"Our approach is exciting because traditionally physiologists haven't considered bacteria or disease as a natural environmental barrier, so it's a pretty open field," says Louis Burnett.
Apparently, if marine animals are challenged with a pathogen, a large number of their blood cells disappear within a few minutes. The blood cells clump up to attack the pathogen, but also lodge in the gills (the sea critter version of lungs), where the body gets it oxygen. The scientists see evidence that sea animals fighting off infection lower their metabolism, which slows down other important processes like making new proteins.
"Everything we see points to the fact that if an animal that mounts a successful immune response then their gill function and ability to exchange oxygen is reduced by about 40 percent, which is why they seem to be having such problems living in low oxygen conditions," says Karen Burnett. "If you add high carbon dioxide to that, it gets worse."
The researchers are now using microarrays to measure changes in gene expression in marine organisms that are exposed to bacteria under low oxygen, high carbon dioxide conditions.
"After exposure to these conditions for only a day, animals at the molecular level have given up in trying to adapt to the situation, and they are going into molecular pathways that indicate cell death," says Karen Burnett.
The coastal animals the Burnett's study live in environments where natural levels of oxygen and carbon dioxide fluctuate. Theoretically, these animals are already adapted for varied environments, and yet they still struggle with these changing conditions. It's alarming that deep-water animals may be much more affected by ocean acidification, since they are not used to the ebb and flow
|Contact: Donna Krupa|
American Physiological Society