From before sunrise, the water is very calm - as silky as oil. It's already hot by seven. On the Vaka-lele, Harmut starts the day with 'Va, pensiero, sull'ali dorate' (the slave chorus from Nabucco). A hundred yards off spinner dolphins cut through the air.
Later, a green turtle passes leisurely by, close to the boat. I think we've been seeing the same character everyday since we arrived. He surfaces for two or three breathes, floating easily along before plunging out of sight again: "Sacre Bleu", says the turtle (that's French for 'by gum'), "my folks have been doing just this for over 150 million years, and I see no reason to stop now".
The crew on Ceres went to bed early last night, and Tom is eager to start work first thing ready first thing before it gets too hot. He wants to place two scientific instruments on the seabed and begin measurements with a third.
But there's a long delay in getting going. The dive equipment and the dive boat Eurydice are on Orphee, where people worked late last night and stayed up much later. It's several hours before we can raise any signs of life on Orphee. To help pass the time Peter Goreau recites several Kipling poems - including 'Municipal', about of a pompous District Commissioner in British India who take refuges in a stinking sewer from an angry bull elephant. Roman, in a corner, reads Chomsky in Spanish.
Tom has three machines. The first, an accoustic Doppler current meter, will gather data on the tides. It works by measuring sound waves that it bounces off particles in the water, building up a three dimensional picture of the current.
The idea is to determine whether the currents and tides over this part of Saya would be sufficient to power for Gorlov helical turbines. In the right conditions Gorlov turbines generate large amounts of clean, renewable energy. Singly, in arrays or in combination with solar panels, they could provide electricity for mineral accretion for coral arks, larger artificial reefs or even an artificial island.
The second instrument will give some indication of nutrient levels in the water. It uses a light emitting diode to excite chlorophyll in phytoplankton (microscopic plants which are the base of the food chain) in a small volume of seawater that passes through the meter and measures the fluorescence that results.
This will give an idea of how much phytoplankton there is in the water and when. The movement of phytoplankton can then be linked to the tides and some indication of when, for example nutrient rich currents are upwelling from around the bank. Only a few miles away at the edge of the bank, the sea plunges down thousands of metres. The environment on the edge could have significant differences, and study there could yield valuable insights. It's looking unlikely we'll get there on this trip.
"Closer to one edge of the bank we would expect to be in an area of even higher nutrients. The character of the community of animals that depend on them would probably be different. To get a better handle on the nutrients at Saya we'd need a full lab. It would take a whole room on a research vessel. That's way beyond what we can do on this trip".
"Also, we really need a fish cam to explore the bank from one end to the other". As the name suggests, this underwater camera is flexible and can gather large numbers of images very rapidly. Saya 2002 was to have had one, but the machine needed repair and was not ready in time.
The third instrument measures water temperature, salinity and most importantly oxygen saturation. This means it can give an idea of 'net community metabolism' - that is, whether Saya is a net source or sink of carbon dioxide. "There's a common misconception that the world's oceans are carbon sinks [absorb more greenhouse gases than they produce]" says Tom. "But that's simply not true. Global average ocean conditions are the exact opposite". This is why he pressed the drafters of the 1992 Framework Convention on Climate Change to require a full accounting of all sources and sinks, both natural and manmade.
"My guess is that [Saya] is autotrophic - a net supplier of oxygen to the atmosphere. Plant material [containing carbon] is probably sinking to the abyssal plane around the bank. We have only seen a few turtles [which eat seagrass]. The dolphins here this morning indicate that there are some fish here in reasonably large numbers. But we are not seeing large schools of fish eating the seagrass".
According to Tom, many reefs that are now dead such as those in Jamaica and Panama are now 'heterotrophic'. This means they are net contributors of carbon dioxide to the atmosphere, and hence likely to increase the rate of climate change. This is one of several reasons why the death of the Australian Great Barrier reef would be serious.
At last, towards midday, there are signs of life on Orphee. Pete Lucas organises dive gear for Tom, Peter Goreau and Roman, and takes them in Euridyce to the surface above a site near the old structure. Tom, Peter and Wolf secure the instruments on the seabed and reconnoitre and photograph the surrounding area. Roman and Peter take another look at the steel we dropped on Friday.
Not surprisingly, some of it has aquaplaned over a wide area, including on top of some corals. It has been proposed that divers gathering it together in one pile, where it can easily be located and protected with a sacrificial aluminium anode [aluminium is more reactive than steel. In seawater it becomes a positive electrical pole - the anode - gradually oxidising and dissolving, while the steel as the negative pole - the cathode - remains untarnished].
Pete and I stay on the Euridyce to monitor the divers below. Every now and then we get in the water to escape the fierce heat. Pete Lucas talks about the potential for coral arks for artisanal fishermen the Tanzanian coast. There is money available from the European Union to promote sustainable, community-based fisheries, and it looks like Pete has identified an opportunity to bring coral arks into use here.
After the dive, Tom shows Pete and I how to use the instrument that measures oxygen saturation. He has decided to go back to the Seychelles with the Ceres later today in order to continue work on a coral ark with the Marine Park Authority. Ideally, we are to monitor oxygen saturation in day and night and when the tide is running in different directions. We will pick up the other two instruments from the seabed just before we leave.
On Orphee another search is made for the cutting blades, without success. Without the blades it will not be possible to build base units for a structure that will ultimately rise out of the water. Wolf revises his design. We will build a robust steel framework for a coral ark just two meters high, anchor it on the seabed and attach a solar raft. It will be a different shape, more substantial and powerful than the simple pyramid installed in 1997, but still a seabed structure and not the tower rising from the water that Wolf had hoped for.
Towards evening, Nico hosts a farewell party on the Ceres. He is taking Caroline, Steve, Roman, Tom and Peter Goreau back to the Seychelles, where all except Tom will board flights home.
Over the last few days the Ceres has become universally now known as 'the Serious' because of Nico's intense mood. He's been like Achilles, sulking in his tent (he has left behind major drama in Madagascar). But now he is almost Falstaffian. There is mostly good music (but, alas, no escape from the excessively right-on Manu Chau even a thousand miles from land) and we dance on the small mid deck. Dancing is something we've sorely missed. Every one is immensely friendly mood. At one point Nico dances with Alexandrine: she a beautifully proportioned African goddess shaking her booty; he a tall, broad-shouldered and dashing European warrior.
But there are strands of disappointment and caution at the party. "We came to build a reef and instead we destroyed one" says Roman, referring to the steel bars lying on top of corals. Steve says little has been gained by surveying an area that is as adjectival flat as a pancake. He thinks there could have been useful insights from going further afield to the edge of the bank just a few miles away.
Steve also tells me that the head of the Shoals of Capricorn project would not allow any diving at such a remote location without a decompression chamber on board: we really are out on a limb here. Caroline would love to stay and study life on the reef and help with the structure, but her academic commitments demand that she get back. I will miss, among other matters, her lessons on Scots words that have no English equivalents - like 'numpty'.
As Ceres departs it swings by close to the Vaka-Lele with all those on board cheering and waving. Harmut digs out a hunting horn to see them of. The scene is like people leaving in a taxi after any good party. The difference is that their ride home tonight is across four hundred miles of open ocean.
Caspar Henderson
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