A Better Understanding of Coral Reef Ecosystems

Pelagic predators such as these barracuda, Sphyraena qenie, are part of the coral reef ecosystem in the U.S. Line Islands (NOAA Photo by Kevin Lino).
A team of scientists have embarked from Hawai'i on a three-month survey of coral reef ecosystems at Johnston Atoll, the U.S. Phoenix Islands, the islands of American Samoa, and the U.S. Line Islands in the tropical Pacific Ocean. The overarching objective is to better understand the coral reef ecosystems of these areas, many of which are seldom explored. The research expedition is part of a regular monitoring program, conducted by the Coral Reef Ecosystem Division (CRED), headquartered in Honolulu, Hawai'i. The expedition is supported by NOAA's Coral Reef Conservation Program and involves extensive cooperation among NOAA scientists and research partners, including the University of Hawaii Joint Institute for Marine and Atmospheric Research (JIMAR), the U.S. Fish and Wildlife Service, San Diego State University, and the Papahānaumaokuākea Marine National Monument.

The research expedition will be carried out from February 27 to May 24, 2012 aboard the NOAA ship Hi'ialakai. Under the leadership of Chief Scientists Dr. Jill Zamzow, Dr. Bernardo Vargas-Angél, and Jamison Gove, a diverse team of researchers will be conducting multidisciplinary coral reef ecosystem surveys, assessing the status of fishes, corals, algae, marine invertebrates, and the oceanographic conditions in which these organisms exist. The scientific data collected during the three-month research expedition will enable informed and effective implementation of ecosystem-based management and conservation strategies for coral reef ecosystems, helping to ensure their protection for generations to come.

Wednesday, March 31, 2010

Jarvis Island

by Paula Ayotte, photos by Jamison Gove

After five days of transit from Pago Pago, we’ve finally arrived at Jarvis Island, the sixth island in the Line Islands chain. This puts us once again close to the equator, about 1,000 miles from American Samoa, 1,200 miles from Honolulu, and 400 miles from our next stop, Palmyra Atoll.  For some of us on board, this is a return trip to this remote island chain. For others, this will be their first expedition to the Line Islands.  Regardless of how many times we’ve been here, how many dives we’ve already done, how many fish or corals we’ve counted, or how many oceanographic instruments we’ve deployed or retrieved, all of us are looking forward with great anticipation to getting in the water and conducting research at Jarvis Island.

The coral reef ecosystem at
Jarvis Island.
On land, this low-lying, arid, warm, lopsided rectangle of land seems unprepossessing, but underwater it’s a wonderland of swirling anthias, curious sharks, and schools of jacks amid an impressive variety of colorful corals. What contributes to the amazing diversity at Jarvis is the remote location and isolation from detrimental human impacts, along with its location in the path of the easterly flowing Equatorial Undercurrent which brings nutrient rich waters upward, enriching the primary productivity of the surface waters surrounding Jarvis.

Though Jarvis is relatively free from human exploitation, like Howland, Baker, Palmyra and Kingman, Jarvis was claimed for the United States under the Guano Islands Act of 1856.  Baker, Howland, and Jarvis Islands were also claimed by the United Kingdom as British Overseas Territories from 1886 to 1934, and guano mining was conducted by both British and American companies through the end of the nineteenth century, after which guano deposits were largely depleted.  As at Howland and Baker, a small colony of Kamehameha School graduates was established in 1935, which became known as Hui Panala'au (Society of Colonists).  These colonists occupied these islands continually, in three-month shifts of four men per island, in an attempt to help the United States assert territorial jurisdiction over the islands, a jurisdiction crucial to air supremacy in the Pacific. Water and bulk food were supplied from Hawaii. During the period between 1935 and 1942 era; at least 26 trips were made to Jarvis Island by various United States Coast Guard (USCG) cutters. Jarvis Island was evacuated at the beginning of World War II and was unoccupied during the remainder of the war.

A Green Sea Turtle drifts gracefully by. 
Post World War II, there were no attempts to re-colonize the island, and in 1948 the United States Coast Guard began making annual visits to maintain claim to Jarvis. In March 1963, and for the following 2 years, Smithsonian Institution employees made a number of visits to Jarvis Island as part of the Pacific Ocean Biological Survey Program. The island and its territorial seas were transferred to the US Fish and Wildlife Service (USFWS) in 1974 from the Department of the Interior. This area is now managed as a unit of the National Wildlife Refuge System and in 2009 was established as part of the the Pacific Remote Islands Marine National Monument.

Monday, March 29, 2010

Safety First

by Jamison Gove
The NOAA Ship Hi'ialakai
Painted in sizable black letters and readily seen against the stark white background of the towering exhaust stacks are two important words: Safety First. These words provide not only a daily reminder of the often unpredictable and precarious nature of seafaring work, but also serve as a testament to the professionalism and commitment of those aboard the Hi'ialakai to conduct safe and impact free operations wherever the ship may travel.

