Mesophotic Corals and Fishes Studied in the Au'au Channel

One of the goals of the PIFSC Ecosystem and Oceanography Division is to gain a better understanding of the biodiversity, ecology, and function of deep reef ecosystems. In a recent research expedition EOD scientists joined colleagues from the Coral Reef Ecosystem Division and the State of Hawaii to survey the seafloor in mesophotic habitat of the Au'au Channel between the Hawaiian islands of Maui and Lanai. The survey was carried out with the NOAA Ship Hi'ialakai.

Leptoseris sp. coral bed at 275 feet in the Au'au Channel.

The team used a drop camera to survey more than 80 kilometers of bottom. In addition, they made seven scientific dives using mixed-gas scuba gear to survey the benthic habitat for coral coverage and fish species. The makeup of bottom habitats varied. Some consisted entirely of Leptoseris sp. corals (as shown in the accompanying photo).Others were characterized by a mixture of Leptoseris and algae, a mixture of algae and a yet to be identified coral species, or just algae. Information from fish surveys will be used to compare and contrast the fish communities in the various habitats.

During the Hi'ialakai cruise, two moored oceanographic instruments recording temperature and bottom currents were recovered by the scientists along with two acoustic devices placed on the bottom to record the presence of tagged marine animals in the area. A pair of replacement moorings was then deployed to continue the collection of observations on temperature, bottom currents, and acoustic tag signals.