The New England Seamount Chain (NES) originates at the edge of Georges Bank in the Atlantic Ocean off Massachusetts and extends southeast to the Bermuda Rise, a distance of over 1,000 kilometers. Composed of more than 20 named extinct volcanic peaks, these seamounts have recently caught the interest of biologists investigating deep sea faunal communities.
View Specimens from the Seamount.
Although scientists have been aware of the seamounts for decades, earlier investigations have focused solely on their geologic makeup. In December 2000 a team of scientists aboard the National Oceanographic and Atmospheric Administration (NOAA) research ship R/V Delaware II collected fish and invertebrates at Bear Seamount, the peak closest to the edge of Georges Bank. Of the 20 trawls made at Bear, almost half contacted the bottom at about 1,100 to 2,500 meters below the sea surface, collecting for the first time living benthos of the NES, many to be deposited in the collections at the Yale Peabody Museum.
Accompanying this first survey cruise to Bear Seamount was Jon Moore (Yale Ph.D. 1993, Biology; at left, aboard the Atlantis). Moore first became interested in deep sea fishes while researching the phylogeny of beryciform fishes (a deep sea group that includes orange roughy) and working part-time in the ichthyology section of YPM’s Division of Vertebrate Zoology. After earning his doctorate, Moore spent a year as a curatorial assistant in the Division of Invertebrate Zoology before accepting a lecturer position at Yale teaching organismal biology courses. During his work in the Invertebrate Zoology Division, he and Senior Collections Manager Eric Lazo-Wasem developed a collaborative interest in deepwater invertebrates, and laid plans for acquiring new material for YPM’s collections. While at the Woods Hole Oceanographic Institution in the late 1990s, Moore was instrumental in acquiring new deepwater material for the Peabody, and encouraged agencies there, especially from cruises undertaken by the National Marine Fisheries Service, to deposit voucher material at YPM.
Now an assistant professor at Florida Atlantic University, Moore has been a participant on several research cruises to the NES, including one sponsored by the National Science Foundation, and another by NOAA this past summer, both of which used the deep submersible Alvin (at left) to investigate the seamount fauna to depths greater than 2,100 meters. From these expeditions, Moore was able to secure for Yale a major portion of the invertebrates and fishes; the rest were divided among several other institutions, including Harvard University’s Museum of Comparative Zoology and the National Museum of Natural History, Smithsonian Institution.
Specimens collected during these investigations are allowing scientists to sketch a preliminary picture of the faunal communities inhabiting these isolated undersea mountaintops. Although the precise identity of most of the invertebrates is as yet unknown, the number of recognized morphotypes is staggering, especially considering the traditional viewpoint that the cold, deep ocean bottom of the Atlantic is largely uninhabited.
Corals, echinoderms and crustaceans dominate the list of invertebrates; some of these animals are quite rare in museum collections and have been collected in the Atlantic only a few times before. For example, one small, solitary coral collected at Bear Seamount has been seen for the first time since it was originally described over 100 years ago. Although most people associate coral reefs with the tropics, vast coral communities of species such as Lophelia, Metallogorgia and Paragorgia have arisen on the seamounts. These attract a broad array of invertebrates and fish; the overall diversity so far encountered exceeds 600 species and will probably rise to more than 1,000 as more specimens are identified.
While diving at the NES aboard the Alvin this past summer, Moore focused his collecting, in part, on xenophyophores, large single-celled protists found only in the deep sea environment. These organisms are a current research interest of Moore’s wife and collaborator, Susan Richardson (Yale Ph.D. 2000, EEB), currently a research associate at the National Museum of Natural History, Smithsonian Institution. Xenophyophores create an agglutinated shell, or “test,” consisting of a secreted organic adhesive that binds together fine sediments and the tiny shells of other single-celled protists. Known as the giants of the protozoan world, some xenophyophores, such as Syringammina fragilissima, can have tests exceeding 10 centimeters in diameter. Richardson is currently working to identify the xenophyophores collected at the NES. Also of interest is a crustacean, the amphipod Liljeborgia sp., unexpectedly found associated with the xenophyophores; the relationship of this amphipod to the protist is unknown.
The acquisition of deep sea collections is not a new endeavor for the Yaale Peabody Museum. In the late 19th century, the United States Fish Commission began surveying the coastal waters from Newfoundland to the Carolinas. Addison E. Verrill, Yale’s first professor of zoology and one of the original curators of the Peabody Museum, was for many years in charge of the U.S. Fish Commission’s dredging operations and the person primarily responsible for identifying the collected fauna. Many of the collecting stations were in deepwater, some at depths exceeding 4,000 meters. Ultimately, Verrill produced dozens of papers on the Atlantic coast invertebrates, and described hundreds of new species from U.S. Fish Commission samples. As part of his arrangement with the U.S. Fish Commission, Verrill was able to retain a major portion of this material, and today it forms a core historical collection of the Division of Invertebrate Zoology.
Currently more than two dozen specialists are identifying or otherwise studying the NES fauna. Long-term goals include describing any new species and mapping the distribution of the deepwater coral communities. Of particular interest are questions of genetic isolation in the invertebrates inhabiting the seamounts. Because some of the benthic invertebrates do not have planktonic larvae for dispersal, it is expected that several species in these groups could be restricted in their distribution to just these seamounts. This limited distribution is particularly true for those invertebrates nestled in the bottom substrate, and which do not spend much time in the water column subjected to dispersing currents. In this regard, historical collections, such as those housed at the Peabody, are being surveyed for comparative material. Scientists such as Les Watling at the University of Maine, another alumnus of this past summer’s Alvin dives, are beginning to investigate the potential negative impact that commercial fishing may have on deepwater coral communities.
Recent studies have indicated that the corals Paragorgia and Lophelia, which both occur in dense underwater “forests,” are slow growing and provide crucial habitat for associated invertebrates. When commercial trawlers drag nets through these fragile habitats, they essentially “clear-cut” the reefs; the resulting loss of habitat forces many animals to move elsewhere. The scars from these activities can take years to heal. One proposal under consideration is to establish some of these seamounts as protected areas to conserve their unique habitats and faunas. While the lack of commercial fishery species and the geographical isolation of these seamounts means they are currently not a focus for commercial fishing, the discovery of a commercially important deepwater fishery (such as orange roughy) could encourage trawlers to venture out to these areas.
For now, Moore, Richardson, Watling and other scientists will continue their explorations of these deep sea mountains to further our understanding of the biodiversity and ecology of the faunal communities and provide information on what animals live in these pristine habitats. Another cruise is planned for the summer of 2004, and if the past is any indication, it will likely yield even more new and exciting discoveries.
— Eric Lazo-Wasem,
Invertebrate Zoology Senior Collections Manager
Originally published in Yale Environmental News, Spring 2004
vol. 9, no. 2. © 2004 Yale University. All rights reserved.