Final answer:
Protists play crucial ecological roles, specifically in oxygen production and nutrient cycling. They contribute to the oxygen in our atmosphere through photosynthesis and aid in decomposing organic matter, thus facilitating nutrient recycling.
Step-by-step explanation:
Two examples of the ecological role of protists are oxygen production and nutrient cycling. Protists such as algae play a fundamental role in the world's oceans by contributing to the oxygen supply through the process of photosynthesis. They are also key players in nutrient cycling, helping to decompose organic matter and recycle vital elements back into the ecosystem, supporting the growth of other organisms.
In addition to oxygen production and nutrient cycling, protists serve as essential food sources for a variety of marine life. Photosynthetic protists act as primary producers, and through symbiotic relationships, such as those between coral polyps and zooxanthellae (photosynthetic dinoflagellates), they provide nutrients in nutrient-poor environments. On the decomposer side, protists help in breaking down dead organic material, thus playing a crucial role in maintaining ecosystem stability by recycling nutrients.