A PNAS paper released today which looks at domoic acid (DA) production in past OIF experiments has concluded that DA was increased in some of the projects. Though the conclusions from the paper itself were relatively conservative:
"Although there remain uncertainties in extrapolating our results to large oceanic scales, the findings establish potential consequences for developing toxic phytoplankton blooms in pelagic ecosystems,
which so far have not been adequately investigated."
Headlines have ranged from the dramatic "Ocean Geoengineering Scheme May Prove Lethal", and at the NY Times, the oddly phrased, "A Risk of Poisoning the Deepest Wells" to the more subdued, "Carbon-capture scheme could cause toxic blooms".
All fail to explore the obvious flaw in this sort of analysis. Namely, that phytoplankton underpin open ocean productivity, that this productivity relies on iron, and that when iron-fed naturally occurring blooms happen, they likely favor--in certain regions--Pseudonitzschia or other DA producers. In short, we know that the availability of iron drives much of the oceanic carbon
cycle. If DA is produced by artificially stimulated OIF blooms, it is likely produced during natural ones as well.
Moving forward, we need to understand exactly
how deep-ocean phytoplankton respond to iron--be it naturally
or artificially supplied, whether and in what situations DA is produced, and how the ecosystem is or is not already adapted to
this. If it occurs naturally, are organisms that live there used to blooms containing DA? In past climate cycles, when productivity in the deep ocean was much greater, was DA characteristic as well?
These are questions that remain unresolved and need
well defined research programs to address.
"It's a great paper, but I remain a proponent of iron fertilization -
if it does indeed work on a very large scale - because it's the only
process that takes carbon dioxide out of the atmosphere," Johnson said.
Coale said that "in some cases" his colleagues had also seen large
increases in the domoic acid toxin during their own earlier iron
But he added: "I'm with Ken (Johnson) on this. We do need to explore
all the options and their consequences. My feeling is that iron
fertilization is no magic bullet, but it may need to be considered among
a large portfolio of carbon sequestration efforts."