The uniqueness of life on the Galapagos Islands is well documented and, for nature lovers, a visit to the region can be an inspiring and life-changing experience. For those embarking on a Galapagos wildlife cruise, understanding the reasons behind its extreme diversity can contribute to a deeper appreciation of this incredible part of the world.
A Phenomenon of Nature
There’s one natural phenomenon that can take the major credit for the abundance and diversity of both the marine and terrestrial wildlife of the archipelago. The chilly Humboldt Current originates in the Antarctic, driven by strong winds to flow up the west coast of South America and push the cool waters on a path straight through the Galapagos Islands. It brings with it nutrients that it gathers from the dead and decaying matter on the sea bed, and when it mixes with the warmer South Equatorial Current, these nutrients rise from the deep to sustain the plankton that forms the basis of the islands’ food chain.
The current affects every aspect of life, both on land and in the surrounding oceans.
The Water Temperature: Some people who visit on a Galapagos wildlife cruise are taken aback by the chilly temperatures of the water, due to the presence of the Humboldt Current. June to December is when the oceans are at their coldest, as these months are marked by an increase in the current. From November to May, the current is still present, but is significantly weaker, allowing warmer waters to reach the islands.
The Weather Patterns: The current is also responsible for the two distinct seasons that are experienced on the archipelago: the cool, dry season and the hotter wet season. In the dry months (from June to October), powerful trade winds cause the current to pick up. Since the waters surrounding the islands are cooler, there is less evaporation, and therefore fewer rain clouds form. While a Galapagos wildlife cruise can be enjoyed at any time of the year, the two seasons can offer quite different experiences.
The Wildlife: Even beyond this remote archipelago, the presence of the Humboldt can be felt and it is credited as the “most productive marine eco-system in the world” – responsible for an astounding 20% of the entire world’s marine catch. Every single species – reptile, mammal, bird, invertebrate or marine – on every single island, including the surrounding waters, is affected by and dependent on this powerful current. The nutrient-rich waters it brings directly or indirectly provide the food sources that sustain the huge wildlife population.
The El Niño Effect
The effect of the current can perhaps most clearly be seen in its absence. During the weather phenomenon known as El Niño, it is weakened by warmer winds and a decrease in air pressure. During these times, which occur cyclically every two to seven years, there is a marked reduction in breeding activity of the local wildlife. There are far fewer fish, and therefore a massive decline in the food sources of the islands, resulting in great numbers of animals starving to death.
The complex and definitive role this cold ocean current plays in sustaining the rich biodiversity of the islands is yet another fascinating aspect of one of the most intriguing places on the planet.
Marissa Ellis-Snow is a freelance nature writer with a special interest in the Galapagos Islands. For those interested in a Galapagos wildlife cruise, Marissa recommends the itineraries organised by Naturetrek, which have brought her unforgettable sightings of a wide range of species in one of the most spectacular regions on Earth.