October 7th : Assessing the Atoll
Written By Dan Suthers October 7-8, 2004
In the morning of this last day at Kure Atoll, I observed and interviewed team members assessing a shallow water reef in the morning. Meanwhile, the towboarders continued their usual work, and the mooring team replaced two STR (surface temperature recorders) and conducted a series of salinity and temperature measurements around the atoll (see article on reef oceanography). Stephani and Susan were diving off Gaetano's Zodiac in the morning. In the afternoon, a second zodiac came out from the ship to take crew members snorkeling. We arranged for HI-1 to rendezvous with the two Zodiacs for swapping people various ways, and I joined the snorkelers.
Rapid Ecological Assessment (REA)
HI-1 is the second boat to launch (HI-3, the Towboard team, is launched first, as they typically have long days). It's an easy launch compared to those I have been frequenting. HI-3 and HI-5 both are launched by crane, after which passengers must climb down a ladder onto a boat that is often rising and falling as much as one's own height with the swells. HI-1 and HI-2, as shown in the image to left, are launched by a davit, a device that enables gear and people to be loaded from an upper deck before the boat is lowered into the water.
The REA team is the largest group. On the boat were Peter Vroom and Erin Looney of the algae team; Greta Aeby and Jean Kenyon of the coral team; Randy Kosaki, Craig Musberger and Darla White of the fish team; and Rayna Henson covering invertebrates. (See the participant list for roles and affiliations.) The cox'n, Keith Lyons, has years of experience in the NWHI. He confidently navigates the route through a channel into the atoll where most of us can see only open ocean with a subtle change of color and occasional tips of white on the chop.
Our first REA was near the CREWS buoy deployed by the Mooring Team two days earlier, near the center of the lagoon. This site ranges in depth from about 1 foot to 20 feet. Following their usual protocol (to be described in detail in a feature article), the fish team entered first. Randy immediately swam off into the murk to conduct wide area scanning for large fish, while Craig laid out a 25 meter transect line along the reef and Darla followed, taking notes on fish observed (see image above). I followed behind them so as to not scare away any fish before they are observed. Then Craig and Darla returned along the same line, conducting a more detailed observation of fish populations, with me following them. Finally, they went back out to the end of the transect line and started a new transect, repeating this procedure twice more for three transects total.
On the second transect, we crossed a small canyon between two coral mountains. Taking refuge in this protected area was a large school of brown chub (Kyphosus bigibbus, or nenue in Hawaiian [1]). Initially they scattered, but soon they trusted us and engulfed us within their school, making for some fun photography. Although most are grey, one had turned yellow and white (pictured at right). At one point, this cloud of fish surrounding us suddenly exploded and scattered up the canyon: a large kahala or amberjack (Seriola dumerili) had charged into the school. Craig later told me that he heard the "crunch" of a chub being eaten. This abrupt change was so startling that Darla and I both broke out laughing: I could hear her through the water perhaps 15 feet below me. After a while the kahala swam off, the nenue returned and continued to delight me as I observed them trying to eat small air bubbles coming up from the divers (pictured).
I am not very practiced at deep skin diving nor very comfortable with holding my breath, and in fact when I began this day's swim I experienced some anxiety and pressure to surface on my first dives. It's clear that this is partly a psychological issue, because when my level of fascination with the target of my dive was sufficiently high, I found it a lot easier to dive deep and stay a little while before letting the buoyancy of my wet suit carry me back up unhurried. On the third transect, twice the divers pointed out something interesting at a depth a little beyond what I would normally attempt. Peer pressure had its effect and I was able to obtain photographs of a Triton and a leaf scorpionfish (shown). Yet, on some of these dives I could feel painful pressure in my sinuses, perhaps due to the remnants of a cold.
The fish were engaging enough that I did not get back to the other REA members until late in the transect. The fish team is followed by the algae, coral and invertebrate teams, each conducting their own data gathering protocol along the transect line. I photographed Peter and Erin as they used a camera mounted on a stand that demarcates a square to take "photoquads" (pictured), and wrote down the algae species as well as coral and invertebrates seen within the square. After finishing this documentation, they swam around to look for other algae species in the area. Rayna conducted a similar protocol, using a square to mark sampling areas within which she counted invertebrates, but not taking photographs; and then swimming around to find other invertebrates. I found the coral team just in time to see Greta inspecting the shallowest part of the reef.
