Growing low-oxygen zones in oceans worry Scientists

Lower levels of oxygen in the earth's oceans, particularly off the US Pacific Northwest coast, could be another sign of fundamental changes linked to global climate change, scientists say. They warn that the ocean's complex ecosystems and fragile food chains could be disrupted.  "If the earth continues to warm, the expectation is we will have lower and lower oxygen levels," said Francis Chan, a marine researcher at Oregon State. 

As ocean temperatures rise, the warmer water on the surface acts as a cap, which interferes with the natural circulation that normally allows deeper waters that are already oxygen-depleted to reach the surface. It's on the surface where ocean waters are recharged with oxygen. Scientist are not sure how low level oxygen is going to affect the ecosystem.  But one thing seems very likely that any desruption in the food-chain cycle is bound to have some negative effects.

source:  Lee Blumentha, McClatchy Newspaper