And so we bring in the new year. So often this is done with much fanfare and with hopes and aspirations for a better one than last…less fat, more exercise, a submitted PhD, a mastery of knitting or a smaller carbon footprint! I, for one, resolve to blog more about geo-engineering solutions, the good, the bad and the outright nonsensical (my favourite). So let’s start with one close to my heart, iron fertilization. The ‘solution’ lies in the ability to stimulate phytoplankton productivity by alleviating the chronic iron limitation found in enormous tracts of our oceans. By fertilizing the oceans, microscopic plants photosynthesize drawing down CO2. When they subsequently sink into the deep ocean, that carbon is sequestered for 100s to 1000s of years. Or even better the biomass gets locked up in the sediments and then we can hope for sequestration on geological timescales. It’s a win!
Easy-there purveyor of pollution, or collector of carbon credits, there are a number of things we need to THINK about before we find a use for that anvil you just don’t seem to use anymore. First of all you have assumed that all that biomass even makes it to the deep-sea. Sorry, but a lot of biomass is actually recycled in surface waters, as I have previously discussed. But what is also rarely discussed, is the fate of the deep-sea ecosystems that lie beneath.
And so, my second new years resolution comes into play, to write about more articles that EVERYONE can access. That’s right, the open journal, no subscription required. This article appeared in Plos One nearly a year ago but I was reading it again recently when thinking about what may effect my deep-sea coral, so I though I would quite literally share it with you.
In the study, the authors compared the ecosystem structure and function of two different habitats 460km apart. One site (4200m) lay beneath typically iron limited water (or HNLC*), and the other (also 4200m) lay beneath a sea surface naturally fertilized by iron (in this instance from dissolved iron leached from nearby oceanic islands). What they discovered is that two distinctly different deep-sea communities had evolved. Not only was there a greater quantity of organic matter raining down from the surface in the iron fertilized region but that it is was of a different quality. The surface waters supported very different species of phytoplankton which determined the fatty acids and lipids delivered to the seafloor, and so not surprisingly, resident deep-sea community adapted to different conditions.
So if you seed the surface waters that will respond most dramatically to fertilization, you ultimately seed a deep-sea community least evolved to cope with eutrophication (or excees nutrients). Think what happens when nitrate fertilizer is in excess on the Great Barrier Reef…no matter what Alan Jones says, too much of a good thing is almost always a bad thing somewhere down the line.
Haemoglobin is iron rich. May I suggest we fertilize the ocean with people who don’t believe in behavioural change, and would rather a quick-fix to our current climate crisis? Just a thought, albeit a controvertial one.
For access to the full article, click here.
* HNLC refers to High Nutrient Low Chlorophyl, where macronutrients are plentiful i.e nitrate and phosphate, yet comparatively chlorophyl (as an analogue for productivity) is low due to the lack of micronutrients required for growth. such as iron are in such low abundance that there is low chlorophyl.