Hydrothermal vents can only occur where there is volcanic activity. Cracks that form in the sea floor allow water to flow through the ocean crust, where it is heated by nearby magma chambers. Water can reach temperatures of up to 400°C where it dissolves metals and salts as it travels through the rocks. It then travels back into the ocean via hydrothermal vents.

Life in a hostile environment

Today, scientists have discovered hundreds of hydrothermal vents around the world however they were only first discovered in 1977 by a team working off the coast of Galapagos. The discovery revolutionised scientific thinking on how and where life could exist. The exploration of the hydrothermal vents along the Galapagos Ridge has lead to dozens of new and intriguing creatures being described. Scientists today are still exploring deep sea vents, trying to answer the many unanswered questions around these unique ecosystems.

A hydrothermal vent © NOAA

The environment around these vents is extremely hostile as there is often no light. There is also a lot of pressure because it is deep below the ocean surface and the vent plumes can include a lot of toxic chemicals including hydrogen sulphide which is poisonous to many animals. However, vents still manage to host an assortment of different creatures including tube worms and crabs which thrive in this environment.

A new type of bacteria has been discovered which uses the toxic gas as an energy source, and in turn this bacteria acts as a food source for crabs, clams and tube worms.

An image of a community of galatheid crabs, taken by oceanographer Robert Hessler of the Scripps Institution of Oceanography during a 1979 expedition to the Galapagos Rift © Robert Hessler/Woods Hole Oceanographic Institution

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.

Many unique ecosystems can be found in the Galapagos Islands. With so much animal and plant life, the Islands need to be carefully managed to protect the wildlife. In this chapter we will learn about how areas can be managed to protect biodiversity and the importance of involving local people in this process.

The value of biodiversity

Biological diversity or ‘biodiversity’ is a term that is used to describe the number of different living things, such as plants and animals, in an area. For example, an area that has many different types of bird, mammals and insects can be categorised as being more biodiverse than an area with only a few different types of birds, mammals and insects.

What is biodiversity like on the Galapagos Islands?

The Galapagos Islands are home to a wide range of species ranging from the iconic giant tortoises to lesser known plant and bug life that are often hidden away in the hard-to-reach areas. The Galapagos Islands are so biodiverse because of the many different habitat zones that can be found across the Islands. There are coral reefs, highland forests, sand dunes and scrubland, and the changing habitats from island to island.

Habitat Zones of Galapagos

Species diversity is only one piece of the biodiversity puzzle. There are many other parts that add up to make an areas biodiversity. Species diversity refers to the number of different species that can be found in an area. For example, in Galapagos there are 15 different types (or species) of Galapagos finch.

What makes the Islands so unique?

The Galapagos Islands are famous for their wide range of endemic species, species that cannot be found anywhere else in the world. When a species only exists in one place (such as the Galapagos giant tortoise) it is known as being endemic. Endemism on Galapagos is high due to the geographical isolation of the Islands from other places. 

The protection of endemic and keystone species is essential to ensure the sustainability of the Islands and ensure the Islands remain biodiverse. A keystone species is one that has an important impact on the whole ecosystem. If something were to increase or decrease the number of keystone species in an area, it would have a direct effect on many other species within the same ecosystem. You can learn more about the relationship between species in an ecosystem in the Ecology and Habitats chapter.

What is impacting biodiversity in Galapagos?

The influence of human beings on the Galapagos Islands is making its environment unsustainable. Farmland is often planted with just one species of crop (monoculture) to make it easier to farm and control pests and weeds. However this also makes it more likely to suffer from the effects of diseases: if a farmer is only growing one crop a single disease can wipe out his entire harvest for that year.

Therefore biodiversity has both economic (e.g. protecting crops from diseases which would otherwise reduce their profit) and environmental value. Biodiversity also has a social value but it is harder to recognise: we appreciate the way wildlife looks and many people believe it deserves conservation because they see human beings as guardians of the earth. Biodiversity therefore, has a role within each of the sustainability parts and this makes the case for its conservation in the Galapagos Islands ever stronger.

A sustainable environment is one where the land, the plants and the animals (together known as an ecosystem) are able to live in a balanced way.

How can we become more environmentally sustainable?

Natural resources, such as wood, can be used by human beings in order to build homes and other structures. In Galapagos, if people were to keep chopping down trees for wood until all the trees in the area were gone, we would call this behaviour ‘unsustainable’. If the people wanted to act in a ‘sustainable’ way, they could think about only cutting down mature (adult) trees, and every time a tree is removed, at least one more could be planted. This would mean that in the future, the new trees will have grown and will also be able to provide the people with wood. The people could also make sure they only cut down the trees that are needed, instead of cutting down every tree and then deciding what to do with the wood. This way the animals and birds of Galapagos (such as Darwin’s finches) that rely on the trees for shelter and food can continue to thrive.

Electricity is an important necessity for homes in this day and age. To reduce the amount of damage we cause to the environment (see our chapter on Renewable Energy), we can aim to generate electricity in ways that work with nature rather than against it. For example, we could invest in new renewable energy sources such as solar or hydroelectric power rather than rely on fossil fuels that release harmful greenhouse gases into the atmosphere. All these damaging fossil fuels also need to be transported to the Islands, meaning a risk of oil spills into the fragile marine ecosystem (see our blog article on Recent Ship Groundings).

Why is Environmental Sustainability important?

If we don’t think about the environment when we make decisions, it might become so damaged that it would be impossible to repair and restore. In Galapagos, the scalesia forests help to absorb harmful carbon dioxide from the atmosphere. We also have to consider that if we continue to damage the Islands, would tourists still want to visit? This could effect the businesses of people who rely on tourists coming to the Islands (such as hotels, restaurants and tour guides).

Case Study: The Scalesia Forests of Santa Cruz, the Galapagos Islands

The unique nature of the Galapagos Islands means that their environment is highly vulnerable to the unsustainable actions of human beings. One example of this happened on the island of Santa Cruz, at the centre of the Archipelago.

In the early 1970s, Santa Cruz had a forest dominated by Scalesia, a type of tree that can only be found in Galapagos (they are endemic). There are fifteen different types of Scalesia that can be found in Galapagos and these trees can grow to be around 12 metres in height. They create a thick canopy which shades the lower forest levels from light, heat and heavy rainfall, protecting the soil from erosion.

Scalesia pedunculata © Patricia Jaramillo and Charles Darwin Foundation

In 1982, there was very harsh weather in the Galapagos Islands caused by what is known as an El Niño event. For eight months, heavy rains fell on Santa Cruz and almost all the adult Scalesia trees died. In the following two years, Santa Cruz experienced the opposite weather conditions, known as La Niña, with drought and poor rainfall. There was little sign of the forest making a recovery back to its condition back in the 1970s.

With little competition, the space left by the trees became a new home for introduced species. The Common Guava, Psidium guajava, was introduced to the Galapagos Islands in 1870 for food. Around the same time, Spanish Cedar, Cedela odorata was planted as a source of timber. Both have now spread throughout the Islands, taking over the Scalesia forest areas.

By 2007, very few Scalesia trees remained in the forest of Santa Cruz. Now, new species such as Himalayan Hill Raspberry are making their way into the forest and changing the ecosystem again. Although human beings could not control the timings of the El Niño and La Niña extreme weather events, the impacts on the Scalesia forest were made worse by the unsustainable actions of people who brought the introduced species to the Islands, leaving the Scalesia forest with little chance to grow back naturally.

Conservation projects are now at work to reforest areas of the Galapagos Islands with their native Scalesia trees.

Himalayan Hill Raspberry © Galapagos Conservation Trust

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.