The Galapagos Islands are famous for plant and animal life which has been there for thousands of years before human beings appeared on the islands. As the population of the Islands grow, it is important to monitor the impact of the human population on the environment.

Where do people live in Galapagos and how is the population growing?

Only four of the archipelago’s thirteen major islands have human populations: Santa Cruz, San Cristobal, Isabela and Floreana. In total, only three percent (or 300km²) of the Islands have human settlements, (the remaining 97% of the Galapagos Islands is maintained as national park). Therefore, as the population of the Islands grows, this space gets more and more crowded. The permanent resident population of the Islands is currently growing by around 6.4% a year, compared to population growth of 2.1% in mainland Ecuador. Both natural population growth and migration to the Islands are having an impact on this growth as the Islands become a more attractive place to work and live.

Land Zoning

“The ultimate purpose of zoning is to avoid or minimize the negative effect of human impact. Galapagos ecosystems are subjected to and allow for a rational use of goods and services these ecosystems offer to society.”- Galapagos National Park

Isolation is the key to the special nature of the Galapagos archipelago. Because human colonisation in Galapagos did not occur until relatively recently compared to the majority of the rest of the world, the unique ecosystems have been preserved and species have survived. However, population increase and urban expansion means that land zoning of areas for human use and rules for the use of the zones has become necessary.

Prior to 1959, protected areas and unprotected areas were considered independently and the interconnectedness of the zones was not taken into account. There was no real difference in the management of the human and natural space. When the Galapagos National Park was defined in 1959, 97% of the islands around populated areas were declared protected natural areas. The remaining 3% of the land is used by Galapagos communities both rural and urban. The new zoning model recognises that hazards such as invasive species and pollution come from populated areas and that the populated areas depend on the unique ecosystems and their conservation, so demonstrating the inter-connectedness of the zones.

A digram showing land use in the rural part of Santa Cruz © Galapagos National Park

Rural areas are in the upper parts of the inhabited Islands and are privately owned. They are wetlands which allowed the formation of soil suitable for agriculture. This importance of agriculture has declined and the land has gone out of cultivation. This has led to an increase in the invasive plant species such as guava, blackberry and passion fruit, that were introduced when the land was cultivated. The responsibility of recovering these areas, preventing further invasions and removing the invasive species lies with the owners, local government and government. A pilot plan on Santa Cruz Island in 2009 used chemical and physical controls such as cutting back plants, foliage spraying and fumigation.

The urban areas around ports are where most human activities take place, such as the arrival of cargo and people from other islands and the mainland. Human activity causes the greatest changes to the environment through construction of buildings and roads, pollution and introduced species. It is therefore very important to have clear land use policies and planning.

Urbanisation in Galapagos © Galapagos Conservation Trust

Surrounding rural and urban human spaces on each populated island is an area defined as low impact. These are areas which have much of the original ecosystem still intact but have been altered to some extent by human activities. The establishment of Special Public Use Sites is allowed so that some timber can be extracted and non-recyclable solid waste can be disposed of.

The Marine environment is also subjected to zoning with a Marine Reserve and coastal areas with different uses in specific locations for fishing, research, conservation and education. There are sub-zones for special management and recovery, in which human activity is particularly relevant.

A new island is formed when volcanic lava erupts out of the sea bed, over 1,600m below sea level. On contact with cool sea water, the lava solidifies into volcanic rock at the bottom of the ocean. As the eruptions continue, rocks build up until they rise above sea level to create a new island.

Colonising Galapagos

Galapagos colonisation: starting life on bare rock

Newly formed islands are devoid of life. The first things to colonise the islands are small and basic organisms (e.g. lichen, algae and mosses), able to cope with the harsh environment. Washed up on the shoreline or blown by the wind from the South American mainland, these pioneer species are the first forms of life on the bare rock.

Pioneer species are producers, so are able to create their own food from only sunlight, water and air (photosynthesis). Over time, they break down the rock to create soil and help to provide a more hospitable environment. This process allows more complex, less resilient plants to grow on the island.

Mosses and lichens are often the first colonisers of bare rock © Galapagos Conservation Trust

Establishing an ecosystem

An ecosystem is the community of living things found in an area and also the non-living things that make up the environment such as rock, water and air. All of these elements interact with each other in a system… an ecosystem!

As the amount of life on the island increases, the environment continues to change. A deeper, more nutrient-rich soil can support the growth of species that would previously have struggled to live on the island. With time, this allows larger plants and trees to grow. The transformation of bare rock into rich habitats is known as lithosere succession. 

Once sufficient vegetation is growing on the island, animals are able to survive in this new environment. Small animals such as insects will often be the first to arrive as they are primary consumers and only need plants to survive. The presence of insects in turn helps more plants to colonise the island due to their important role in pollination.

As ecosystems develop, the islands will be able to support secondary, tertiary and quaternary consumers, such as iguanas, birds and sea lions.

A long way to travel

Remember, animals have to travel almost 1,000 kilometres from the South American mainland to reach the Galapagos Islands. This is just over the length of the British Isles from north to south.

There are two key methods of transport – by air or by sea. Since many plant seeds cannot survive submersion in saltwater, they would not have been able to colonise the volcanic islands. Only the hardiest seeds, that can survive in saltwater for long periods of time, would have been able to travel to Galapagos. Spores would be able to reach the island by travelling in the air, as they are much smaller and lighter. Seeds and spores may also arrive via animals for example, on the feather of a bird or via its dung if eaten on the mainland.

Sea birds that are strong flyers may be able to cross the ocean to the island during their long migrations but weaker, smaller land birds and insects rely on just the right wind conditions to help them along on their journey.

Strong swimming marine life such as tuna and sharks may swim to the island but smaller species of fish and seabed dwelling animals such as crabs depend on ocean currents to reach the new island. The Galapagos penguin is the most northerly penguin species in the world.

The cold Humboldt Current that travels up the western coast of South America from Antarctica, is likely to be the route that the ancestors of the Galapagos penguin originally took when they first colonised the Galapagos Islands.

The Galapagos penguin is the only penguin to be found on the equator from left to right – ©Bart Goedendorp, ©Antje Steinfurth, and ©Jonathan Green

Some animals, such as lizards, probably floated from the South American mainland on rafts of vegetation. Young giant tortoises may have also arrived this way but it is possible that adult giant tortoises could have floated that distance due to their ability to survive for long periods without food or fresh water.

Not all colonisers make it however. The isolation of Galapagos and inhospitable nature of a new volcanic island limits the number of species that can populate. For example, mainland Ecuador has a wide variety of plant life – more than 20,000 species – whilst Galapagos has around 1,500 species. The 1,000 km of saltwater between Ecuador and the Islands acts as a barrier to the migration of many plant and animal species.

Often colonisation depends on the right environmental conditions and a species can only succeed if it can reproduce. Physical capabilities and a degree of luck have therefore determined the wildlife that is now established in Galapagos.