Scientist Chip Young
dons a survival suit
The past few days have been spent instructing the new members of the expedition on the safety procedures in place aboard the ship in addition to providing refresher training for existing personnel. Abandon ship drills, life-raft familiarization, fire drills, dive-gear check outs, oxygen delivery and reviewing diver rescue protocols are just some of the trainings being conducted en route to Jarvis, ensuring that everyone aboard is well equipped to avoid a potential hazard and navigate any situation that may arise.

Chamber Supervisor Jim Bostick
provides an overview of the
recompression chamber

An intrinsic part of coral reef research is repetitive and arduous SCUBA diving. Since this expedition began, scientists have conducted over 2000 dives, quite a lot considering the ship left Honolulu just over 2 months ago!  Due to the high quantity of dives combined with the remote island locations visited during this research cruise, an essential piece of safety equipment carried on board is a Recompression Chamber, a 52-inch diameter pressure vessel used to treat dive related maladies such as Decompression Sickness (DCS). The chamber has been on the Hi'ialakai since the ship was first commissioned in 2004 as a vast majority of the research conducted on board is diving related. Although the chamber is autonomous, meaning it can operate independent of the Hi'ialakai's power supply, it does require a Chamber Supervisor to properly operate the chamber, a Dive Medical Officer (DMO) to coordinate medical treatment and a Dive Medical Technician (DMT) to tend and care for the injured diver inside the chamber. Each of these people are extensively trained and are present for every dive expedition the Hi'ialakai embarks on, providing security and piece of mind to each of us divers on board the ship.

Saturday, March 27, 2010

Goodbye to Amercian Samoa

by Jamison Gove
The Hi'ialakai heads to Jarvis Island
After spending nearly six weeks conducting coral reef research in and around American Samoa, the day has finally arrived to say our goodbyes to the island of Tutuila. With all twenty-two scientists and twenty-five crew members aboard, the Hi′ialakai cast off her lines from the pier early this morning and made a slow and steady departure out of Pago Pago, gently swaying back and forth as we emerged from the quiescent harbor and into the rolling seas of the open ocean. Heading northeast, we’ve now begun the five day journey to Jarvis Island, our first destination of the third and final leg of this expedition. These next few days will be filled with safety drills, scientific planning meetings, trainings, and gear preparation in anticipation for our arrival to Jarvis.

Thursday, March 25, 2010

Back in Pago Pago

by Benjamin L. Richards
The Hi'ialakai is back in Pago Pago for the change-out between Leg 2 and Leg 3 of the expedition.  We held a one day education and outreach program for local school children and members of the public on March 23 and conducted calibration dives between the outgoing and incoming researchers on March 24.  We will be spending the next few days refitting the ship and small boats for the next leg of the expedition, meeting with local government and agency representatives and getting some much needed rest before we head off to the Line Islands (Jarvis, Palmyra, and Kingman Reef) on March 27. Stay tuned for new discoveries as we reach the Line Islands and start making our way back north.

Sunday, March 21, 2010

A few more questions on Rose Atoll

Coralline algal formation at Rose Atoll,
Porolithon craspedium (Photograph by
Cristi Richards)
We have received more questions regarding Rose Atoll from Samoana High School students and would like to take the time to provide these answers. We are excited that our work has generated such interest and hope that the questions keep coming. It is important to monitor reef health, but it is just as important to be sure that our findings are reaching the public and those interested. We hope that these answers help to clarify and provide more depth to our previous posts. Enjoy!

Soshana asks: Whenever you guys visit the Rose Atoll Island, do you discover anything new?

Good question Soshana!
I am not aware of any new discoveries made by us at Rose Atoll during our past visits. Every once in awhile our scientists have discovered a new species and that is always quite exciting!

More often the “discoveries” we’ve made have been documenting natural phenomena such as coral bleaching, sites with internal tides, and range extensions for various species of fish, algae, and corals. Many other discoveries are known to the local population and those living in the area, but may be unknown to the scientific community or to people living in other parts of the world. This trip we “discovered” that South Bank is a drowned atoll. As far as we know, this was previously unknown until our team completed multibeam surveys of the area!
- Kerry Grimshaw

Marissa asks: According to the picture (Photograph from noaa.coris.gov), is there any other possible ways to help save Rose atoll from sinking?
[The picture Marissa is referencing can be found on an earlier blog post]

I’m sorry to report that there is no easy answer to your question, although I like where your heart is! Islands may have many different fates over time and it all comes back to the geologic processes that take place. Fortunately, these processes generally take millions of years to happen, so it’s unlikely that you’ll see much change in the sinking of Rose Atoll during your lifetime.

