View from a Rhino House: collective security beneath the waves

When a vicious killer seaweed touches a particular kind of spiky coral, the coral “sounds” a chemical siren that brings small reef-resident fish to the rescue.

Without a some sort of control, seaweed & algae can overrun a coral reef, as the polyp community dwindles in “a descent into slime,” says marine ecologist Mark Hay of the Georgia Institute of Technology. But within less than 15 minutes of contact with a toxin-making seaweed, an Acropora nasuta coral releases chemical compounds that prompt goby fish to seek out and eat-back back the seaweed, Hay & colleague Danielle Dixson reported in the issue of Science released on 9th November.

In reefs, corals & the seaweed algae that form lawns or shrubby thickets compete for light & space. As coral reefs reduce in size as a result of pollution, overfishing, climate change & other problems, biologists have seen swathes of seaweed take over. Rich seaweed intrusions repel or smother larval corals, accelerating what Hay calls the reef “death spiral.”

In this scenario, corals dwindle, & fish & other reef creatures find fewer safe coral-caves & valleys to live in. The reef then has fewer algae-eating fish, which means even less protection for the habitat-maker corals that support other co-operating forms of aquatic life. “Without these,” Hay says, “you have these algae-covered parking lots & not much else.”

It’s all a left-wing, liberal plot….. the coral has always looked like this