Repelling invaders

Ken Collins with marine iguana

Ken Collins with marine iguana

10 May 2013 by Tom Marshall

The unique wildlife of the Galapagos is under threat. Tom Marshall talked to Ken Collins of the University of Southampton to find out why, and what researchers and conservationists are doing about it.

The Galapagos Islands form a giant natural experiment on how organisms respond to an isolated environment. The incredible range of unique plants and animals that live there inspired Darwin's theory of evolution, and thousands still come each year to see the likes of giant tortoises and aquatic iguanas.

But this natural cornucopia is in danger. Growing tourist numbers are a welcome boost to the locals' incomes, but put serious pressure on the very wildlife they come to see. And invasive species are proliferating, threatening to overwhelm natives that have evolved over millions of years with few predators and little competition or disease.

Dr Ken Collins, a marine scientist at the University of Southampton, based at the National Oceanography Centre in the same city, has been visiting the islands regularly since the mid-1980s, and between 1997 and 2000 played a central part in setting up the Galapagos Marine Management Plan. He's now leading a project funded by the UK government's Darwin Initiative, aimed at preserving the islands' marine biodiversity.

The Galapagos are the land of reptiles and birds, not of mammals.

We've learned the hard way that the island environments need protection even from seemingly innocuous arrivals. Goats have been one particularly unwelcome guest. Back in the age of sail, when protecting native wildlife got no consideration at all, whalers and other ships were in the habit of dropping a few of them off when they passed by, with the idea that they'd breed and provide a welcome source of fresh meat at the next visit.

The goats didn't just breed; they set about the islands' vegetation like a swarm of locusts, defying repeated efforts to bring them under control. They've only recently been eradicated at last from a few islands, after a long and costly campaign involving marksmen in helicopters.

"The Galapagos are the land of reptiles and birds, not of mammals," Collins says. "All the mammals we've introduced have caused huge problems - not just goats but rats, cats, pigs and donkeys."

Diving survey team at work in Galapagos

Diving survey team at work in Galapagos

Other threats are subtler. The islands are a largely barren volcanic landscape; most of the food for 25,000 residents and 200,000 visitors each year arrives on cargo ships, and we've only recently realised these were bringing mosquitoes in their holds, lured onboard from the tropical swamps of Ecuador by their bright white deck lights. Some of these arrivals carried diseases like malaria and dengue fever, or other infections that threaten the survival of unique local bird populations.

Just changing from normal filament light bulbs to orange sodium lights - invisible to insects - has largely solved that problem, along with fumigating plane and ship holds. But many more remain - some blatant and some more insidious.

Early settlers didn't confine themselves to mammalian imports; they also planted vegetation they thought would be helpful. Examples of out-of-control plants include Chinchona trees, intended to provide quinine to combat the malaria spread by those mosquitoes, castor oil plants and the humble blackberry bush. This infiltrated much of the countryside, spreading along roadside verges and covering whole fields in a riot of brambles. Goats can be herded or culled from a distance; blackberries have to be killed one sturdy bush at a time.

But changes in the underwater environment are much harder to spot, and are increasingly the focus of conservationists' concern. Collins and his team helped carry out the first underwater surveys of the islands' main ports.

At present the picture's mixed. There are a few worrying signs, but with vigilance it should be possible to stop the waters round the islands suffering the same fate as has befallen many other places, particularly busy ports. Southampton's docks have been receiving hitchhikers from all over the world for more than a century, clinging to the bottoms of ships or carried in ballast tanks. Its original ecosystem is now barely recognisable.

"We get shipments from all over the world, and as a result our underwater environment is now completely alien," Collins says. The whole seabed of Southampton Water and the Solent is covered in American slipper limpets, invasive sea squirts and the long fronds of Japanese seaweed. "We want to stop anything like that happening in the Galapagos," he adds. "We've learned it's a lot easier to stop something coming in than to eradicate it once it's established."

The situation is nowhere near that bad around the islands, but there's cause for concern. Two new kinds of algae that have caused problems elsewhere have already been spotted in the Galapagos Marine Reserve, a world heritage site. The rampantly aggressive white coral Carijoa racemosa has already been reported off the coast of Ecuador, and it wouldn't be surprising if it reached the islands.

In the longer term, the lionfish could be an even bigger problem. A native of the Indian Ocean, it has a voracious appetite and can eat its way through whole fish populations at amazing speed - an individual can eat 20 small wrasse in half an hour, its stomach stretching to 30 times its normal volume if necessary. It's already rampaged through the entire Caribbean in just a decade since its accidental introduction, and there's no reason it couldn't make it through the Panama Canal and ultimately reach the Galapagos.

The long-term monitoring and surveillance programmes Collins and his team have put in place should provide early warning of such invaders, allowing conservationists to tackle problems while they can still be solved. They'll also provide a baseline so we can understand changes as they happen.

Overfishing is causing serious damage around the islands too. Collins has been working with locals to get them to understand that conservation is in their interests too. "Most fisheries management is reactive - it's only after a serious problem has appeared that people start to do something about it, and by that time it can be too late," he says. "We want to talk to fishermen before that happens and engage them with our monitoring programmes so that we can manage these resources sustainably."

Fishermen are just trying to make a living, and it's often much more effective to show them the consequences of their actions directly - for example, that the sea cucumbers they depend on are in trouble and that they should go easy for a while - than simply to lecture them about it. On their latest trip to the islands, the team also talked to the Ecuadorian navy and civilian maritime authorities about how they can contribute.

The damage averted by these marine conservation efforts may not be as obvious as that caused by invasive species on land, but Collins thinks it's just as worthwhile; the islands' underwater life is as unique as its terrestrial and avian inhabitants. "Bigger fish like sharks can swim to and from the islands, but smaller ones mostly can't and so the few that make it there evolve into new species," he says. "So there's fantastic diversity under water, just like on land."

The Galapagos project is led by the Charles Darwin Foundation and University of Southampton, along with the Galapagos National Park Service, the Navy's Oceanographic Institute, National Direction of Aquatic Spaces, Ecuadorian Agency for Quality Assurance and the University of Dundee.