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10/4/05 - More REAs
by David Nichols, State of Hawaii, DLNR, HIHWNMS

REA divers Paula Ayotte, Fenny Cox and Holly Bollick relax between dives.

We finally arrive at Necker Island, a dry volcanic island shaped like a fishhook and includes about 45 land acres of land. Geologists claim it was once the size of O'ahu but waves have worn down the rest so that it is now a submerged shelf about 40 miles long and 15 miles wide. There is more than 380,000 acres of coral reef habitat here but severe waves and currents keep coral growth low in many areas. Necker is also known by the Hawaiian name Mokumanamana, and is spiritually significant in the Native Hawaiian culture.

After spending three days traveling from Kure Atoll to Mokumanamana the Rapid Ecological Assessment (REA) divers were starting to dry out. It is obvious they would much rather spend their time beneath the waters surface. I don’t doubt that some of them have even retained those gill slits that we all had early on in our embryonic development. There are a total of nine REA divers and they perform three dives per day when the ship isn’t moving us between atolls. Each REA diver has made around 39 dives this cruise. That is over 350 assessment dives throughout the NWHI in the past three weeks.

As I mentioned in an earlier update the REA team consists of three fish experts (Darla White, Paula Ayotte and Kosta Stamoulis) who enter the water first, lay the transect lines, then begin the process of identifying, counting, and estimating the size of the fish along the line. This will provide insight into the diversity and richness of fish species in the area as well as biomass estimates and even age-class structure.

Fish REA diver Kosta Stamoulis interrupts Holly Bollick as she searches for invertebrates at Mokumanamana.

After giving the fish folks some time to do their thing the remaining REA divers enter the water. This includes the two coral experts (Greta Aeby and Fenny Cox) who identify and photograph the corals along the transect to get a better understanding of the density, community structure and percentage of area covered by corals. They also monitor the health of the coral in the area by looking for any bleaching (none was found this cruise), predators (not a problem in the NWHI), and disease.

The invertebrate team (Scott Godwin and Holly Bollick) spend their time along the transect focusing under rubble and in cracks and crevices in their search for non-coral invertebrates. The information they collect helps determine the status of the invertebrate community. The phycology (algae) team (Sheryl Squair and Richard Osada) are responsible for documenting, collecting and photographing algae along the transect line. The process of identifying many algae species requires much time and equipment that is not available on the ship so samples are collected to later be identified back in the lab.

Algae are an important component in maintaining the NWHI’s ecological balance as a food source for a number of reef organisms, including the green sea turtle, and also serve as settling and attachment sites for small and cryptic reef species. Some 205 species of marine algae were identified in 1989 in the NWHI. Since then, these numbers have nearly doubled and will continue to increase as the recent collections are fully identified and recorded.

At Mokumanamana Cheryl also spends time searching for an alien alga (Hypnea musciformis) that had been reported near the island earlier this year. Cheryl performs a deep dive near one of the areas where it had been reported and also searches nearshore along Shark’s Bay but finds no evidence of Hypnea. Shark’s Bay is a high energy, not-so-protected area on the northwest side of the island. Today the water is calm enough to allow a search close to the shoreline. The bottom of almost the entire bay is carpeted by a green alga, Caulerpa. If an alga is going to make it on our unofficial NWHI poster then Caulerpa may be the one. This alga is pretty amazing and difficult to describe, but each individual plant (I saw some at least a foot long) is a single cell (with many nuclei). They have small round nodules associated that look like peas and can be popped like bubble-wrap. They have a unique ability to quickly repair any tissue damage or break in the cell wall. They are definitely tough enough to be considered for our NWHI poster. I found out later that Caulerpa is edible but I didn’t have a chance to try it and can’t vouch for the taste.

REA diver Richard Osada holds the photographic quadrat (photo-quad) while phycologist Cheryl Squair examines the area for algae.

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