Major threats to ocean ecosystems include:

1. Dynamites devastate a whole ecosystem.

2. Cyanide stuns target fish, but kills smaller organisms such as corals.

3. Harvesting commercial fish such as bluefin tuna and Atlantic cod upsets complex symbiotic relationships.

4. Inland pollution introduce sediments, toxins, and excess nutrients.

5. Plastics and other debris can smother marine animals.

6. Oil spills can be toxic to coastal ecosystems.