UPDATE ON THE EL NIÑO PHENOMENON
MARCH 1999

The Galapagos Archipelago was affected by the El Niño phenomenon between June 1997 and June 1998. The ongoing compilation of scientific results is showing a wide range of both negative effects and positive impacts that the increased rainfall and warmer water temperatures had on Galapagos flora and fauna.

During the phenomenon most of the marine species populations decreased significantly. Terrestrial flora and fauna was flourishing with the plentiful rainfall, with abundant vegetation and food for land birds and reptiles. Now, the marine species are showing signs of recovery thanks to the return of nutrient-rich cold waters.

Some species of algae were drastically decreased during the phenomenon (e.g. the green algae (Ulva lactuca) which serves as food for marine iguanas and crabs). The brown algae (Hincksia mitchellae) increased considerably and might have been one of the causes of death among marine iguanas. Due to the lack of green algae, marine iguanas were feeding on these brown algae instead, which is unfortunately toxic to them. On North Seymour there may have been a loss of 90% of the marine iguanas. The green algae are now coming back, and so are the iguanas.

The sealions suffered badly from the El Niño phenomenon. 90% of the pups born in 1997 and 67% of the dominant males died from starvation. Their basic food is sardines, which were absent during the phenomenon. The sea lion colonies are slowly increasing now.

The coral live in symbiosis with an alga that disappeared during the phenomenon. The coral is still alive, but as a consequence 70-80% were bleached. This process is reversible, and since the algae are reappearing, they are pigmenting the corals.

The Galapagos penguins were severely affected by the phenomenon. The population was decreased by 65% because of the lack of food. The penguins stopped mating, which can be explained by the fact that they don't nest when the water temperature is higher than 23oC. The situation became worse as rats ate the penguin eggs and chicks. The need of a rat eradication program is urgent!

Cormorants were not affected by the phenomenon, but other seabirds were, notably the boobies. Unsuccessful breeding was their biggest problem, caused by the nests being filled with rainwater and stressed adults having to go further to seek food. The seabirds are nesting and breeding again and some species already have chicks. Land birds, like Darwin's finches, the Galapago dove, owls and hawks have all been flourishing during the phenomenon due to the abundance of food.

Sharks and a lot of fish disappeared from their normal ranges and were found at unusual depths, probably due to the higher water temperatures in their usual habitat. Now, the animals are coming back to their normal range again. Both hammerhead and Galapagos white-tipped sharks are easy to find while diving.

One of the biggest concerns during an El Niño phenomenon is the establishment and dispersal of exotic species. Conditions are perfect for many of the introduced species and thrive in the wet conditions that provide an abundance of food. New species have been reported, and an increase in rat and mouse populations as well. This could cause a permanent ecological change in the Galapagos Archipelago.

In conclusion, we can say that the species affected during El Niño 1997-98 are now returning to their normal populations and behavior patterns. Exactly how long it will take is impossible to determine. However, it is still possible to see and experience many of these incredible species when you come to visit the Galapagos!