Jun 25
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Spotlight on: Islands

There are over 175,000 islands on Earth, from tropical paradises in the warm blue waters of the Caribbean Sea to isolated rocks in the freezing Southern Ocean. Islands are well known for their high levels of biodiversity as well as being home to unique and unusual species, many of which are endemic to a single location and are found nowhere else on Earth. This species richness was the inspiration behind our new islands feature page, which aims to highlight the importance of islands and the conservation work being done to protect them.

Polynesia photo

Formed from continental fragments or the exposed peaks of oceanic volcanoes, islands vary greatly in size, climate and landscape. Islands and their surrounding waters account for around a sixth of the world’s total area, and estimates suggest that they support 20 percent of all species of birds, reptiles and plants, as well as 50 percent of the world’s marine biodiversity.

Hawaii photo

Species such as the lemurs of Madagascar and the solenodons of Cuba and Hispaniola are unlike species found anywhere else in the world. Madagascar alone has over 8,000 endemic species, and in Hawaii over 90 percent of the species are endemic.

 

 

 

 

 

 

Having evolved in isolation over thousands of years, island species are not only very different from their mainland ancestors, they are also very vulnerable to the impact of invasive species. They often lack the adaptations necessary to avoid predation or cope with competition for resources, and over the past 400 years, around half of all animal extinctions have occurred on islands. Fortunately, many conservation organisations work tirelessly to protect island species and habitats, with some standout success stories.

Codfish Island photo

Check out our islands page today to find out more about island biodiversity, island species and island conservation.

Claire Lamb, ARKive Researcher

Sep 19
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In the News: West Nile virus threatening Galapagos wildlife

West Nile virus is threatening the unique wildlife of the Galapagos Islands, prompting scientists to call for increased vigilance over the ‘biosecurity’ of the archipelago’s exceptional biodiversity.

Galapagos marine iguana

Galapagos marine iguana

Scientists from the Zoological Society of London (ZSL), the University of Leeds and the New York State Department of Health, together with the Galapagos National Park Service and University of Guayaquil, have studied the risk to wildlife posed by the West Nile virus (WNV).

The research is published in the current edition of the American Journal of Tropical Medicine Hygiene.

Deadly discovery

The scientists discovered that a species of mosquito now found in the Galapagos is capable of transmitting the virus, which could be potentially deadly for the island’s many endemic species.

Although the virus most commonly affects birds, it can also infect mammals, including humans, and reptiles.

WNV has recently invaded South America, but has yet to reach the Galapagos. However, the southern house mosquito, Culex quinquefasciatus, has previously been found by scientists to ‘hitch a ride’ to the Galapagos Islands on tourist boats and planes.

Mosquito species in the genus Culex are renowned vectors of the disease, and the presence of this particular species on the Galapagos Islands is causing huge concern among the scientific community.

Galapagos penguin

Galapagos penguin

Unique biodiversity

The Galapagos Islands are famous for their unique wildlife, being home to many endemic birds and reptiles, including the truly unique Galapagos marine iguana. The world’s only flightless cormorant, as well as the only penguins and albatrosses found on the equator are also residents of these amazingly biodiverse islands.

The Galapagos Islands are also home to many lesser known species, including 3 species of endemic rice rat, 57 endemic species of land snail, and a very large number of insect species. Plants also thrive on the Galapagos, with 560 native plant species, of which 180 are endemic.

Assessing the threat

To determine the threat that Culex quinquefasciatus poses to the diverse Galapagos wildlife, the researchers decided to measure the mosquito’s ability to pick up and transmit WNV in the lab, under conditions that simulated those in the wild.

Their findings indicate that this particular mosquito species is indeed an effective vector for the virus.

Professor Andrew Cunningham from ZSL says, “We now know that mosquitoes capable of carrying West Nile virus have a route onto the Galapagos, and once there, the virus could also spread into the local mosquito population. This means there is potential for large impacts on endemic species. There is no doubt that West Nile virus poses a serious threat to the survival of the Galapagos’ iconic wildlife.”

Waved albatross

Waved albatross

Protecting the wildlife

According to the authors of the study, further research must now be done to determine the presence of WNV in the mainland Ecuador so that they can assess the likelihood of the virus reaching the Galapagos. They also suggest that strict insect control measures on aircraft and ships moving between the mainland and islands should be enforced in order to reduce the chances of West Nile virus reaching the archipelago.

Gillian Eastwood, the lead author of the study and a PhD student says, “Whilst WNV does not yet exist in Galapagos, it is important to envisage what future disease scenarios could be by looking at how this particular virus would interact within this unique ecosystem.”

“Evaluating the role that mosquitoes could play is therefore vital. This recent part of our work is however only one aspect to understanding potential WNV transmission on the Islands; it remains to see how severely Galapagos wildlife might be affected but all precautions should be taken.

Dr Simon Goodman from the University of Leeds reinforces this view, saying, “Once WNV has been introduced onto the Galapagos, it would be much harder to contain. Therefore the best strategy is to have strict preventive measures to reduce the chance of the disease reaching the islands in the first place.

Read the University of Leeds press release.

Read the article in the American Journal of Tropical Medicine Hygiene.

Find out more about conservation in the Galapagos.

Helen Roddis, ARKive Species Text Author

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