Geography
The Galapagos Islands were formed from a mantle plume that slowly emerged from the Earth over a period of time. Mantle plumes are composed of hot rock from the Earth that rise to the surface due to their high heat which reduces their overall density. The mantle plumes melting as they rose to the surface combined with volcanic activity thickened the crust of the Earth in specific areas forming the Galapagos platform and eventually the islands themselves. Typically islands that form from a “hot spot” like a mantle plume form a linear chain of islands progressing by age but, the Galapagos Islands do not. The oldest exposed rocks on the islands are only three million years old. However, even with the unusual progression of the islands, scientists were able to determine that the region began developing islands much older than 3 million years old.
One of the most notable characteristics of the Galapagos is the very high number of endemic species that can be found within such a small region. These species are not just an attraction to eco-tourists, they have played a significant role in scientists' understanding of the age of the islands. The Galapagos Islands are home to the marine iguanas which evolved from land-dwelling iguanas over ten million years ago. Using this information combined with the preexisting knowledge at the time that ocean islands sink when carried away from a hotspot, scientists discovered old sunken islands that were once apart of the Galapagos. These islands sunk when the lithosphere began to cool and some sunken islands (seamounts) were found to be fourteen million years old. It is still unclear how old the original mantle plum the formed the islands is, some sources suggest it may be up to ninety million years old.
Species Arrival to the Galapagos
When the Galapagos islands formed millions of years ago they were a blank slate for new life to begin. The barren rock that was the initial state of the islands was eventually transformed into the unique environment that exists today as species slowly made their way to the islands and evolved over time. Since the Galapagos Islands are isolated from other landmasses, the first species arrived by sea or by air.
The limited opportunities for species arrival led to the “unbalanced” biodiversity of the islands. An example of these unbalanced conditions is the types of plants that inhabit the island. Plant species mainly arrived at the islands through the wind. Due to this, plants that have heavy seeds that cannot be carried in the breeze are unlikely to be found in the Galapagos. However, after initial plant life became established, new types of seeds were unintentionally deposited by birds that came to the island by air. Birds and animals that can fly or swim long distances came to the island in these ways. For example, the Galapagos is a popular home for sea birds as well as turtles. Some other land and sea species arrived in unique ways. Rafts of vegetation floating in the sea were the main way animals such as rats and reptiles made their way to the islands. Another reason why biodiversity is unbalanced on the island is that species that are more resilient had a better chance of surviving the journey to shore. This is why there are few land bird species and many salt-tolerant plant species along the coast. Additionally, after arriving at the islands, species had to have some tolerance to their new conditions in order to survive. Even with all of these challenges, small mammals, plants, birds, and reptiles began to inhabit the island which would eventually become an icon for evolution and a biodiversity hotspot.
Challenges in eradicating feral pigs, donkeys, and goats from islands
Plant species on the islands are threatened by non-native species, with goats and donkeys acting as a large force behind plant extinction, pigs impacted this as well. With limited conservation funds efficiently eradicating non-native species that pose a threat is essential.
Donkeys are herbivores that posed a significant threat to plants on the islands. Additionally, donkeys threatened tortoises and iguana populations by trampling nests. Campaigns to eradicate donkeys increased to the level of aerial hunting and the donkeys were removed by 2004.
Goats like donkeys posed a significant threat to plants and also increased erosion. Goats were harder to eradicate than donkeys, especially when the populations were low in density making them hard to locate. A unique method to take care of the goat problem in the Galapagos was the “Judas goat” method. This involved capturing an isolated goat and then releasing it with a tracker so that the hunters can be led to the main flock. While this method was needed when goats avoided being eradicated with other techniques, ground hunting was the most used for goat removal.
On Santiago Island in the Galapagos, a widespread eradication of pigs took place to help protect the island’s endemic species. Pigs prey on tortoise eggs and plant life as well as other species, disrupting the natural ecosystem. The first significant effort to get rid of the pig population on Santiago Island began in 1985 with a poisoning campaign and ended in 2000.
Overall, research shows that the environments once the goats, donkeys, and pigs are removed recovered/will recover fairly quickly.
Biodiversity
Plants: Even though the Galapagos is a small region, the islands contain over 600 native plant species and 30% of those native species are endemic as well. The plants vary in characteristics and location. There are coastal plants, desert-like plants found in dry regions, and lush greenery including mosses and Scalesia trees in the humid regions. However, the plant life of the Galapagos is at risk. Humans have introduced an additional 825 species, some of which are harming the existing environment and rare endemic species.
Giant Tortoises: The tortoises of the Galapagos became at risk decades ago when they became a food source for those traveling by boat. As the species can last a long time without food or water (a good traveling food source) and can be used for oil to light lamps, humans exploited this and hunted them severely reducing their population. Without human intervention, their population would be much larger than the 20,0000-25,000 it is today.
