Final answer:
Once expelled from the coral, zooxanthellae's survival depends on environmental conditions. They require light for photosynthesis and may survive if conditions are favorable. Prolonged adverse conditions, such as high ocean temperatures, can lead to their death.
Step-by-step explanation:
Zooxanthellae are photosynthetic dinoflagellates that have a symbiotic relationship with coral polyps. Once these zooxanthellae are expelled from the coral after a bleaching event, their survival on their own depends on several factors, including the availability of light for photosynthesis and the correct environmental conditions. Without their coral hosts, zooxanthellae lose their access to nutrients and a protective environment, which compromises their ability to survive independently. However, if they are expelled into waters with favorable conditions, they may resume photosynthesizing and survive for some time. Should the stress causing the bleaching event (such as ocean water temperature increase) be prolonged, the zooxanthellae, as well as the coral polyps, may eventually die, leading to further decline in the health of coral reefs.
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