On another note, the current hot topic of climate change could have significant effects on Rose Atoll in the future, particularly related to sea level rise and ocean acidification.
The excerpt below is from an article posted May 29, 2007 on the BBC website:

The Death of Islands
Exposed reef covered in coralline algae at Rose Atoll
(Photograph by Cristi Richards)
The world is constantly changing and islands will not live forever. There are four main fates for an island:

  • It may be brought up against a larger land mass by continental drift. 40 million years ago, this happened to the island of India, when it collided with the continent of Asia. The resultant crash hasn't finished yet - the Himalaya mountains are the crumple zone, where the folded Earth's crust absorbs the impact of India with the rest of Asia.
  • A small island may be eroded by the elements until there is nothing left above water. This was the fate of the westernmost of the Hawaiian Islands, which are now under the sea.
  • An island on an oceanic tectonic plate may be slowly dragged under the ocean as the plate collides with another plate and is subducted, that is, is pushed in under the other plate. This is the ultimate fate of each of the Galapagos islands. After they are created over a mid-ocean hot spot, they travel east until the plate they are on collides with and slides under the South American plate. The easternmost islands of the group are sliding back down into the ocean.
  • Changing currents in the Earth's mantle can cause a section of the ocean floor to be raised up, and subsequently to sink back down again. The Kerguelen Plateau, in the southern Indian Ocean, is now about two kilometres under the sea, with just a few isolated peaks showing above the surface as the Kerguelen Islands, but 100 million years ago, it was raised up to form an island three times the size of Japan. It is likely that it had animals and plants living on it. Then about 20 million years ago, the mantle currents changed and it slowly sank back down into the sea.

All of these slow deaths take millions of years to come about. In the meantime, islands continue to exert a fascination on mankind.
- Kerry Grimshaw

Valentine asks: Are there any human beings living on Rose Atoll?

No one lives at Rose Atoll and historically it has mostly been uninhabited with the exception of a brief time in the 1860s when the German government tried to establish a fishing station and coconut plantation. They didn’t have much luck as one of the 2 islands is often nothing more than a shifting sand bank!
- Mark Manuel

Oina asks: Are we allowed to visit Rose Atoll on our own or do we have to go with some sort of researchers?

Hi Oina,
As of now, the Rose Atoll National Wildlife Refuge is closed to the public. This closure is to protect fragile seabird colonies, endangered species, and island habitats. Special use permits to conduct scientific research can be obtained from the Pacific Remote Islands National Wildlife Refuge Complex office in Honolulu. For more information see www.fws.gov/roseatoll

With Rose Atoll recently being designated a Marine National Monument there are likely to be more regulations established for the area in the near future as visitor access is often considered in the regulations governing National Monuments. Until those new regulations are in place it is hard to answer your question completely. I would expect that there will be a permit system set up for controlling the work that can be done within the Monument. While it sounds like there may be lots of rules, we are used to obtaining permits for our work within various protected areas such as Sanctuaries, National Parks, Marine National Monuments, National Wildlife Refuges, and other territorial or commonwealth Marine Protected Areas.
- Kerry Grimshaw

Wednesday, March 17, 2010

Swain's Island

by Kerry Grimshaw
Swain's Atoll (Photograph by Kerry Grimshaw)
This morning we started work at the last of the islands in the Territory of American Samoa: Swains Island. Although Swains is part of American Samoa, geologically and geographically it is an atoll in the Tokelau Archipelago. Swains Island is the northernmost island in the Territory of American Samoa and lies about 350 km (220 mi) north-northwest of Tutuila.

It is thought that the first European to discover the island was Pedro Fernandez de Queiros in 1606 and named it Isla de la Gente Hermosa (“island of the beautiful people”). After that the island was unvisited by Europeans until 1840 when Capt. W.C. Swains of New Bedford, Massachusetts visited and thinking he was the first to land there, he named it Swain’s Island. The British Capt. Turnbull also claimed to have discovered the island and sold Swain's Island to the American Eli Hutchinson Jennings Sr. In 1856 Eli and his Samoan wife Malia moved to the island and claimed it with the US flag (as a semi-independent proprietary settlement of the Jennings family). Swain's Island was also claimed by the US Government under the Guano Islands Act in 1860. The ownership of the island was passed down to Eli Jr. who managed the copra plantation which was established by his father. Upon Eli Jr.’s death, the US government on March 4, 1925 granted the right of administration jointly to his children Ann (the estate) and Alexander (the island) while concurrently making it officially part of American Samoa by annexation. The island is currently inhabited by 4-30 people at any given time in order to retain private ownership by the Jennings family and as part of the Territory of American Samoa.

Swains Island as seen from space
Swains as an atoll is unusual due to its unbroken circular island which encloses a central “brackish” lagoon. Swains has a total area of 1.9 sq km (0.7 sq mi) and is approximately equivalent to 380 football fields. The ring-shaped island is still encircled with coconut trees although the copra plantation is no longer active. The outer edge of the atoll consists of coral reef flats that are awash at low tide. CRED multibeam mapping surveys in 2006 revealed that like Ta’u there are little or no shallow banks surrounding the island and the reef descends to abyssal depths less than 1 km off shore. After our 20 hour transit to Swains we’ll be spending the next 3 days working and monitoring the coral reefs here.