We all climbed back into the boat and begin a midmorning snack as Keith motored us to this next dive, which was located in a shallow area at the northern edge of the atoll. The fish team went out first, while the others lounged on the boat: not out of lazyness, but because the protocol requires that the "bottom feeders," as the fish team jokingly calls them, enter the water about 20 minutes later. The water was about 7 feet deep, so some scientists elected to snorkel rather than SCUBA, but algae and coral folks donned SCUBA so that they could inspect the bottom closely. After following the fish team for their first transect, I returned to join the others so that I would not miss their activity. As Greta and Jean had explained to me on the way over, they collect data on two of the transect lines. Jean identifies coral colonies to the species level and categorized by size, and also videotaptes the entire transect line for later analysis and as evidence for her visual counts. She then collects samples for two studies discussed in previous journals: one on algae symbiosis, and another for DNA analysis to study coral distribution between the Main and Northwestern Hawaiian Islands. Meanwhile, Greta recorded the occurrences of coral diseases along the transect and the nearby area. Peter and Erin continued photoquads discussed previously, while Rayna took deep breaths, dove to place her square on the bottom, and counted visible macroinvertebrates (mollusks, crustaceans, echinoderms, etc.).
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I saw evidence that sea urchins are a popular meal for some creature in the area. |
During this REA I discovered that I had a bloody nose. Keith requested that I leave the water until it stopped so as to not attract sharks. Apparently the deep diving at the previous location had done some damage to my sinuses.
If you are interested in a layperson's summary of the REA data gathering protocol, please see the feature article. Some organizations conduct similar assessments in the Main Hawaiian Islands, although currently some of the techniques and the comprehensiveness of the REA are unique to the NWHI expeditions. It will be interesting to compare the results from the populated and unpopulated areas.
Shipwreck
Around lunchtime HI-1 met with the Zodiac HI-5 so that I could join the latter boat's collection of snorkelers: a mental health break for the ship's crew. Gaetano zipped us across the atoll to the site of a shipwreck still visible as one of the area's landmarks above the horizon.
The history of Kure is replete with shipwrecks and castaways who spent many months on Green Island before being rescued or sailing in a craft improvised from their wrecks. Rauzon's book [3] provides interesting accounts of disasters on this and other NWHI. In 1870, even a steamship that came up from Midway to look for castaways from other wrecks was itself wrecked, in spite of full knowledge of the location of the atoll!
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But our objective was a more recent casualty. In winter, Kure's northern location can expose it to rough winter storms from the North Pacific. In February 1976, the Japanese fishing ship Houei Maru #5 ran aground during a storm. Seventeen fishermen were reportedly aboard, but none were ever found, presumably drowned and/or eaten by sharks just a few miles away from the US Coast Guard station that was on Green Island at the time [3].
The hull is deteriorating rapidly (compare my photo to that in [3]), but still offers refuge for a school of Yellowfin Goatfish (weke 'ula or Mulloidichthys vanicolensis, pictured), as well as Spectacled Parrotfish, Yellowstrip Coris (hilu, or Coris flavovittata), Threadfin Butterflyfish (Chaetodon auriga), and others [1]. Healthy communities of pencil urchins (Heterocentrotus mammillatus) were found in the area, and Brown Noddys adorned the wreck's skyline. Susan, whose camera had just run out of power, pointed out a Hawaiian Lionfish (Pterois sphex or nohu pinao) in a cave to me, and I managed to get an image (a little blurry) before my camera ran out of memory space. |
Tonight in the wet lab, there is another specimen of the potential new species of sea cucumber. To my eye, it looks similar to the "black-spotted sea cucumber" in Hoover's book [2], but Rayna tells me that our specimen is not a Holothuria, the genus ascribed to the specimen in the book. There are several species of sea cucumber that have been observed by divers but not scientifically described.
[1] Hoover (1993)
[2] Hoover (1998)
[3] Rauzon (2001)
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