Fluctuations in climate can drastically affect the habitability of marine ecosystems, according to a new study by UCLA scientists that examined the expansion and contraction of low-oxygen zones in the ocean.
The UCLA research team, led by assistant professor of atmospheric and oceanic sciences Curtis Deutsch, used a specialized computer simulation to demonstrate for the first time that the size of low-oxygen zones created by respiring bacteria is extremely sensitive to changes in depth caused by oscillations in climate. These oxygen-depleted regions, which expand or contract depending on their depth, pose a distinct threat to marine life.
"The growth of low-oxygen regions is cause for concern because of the detrimental effects on marine populations entire ecosystems can die off when marine life cannot escape the low-oxygen water," said Deutsch. "There are widespread areas of the ocean where marine life has had to flee or develop very peculiar adaptations to survive in low-oxygen conditions."
The study, which was published June 9 in the online edition the journal Science and will be available in an upcoming print edition, also showed that in addition to consuming oxygen, marine bacteria are causing the depletion of nitrogen, an essential nutrient necessary for the survival of most types of algae.
"We found there is a mechanism that connects climate and its effect on oxygen to the removal of nitrogen from the ocean," Deutsch said. "Our climate acts to change the total amount of nutrients in the ocean over the timescale of decades."
Low-oxygen zones are created by bacteria living in the deeper layers of the ocean that consume oxygen by feeding on dead algae that settle from the surface. Just as mountain climbers might feel adverse effects at high altitudes from a lack of air, marine animals that
require oxygen to breathe find it difficult or impossible to live in these oxygen-depleted environments,
|Contact: Kim DeRose|
University of California - Los Angeles