Tuesday, March 16, 2010

Rose Revisited

Coralline algal and coral formation at Rose
Atoll (Photograph by Cristi Richards)
It’s always great to know that people are interested in the work we do to monitor and conserve coral reefs. Recently we’ve learned that Ms. Lui’s Marine Science class form Samoana High School class in Utulei, American Samoa has been following our blog. We’ve recently received a list of questions from them that we’ll be answering in the next few blog posts. It’s a good feeling knowing that the next generation of young people are as excited about Marine Science as we are!

Joseph writes: What types of corals did you see at Rose Atoll that are different from those at Johnston Atoll?

Hi Joseph,
That’s an excellent question! Rose and Johnston Atoll are located in distinct geographical regions and as such, they exhibit unique coral faunas. For example, the table coral Acropora cytherea and the rice coral Montipora capitata are quite common and abundant on the shallow reticulate reefs at Johnston Atoll lagoon. In contrast, corals of the genera Montastrea, Coscinaraea, and Astreopora which are absent at Johnston, are quite common around Rose Atoll. However, regardless of how far away are Rose and Johnston from each other (>1000 miles), there are a few, shared coral faunal elements, including the cauliflower coral Pocillopora mendrina, and the corrugated coral, Pavona varians.
- Dr. Bernardo Vargas-Angel

Lita writes: How come there are different species around the rose atoll island when it’s just a small remote island?

Hi Lita,
It is difficult to answer why the corals are so different at Rose compared to Tutuila, although distance (240 km from Tutuila), differences in geomorphology (Rose is a low lying atoll compared to a mountainous island), island size and shape (Rose has a land area of 21 hectares and a height of 4 meters, while Tutuila has a land area of 14,181 hectares and a maximum elevation of 653 meters) likely contribute. Many of the corals that are found around Tutuila are also found around Rose Atoll, although there are not as many coral species that inhabit Rose. Also, the relative abundance of species is very different between the areas. Tutuila likely harbors more species of coral because there is more reef area and thus more chance for different types of habitat to develop, which can provide homes for corals. Certain corals like a lot of water motion from waves, while others prefer very calm waters. Some corals like a lot of sunlight, so they live in the shallows, while others prefer deeper darker waters. Since Tutuila also has mountains, waterfalls, and streams, lots of sediment and nutrients may flow into the sea creating another habitat that is not found at Rose since the island is so short! Also, due to Rose Atoll's tiny size, wave swells originating from far away can impact almost all sides as the waves wrap around the atoll. Whereas ocean swells which approach Tutuila will likely be blocked by the shores of the island in certain areas which create more protected habitats. Likely a combination of these factors and potentially others result in the difference in coral communities between the islands.
- Jason Helyer
While Jason’s answer speaks mostly about corals, this same reasoning can be used to explain the differences in the species of fish, algae, and other invertebrates.

Motina writes: How would you compare the Rose Atoll with the other atolls you have visited? Was the Rose Atoll the best view of the underworld you have ever seen? Are there any changes of the Rose Atoll?

Hi Motina,
Every one of the atolls we visit is different from the rest. A lot of this has to do with what geographic region it is located in. Rose Atoll is pretty spectacular and is unlike many of the other places we visit due to the incredible abundance of the crustose coralline algae. It’s this algae that give the reef its vibrant pink color! The vivid pink color combined with the clear blue water and the various other colors found among the corals, fish and algae certainly make it a beautiful place and fantastic for underwater photography!

As far as changes to Rose Atoll from previous years I did not observe any noticeable differences from my visit to Rose Atoll in 2008. However, sometimes differences can be quite small and may not be realized until we take a deeper look into the data and comparing it to years past.
- Kerry Grimshaw

Soshana writes: How long have you guys been visiting the Rose Atoll Island?

Hi Soshana,
We (NOAA’s Coral Reef Ecosystem Division) have been visiting Rose Atoll since 2002 during our biennial American Samoa Reef Assessment and Monitoring Program cruise. This year was our 5th trip to Rose Atoll.
- Paula Ayotte

Thank you for all of your questions and we will continue to answer them in the upcoming days!

Sunday, March 14, 2010

The Oceanography Team

by Oliver Vetter
Frank Mancini and Oliver Vetter using a liftbag to deploy the Remote Access Sampler
(Photograph by Noah Pomeroy)
As part of our Pacific RAMP cruises, several types of oceanographic instruments are deployed to continually measure water conditions at our research sites. These instruments remain in place for a period of 2 years and are maintained during each cruise. To accomplish this, the oceanography team’s daily operations typically include deploying and recovering oceanographic instruments. These can be small, like the numerous subsurface temperature recorders we’ve deployed, or larger like a wave and tide recorder or sea surface temperature buoy. The larger instruments require the installation of large anchors to hold them to the sea floor under strong currents and waves. The anchors we typically use are 250lbs, which are obviously too heavy for a single person to carry either above water or below. To deploy these anchors we use lift bags, which are basically bags filled with air that float the anchor when full. At the surface the bag is full and the diver slowly releases air out of the bag until the weight of the anchor, being pulled down by gravity, equals the upward buoyancy of the lift bag. At this point the bag can be submerged and starts to slowly descend to the sea floor, preferably under the control of the oceanographer. Since the water pressure increases with depth as you descend through the water column the additional water pressure compresses the volume of the lift bag and so reduces its buoyancy. This causes the anchor to sink faster and in turn reduce the buoyancy and sink even faster, so air has to be slowly added again and again to keep the lift bag from dropping too quickly and out of control. This can be a tricky balance of releasing and adding air, to drop the anchor under control to the seafloor.

