Carbon and climate change, Community action, ecological action

Aliens, climate change & tourism: A deadly cocktail

“80 per cent of known species extinctions have occurred on islands and currently 45 per cent of IUCN Red List endangered species occur on islands.” – IUCN

Islands are the abode of the world’s tallest sea cliffs, beautiful beaches, clear waters, most active volcanoes, rare and wonderful animals including orangutans, carnivorous plants, birds of paradise and giant monitor lizards. Even though, they constitute only 10% of worlds total landmass they accommodate major ecological regions varying from coral reefs and sand dunes to high alpine deserts and rainforests. 180,000 islands world-wide harbor over 20% of the world’s biodiversity (Kier et al., 2009). The rate of endemism seen in islands is 9.5 and 8.1 times higher than continents for vascular plants and vertebrates respectively (Kier et al., 2009). 104 of the 218 endemic bird areas are confined entirely to islands. This can be further emphasized by the fact that out of the 35 biodiversity hotspots identified by Mittermeier et al in 2012, 10 constituted only or mainly of islands. These are called insular hotspots. Also, 7 out of 10 coral reef hotspots surround islands and 12 out of 18 centers of marine endemism are around islands. Most of the island biota is unique and irreplaceable. Thus collectively islands can be thought of as the richest of the hotspots on Earth.

A crisis unfolding……

Unfortunately, the richest of the hotspots also happen to be the most threatened. Compared to continental systems, islands claim the greatest number of extinctions in the world and include greater concentrations of threatened species. Of the 724 recorded animal extinctions in the last 400 years, about half were of island species. At least 90% of the bird species that have become extinct in that period were island-dwellers.

Island ecosystems are the most threatened ones on our planet as highlighted by the Report of the Global Conference on the Sustainable Development of Small Island Developing States also known as The Barbados Programme of Action for the Sustainable Development of Small Island Developing States. Furthermore, the Millennium Ecosystem Assessment concluded that the main drivers of island biodiversity loss would either continue or increase rapidly.

Biodiversity, endemism and Island vulnerability

What makes our islands so vulnerable? There are mainly two reasons. Firstly, due to competition with relatively few other species peculiar to insular conditions, the island biota has evolved to be more fragile than on the mainland. This also made the native populations highly specialized without much developed defense mechanisms against a broad range of problems making them especially vulnerable. Secondly, the coastal zones in islands are especially large compared to their inland area making them very much prone to erosion. Also, the small size reduces their ability to maintain critical ecological functions in times of population growth, increased exploitation or a natural disaster. These reasons coupled with isolation, makes the island especially vulnerable to natural, technological and anthropological threats.

Major causes of biodiversity loss on Islands

  • Invasive Alien Species– Island species have evolved to be small, localized and highly specialized to the immediate environment. They do not possess any defenses to the invasive populations, making them especially vulnerable.

o  The carnivorous snail Euglandina rosea, introduced to control the giant African snail (Achatina fulica), brought to extinction most of the endemic partulid land snails of the island of Moorea in the Society Islands

o  The introduction of the brown snake (Bioga irregularis) into the formerly snake free island of Guam in the 1940s brought to extinction almost all of the indigenous forest birds and endangered the fruit bats, geckos and lizards of Guam. The cost to the island’s economy from the establishment of this single invasive alien species is estimated at US$ 5 million a year.

  • Unsustainable tourism – even though tourism is one of the major source of income for small island developing states (SIDS), it has destroyed the biodiversity beyond repair by destruction of wildlife habitats, deliberate or unintentional introduction of invasive alien species, degradation of habitats by solid and liquid wastes and tourism activities including illegal diving, unregulated fishing activities, off-road driving etc. It’s a double edged sword – given tourism’s dependency on biodiversity to some extent, it is also recognized as having a high potential for biodiversity conservation and sustainable use. Eco tourism market makes up 6% of the GDP all over the world. The yearly growth rate is 5%.
  • Climate change and variability, with subsequent global warming and sea-level rise– As most islands are low lying, they stand at the front lines of the battle of climate change. Worst case scenarios of ice sheet melting and sliding lead to estimates of sea level rise of 4m to 6m in the next century (Overpeck, Jonathan T., et al.,2006). At least eight low-lying islands in the Pacific Ocean have disappeared under rising seas. In 2016, a study led by Simon Albert at the University of Queensland in Australia found that five of the Solomon Islands had been lost since the mid-20th century. Apart from rising sea level, another impact of climate change is the increasing mean surface temperature. Scientists predict that by the end of the 21st century, the Earth’s mean surface temperature will warm anywhere between 1.4?C to 5.8oC. Rises in sea temperature can cause coral bleaching. This phenomenon has a major impact on the health of marine ecosystems, affecting fish, sponges, giant clams, mollusks and other sea creatures that rely on reefs to survive. The 1998 El Niño caused unparalleled coral bleaching, killing 85% of the corals in the western Indian Ocean.

The deadly cocktail gets even more potent as we add the impact of natural disasters, over exploitation of resources, waste disposal and pollution.

Before it’s too late…

About time the global environmental, sustainability & biodiversity forums and supporting agencies / governments took serious note and put into place action plans that work towards conservation of our island biodiversity as not only are they of importance to the island dwellers but also repositories of genetic information representing a record of millions of years of evolution on our planet. This biodiversity has an inherent value to humankind the world over.

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