1) climate change overall because a change in the temperature of oceans can cause interruptions in migration and reproduction cycles. Hence, coral bleaching occurs as a result of increase in surface water temperature for example.
2) predator-prey cycles. this is a more general factor that is also linked to climate change. the loss or extinction of certain species of fish can cause an imbalance or proliferation of other species. for example, sharks are a keystone species. the extinction or decrease of sharks would lead to the proliferation of certain algae and a decrease in certain species of fish.
hope that helped!:)