For a few days each year, most coral in the Great Barrier Reef spawn all at once, broadcasting buoyant bundles of egg and sperm that float to neighboring coral for fertilization. Now researchers have shown how reefs efficiently trap the huge influx of nutrients. Chock-full of nitrogen and phosphorus, the gametes fuel a bloom of microalgae, which then nourishes other parts of the ecosystem, including fish and bacteria, says Ronnie Glud, a marine biochemist at the Scottish Association for Marine Science.