WEIRD weather in the Gal谩pagos Islands is threatening to alter forever
the ecosystems that support the archipelago鈥檚 unique plants and animals.
The high temperatures and rainfall brought by the El Ni帽o event
currently gripping the Pacific could cause populations of several species living
in the archipelago to crash, biologists warn. They fear that alien species which
have invaded the islands will then establish such a foothold that native species
won鈥檛 bounce back. 鈥淚t鈥檚 going to be a catastrophe,鈥� predicts Jennifer Stone of
the Gal谩pagos Conservation Trust, a British charity.
The current El Ni帽o is shaping up to be at least as severe as the
devastating event of 1982-83. Fifteen years ago, the Gal谩pagos had 2770
millimetres of rain鈥攁lmost six times as much as normal. When the El
Ni帽o reached its peak, the sea temperature was 3 掳C higher than
average for the time of year.
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The outlook is grim, says Michael Bliemsrieder of the Charles Darwin Research
Station on the island of Santa Cruz. In 1982-83, the number of flightless
cormorants, which are unique to the Gal谩pagos, fell by 45 per cent, while
78 per cent of the rare Gal谩pagos penguins died. Waved albatrosses failed
to breed. In the sea, green algae鈥攅aten by marine iguanas鈥攚ere
replaced by inedible red algae. On some islands, 70 per cent of iguanas
starved.
The heavy rains of 1982-83 also triggered an explosion of plant growth on the
islands. This encouraged the spread of introduced pests, such as fire ants and
rats.
Under the current El Ni帽o, the cool misty season, known as
garua, which is supposed to arrive in June, never materialised, and the
climate remains hot and sticky. 鈥淚t feels more like the tropical jungles of the
Amazon than the arid Gal谩pagos Islands,鈥� says Bliemsrieder.
The rains, which in a normal year don鈥檛 start until February, began with a
vengeance in November, which saw 147 millimetres. Biologists working on the
normally dry island of Espa帽ola reported 204 millimetres of rain in just
two days in mid-December. Rain is forecast to continue until El Ni帽o
reaches its peak in March.
There are already signs that the wildlife catastrophe of 1982-83 may be about
to repeat itself. Many seabirds have failed to nest, including the waved
albatrosses. A shift from green to red algae is in progress, and hammerhead
sharks have moved into deeper, cooler waters. On land, meanwhile, normally dry
and barren islands are once again blooming with luxuriant vegetation. 鈥淓ven the
most arid islands are covered with a green carpet,鈥� says Bliemsrieder.
In the past, native species eventually recovered. But since 1983, alien
species have become further established, and biologists fear that they could now
stop native animals making a comeback. 鈥淚ntroduced species are by far the most
serious threat to the biodiversity of the Gal谩pagos,鈥� says Robert
Bensted-Smith, director of the Darwin research station.
Conservationists have been battling against rats, cats and goats for years.
More recent arrivals include two species of fire ants and an unpleasant biting
fly. 鈥淪ome islands are now completely infested with fire ants,鈥� says Charlotte
Causton, an entomologist at the Darwin research station. 鈥淎nd the fly breeds in
running water, so you would expect it to increase when there is more rain.鈥�
