If, while looking for a new apartment, you happened upon a pungent neighborhood, you’d look for a home in another area, right? Well, fish and coral are no different. New research from the Georgia Institute of Technology shows that damaged reefs emit an unpleasant odor that fish and coral can smell; this scent subsequently drives the creatures to try to settle somewhere else.
Evolutionarily speaking, the odor has probably usually been a good thing. It keeps coral and fish from settling in unsafe environments. Alas, with the fishing industry and other human interference destroying so many reefs, having this scent drive away sealife from most areas is probably a detriment at this point.
This study likely explains why areas that marine biologists designate in the hopes of having a coral reef “recovery” aren’t especially successful. Evidently, fish can still sense that something smells fishy… I mean suspect, and flee the area. With the stench of “failed habitat” lingering, scientist intervention might not be enough to revive a degrading reef.
Coral reefs are a delicate ecosystem. Seaweed generally prevents coral from growing, which is why it’s great to have seaweed-eating fish frequent coral reefs. When the fish are not around to keep the amount of seaweed limited, old corals die out and new corals look elsewhere for a home. This seaweed, it turns out, also lets off a stinky scent, giving fish and coral yet another odorous reason to stay away from declining reefs.
One of the more discouraging findings of the study is that even coral larvae smell and make living choices based on the water’s scents. With studies showing that baby coral avoided the smelly water five times more than it went to it, that means that coral avoid this type of water even more than it does algae, which is toxic to coral. Obviously, that suggests that reviving old coral reefs will be a tricky task.
Fish are even pickier about the scent, apparently. Scientists looked at 15 different species of fish and found that each one greatly preferred taking up residence in less stinky water, sometimes by as much time as eight times more than they did in the smelly former reefs.
Fortunately, scientists won’t give up on trying to bring back dying reefs, they’ll just likely alter their tactics in light of this information. At the present, some experts believe the best tactic will be to clear certain parts of the ocean floor of seaweed and dead coral altogether in the hopes of preventing the water from being foul-smelling. With any luck, this will be just the adjustment necessary to achieve more success in restoring coral reefs.