Many things can cause catastrophic effects on ocean life.
One of the most harmful ones are Oil Spills. They happen really fast, and it takes a monumental amount of time to recover, and the results are really catastrophic, killing various species of marine animals, as well as their habitats.
The first thing that comes to my mind is oil spills. Not only is that harmful to the environment, but to marine life. It all happens so fast and takes so long to recover.
