Answer:
Pollution: Infecting all organisms including humans, which then gives the increased chances of creating new diseases.
Global Warming: Destroying the reef and sea life, which when the turn comes, will kill us humans.
Illegal Fishing/Poaching: We are killing the sea, the ocean makes about 85% of the Oxygen we breathe, and whales are apart of this process. So you make whales extinct, then the CO2 and Oxygen get depleted. No life on earth can live with a dead sea.