What is the fine-grained topic of the following text: dc.description.abstract Spatial variation in the photophysiology of symbiotic dinoflagellates (zooxanthellae) of the scleractinian coral Pocillopora damicornis was examined along an environmental gradient in the Whitsunday Islands (Great Barrier Reef) at two depths (3 m and 6 m). Only return the topic.
Photophysiology of symbiotic dinoflagellates in Pocillopora damicornis along an environmental gradient in the Whitsunday Islands (Great Barrier Reef) at different depths.