Corals, fish know bad reefs by their whiff
Compounds drifting off certain overgrown seaweeds discourage youngsters from settling in failing habitats
NEXT GEN REEF Little pink bulges indicate this coral is about to release gametes for open-water fertilization. Where the resulting babies will settle down to live could depend on how badly reefs stink.
Danielle Dixson
Young corals and fish can tell bad neighborhoods from good ones in part by the stink of overgrown seaweeds.
This distaste for compounds leaching from seaweeds is the first evidence of a “bad habitat” chemical cue that could discourage youngsters from even trying to make their homes on degraded reefs, says Mark E. Hay of the Georgia Institute of Technology in Atlanta. The discovery reveals a conundrum for reef conservation, because the places biologists are trying to attract young corals and fish are usually disintegrating reefs where seaweeds are taking over.
Seaweed thickets can outcompete tiny corals and offer few rocky hidey-holes for little reef fishes. Exactly how the youngsters sense the taint of seaweeds isn’t clear. But in tests with paired water samples, young corals and fishes normally liked seawater dipped from coral-rich protected reefs from Fiji — but not when certain fast-spreading seaweeds had been sitting in those water samples for
