Farmerfish are territorial and protect their algae gardens
ArteSub/Alamy
Fish that tend patches of stringy algae seem to shield branching corals from the worst effects of marine heat waves and help them recover after bleaching.
In 2019, the reefs near the French Polynesian island of Moorea in the South Pacific Ocean endured their worst heat stress event in 14 years. Because of some six weeks of unusually warm waters, branching corals there bleached en masse, in which they lose the symbiotic algae living in them that supply most of their food.
In …