In a paper published in the Proceedings of the National Academy of Sciences on Monday, scientists from the University of Southern California, Mexico's Autonomous University of Baja California and the University of Hawaii say there are vast zones in the Pacific lacking in B vitamins. Such conditions may hamper the growth of microscopic phytoplankton that form the base of the marine food chain.
This is another twist to what limits life in the ocean, USC researcher and lead author Sergio Sanudo-Wilhelmy said in a statement Monday.
The team took water samples from different depths at six locations around the southern California-Baja California coast in October 2009. They found a new way to concentrate the water samples and examine them with a mass spectrometer, which is used to deduce the chemical composition of a sample.
They found that the five major B vitamins vary in concentration, and different depths are home to different kinds of B vitamins than water above or below.
These conditions could lead to complex interactions among populations of microbes, from symbiosis to intense competition, senior author and University of Hawaii oceanographer David Karl said in a statement Monday.
Phytoplankton aren't just an essential food source for ocean life; they're also big consumers of carbon dioxide, which makes them even more important given today's current rate of greenhouse gas emissions, the authors say.
Climate change may be behind the dearth of B vitamins, thanks to effects on ocean circulation and on the water column that would reduce the migration of vitamins to the ocean surface from the lower depths.
This climate shift might disrupt ecosystem function via important vitamin-dependent biological processes, the authors wrote.
SOURCE: Sanudo-Wilhelmy et al. Multiple B-vitamin depletion in large areas of the coastal ocean. PNAS online ahead of print 23 July 2012.