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Click below to go to the Cruise Logs - (photo credit: Lophelia Coral - Open-File Report 2008-1148 & OCS Study MMS 2008-015)


Cruise Log: 12/05/2009    

Life on the Deep Reef - Understanding the cold-water coral environment

C.S. Martens UNC-Chapel Hill, Robert Byrne U. South Florida

 - click to enlarge
- click to enlarge
Cold-water coral ecosystems are typically found at depths of 200-1000 meters along continental margins throughout the world ocean. These upper slope environments are subject to highly variable physical and chemical conditions whose impacts on coral animal survival and carbonate reef development are not well known.

One of the first steps in understanding cold-water coral ecosystems is to examine the dynamics of their environment. The experimental objectives of the UNC-Chapel Hill and U. South Florida team, linked with studies by other investigators from the US, the Netherlands and the UK, are twofold. Our first and primary objective is to deploy a state-of-the-art instrumentation module armed with autonomous sensors that continuously monitor changes in dissolved oxygen, turbidity, current velocity and direction, salinity and temperature for a full year. This instrumentation module will be deployed on a lander vehicle immediately adjacent to live coral thickets in early December 2009. We seek to better understand how gradients in dissolved oxygen concentrations within centimeters to several meters above the seafloor are linked to seasonal and abrupt event-driven changes in turbidity and water transport rates. The development and growth of coral thickets, with living coral often found several meters above the bottom, may be closely related to such chemical gradients.

SEAS II developed at the University of South Florida - click to enlarge
SEAS II developed at the University of South Florida - click to enlarge
Our second objective is to precisely measure the acidity of the water column surrounding cold-water coral thickets. Just like their tropical relatives, cold water corals develop a skeleton of calcium carbonate through a process that is sensitive to the pH of their environment. By parameterizing the conditions under which these corals live and grow, we can learn about their tolerances for disturbance or environmental change. On this cruise, we will utilize the SEAS II pH monitoring instrumentation developed at the University of South Florida, during hydrocasts to determine water column pH gradients and will attempt a brief (several days) seafloor deployment of SEAS II instrumentation on one of the lander vehicles if time permits. SEAS II instruments are capable of pH measurements at a precision of ± 0.001 units or better, making them ideal for future monitoring of variability in pH at cold-water coral ecosystem sites. Tools and collaborations like these allow us to understand the deep coral environment in ways that were until recently impossible.

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