A very busy work schedule this morning as we try to make sure that we finish off all that needs to be done on Salomons atoll before moving on this evening. The divers will return from their afternoon dives and stow the equipment, because in the early hours of tomorrow morning we will leave Salomons Atoll and sail for Nelsons Island on the Great Chagos Bank, and also (weather permitting) a stop on the completely submerged atoll shaped reef called Victory Bank.

The good weather of the past week looks like it might be over for a day or two at least as the wind is certainly up and the seas are significantly higher. This makes our work much harder, from loading equipment from the ship onto the inflatables, getting over the reef, and being bounced up and down by the swell when working in shallow sites.

As with all expeditions like this, we are trying to pack the proverbial quart into a pint pot, and any delays can play havoc with the schedule. We have deliberately kept a flexible schedule as it is sometimes difficult to predict how much you will be able to achieve on a dive. If there is a strong current for example, or if some piece of equipment fails or, as might happen here, the weather changes, then parts of the work need to be trimmed to suit. We are packing things in as efficiently as we can just in case of any delay.

Today more temperature loggers were deployed at 25 metre and 5 metre depths on the stunningly diverse and rich seaward slopes of Salomons. These loggers are set at depths of 5, 15 and 25 meters depth, to record at two-hour intervals, and keep going for 2-3 years. At two-year intervals they need to be collected and replaced.

anne sheppard coral cover recording

Anne Sheppard coral cover recording; photo: Anne & Charles Sheppard/ Chagos Conservation Trust

The reason for carrying out this work is that temperature is crucial to coral growth and in the past warm water episodes have caused mass mortalities all over the world. We have had several placed since 2006, and have already used results so far to detect most unusual internal rises and falls of a cooling thermocline – which may be one reason why the corals here recovered so well and are doing so well now. Numerous BRUVs (the stereo underwater HD video systems for collecting fish data in deeper water) ) were set on the seaward side of reefs, more cryptic fauna sites were sampled and the last of the various fish transects for this atoll were completed.

Routine recording to obtain time-series data is all important. The fish counts, started in 2006, were repeated in 2010 and now again in 2012. The coral cover measurements have been repeated at various intervals since 1978, one of the longest continuous coral cover monitoring anywhere in the world.

Of course there are new projects on every expedition: on this one they are the BRUVs and the fish response times, and a large project on cryptic work, or which more later. The evenings are filled with sample sorting for those who collect samples, with data entry and photo transfers.

Previously in this series:

Conserving Chagos: Science Expedition to World’s Largest “Ocean Park”

Conserving Chagos: Starting Out

Conserving Chagos: Manta Rays

Conserving Chagos: Last Day around Diego Garcia

Conserving Chagos: Salomons Atoll