This is when a water body has a lot of pollutants containing nutrients thrown into it in a way that increases algae and plant growth in the water. This hurts animal life in that water because soon, the massive growth of algae consumes all the oxygen in the water, starving other animal life. Eutrophication is caused by increased application of fertilizers, waste from animal and households, as well as land clearing for agricultural purposes. Eutrophication is common in estuaries, but with recent increase in global temperatures, there is a threat that the effect will be felt in the oceans to which the estuaries are connected.