Once at the bottom, the new instrument is clamped to the anchor and the old instrument and anchor are removed in the same, but opposite way; the air bag is refilled, and the anchor is raised from the bottom. This time the oceanographer has to be particularly careful not to raise the anchor too fast, or let it get out of control. When diving shallower than 130 feet on normal SCUBA, the diver should ascend at a rate no quicker than 30 feet per minute to avoid decompression sickness. With proper training this kind of work is safe and it’s a matter of pride among the oceanography team to get a good lift.

In the picture, Oceanographers Oliver Vetter and Frank Mancini are retrieving a Remote Access Sampler (RAS), an instrument that can be programmed to collect water samples at predetermined intervals. This RAS was programmed to collect water samples every hour through out a 48-hour period at Rose Atoll. The water samples will be analyzed for Dissolved Inorganic Carbon and Total Alkalinity in an effort to understand the water chemistry of the reef throughout the day. This is part of a larger effort to understand and predict the ecological impacts of ocean acidification.

Friday, March 12, 2010

Ancient Corals of Ta'u, American Samoa

by Douglas Fenner
The largest known coral colony
(Photograph by Paul Brown, NPAS)
On the southwest coast of Ta’u Island, American Samoa, there is a coral of massive proportions. It is a smooth hemispherical coral in the genus Porites. It measures 7 m (23 feet) tall and has a circumference of an amazing 41 m (135 feet). It is in near-perfect condition, with one narrow cleft that is dead and one low tumor the size of person. The tumor retains the color and polyps of the normal coral, it is just raised a little, and these types of tumors appear not to hurt the coral. It is the largest circumference coral we know of in the world (so far), although it is not the tallest. There is another coral in Taiwan that is taller.

This ancient coral is estimated to have 200 million tiny polyps, and to weigh 129 metric tons. It is clearly old, but we don’t know for sure how old. Australian researchers have come up with a formula for how fast this type of coral grows, based on water temperature. Due to relatively high water temperatures in American Samoa, corals grow faster than elsewhere. The formula indicates it should be about 360 years old. The only way to find out for sure is to remove a core from it, which has not been done. Whatever its age, we know from its good health and size that conditions there have been favorable for corals in this area for a longtime.

Diver next to the tumor on the
largest known coral
(Photograph by Paul Brown)
Small samples of the skeleton show that it is in the Porites lutea group of corals. Genetics indicates that there are at least three species in this group, all of which have similar skeletal details. Coral species identification is based on details of the skeleton.

This coral was originally pointed out to researcher Dr. Alison Green by a Samoan employee of National Parks, Fale Tuilagi. Subsequently, CRED has found more corals of similar size on the east side of Ta’u. Ta’u is a shield volcano like Mauna Loa in Hawaii, the youngest island in the Samoan archipelago at a mere 100,000 years, and home to the village from which voyagers set out over a thousand years ago to settle all of the Polynesian islands. It is also where Margaret Mead did her research that led to her famous anthropological book, “Growing up in Samoa.”

Brown, D. P., Basch, L.,Barshis, D., Foresman, Z., Fenner, D., Goldberg, J. 2009.
American Samoa’s island of giants: massive Porites colonies at Ta’u island. Coral
Reefs 28: 735.

Thursday, March 11, 2010

Ofu & Olosega Islands

View of the south side of Ofu (left) and Olosega (right)
(Photograph by Kerry Grimshaw)
By Kerry Grimshaw

We are currently working near the islands of Ofu and Olosega, which are part of the Manu’a group of islands (which also includes Ta'u). They lie approximately 100 km northeast of Tutuila. Although geographically separate, these islands are often referred to together because they are only separated by a narrow straight (approximately 75 m) that is bridged by a shallow coral reef. The twin islands of Ofu (on the west), and Olosega (on the east) are formed by two sharply eroded, overlapping shield volcanoes which gives these islands a dramatic landscape.

Ofu and Olosega are inhabited with the majority of their population (approximately 500 people according to the 2000 census figures) living in the 2 main villages of Ofu and Olosega. An interesting fact I learned from the National Park of American Samoa’s website is that the To’aga archeological site near Ofu Beach has evidence of more than 3,000 years of continuous human occupancy and some modern descendants still live nearby in Ofu Village.

The south-coast beach of Ofu-Olosega with it’s the 4km (2.5mi) stretch of white sand is one of the most beautiful in the South Pacific. Much of the southern coast is also part of the National Park of American Samoa. Along this stretch there are excellent opportunities to snorkel and see some of the 300 species of fish and 150 species of coral that can be found there. Through our shallow water multibeam mapping in 2004 we learned that Ofu and Olosega had a previously uncharted bank top that is less than 300m deep and extends between 0.2 – 2km offshore before dropping to abyssal depths.

