You are here: /main/research expeditions/May 2005/Day 3 Midway Atoll

Midway Atoll, Day 3
by Kelly Gleason, Maritime Archaeology Team

Until this afternoon, we have been blessed with nearly perfect weather nearly every day. While field operations were still successful today, by about noontime wind and waves at the atoll had increased to the point that all of the small boats were recalled to Hi`ialakai and we ended our work a few hours early. Nevertheless, the day was extremely successful on many levels and it was an opportunity to see how well the crew of the ship is able to operate and retrieve the small boats under rough conditions. No matter what, they are able to make the complicated task of lifting an 8 meter jet boat out of the water seem routine and safe.

This afternoon, before heading on to Kure Atoll the ship is conducting multibeam mapping operations in order to add to and fill in gaps in the information that the mapping team has about Midway Atoll. Because Midway is a more accessible location than many of the other atolls in the Northwestern Hawaiian Islands, there is more data for this atoll, and many scientists are involved in work analyzing this data in greater depth. For example, the data collected today at Midway will be used by a graduate student who is working on modeling the interactions of currents. As is done at least once a night, the team is dropping a CTD probe in the water in order to get a sound velocity profile. Getting acoustical information is important for the mapping team since sound is the highest source of error in multibeam mapping. Highly sophisticated sonar systems such as the one on the Hi’ialakai are sensitive to the changes in sound velocity. At Midway, an atoll with more activity, the CTD probe information was critical. For the mapping team, Kure Atoll is an important target for their work in the Northwestern Hawaiian Islands. There is very little multibeam data at Kure Atoll and their work over the next couple of days will fill in gaps beginning with the one hundred fathom curve, which will be an important tool for this area.

Today, the coral team had an exciting morning working out of the zodiac. They continued to set more permanent transects, and have made huge contributions over the course of this cruise towards the establishment of permanent monitoring sites for coral ecologists. Today’s sites for the coral team were shallow, something team member Jen Salerno particularly likes because it means she gets to see more invertebrates during her work along the transects. The coral team has definitely found a rhythm in their work and ability to set permanent transects. Like many of the teams, the first couple of days of work were challenging as we figured out how to best work in our small teams. By now, we are familiar with one another and work is more efficient, and of course, more fun as we continue to enjoy each other’s company in the field.

For the fish team, they began their day at a site called the “fish hole” where photographer John Brooks accompanied them to take high-definition video footage of fish that are important species in this region. The hapu`upu`u or Hawaiian grouper (Epinephelus quernus) and is found at depths of 50 fathoms in the main Hawaiian Islands, far deeper than normal scuba diving depths. Here in the Northwestern Hawaiian Islands they are found in much shallower depths in great abundance. The hapu`upu`u is a Hawaiian endemic, and is found nowhere else in the world. The knifejaw (Oplegnathus punctatus) is a southern Japanese fish that is seen in the NWHI but not in the main Hawaiian Islands. Both are fishes that characterize the unique fish fauna of the NWHI. Another fish that the team is interested in collecting while in the Northwestern Hawaiian Islands is the oval butterflyfish (Chaetodon lunulatus), which they have been able to locate at spots on the backreef here at Midway. Feeding exclusively on live coral, the oval butterflyfish is only found in coral-rich habitats. Studying the genetics of this and other species can answer important theoretical questions about the evolution and dispersal of fish species, and they can also answer practical management questions regarding fish populations in the Main and Northwestern Hawaiian Islands.

Leaving each atoll is always bittersweet. We’re all excited to visit a new site, and collect more data from another breathtaking location. However, it also means we’re a little closer to the end of this cruise, and I don’t think that anyone on this ship is quite ready for this incredible experience to be over any time soon.