Biosphere Expeditions 2015 reef survey of the Maldives is on ‘bleaching alert’
In 1998 there was a significant global El Niño event that virtually stopped water circulation in the Pacific and Indian Oceans, resulting in floods in west, north and south American arid regions, and drought in the Australian and New Guinea rainforests, eventually resulting in forest fires. It upset the Asian subcontinent monsoons and led to crop failures and food shortages in the tropical nations of the world.
In the ocean, the ‘blocking’ of the equatorial oceanic gyre of currents led to significant warming of the shallow seas of the tropics, failure of the anchovy fishery of Peru, and the death of many coral reefs. The Maldives reefs suffered at least 90% coral mortality, because a lens of hot water, about 3-5 degrees (Celcius) above the usual maximum (that is 30-31 degrees Celsius) lay over the reefs of the country for four weeks. This stressed the corals and led to significant ‘bleaching’. Bleaching is a process where stress to the corals results in them expelling their colourful symbiotic algae (called zooxanthaellae), thus going pure white and exposing their calcium carbonate skeletons. It is often the initial cause of death to the corals as the symbiotic algae give up to 80% of the energy to the corals from the sugars they produce by photosynthesis. Corals can survive initial bleaching, but only if the hot water stays over the corals for a short period, or at a lower temperature. In these circumstances, corals can reabsorb zooxanthellae into their tissues from the water column. However, the 1998 Maldives bleaching event was so severe, that it killed most corals outright. The recovery of the reefs has been from juvenile corals settling on the dead coral reefs, and re-growing.
Biosphere Expeditions has in collaboration with the Marine Conservation Society (MCS) has been doing four things since 2011:
1. Monitoring the recovery of the 1998 bleaching event at reefs that were first surveyed before the event, in order to see the amount of live coral that now exists at shallow depths.
2. Re-surveying sites first visited by MCS in 2005, such that we have indications of reef health, fish populations, and any large megafauna such as whale shark, manta rays, turtles, large fish and reef sharks. We recorded a ‘new’ whaleshark in 2011.
3. Training, via Biosphere Expeditions’ placement programme http://www.biosphere-expeditions.org/placements, of local Maldivians from government and civil society to monitor their own reefs and providing training and funding, courtesy of LaMer and the Rufford Foundation, for exceptional individuals to become Reef Check trainers themselves. These individuals trained up three local Reef Check teams since 2014 and undertook the first ever all-Maldivian Reef Check survey in November last year.
4. We have published four technical reports on the condition of the reefs since 2011.
This and last year are also El Niño years, where the east–west surface current movements of water across the planet’s equator is stalling and stopping. This results in the sun heating up surface waters in some locations, such that bleaching events have occurred. They have occurred in the tropical west pacific, Hawaii, French Polynesia, and to a lesser extent, the Maldives. Northerly Indian Ocean reefs (around the Arabian Gulf, Thaliand and Andoman and Nicobar Islands) appeared to have had the brunt of the hot water, but the Maldives remains on high alert, as this El Niño event is not over yet, and indeed could strengthen.
This year’s expedition is therefore ‘highly tuned’ to looking for bleaching events in the Maldives, or evidence of recent bleaching events (where the whitened corals start to be overgrown by algae). We are re-visiting sites we first surveyed in 2005 and four other sites that have been regularly monitored (once every two years) since 2011, going down the beautiful Ari Atoll from north to south. We have a survey team of eleven individuals, two trainers – one British and one Maldivian – and nine trainees (including two Maldivian placement recipients). The two placements are from the local NGO ‘The Maldives Whaleshark Research Programme’ and a local marine consultancy. The trainers on the expedition have both been trained by Dr Jean-Luc Solandt of the Marine Conservation Society, a Reef Check Course Director and the national coordinator of Reef Check for the Maldives.
From our scuba diving conservation holiday with whale sharks and coral reefs of the Maldives