Our work this year will continue efforts to monitor fish, coral, algal, invertebrate, and microbial communities at depths ranging from 3 - 30m (10 - 100 feet) deep, as well as a suite of oceanographic observations to better understand the processes influencing these organisms. This data will be compared with that from the other islands we've visited to get an understanding of overall reef health of this area of the world.

Wednesday, March 10, 2010

Exploring South Bank

by Cristi Richards
Exploratory map of South Bank, American Samoa
(ARC GIS map created by Tomoko Acoba)
South Bank is a sub-surface rise in the ocean floor, or seamount, located approximately 37 miles south of the island of Tutuila. Until recently, there has been little scientific knowledge about the depths, habitats, or living communities of South Bank. Reported minimum depths varied widely and proposed minimum depths from 10 meters (30 feet) to 30 fathoms. Fisherman have known about and frequently visit South Bank in search of wahoo, tuna, and other pelagic fish that are attracted to the shallower depths. However, it appears that South Bank has only very rarely been observed underwater.

South Bank is probably not part of the Samoan chain, in geologic terms, due to its location and age. The Samoan chain has been building from the Pacific plate moving over a hotspot, creating islands in a similar fashion to the Hawaiian chain. The older islands are found to the west with the youngest islands in the east. However, South Bank may be greater than 10 million years old, much older than the other Samoan islands in the area. This is similar to how Swains and Rose Atolls are geologically not part of the Samoan chain either, despite their proximity.

Heliopora coerulea, Blue Coral at South Bank
(Photograph by Cristi Richards)
In an effort to understand more about this area, we spent several nights last week mapping South Bank using the multibeam sonar installed in the hull of the NOAA Ship Hi’ialakai. For the first time, we found that not only is South Bank a shallow spot in the ocean floor, but it is a former coral atoll which drowned at some point. We can tell that it is a former atoll by the submerged barrier reef, a ring of shallower depths, surrounding a deeper lagoon with a minimum depth of approximately 25 meters (85 feet). There was only one previous known dive to the area that reported the presence of a rubble flat and high currents. Based on this, we planned a series of reconnaissance dives with members from the fish, benthic, oceanography and towed-diver survey teams aboard the Hi’ialakai. Our survey techniques had to be modified to accommodate the deeper habitat and reduced dive times. We were able to complete a total of 36 person dives and approximately 5 km of towed-diver surveys along the raised rim, encircling the lagoon. We encountered mostly rubble flats with a high abundance of macroalgae and low coral cover and diversity. The area seemed highly scoured and although we experienced only moderate currents, it is probable that the area is subjected to high currents.

South Bank appears to be a reef that has not kept up with sea-level rise, the sinking of the atoll due to the weight of the original island at its center and the sinking of the Pacific plate. It is unclear what the original reef ecosystem was like and it is a mystery why this reef wasn’t able to keep up with these processes. Rose and Swains Atolls experience similar conditions, yet continue to have thriving reef ecosystems. South Bank is an area that will require more investigation to fully understand the history and processes of this submerged atoll. It is exciting that the new investigational maps and surveys may provide more information to aid in future explorations.

Tuesday, March 9, 2010

More cool critter sightings

We are currently at the dock in Pago Pago Harbor, waiting for deliveries so that we can continue our work eastward to Ofu / Olosega and Ta'u. Until we are able to leave dock, these are a few more photos of critters that we see while on the reef. All of these pictures were taken in a reef environment between 10 and 20 meters (30 and 60 feet). Enjoy!

Gomophia sp., a type of Sea Star
(Photograph by Molly Timmers)
Crinoid (Photograph by Erin Looney)
Dardanus sp., a type of Hemit Crab
(Photograph by Molly Timmers)
Gymnothorax sp.,  a species of Moray Eel
(Photograph by Erin Looney)
Octopus sp. (Photograph by Molly Timmers)

Sunday, March 7, 2010


by Kaylyn McCoy
Acanthuras triostegus, Convict surgeonfish forming a feeding
aggregation (photograph by Cristi Richards)
As my dive buddy and I are ascending from a dive, she points behind me and puts her hand to her forehead, making the sign for “shark.” I whip around, full of anticipation and hoping to catch a glimpse of a 12 foot Tiger Shark (Galeocerdo cuvier), preferably swimming away. But, it’s just a three foot Black-Tip Reef Shark (Carcharhinus melanopterus), cruising around below us. Big fish like sharks and jacks are exciting and important, but we can’t forget about the little guys! Above is a picture of a school of Convict surgeonfish (Acanthurus triostegus). These fish are herbivorous, and feed on the algae that grows on the reef. Certain species like these Convict Tang form dense feeding schools possibly to overwhelm smaller, but incredibly aggressive damselfish defending their territories.  Herbivorous fish play an important role in maintaining equilibrium in an ecosystem. Without these fish, certain species of algae can grow out of control, smothering the corals of the reef.

