Briefly summarize the steps of the six natural cycles of Earth. 1. rock cycle: 2. tectonic cycle: 3. water cycle: 4. carbon cycle: 5. nitrogen cycle: 6. phosphorus cycle:

The first means of speeding up reactions mentioned by the speaker is raising the enzymes 

Although i don't know what is the simulated system, starfish are predators that eat mostly  microalgae,  snails, sponges, bivalves, mussels and other small marine animals. removing starfish from any system would definitely increase this animals that they prey.