WASHINGTON -- Researchers say low-oxygen zones in the oceans where sea life is threatened or cannot survive at all are growing.

In a report published in the journal Science, the researchers said it's because global warming is raising ocean temperatures. And they said continued expansion of these zones could have dramatic consequences for both sea life and coastal communities.

One of the study's co-authors explained that warmer water does not absorb as much oxygen as colder water, and without oxygen organisms can't live there.

Another oceanographer said many species will end up losing their deep habitat and that will increase competition for the areas that remain. And that will likely lead to more animals preying on each other.

The researchers found oxygen-depleted zones around the equator in the central and eastern Atlantic and the Pacific had expanded over the last 50 years.