Fertilizer grows crops and kills fish ???

http://www.allatsea.net/the-gulf-of-mexicos-zombie-dead-zone/

The Gulf of Mexico’s Zombie Dead Zone

"The National Oceanic and Atmospheric Administration (NOAA) hypothesizes the annual agricultural and treated sewage discharge into the Gulf of Mexico via the Mississippi River exceeds 1,700,000 tons or 3,400,000,000 pounds of potassium and nitrogen. To put that into perspective, it’s the equivalent of dumping 168 million 20 pound bags of fertilizer directly into the Gulf."

Conundrum. Sadly, the Dead Zone is created by essential agriculturally-based, nutrient rich (i.e., phosphorus, nitrogen and potassium) fertilizers. These elements find their way into the warm waters of the Gulf via the Mississippi River and its tributaries. Scientists point to the recent spree of heavy rains and floods in the Midwest and subsequent agricultural crop run-offs for the heavy influx of nutrients. Interestingly, the most negatively affected species are shellfish, as they have limited mobility and are typically unable to escape the devastating effects of the Dead Zone."

Agriculture and Plants killing animals / fish ?