The Chagos 2010 expedition has returned and exceeded expectations with the work accomplished. The trip was hard work but a great success and it was wonderful to see the reefs recovering from the 1998 El Nino event like nowhere else. Many islands too are recovering from the plantation era and the native Indian Ocean habitats are re-emerging.
The fields and skills of the team covered a range of topics on which more information was needed for Chagos. Charles Sheppard, the expedition leader, and Anne Sheppard were working on the recovery and ecology of corals and soft corals following the 1998 Indian Ocean wide mortality from the El Nino warming event. They are delighted to report that Chagos continues to be recovering better and faster than anywhere else in the Indian Ocean. Charles Sheppard said, “Our understanding of the value of these islands to the rest of the world grows with each visit.”
Sara Woodroffe and Scott Smithers are geographers working on how and when the Chagos reefs were formed in the context of the whole Indian Ocean. They completed seven island transects and toe of beach surveys, collecting modern microatoll samples from three different atolls and discovered evidence of former sea level above present in three different locations across the archipelago. This gives a wealth of sea-level data spanning approximately the last 4000 years, evidence of island age and evolution and a measure on what has happened to sea level in Chagos during the last hundred years. Colin Clubbe surveyed the vegetation ecology of the islands, what is there and how it is recovering from the plantation days and assessing potential Important Plant Areas for Chagos. Pete Carr worked with Colin and assessed the current status of the nesting seabird populations.
Andrew Price did rapid environmental assessments at the same sites examined in 1996 and 2006 as a health check on the coastal environment of Chagos which entailed semi-quantitative assessment of the abundance of major ecosystems and species groups and of the magnitude of disturbances such as fishing/collecting, pollution, construction and solid waste. He also did assessment of holothurian (sea cucumber) populations. The surveys were undertaken at the same sites examined in 2006, for an update on population status and possible harvesting effects.
Anne Sheppard also collected sediment samples for analysis at Plymouth Marine Labs for microplastics (tiny pieces of the global plastic waste that, in the marine environment, is fed on by plankton and kills it), the organic pollutant PFOS, and hydrocarbon residues. Chagos waters are so pristine that they are used as a global baseline reference.
Miriam Pfieffer, a paleogeologist, collected thin cores of living corals and also slices of old (often 150yrs old) beach rocks to investigate the palaeoclimatic conditions in the Indian Ocean. More than 10 m of Porites coral were sampled which equates with more than 800 years of climate history (not necessarily consecutive) at Chagos.
Nick Graham and Morgan Pratchett swam miles underwater. Nick counting fish and estimating their sizes for fish biomass estimates to assess the reef fish populations in Chagos and to compare that data with Indian Ocean wide data. These are the least fished reefs in the Indian Ocean and so the data will give us an idea of what fish stocks should be like when they are not exploited. They similarly swam over 7 kilometres of transects estimating shark population numbers for a global survey. Morgan studied the Chagos butterflyfish feeding ecology as part of an Indian Ocean wide study – this group is especially sensitive to the state of the corals.
Simon Williams was the expedition medic who fortunately did not have to ply his trade and Pete Raines was the expedition manager who made all the necessary things happen. Boats and compressors were maintained and Scuba tanks filled without most members really being aware of it. Simon and Pete also completed over a kilometre of tape transects of coral surveys in support of the coral work, as well as holothurian surveys in support of that element of work too.
Between them the expedition members recovered and redeployed instruments which gave 22,000 temperature readings; filled and breathed 380,000 litres of compressed air; counted 4,000 corals in 400 quadrats, including 450 coral aggression interactions with their neighbours; collected over 4,000 years worth of sea-level data; swam over 50 kilometres of transects; counted over 20,000 individual reef fish; collected 800 annual growth rings of corals and watched 289 butterflyfish take 5,114 bites! Many more similar and intriguing facts will be in the next issue of Chagos News.