Iguanas and Lizards: Land iguanas face threats from many sources. The population in 1975 experienced a significant reduction by predation of feral dogs and a breeding program as well as an eradication of feral dogs was needed to save the land iguana population. Marine Iguanas are well adapted to their environment however, they still face threats from land predators. Birds of prey and cats prey on the marine iguanas when they are on land. El Nino events and oil spills also pose significant threats to marine iguanas.
Mammals: Due to the isolated location, the Galapagos is home to only six native mammals. These include the sea lion, fur seal, rice rats, bats, whales, and dolphins. While fur seals were at one time at risk of extinction from being hunted for their fur coats, they are no longer at any risk. The one mammal which faces the most issues is the rice rat. At one time there were four species of rice rats native to the Galapagos but the black rat, introduced by humans out-competed three of the four species.
Land Birds: The Galapagos is home to 29 species of land birds, 22 of them endemic species. Out of the 29 species 5 are listed as “vulnerable”, 2 are listed as “critically endangered”, and 1 is listed as “endangered”.
Sea and Shore Birds: The Galapagos is a hub for numerous sea birds but only 6 species are considered endemic, the Galapagos Penguin, Flightless Cormorant, Waved Albatross, Galapagos Petrel, Lava Gull, and Swallow-tailed Gull. The Galapagos Penguin and Flightless Cormorant are listed as endangered and vulnerable respectively due to increased El Nino events. The Waved Albatross has a very small breeding range which makes it critically endangered. The Petrels are critically endangered from invasive mammals and plants. The shorebirds seem to have stable populations but they are still at risk from climate change impacts, El Nino events, and invasive land animals like the sea birds.
Mangrove forests
Mangrove forests are an essential habitat for numerous organisms. They are considered a group of trees/shrubs that are exceptionally well adapted to saltwater environments. They have many unique features including “breathing roots” and seeds that can float in the water for long periods of time. Much of the marine life that lives near the mangroves rely on this habitat for protection from open waters and the predators that live within them. Mangrove islands also provide a habitat for birds because they provide protection for these animals, nesting areas, and food sources.
The mangroves are at threat from commercial fishing. Increased boat traffic harms marine life and nesting birds as well. Disturbing the animals inhabiting the mangrove islands may be unintentional by some but it has significant impacts, including reducing the water quality. There are no-wake zones around the mangroves and they are considered “off-limits”, but humans continue to develop the shoreline destroying the mangrove forest. Dredging activities can also destroy mangrove forests. In addition to protecting the birds and marine life, mangroves act as a buffer during storms and reducing/destroying them can have negative impacts on regions closer inland. Overall, if we do not reduce climate change and human impacts on mangrove forests the natural world is at great risk.
Note: All sources acquired from course website
The Galapagos Islands were formed from a mantle plume that slowly emerged from the Earth over a period of time. Mantle plumes are composed of hot rock from the Earth that rise to the surface due to their high heat which reduces their overall density. The mantle plumes melting as they rose to the surface combined with volcanic activity thickened the crust of the Earth in specific areas forming the Galapagos platform and eventually the islands themselves. Typically islands that form from a “hot spot” like a mantle plume form a linear chain of islands progressing by age but, the Galapagos Islands do not. The oldest exposed rocks on the islands are only three million years old. However, even with the unusual progression of the islands, scientists were able to determine that the region began developing islands much older than 3 million years old.
One of the most notable characteristics of the Galapagos is the very high number of endemic species that can be found within such a small region. These species are not just an attraction to eco-tourists, they have played a significant role in scientists' understanding of the age of the islands. The Galapagos Islands are home to the marine iguanas which evolved from land-dwelling iguanas over ten million years ago. Using this information combined with the preexisting knowledge at the time that ocean islands sink when carried away from a hotspot, scientists discovered old sunken islands that were once apart of the Galapagos. These islands sunk when the lithosphere began to cool and some sunken islands (seamounts) were found to be fourteen million years old. It is still unclear how old the original mantle plum the formed the islands is, some sources suggest it may be up to ninety million years old.
Species Arrival to the Galapagos
When the Galapagos islands formed millions of years ago they were a blank slate for new life to begin. The barren rock that was the initial state of the islands was eventually transformed into the unique environment that exists today as species slowly made their way to the islands and evolved over time. Since the Galapagos Islands are isolated from other landmasses, the first species arrived by sea or by air.
The limited opportunities for species arrival led to the “unbalanced” biodiversity of the islands. An example of these unbalanced conditions is the types of plants that inhabit the island. Plant species mainly arrived at the islands through the wind. Due to this, plants that have heavy seeds that cannot be carried in the breeze are unlikely to be found in the Galapagos. However, after initial plant life became established, new types of seeds were unintentionally deposited by birds that came to the island by air. Birds and animals that can fly or swim long distances came to the island in these ways. For example, the Galapagos is a popular home for sea birds as well as turtles. Some other land and sea species arrived in unique ways. Rafts of vegetation floating in the sea were the main way animals such as rats and reptiles made their way to the islands. Another reason why biodiversity is unbalanced on the island is that species that are more resilient had a better chance of surviving the journey to shore. This is why there are few land bird species and many salt-tolerant plant species along the coast. Additionally, after arriving at the islands, species had to have some tolerance to their new conditions in order to survive. Even with all of these challenges, small mammals, plants, birds, and reptiles began to inhabit the island which would eventually become an icon for evolution and a biodiversity hotspot.
