Davidson Seamount off the coast of central California, USA. Click image for larger view and image credit.
Mission Plan
Andrew DeVogelaere, Ph.D.
Monterey Bay National Marine Sanctuary
Why study deep-sea corals?
Recent advances in technology enable us to explore deep in the ocean and study corals. There are relatively few studies on deep-sea corals, but initial findings indicate that a diverse group of these corals exist, and that some are hundreds of years old. The corals also seem to provide essential habitat for other groups of smaller species that live among them. Increasing the sense of urgency in studying deep-sea corals is their fragility, and the extensive human impacts to them from fisheries where nets are trawled along the seafloor. These nets effectively catch bottom fishes, but also bring up 'non-target' or 'bycatch' species such as corals. The taxonomy of deep-sea corals, essentially their names and how they are related, is still challenging because of the relatively few scientific collections and high quality images. While we are beginning to see patterns of where they are found in the deep sea, such as on rocky ridges, we are not yet sure why they grow best in these locations. So, with deep-sea corals, we have a situation where lots of basic, exciting science questions have yet to be answered to help address conservation needs of these spectacular organisms.
The Exploration Site - Davidson Seamount
Davidson Seamount is located 120 kilometers (75 miles) to the southwest of Monterey, California (35º 43' 23''N, 122º 43' 23'' W), and is one of the largest seamounts along the Western United States. It is 42 kilometers (26 miles) long, and 13.5 kilometers (8 miles) wide. From base to crest, Davidson Seamount is 2,400 meters (7,874 feet) tall; yet, it is still 1,250 meters (4,101 feet) below the sea surface. Davidson Seamount has an atypical seamount shape, having northeast-trending ridges created by a type of volcanic activity only recently described by scientists at MBARI. It last erupted about 9.8 million years ago, and this large geographic feature was the first to be characterized as a 'seamount.' Seamounts are an important habitat for deep-sea corals, and demonstrate a high degree of endemism (species living on a particular seamount and nowhere else).
Exploration Goals
We have four general goals for our exploration of corals on the Davidson Seamount:
• Understand why deep-sea corals live where they do on the seamount
• Determine the age and growth patterns of the bamboo coral
• Improve the species list and taxonomy of corals from the seamount
• Share the exciting experience with the public through television and the Internet
Methods
On our last exploration of Davidson Seamount in 2002, we found over 20 types of deep-sea corals; we noted they were largely found in dense gardens on ridges near the top of the seamount; and we found the longevity of corals reached hundreds of years. At that time, we were documenting all species, not just corals, and the Davidson Seamount is still 99.98% unexplored.
ROV Tiburon tracklines of the 2002 expedition to Davidson Seamount, with coral locations. Click image for larger view and image credit.
We developed a simple model to predict where corals are most likely to be found, and will test this model by visiting unexplored ridges, valleys, and slopes along the Davidson Seamount. We will then use instruments that measure ocean currents and food particles to describe in more detail the environments where corals are thriving. With this understanding, future studies of deep-corals will be more efficient with targeted rather than random searches of the seamount.
We will be collecting coral specimens to more carefully determine their identity, ages, and genetic diversity. The analyses will be completed after the cruise, and we are likely to find that some species are new (at least to humans) and will need a name; some species are ancient, predicting slow recovery if damaged; and that genetic diversity within a species will be more similar among individuals collected close to each other on the seamount. These types of general ideas will be developed carefully into hypotheses that will be tested after we know what samples we were able to collect.
Sharing the discoveries can be as much fun as making them. The BBC will be joining the scientists to gather footage for an upcoming television series, Planet Earth. We also look forward to interacting with the public on our web site by exchanging information and ideas.
