I have posted information in the past concerning Dead Zones due to man's impact. Unfortunately, now it's routine enough that they have developed a forcast for Hypoxia events based on nutrient loads. It's a shame it only seems to be getting worse not better. Earth Observatory Satellite's can show the highly loaded source areas, But it seems not much else is done to slow or diminish agricultural runoff. looks like hypoxia and toxic algea blooms are just going to increase and get more frequent based on current trends.