Scarus xanthopleura, Red Parrotfish
(Photograph by Paula Ayotte)
Another algae muncher that we see on the reef is the red parrotfish (Scarus xanthopleura). These fish have a specialized “beak” or dental plate used for scraping the algae off of the reef. Some parrotfish simply scrape the algae off the surface while other, usually larger species, bite of sizable chunks of the reef. Sometimes when we are counting fish, we can actually hear them feeding. Much of the sand you see on a coral reef may have passed through the belly of a parrotfish at one time or another.

Some areas of the Pacific are considering protecting specific herbivorous fish to help control invasive algae. So while it’s exciting to think about a shark snacking on a poor unsuspecting fish, don’t forget about the importance of the herbivores, the lawn mowers of the reef!

Friday, March 5, 2010

Sighting the rare Guitarfish

by Marie Ferguson

A Shovelnose Guitarfish (photograph courtesy of www.Elasmodiver.com)
A few days ago, while conducting a fish REA (Rapid Ecological Assessment) survey my dive buddy, Rusty Brainard, and I enjoyed a rare sighting of a Rhynchobatus djiddensis, Whitespotted Guitarfish, along the northwest side of Tutuila. The guitarfish was spotted while conducting a deep SPC (Stationary Point Count) survey, at approximately 70 feet. We had just completed our final SPC and were on our way to the surface for our safety stop when the 4 foot long guitarfish swam by us with a remora (‘shark sucker’) attached to its underside. Up until this point, a Whitespotted Guitarfish has never been observed or recorded by our research team in American Samoa or other locations during the many thousands of surveys we have conducted across the Pacific Islands over the past decade.

Rhynchobatus djiddensis belongs to the Rhinobatidae or Guitarfish family. It is unique in that it resembles a cross between a shark and a ray with the anterior or front half of its body looking like a ray while the posterior or rear half looking like a shark. Like other rays, guitarfish have small mouths with teeth that are flat and pavement-like and generally prey on crabs, cephalopods and small fishes. Most guitarfish species have been known to occur on continental shelves or insular shelves of large islands in roughly 2 to 50 meters of water depth. Due to the variation over its range, this type of guitarfish has been divided into approximately 5 to 6 species. Little is known about the biology of this species, however data collected has suggested that it does have a low fecundity and very slow growth rate.

According to the ICUN Red List of Threatened Species, the large size and nearshore areas that this species inhabits make it highly susceptible to gillnet and shallow-water trawl fishing. In several parts of the world, such as Tanzania, Rhynchobatus djiddensis is being exploited mainly for its fins and is being commercially fished in bottom-set gillnets. Data recorded has also shown that this species is caught as bycatch in prawn trawls. Other documented areas where this species of guitarfish is either fished intentionally or as bycatch include shores off of Kenya, Mozambique, East Africa and the Middle East in the Western Indian Ocean, many areas in which policing and regulatory enforcement is often limited. The ICUN Red List of Threatened Species has evaluated this species as ‘vulnerable’ due to the “commercially high value and growing demand for its fins, restricted nearshore habitat as well as its limiting life history characteristics”.

If you are out diving or snorkeling and see this elegant and fascinating creature, then make sure to grab a photo and relish in the moment of a rare sighting!

For more pictures of Guitarfish, check out Elasmodiver.com who kindly granted us use of the above photograph.

Thursday, March 4, 2010

Lasting Effects of a Shipwreck

text and photographs by Cristi Richards

Typical site at Rose Atoll dominated by coralline algae
(light pink).
Coralline algae or CCA typically dominate the reefs surrounding Rose Atoll, making up 50% - 75% of the benthic cover according to preliminary results of our 2010 surveys. Scleractinian or hard corals comprise another 5% - 30% of the substrate. At the start of each dive, we are greeted by a light pink landscape accentuated by the greens and reds of fleshy macroalgal genera and the browns, purples and yellows of various genera of coral. The coralline algae are a combination of several genera including Mastophora, Porolithon and Peysonnelia.

In general, coralline algae play many important roles in the ecology of a reef ecosystem. They are a food source for many reef inhabitants including parrotfish, sea urchins and mollusks. Coralline algae also act as a stabilizing component or ‘cement’ for the reef and several genera of coral larvae will selectively colonize patches of this algae.

Site of ship wreck at Rose Atoll.
Brown and darker areas are dead coral
and CCA covered by turf algae and
In October 1993, a 135-foot Taiwanese longline fishing vessel ran aground at Rose Atoll, releasing 100,000 gallons of diesel and 500 gallons of oil into the surrounding waters, across the reef flats and into the lagoon. The initial spill killed large numbers of giant clams, urchins, sea cucumbers and the dominant benthic organism, coralline algae, as well as endangering the health of 12 species of migratory seabirds and the threatened green sea turtle.

