When sharknose gobies offer their cleaning services at reefs where there are damselfish, the damselfish chase away the gobies’ "customers." A study uncovers why they do that.
Many of us are familiar with the scenes at cleaning stations, where cleaner fish and cleaner shrimp feed on the parasites and dead tissues of their “clients.”
Under normal circumstances, sharknose gobies (Elacatinus evelynae) would set up a cleaning station at a coral reef, and use it as a base to attend to their “clients”—usually the parrotfish, surgeonfish, butterflyfish, etc— by eating the parasites and dead body tissue off their client's skin, fins and mouth.
However, at reefs with damselfish, things are not always so peaceful.
Increasingly, when these gobies offer their cleaning services at reefs where there are damselfish, the damselfish have no qualms about chasing away the gobies’ "customers."
The reason for this aggressive behaviour appears to be due to climate change.
Cause and effect
As more coral reefs get depleted as a result of climate change, and the incidence of overfishing increases, algae thrive. The deterioration of reefs may cause damselfish to be more aggressive and terrirotial.
“Damselfish act like farmers as they weed out algae they don’t want, to encourage their preferred algae to grow. Damselfish are protective over their algal territories, and these antisocial fish spend a lot of time patrolling their territories, scaring away intruders through biting, attacking, chasing or threatening displays,” explained Dr Katie Dunkley, a behavioural ecologist at the University of Cambridge’s Department of Zoology.
This would in turn lead to fewer fish species to have the opportunity to be "treated" at the cleaning stations, and they may subsequently go to other coral reefs or do without the treatment that would have kept them healthy.
This inadvertently affects species richness and diversity at coral reefs and subsequently the delicate ecosystem found at coral reefs.
Dunkley added that in the future, they would investigate the damselfish's motives for their actions: "Are they driven by wanting to protect their algae farms or monopolise cleaning stations?”