2015 Expedition

Low pH site in Nikko Bay, Palau
Photo Credit: H. Barkley
The goal of our work is to identify coral reefs that are best equipped to survive 21st century ocean acidification. The Cohen lab began working in Palau several years ago, during that time we discovered that Palau's Rock Island habitats have an exceptionally low pH for the vast diversity and coral cover that they harbor. All other naturally low pH habitats that science has studied so far, show negative effects: decline in coral diversity, sharp declines in coral cover, and laboratory manipulations show slower growth rates under lower pH conditions. So why are Palau's Rock Islands different? That's exactly what we want to know.

We are returning to Palau in January and February 2015 to study the coral reefs that are thriving across the natural pH gradient within the Palauan Archipelago. During this expedition, our goals are to:

1) Identify the sensitivity of calcification rates on the reef to the pH of seawater flowing over the reef
2) Characterize the pH and coral community composition around the Palauan archipelago
3) Develop a novel system for measuring Net Ecosystem Calcification (NEC), which is the rate at which calcium carbonate (CaCO3) is produced on the reef

To accomplish these goals, we will deploy a series of instruments on the reef to track the movement of seawater on the reef and to track how the chemistry of the seawater changes as it flows across the reef. This carefully designed experiment tells us the combined rates at which organisms are calcifying - such as corals and coralline algae - and dissolving - such as bioeroding bivalves - calcium carbonate on the reefs of Palau.

Net Ecosystem Calcification rates vary across the Palauan archipelago. We are describing the coral community composition and seawater pH around Palau so that we can identify how sensitive these NEC rates are to the species present and to the pH of the seawater.

During this expedition, we are developing a novel technique to measure NEC on coral reefs, using a system called Robotic Analyzer for Total CO2 System (RATS). Previously, we have collected a series of seawater samples and analyzed the carbonate chemistry of these samples back in the lab, which can take several months. Our new approach will collect continuous, real-time seawater carbonate chemistry data in the field, providing us with a high-resolution picture of how NEC changes throughout the day and over a several week deployment period.

Science Team:

Hannah Barkley 

Hannah is a Ph.D. student in the Joint Program in Oceanography at MIT/WHOI. Hannah's research focuses effective coral reef conservation under climate change, particularly ocean acidification and warming. On this expedition she will be collecting water samples to study the carbonate chemistry of Palau's various habitats.

Bill Martin 

Bill is a Senior Scientist at WHOI, and is joining us on Palau to deploy the newly developed Robotic Analysis of Total CO2 System (RATS) on a coral reef for the first time. Bill's interests include sediment-seawater exchange of bioactive and trace metals, and early diagenesis in marine sediments.

Steve Lentz

Steve is a Senior Scientist at WHOI. Steve is a coastal physical oceanographer, and his interests include coral reefs, wind and wave driven circulation, boundary layers, river plumes, surf zone circulation, tides, and coastal meteorology.

Tom DeCarlo

Tom is a Ph.D. student in the Joint Program in Oceanography at MIT/WHOI. Tom is interested in how coral growth and bioerosion are affected by seawater properties including temperature, nutrients, and pH. In addition, Tom develops geochemical tools to use the chemistry preserved in coral skeletons to better understand how corals have responded to environmental change in the past.

Katie Shamberger

Katie is an Assistant Professor of Oceanography at Texas A&M University. Katie's research focuses on the ocean carbon cycle, its alteration by anthropogenic ocean acidification, and the impacts of ocean acidification on calcifying organisms and ecosystems. She is particularly interested in coastal ocean-carbon cycling, especially within coral reef systems. She has worked on coral reefs in the Caribbean, Hawaii, American Samoa, Palau, and the Great Barrier Reef in Australia.

Andrea Kealoha

Andrea is currently a Ph.D. student at Texas A&M under the direction of Dr. Katie Shamberger. Andrea's interests include the effects of ocean acidification on coral reef ecosystems, and bridging the gap between cultural knowledge and western science in order to develop effective and informed marine resource management plans.

Kathryn Rose 

Kathryn holds a masters degree in Geology from the University of California, Davis. Kathryn manages the Cohen lab, operates a range of instruments, assists with laboratory manipulation experiments and coral reef fieldwork.

Pat Lohmann

Pat Lohmann is Scientist Emeritus at the Woods Hole Oceanographic Institution and is our lead Dive Safety Officer for our expedition. 

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