However there is still damage occurring to the reef ecosystem, 17 years later. Although there are on-going efforts to remove metal wreckage, with 37.5 tons having been removed to date, there are still iron contaminants being released by the remaining portions of the vessel. When we surveyed this site yesterday, it was immediately obvious that the habitat was vastly different than those seen at other areas of the Atoll. The percent cover of coralline algae was up to 50% less than at other areas, with corals comprising less than 1% of the benthic cover. We also noted an increase in the occurrence of cyanobacteria and turf algae.

Cyanobacteria covering a
colony of Favia stelligera
The iron contamination continues to cause a cyanobacteria or blue-green algal, bloom that is detrimental to the health of both the coralline algae and the corals. The cyanobacteria compete for space with coral larvae by settling on the CCA in thick mats, thus blocking the larvae’s access to the CCA. The thick mat also blocks sunlight from reaching the CCA. In addition, strands of cyanobacteria that detach from the bottom can settle and develop directly on corals. The end result is that corals and CCA are smothered and eventually die, thus changing the overall benthic composition of the reef. The presence of the increased levels of cyanobacteria causes a physical and chemical environment that is not suitablefor the growth of the original reef inhabitants.

This scar at the site of the shipwreck can still be seen today as a reminder of how fragile these ecosystems really are. With continued surveys, this will be a valuable documentation of how long it takes areef to recover from a wreck such as this.

Tuesday, March 2, 2010

Rose Atoll, part 2

by Kerry Grimshaw
photographs by Jean Kenyon
Exposed coralline algae at Rose Atoll

Our day began with a beautiful sunrise and light winds at Rose Atoll, which is one of the smallest atolls in the world and is diamond shaped. The outer reef slope around Rose is steep down to depths greater than 200 meters (~650 feet). The atoll also encompasses 2 small islets named Rose and Sand Islands. Perhaps the most outstanding feature of the atoll is the bright pink color of the exposed reef. The reef gets itís pink hue from the dominant crustose coralline algae Porolithon. This crustose coralline alage is one of the primary reef-building species at Rose Atoll.

Rose Atoll has a coral and fish community different from elsewhere in American Samoa. Currently the US Fish and Wildlife Service reports that there are 113 species of coral and about 270 fish species recorded at Rose. The atoll also supports the largest populations of giant clams, nesting seas turtles and rare reef fish species in the territory. In addition, humpback whales, pilot whales and various species of dolphin have been seen in the waters surrounding Rose Atoll.

Reefs dominated by coralline algae
The 2 islets are not without their own claims of importance. Rose Island is home to a grove of Pisonia trees on it, which is the only remaining Pisonia stands in Samoa. Rose and Sand Islands provide vital nesting habitat to the most important seabird colony in the region, including 12 federally protected migratory seabirds. Some of the birds that utilize Rose Atoll are the Red-footed Boobies, Greater Frigate birds, Lesser Frigate birds, Black Noddies, White Terns, Reef Herons and Red-tailed Tropic birds.

Since Rose Atoll is very remote and extremely unique due to its terrestrial and marine communities it provides an excellent place for scientific research. As such, our days spent at Rose Atoll are always a highlight of our cruise!

Monday, March 1, 2010

Rose Atoll, part 1

By Kerry Grimshaw
Photograph by Jean Kenyon
This afternoon we began our transit to Rose Atoll which is about 240 km (130 nautical miles) to the east of Tutuila. It is often referred to as Rose Island or Motu O Manu (meaning “island of seabirds”) and is the only atoll in the US Territory of American Samoa.

Rose Atoll was first documented in 1819 by Captain Louis de Freycinet who named the isle “Rose” after his wife. It was later visited in 1824 by Otto von Kotzebue and in 1839 by Dr. Charles Pickering, as part of the US exploring expedition, who was likely the first scientist to visit the atoll. Rose Atoll has always been uninhabited except for a brief time in the 1860s when there was an unsuccessful attempt to establish a fishing station and coconut plantation by a German firm. In 1920 a concrete monument was erected on Rose Island by the naval governor of American Samoa to commemorate his visit and allow public access to the atoll. Later in 1941, President Roosevelt made the atoll a naval defense area, but it was never used for that purpose. Rose Atoll became a National Wildlife Refuge on July 5, 1973 and a Marine National Monument on January 6, 2009.

Photograph from noaa.coris.gov
The formation of coral atolls was first described by Charles Darwin during his 5 year voyage through the South Pacific aboard the HMS Beagle from 1831 to 1836. An atoll starts with an oceanic volcano in tropical seas. A fringing coral reef forms on the flanks of the volcanic island and grows upward as the island subsides. The fringing reef separates from the island forming a lagoon as the inner part of the reef begins to subside along with the volcanic island forming a barrier reef. The outer edge of the barrier reef continues to grow and remains near sea level. Eventually the island completely subsides below the ocean surface leaving the barrier reef surrounding a lagoon thus forming a coral atoll.

We are looking forward to the diverse ecological community and habitats that an atoll provides. Rose Atoll will be only the 2nd atoll that we've visited on this mission (the other was Johnston Atoll) and it will be interesting to see how the coral reefs of Rose Atoll differ from those around Tutuila Island.