At 7 am on 16 March Steve begins a bathymetrical survey of an area 1 Kilometre square around the old structure. One of the aims is to find any unusual features such as knolls (indicating well developed reefs) or particularly shallow areas. Over the next 2 days he determines that the area is extremely flat and even.
At 8.45 am Tom Goreau makes his first dive to assess the general state of the ecosystem. he reports that live coral cover is greatly reduced from 1997. He thinks this is most likely due to bleaching (which affected around 90% of coral around the Indian Ocean in 1998). Fire Coral which is particularly sensitive, has all died. There are also relatively few acropora species left.
In 1997 porites species were diseased. These are now mostly dead too. The largest corals left alive are Blue corals - normally a relatively sparse group of species. Halamida (calcareous green algae) are present in abundance, indicating that this is a nutrient rich environment thanks to upwelling of deep waters around the bank.
Tom says that there does appear to be quite a new lot of coral recruitment: new small corals are growing back. Fish are beautiful and diverse - but small in size and numbers. As a whole, the area is not as vibrant as it was in 1997 but it is well worth protection.
In the afternoon, Frank leads a team who take core samples from the seabed. The first core shows a surface layer of limestone type cretation about 4 cm thick on top of compacted sand of undetermined depth.
Caroline and Gabriel conduct a biodiversity survey of coral and fish species. Some details about their findings will be included in a later bulletin.
Wolf leads a team on Ophee to build box frame steel units for the new structure at Saya. The design calls for 3 base units 2 m. long and 1.5 m. high, for 3 legs rising to a central tower emerging from the water. Progress in construction is slow.
With help from Peter Goreau and Roman, Tom prepares and deploys 3 scientific instruments. They secure an acoustic Doppler current meter and a fluormeter to the seabed. The current meter will gather data that may be used to determine whether power generation from gurlov turbines is feasible. The fluormeter will measure flows of phytoplankton - thereby giving an indication of new nutrient flows.
The 3rd instrument measures temperature, solidity and oxygen saturation in the water. Tom says this will give a proxy of 'net community metabolism', and that from this it should be possible to see whether Saya is a sink for carbon and source of oxygen (autotrophic) or the opposite (heterotrophic).
Today, around half the team go back to the Seychelles on Ceres. Caroline, Frank Peter Goreau, Roman and Steve all have flights to Europe and beyond on or around 22 March. The expedition began 10 days later than planed. As a result, some 50 hand days have been lost.
Tom goes with them back to the Seychelles in order to spend another week with the marine park authority on the deployment of installation of a coral nursery.
Alexandrine, Gabriel, Hartmut, Peter Lucas, Wolf and I remain at Saya with the ships Ophee and Vaka-Lele. We will continue construction work and to measure physical and biological variables for Tom.
Caspar Henderson
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