Go time!

After all the work of preparing and calibrating the instruments, we've spent the past few days motoring around the atoll doing the fun part - installing them on the reef! We have five different study locations:

but it took multiple days to do them all. That's because the instruments are pretty big, and each of them is weighted down with 60 pounds of lead, THEN staked into the reef. So with all that equipment, it's dangerous to SCUBA dive with it all. Each installation requires at least two dives, then when you include surface interval time and traveling between sites you end up with only enough time for two installations per day.

On our first day of diving, we headed to the northeastern shore of Palmyra. Here we had a little bit of an issue to figure out, since we're trying to put instruments mostly on the same spots that were used by a team from Stanford. This makes the data a lot more useful in the end since between us we'll end up with very long time series of temperature, salinity, and currents... but we have to be careful, since our sites are popular with a bunch of different groups. In particular, coral ecologists from UC San Diego have set up 'transects', or study regions, where they are monitoring different aspects of coral distribution. So we had to do some snorkeling around to make sure that the exact spot we wanted to use wasn't going to be right in the middle of where someone had spent 5+ years studying things! I think we figured it out properly in the end, but it was a bit stressful for a while there.

Our next site was the 'Channel', which is pretty much exactly what it sounds like: a channel connecting the lagoon to the open ocean. It was dredged by the military during World War II, when Palmyra was being used as a base of operations in the Pacific theater, and has been used by larger boats ever since. Having an instrument in the channel will let us see any influences of water exchange between the lagoon and the open ocean: for example, water might heat up more inside the lagoon than outside, or an abnormally large amount of rain might make the water inside the lagoon fresher than the outside. Either of those things could create changes in the oxygen isotopic ratios near the coral site, and therefore influence El Nino reconstructions. Anyway, we went out in the channel, and had another successful instrument deployment.

The site I was most excited about was on the "reef terrace", off the western shore of Palmyra past the channel. My collaborator Kim Cobb collected a set of coral cores from this area in 2003, which have since become one of the best-known paleo-reconstructions of the El Nino/Southern Oscillation (ENSO). So I really wanted to have an instrument as close to that location as possible, so we could be sure that the data we were getting reflected the ENSO influence on that coral specifically. It took us a couple of tries since the currents were fairly strong the first day we went out, but now the instruments are happily in place and hopefully getting lots of great data. Plus the reef was pretty amazing there too! (Photos coming soon from our resident photographer, Dave.)

It all went really smoothly considering the amount of preparation and technique required to get these things down in the water. Just goes to show the skill of the UH dive techs! Here they are in action at our last deployment site off Palmyra's south shore:

(photo credit: Dave Slater)