A wealth of marine biodiversity on the smallest of land masses
Kimberley McCosker
According to IUCN, Earth contains over 100,000 islands which are home to around 20% of global terrestrial and marine biodiversity. There is extraordinary diversity in the geography of islands – from low-lying coral atolls to mountainous and rocky remnants of volcanic eruptions – which creates a vast array of ecosystems in which organisms living in and near the ocean can thrive.
For the month of May, we are taking a closer look at the marine environment in some of the most fascinating island locations: the Maldives, the Galapagos Islands, the Falkland Islands and the Solomon Islands. Each week, we’re choosing an island group to focus on and will be sharing more information on their geography, ecosystems and marine life, as well as new marine research being conducted there. If you’re keen to learn more about these incredible locations, keep an eye on our Facebook, Instagram and Twitter throughout May, and follow #TMDdoesislands on each platform to join us on our deep dive into these amazing locations!
The Maldives
Ah, the Maldives. The name alone conjures images of white sand lagoons, palm trees dipping into the ocean and a cheeky sunset cocktail. Officially named the Republic of the Maldives, the island nation comprises 26 atolls perched atop a submarine ridge that rises from the depths of the Indian Ocean. These atolls were formed when prehistoric volcanoes subsided into the sea, leaving behind the fringing coral reefs, forming atolls. These atolls trap sand and coral gravel, forming islands that dot the edge of a central lagoon, giving the Maldives its unique – and famous – geography.
An uninhabited island in Baa Atoll, showing the unique formation of the Maldives island chain: a fringing coral reef trapping enough sand to form a small island. Photo: Unsplash.
These atolls and islands set a stunning scene for an array of fascinating ecosystems. Terrestrial biodiversity is limited due to the small size of the islands, so marine ecosystems rule. Coral reefs are dominant, but are situated close to seagrass beds, mangroves and deep sea, which has allowed marine biodiversity to flourish. Whale sharks, manta rays and a stunning variety of corals are among the most famous residents of the Maldives – however members of nearly all phyla and classes are found in the Maldives’ seas.
The fascinating biodiversity of the Maldives has led to its status as a hub for marine science, with a vast array of research being conducted on the islands and their surrounding seas. Local and international scientists alike have produced fascinating research in a variety of areas, including marine resource dependency and social resilience, linkages between coral reefs in the Red Sea and Indian Ocean, use of geospatial data to mainstream ocean-based climate change adaption and the population dynamics of oceanic manta rays. For the non-scientists among us, it’s a great place to visit to learn more about our oceans, with many of the Maldives’ famous resorts hosting marine biologists to teach guests how to protect the underwater world.
The Maldives is famous for its population of oceanic and reef manta rays (Mobula birostris and Mobula alfredi), and home to some of the most ground breaking research on the genus. Photo: Unsplash.
The Galapagos Islands
The Galapagos Islands, part of the Republic of Ecuador, lie approximately 1,000 kilometres off the western coast of South America in an isolated area of the Pacific Ocean. Like the Maldives, the 13 islands of the Galapagos sit right on the equator – but the geography of the two groups couldn’t be more different. The Galapagos Islands were formed on a hotspot and shaped after multiple volcanic eruptions over millennia pushed magma above the surface of the ocean, creating the steep, rugged coastline of the islands today. Ongoing seismic and volcanic activity creates a continually dynamic region and has created the context for the adaptation that make the marine species of the Galapagos Islands so special.
The rugged shores of Bartolomé Island showcases the harsh coastal environment typical of the Galapagos Islands. Photo: Unsplash.
The Galapagos was recognised by UNESCO as a World Heritage Site in 1978 and as a biosphere reserve in 1985. This was later extended in 2001 to include the marine reserve – and it’s not hard to see why. As a result of its extreme isolation, the island is home to some of the most interesting and rare species in the world and has become known for showcasing evolution and adaptation traits in a number of species. Some of the incredible and unique species that call the Galapagos home include Phoebastria irrorata, the world’s only tropical albatross; Amblyrhynchus sristatus, the only species of iguana that feeds in the ocean; Spheniscus mendiculus, the only tropical penguin and the only penguin species that lives in the northern hemisphere; and Zalophus wollebaeki, the famous Galapagos sea lion. The abundant marine life includes everything from the emblematic whales, dolphins, and sharks to the smaller (but just as impressive) crustaceans, sea cucumbers, and reef fish that create a high level of marine biodiversity unlike anywhere else in the world.
