Changes in Ocean Oxygen Levels Mean Coastal Creatures Can't Fight Illness

crab on beach photo

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In normal conditions, marine animals are well equipped to fight off infection from the plethora of bacteria and viruses lurking in the oceans. However, that means having a hearty immune system that can react quickly if they get hurt. Researcher are finding that areas with low oxygen, such as within and around dead zones, and high carbon dioxide can wreak havoc on coastal animals' ability to ward off disease. They are finding that for animals living in polluted areas such as these, it takes only half as much bacteria to be lethal. According to PhysOrg,
Louis Burnett, professor of biology and director of the Grice Marine Laboratory of the College of Charleston, and Karen Burnett, research associate professor at Grice Marine Laboratory of the College of Charleston, study the effects of low oxygen and high carbon dioxide on organisms' immune systems. Looking at fish, oysters, crabs and shrimp, they've found that for those living in a low oxygen, high carbon dioxide environment, about half as much bacteria is lethal as compared to what can be withstood and fought off when the animals are living in non-polluted environments. Their immune systems just can't hack it.

They've found that when a pathogen is introduced to the animal's bloodstream, their blood cells bolt to attack the pathogen, but also lodge in the gills and block oxygen. Additionally, their metabolism slows, which makes it hard to keep up strength while fighting infection. Animals exposed to the low oxygen, high carbon dioxide environment for as short a time as a day are pretty much done for.

"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 hoping that by seeing how coastal creatures react to the changing quality of an ecosystem, they can see how deep-water flora and fauna might be impacted -- but it's a troubling thought because coastal creatures, thanks to the frequent changes of oxygen levels with the tides, are more adaptive to such fluctuations than deep-water animals.

We're also seeing that life at the poles may be hit first, and hardest, with ocean acidification, since colder water absorbs carbon dioxide quicker than warmer water. As dead zones grow all over the world, and acidification is essentially guaranteed for the foreseeable future, monitoring the changes in marine life will be crucial to our own survival.

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