Oregon has decided to join Louisiana in having its own "dead zone." This one may or may not be human caused. It's not from river effluent like the one in the Gulf of Mexico, but is instead from the welling up of deep water that is lacking in oxygen. Why this water is coming up from the depths remains the subject of study. Regardless, if you get enough dead zones in the oceans, then one day the ocean will be...dead. Reports of massive dead Dungeness crab currently range from Oregon's central coast to well into Washington.
<br />As for the many human connected versions, there is no excuse for this. The below article describes only the "natural" (huge assumption) one when the massive amounts of dead zones around the world particularly around the U.S. littoral are linked back to overuse of phosphorous and nitrate fertilizers that get washed out by rivers into the sea. There it causes high level plankton/algal blooms well beyond their ecological balance. Like making alcohol, the little buggers breed at a superfast rate then die then as they decompose on the ocean floor they suck up all the oxygen at a much expanded rate, creating a widening "hypoxic" zone, killing everything in its path ... I'm hardly surprised that the corporate piece below ignores that dead zones are human creations as much as the upwelling ones he cites!