There's no doubt that geoengineering brings out passionate emotions both pro and con, as recent debate on TreeHugger about the sort of-moratorium on some research coming out of the Convention on Biological Diversity amply illustrates. Backing up the caution side (which I admit I'm firmly a part of) is a new piece of research coming from UC Santa Cruz, and published in Proceedings of the National Academy of Sciences, which shows that a toxin-producing algae normally thought limited to coastal waters (and perhaps partial inspiration for The Birds) can be stimulated to grow rapidly in the open ocean when iron from natural or artificial sources is present.

Science Codex sums up the nut of it:

Blooms of diatoms in the genus Pseudo-nitschia, which produce a neurotoxin called domoic acid, are a regular occurrence in coastal waters. During large blooms, the algal toxin enters the food chain, forcing the closure of some fisheries (such as shellfish and sardines) and poisoning marine mammals and birds that feed on contaminated fish. But until now, blooms of these algae in the open ocean have attracted little attention from researchers.

Study lead author, Mary Silver says that normally pseudo-nitschia don't have much effect, but "these species are incredibly responsive to iron, often becoming dominant in algal blooms that result from iron fertilization. Any iron input might cause a bloom of the cells that make the toxin." Silver adds that natural deposits of iron in the open ocean (from volcanic eruptions, dust storms, etc) have occurred for millions of years, but are sporadic occurrences.

"To do iron enrichment on a large scale could be dangerous," Silver notes, "because, if it causes blooms of pseudo-nitschia, the toxin will get into the food chain, as it does in the coastal zone."