Scientific American —
Native to the Indian and Pacific oceans, lionfish invaded coral reefs in the Bahamas beginning in the early 2000s—likely when multiple aquarium owners surreptitiously liberated some of these fast-growing tank menaces into the Atlantic. As new predators with no enemies and venomous spines, lionfish have multiplied almost unimpeded and have wreaked havoc on Bahamian coral reef fish species, especially little ones. Invasive predators often capitalize on the naivete of native species that do not recognize them as a threat—at least initially. But heavy predation is presumed, over time, to place intense selection pressure on prey to develop a fear of the new species.
In 2015, a decade after the lionfish invasion took hold in her study area, coral reef ecologist Isabelle Côté was curious: Are native Caribbean fish becoming wary of these dangerous newcomers? She and her graduate student Adrienne Berchtold, both then at Simon Fraser University in British Columbia, conducted a series of experiments at the Cape Eleuthera Institute in the Bahamas to find out. They published their results on Tuesday in Animal Behaviour.
First, the researchers donned scuba gear and collected baby striped parrotfish, which lionfish commonly eat. The scientists took some of these specimens from two reefs known to have many predators (including lionfish) and others from two reefs with few of them. Côté and Berchtold placed the parrotfish in tanks with a sandy bottom and hiding places made of PVC pipe. Then they watched the parrotfish’s behavior before and after lifting a barrier to an adjacent tank so the animals could see one of three things: a lionfish, a grouper (a scary-looking native predator that eats parrotfish) or a control environment containing only seawater.