With all the talk of dead zones caused by phytoplankton, it is important to understand that this menace is not always so devastating. Under normal conditions phytoplankton is provides a much needed element in local ecosystems, also directly effecting us as these little guys produce about half the oxygen that we breath. What causes issues is that; if they hit a nutrient rich area (caused by nitrogen ritch fertilizer for example) they will overfeed, creating what’s known as an algae bloom. As the massive amount of plankton begin to die this process uses oxygen this is normally mitigated by ocean currents churning the waters and dispersing the less originated waters. When the water is stagnating due to location or a higher temperature that’s what creates a dead zone and when the real damage is caused.
So don’t get it twisted, phytoplankton are friends, we just need to make sure to keep them a little hungry by keeping our fertilizer out of the oceans.