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.

Saturday, April 23, 2011

The Makings of a Marine National Monument

by Jake Asher and Annette DesRochers

Farallon de Pajaros (FDP), also known as Uracas, was our northernmost stop of this cruise.  Once known by the pseudonym, “Lighthouse of the Western Pacific”, FDP’s last known eruption was back in 1967. Even after 44 years, the landscape above the shoreline remains largely barren.
The Hi’ialakai positioned in front of FDP to recover dive teams. 
NOAA photo by Edmund Coccagna.
In stark contrast, the Islands of Maug crater—there are three small islands all together with a submerged caldera in the center—are lush with vegetation compared to FDP. As a former Geographic Information Systems Specialist, Maug happens to be one of my favorite places in the Pacific to map because of its unique horseshoe-shaped topography with a subsurface pinnacle rising from the depths in the middle.
 Maug bathymetry (seafloor) map.
Source: Pacific Islands Benthic Habitat Mapping Center.
One of the small boats, HI-1, returning to the Ship with the islands of Maug in the background. NOAA photo by Annette DesRochers.

FDP, Maug, and Asuncion (highlighted earlier this week), make up the “Islands Unit” of the Marianas Trench Marine National Monument. The other two Units of the Monument are the Marianas Trench itself and the Volcanic Unit which includes the numerous submerged volcanoes and hydrothermal vents along the Mariana Arc (click here to see a map). Supply Reef, also one of the places surveyed during this mission, is one of the undersea volcanoes that are protected by the Monument designation under the Volcanic Unit.
Abundant marine life can be found throughout the Marianas Trench Marine National Monument. NOAA photo by Edmund Coccagna.
Declared in early 2009, the Monument seeks to protect the biologically diverse and abundant marine life found in the waters of these islands, seamounts, and hydrothermal vents.  These unique habitats are home to one of the most diverse collections of corals found in the Western Pacific, and also support some of the largest biomass of reef fishes found in the region.
Large schools of bigeye jack (Caranx sexfasciatus) present at both FDP and Maug, providing divers with an eyeful. NOAA photo by Jake Asher.
Maug, in addition to having a diverse and abundant benthic environment, is of particular scientific interest due to its underwater vents.  Hydrothermal vents within the caldera seep hot (60oC), acidic water into the environment around it and provide a unique platform for researchers to study the effects of highly acidic water in a coral reef environment. This is of particular interest as the pH of the world's ocean water appears to be lowering due to the uptake of anthropogenic CO2. This ‘acidification’ of the water is reducing the availability of bicarbonate in the oceans, which is the main building block for calcifying animals, such as corals, to grow and survive.
REA fish diver Marie Ferguson takes advantage of the warmth emitted by the hydrothermal vents at Maug. NOAA photo by Jill Zamzow.

In close proximity to the vents are some of the most impressive Porites rus stands that divers on this cruise have ever seen.   NOAA photo by Jeff Anderson.
Both the REA benthic and fish teams surveyed the areas near the vents, and the oceanography team used an auto-sampler to take water samples at a high frequency.  The hourly samples will be analyzed for dissolved inorganic carbon and total alkalinity and from these the aragonite saturation levels in the water can be determined.  The saturation level of aragonite determines the amount of the ion that is available for corals to use as building blocks for their structure.  Theoretically, the more acidic the water, the less aragonite ion is available in the water for corals to use for growth.  Salinity, temperature and current flow was also measured using additional instruments in the area.  These data will help us understand more about a natural coral reef environment under highly acidic conditions.
A remote access sampler (RAS) was deployed near a vent site inside the caldera at Maug for two days in order to collect hourly water samples over a 48 hour period. NOAA photo by Jake Asher.

Maug just might be considered the “crown jewel” of the Monument.  Listening to divers recount the highlights from their surveys at Maug certainly substantiates that notion. With astounding coral cover reaching up to 75% in some places, the benthos teems with life, keeping scientists on both the benthic REA and towed-diver teams occupied.
A diver photo-documenting the unique habitat and organisms found in the Monument. NOAA photo by Edmund Coccagna.

While the benthic environment at FDP is largely depauparate in places, likely the result of ‘recent’ geologic activity, it too has its gems. That being said, some of the most spectacular views during our short time at FDP happened to be topside.
Sunrise over Farallon de Pajaros. NOAA photo by Jake Asher.
Moonrise over Farallon de Pajaros. NOAA photo by Jake Asher.

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