Iron-poor oceans may cause populations of phytoplankton — a critical base of the marine food chain — to decline.
By Jessica Marshall | Thu Jan 14, 2010 09:55 AM ET Rising acid levels in the world’s oceans appear to be robbing the tiny animals that form the bedrock of the marine food web of a vital nutrient. This shift in the ocean’s chemistry could reduce populations of phytoplankton, which could touch off a cascade of changes to ocean life. Roughly one-third of the oceans contain phytoplankton that are limited in their growth by the amount of iron available to them. A study published today in Science, suggested that zone could grow. “The concept of changes to ocean productivity and ecosystems due to acidification is a very important one to consider,” said Ken Buesseler of Woods Hole Oceanographic Institution in Woods Hole, Mass., who was not a part of the study. “If half of the photosynthesis on the planet is in the ocean and if you reduce that because of acidification, that is a big deal.” Ocean acidification is a trickle-down effect of climate change. Higher levels of carbon dioxide in the atmosphere drive more CO2 to dissolve into the ocean, making it more acidic. In photosynthesis, plants — including phytoplankton — convert CO2 from the atmosphere into their tissues, and produce the oxygen that we breathe. Other animals up the food chain feed off of this carbon that was pulled out of the atmosphere by the miniscule plants. A lack of iron appears to slow this process down, which could affect the food supply for other ocean life, and reduce the amount of heat-trapping carbon dioxide the ocean can soak up. “We are messing with a lot of things that are very big,” said study author François Morel of Princeton University in Princeton, NJ. “One of them turns out to be the chemistry of the ocean.” …
Rising ocean acidity may deplete vital phytoplankton