The Galapagos sea lion is one of the many species that have uniquely adapted to living in the warm waters of the Galapagos islands. Photo: Unsplash.
Charles Darwin may be the most famous scientist to have worked in the Galapagos, reportedly solidifying his theory of natural selection after observing differences in the beaks of Galapagos finches. However, Darwin was only the first in a long line of scientists making important breakthroughs in the area. Recently, marine scientists in the Galapagos have been attempting to identify the pupping grounds for pregnant whale sharks, re-discovering a species of sea kelp that was previously thought to be extinct, and investigating the arrival of non-native marine species including sea squirts and marine worms.
The Falkland Islands (Islas Malvinas)
The Falkland Islands sit around 480km east of South America’s Patagonia coastline. The island’s locations can be traced back to the break-up of the supercontinent Gondwana, when minor fragments detached from what is present day Africa and drifted west, before coming to rest on the South American continental shelf. There are over 700 islands in the archipelago, but two principle islands – East and West Falkland – comprise the majority of the landmass. The islands and their ecosystems are greatly influenced by Antarctica, with cold currents from the Southern Ocean and violent winds from the Antarctic continent characterising much of the land and seascape.
King penguins call the harsh sub-Antarctic coastline of the Falkland Islands home. Photo: Unsplash.
The position of the Falkland Islands in deep waters in the far south Atlantic Ocean is key to the richness of marine life. The movement of the Malvinas (Falkland) Current northwards along the edge of the Patagonian shelf creates a strong upwelling of cold, nutrient-rich, sub-Antarctic water. As well as creating beautiful phytoplankton blooms visible via satellite, these upwellings create a feeding paradise for whales, including the blue whales and humpback whales that are frequently spotted in the water surrounding the Falkland Islands. The islands act as a breeding ground for a number of pinniped species, including the iconic southern elephant seal (Mirounga leonine). The Islands are the most important breeding locality of Thalassarche melanophrys, the black-browed albatross – over 85% of the global population of these seabirds call the Falkland Islands home.
Black-browed albatross hunt in the waters of the Falkland Islands. Photo: Unsplash.
The Falkland Islands offer a fascinating world for marine science, as both the gateway to the Antarctic continent and a unique ecosystem in their own right. Recent developments in the Falkland Islands include the monitoring of sub-Antarctic kelp forests to establish their role in primary production, the mapping of marine megafauna to inform marine spatial planning and, unfortunately, documenting the high level of microplastic pollution in the most remote locations of the southern Atlantic ocean.
The Solomon Islands
The Solomon Islands, located to the south east of Papua New Guinea, host an array of ecosystems, from tropical rainforests that drop straight into the ocean, to coral atolls with uninhabited sand islands, to rugged volcanic mountains with lava flows reaching the sea. The archipelago was formed by the convergence of the Pacific and Indo-Australian tectonic plates, which has resulted in the volcanic activity still present in some areas of the Solomon Islands today.
The Solomon Islands are located in the eastern corner of the Coral Triangle. Photo: Ethan Daniels (Shutterstock).
The Solomon Islands are located in the eastern corner of the Coral Triangle, an area of ocean stretching from the Pacific to central Indonesia and north to the Philippines that is renowned for its staggering diversity of coral and abundance of marine species. The Solomon Islands is often referred to as the last great reef ecosystem on earth, with the nation’s remoteness leading to untouched networks of diverse coral reefs. The wide range of marine habitats, including the proximity of deep ocean trenches and volcanic runoff, has created spectacular marine biodiversity: almost 500 coral and over 1000 reef fish species have been identified in the archipelago, as well as 80% of known seagrass species and multiple species of mangroves. Some of the most loved sea creatures call the Solomon Islands home, from tiny pygmy seahorses and nudibranch to napoleon wrasse, manta rays and dugongs.
Dugongs are often found feeding in seagrass beds in the Solomon Islands. Photo: Unsplash.
Marine science is a developing field in the Solomon Islands. The nation only recently compiled hundreds of data sets into an accessible digital resource, and is working to integrate ocean science into other existing fields, including through the recruitment of the Solomon Islands’ first oceanographer to work within the National Meteorological Services just 12 months ago. However, it is a growing field with focus being placed on protecting keystone species including sharks, ocean-driven climate resilience, and sustainable fisheries management to ensure the ocean nations’ resources are protected in the face of increasing globalisation.