Challenges in eradicating feral pigs, donkeys, and goats from islands
Plant species on the islands are threatened by non-native species, with goats and donkeys acting as a large force behind plant extinction, pigs impacted this as well. With limited conservation funds efficiently eradicating non-native species that pose a threat is essential.
Donkeys are herbivores that posed a significant threat to plants on the islands. Additionally, donkeys threatened tortoises and iguana populations by trampling nests. Campaigns to eradicate donkeys increased to the level of aerial hunting and the donkeys were removed by 2004.
Goats like donkeys posed a significant threat to plants and also increased erosion. Goats were harder to eradicate than donkeys, especially when the populations were low in density making them hard to locate. A unique method to take care of the goat problem in the Galapagos was the “Judas goat” method. This involved capturing an isolated goat and then releasing it with a tracker so that the hunters can be led to the main flock. While this method was needed when goats avoided being eradicated with other techniques, ground hunting was the most used for goat removal.
On Santiago Island in the Galapagos, a widespread eradication of pigs took place to help protect the island’s endemic species. Pigs prey on tortoise eggs and plant life as well as other species, disrupting the natural ecosystem. The first significant effort to get rid of the pig population on Santiago Island began in 1985 with a poisoning campaign and ended in 2000.
Overall, research shows that the environments once the goats, donkeys, and pigs are removed recovered/will recover fairly quickly.
Biodiversity
Plants: Even though the Galapagos is a small region, the islands contain over 600 native plant species and 30% of those native species are endemic as well. The plants vary in characteristics and location. There are coastal plants, desert-like plants found in dry regions, and lush greenery including mosses and Scalesia trees in the humid regions. However, the plant life of the Galapagos is at risk. Humans have introduced an additional 825 species, some of which are harming the existing environment and rare endemic species.
Giant Tortoises: The tortoises of the Galapagos became at risk decades ago when they became a food source for those traveling by boat. As the species can last a long time without food or water (a good traveling food source) and can be used for oil to light lamps, humans exploited this and hunted them severely reducing their population. Without human intervention, their population would be much larger than the 20,0000-25,000 it is today.
Iguanas and Lizards: Land iguanas face threats from many sources. The population in 1975 experienced a significant reduction by predation of feral dogs and a breeding program as well as an eradication of feral dogs was needed to save the land iguana population. Marine Iguanas are well adapted to their environment however, they still face threats from land predators. Birds of prey and cats prey on the marine iguanas when they are on land. El Nino events and oil spills also pose significant threats to marine iguanas.
Mammals: Due to the isolated location, the Galapagos is home to only six native mammals. These include the sea lion, fur seal, rice rats, bats, whales, and dolphins. While fur seals were at one time at risk of extinction from being hunted for their fur coats, they are no longer at any risk. The one mammal which faces the most issues is the rice rat. At one time there were four species of rice rats native to the Galapagos but the black rat, introduced by humans out-competed three of the four species.
Land Birds: The Galapagos is home to 29 species of land birds, 22 of them endemic species. Out of the 29 species 5 are listed as “vulnerable”, 2 are listed as “critically endangered”, and 1 is listed as “endangered”.
Sea and Shore Birds: The Galapagos is a hub for numerous sea birds but only 6 species are considered endemic, the Galapagos Penguin, Flightless Cormorant, Waved Albatross, Galapagos Petrel, Lava Gull, and Swallow-tailed Gull. The Galapagos Penguin and Flightless Cormorant are listed as endangered and vulnerable respectively due to increased El Nino events. The Waved Albatross has a very small breeding range which makes it critically endangered. The Petrels are critically endangered from invasive mammals and plants. The shorebirds seem to have stable populations but they are still at risk from climate change impacts, El Nino events, and invasive land animals like the sea birds.
Mangrove forests
Mangrove forests are an essential habitat for numerous organisms. They are considered a group of trees/shrubs that are exceptionally well adapted to saltwater environments. They have many unique features including “breathing roots” and seeds that can float in the water for long periods of time. Much of the marine life that lives near the mangroves rely on this habitat for protection from open waters and the predators that live within them. Mangrove islands also provide a habitat for birds because they provide protection for these animals, nesting areas, and food sources.
The mangroves are at threat from commercial fishing. Increased boat traffic harms marine life and nesting birds as well. Disturbing the animals inhabiting the mangrove islands may be unintentional by some but it has significant impacts, including reducing the water quality. There are no-wake zones around the mangroves and they are considered “off-limits”, but humans continue to develop the shoreline destroying the mangrove forest. Dredging activities can also destroy mangrove forests. In addition to protecting the birds and marine life, mangroves act as a buffer during storms and reducing/destroying them can have negative impacts on regions closer inland. Overall, if we do not reduce climate change and human impacts on mangrove forests the natural world is at great risk.
Note: All sources acquired from course website