Christmas tree coral discovery

Date: March 10, 2005

New deep sea discoveries are being made all the time. Several new species of black corals have been discovered this year alone, including a new shrub-like black coral that shines like a pink and white Christmas tree. Yet their delicate structures can be removed with one pass of a bottom dragging net and may take decades to recover.

Marine biologists recently discovered a new black coral that resembles a pink and white Christmas tree and can grow up to 2m tall and 4.5m wide. That a coral this size can remain undiscovered off the coast of one of the United States’ largest cities – Los Angeles – for so long, is a testimony to the wealth of deep sea life just waiting to be discovered. The discovery was first made by Dr. Milton Love, at the University of California, Mary Yoklavich from the National Oceanic and Atmospheric Administration and their team of researchers while conducting rockfish surveys off the Californian coast six years ago. But it was not until 2002 that they really started to take notice of the coral and were able to more closely examine it with the aid of a two-person submarine, named Delta, which can drop to depths of 365 m (1200ft) and is typically used for researching fish populations around oil rigs. Yoklavich said a closer examination of the coral showed that its physical structure was unique, thereby classifying it as a new species. Love and Yoklavich decided to give the coral its festive name after repeated comments from divers who would come up after studying fish populations and report that they had seen yet another Christmas tree. It was only recently determined that the coral is in fact a new species, after samples were sent to the world’s leading black coral expert, Dennis Opresko at the Oak Ridge National Laboratory in Tennessee. The scientific name he gave to the coral (1) – Antipathes dendrochristos – reflects both its resemblance to a Christmas tree and an ancient belief that black coral amulets can prevent illness. There may in fact be two coral species although DNA testing is required to determine this. And scientists have also found a new species of worm associated with the coral – a new animal living on the new animal. (Though corals may look like plants, they are actually colonies of animals, related to sea anemones, each individual or “polyp” being connected by tissue to others and living together, usually within a skeleton that they secrete for support. Although vivid in life, having a large branch-like structure and bright red, pink and white colours, the Christmas tree coral is a type of black coral, turning black when it dies. There are roughly 230 species of black coral found in the world’s oceans, from warm, tropical waters to the freezing waters of Antarctica. Several new species, including one from the Aleutian Islands, have been described this year alone. Most black corals live in deep water, some at great depths, while others are collected by divers as part of the jewelry trade, especially in Hawaii. Home to vibrant undersea communities, the Christmas tree coral can be found along the entire coast of Southern California, including the area between the Channel Islands and the Santa Barbara coastline. One of the largest organisms at its depth, it sometimes grows up to 2m (7ft) tall and 4.5m (15ft) wide, favouring rocky habitats between the depths of 90m (300ft) and 230m (750ft). In fact, deep sea corals extend over a much greater area of the ocean seafloor than the much more familiar tropical coral reefs. Yet they are among the poorest known and least studied communities on the Earth. A common comment is that we know more about the moon than we do of the deep sea. The first large-scale exploration of the deep sea began in 1872 with the British Expedition on board H.M.S. Challenger. This four-year expedition navigated the globe, collecting specimens and revealing for the first time, extensive marine life in the deep sea (at depths of greater than 200m (650ft)). Subsequent deep sea exploration has discovered that life extends to the furthest depths of the oceans, including the Marianas trench which is over 10,000m (32,800ft) deep, and exciting discoveries continue to be made as marine scientists finally have the tools (such as submarines and remotely operated cameras) to view the seafloor. While knowledge of deep sea biology and corals is still in its infancy, submersibles and remote cameras are beginning to open up the deep sea. The limited studies that have been conducted to date suggest astonishing levels of biodiversity in the deep sea. For example, recent reports document that over 1300 species have been recorded from deep sea coral, Lophelia pertusa reefs in the north Atlantic. This and other studies challenge conventional wisdom regarding the global distribution of biological diversity. Deep sea corals, similar to their tropical cousins, provide habitat complexity and structure to the seafloor that supplies shelter, nursery, and feeding sites for a variety of commercially important species that are now depleted (e.g. Atlantic cod, rockfish) and large numbers of non-commercial species of fish and other organisms. They also have untold value to the pharmaceutical industry and human health and can provide ancient archives of global change in their calcareous structures. The discovery of the Christmas tree coral, for example, is also significant, because the health of the coral can serve as an indicator of environmental conditions off the Southern California coast. Deep sea corals are extremely sensitive to pollution and destructive fishing practices especially commercial bottom trawling. These delicate structures can be removed in one pass of a bottom dragging net, and it might take decades to recover from this one time event. A moratorium on deep sea bottom trawling on the high seas is essential to protect deep sea species from being destroyed before they have even been discovered. The fact that there are still habitats of Christmas tree coral in good shape all along the coast suggests that the seafloor environment off southern California is still capable of supporting rockfish populations should they be given opportunities to recover.

Notes: (1) Dennis Opresko’s description of Antipathes dendrochristos was published in the 8 February, 2005 issue of the online scientific journal, Zootaxa. Dr. Lance E. Morgan organized the 2004 AAAS Meeting symposium on The Forgotten Forests: Deep-Sea Coral and Sponge Beds. He is an author of Occurrences of Habitat-forming Deep Sea Corals in the Northeast Pacific Ocean and of the first rigorous, quantitative, comparative study of bycatch and habitat damage caused by commercial fishing methods Shifting Gears: Assessing Collateral Impacts of Fishing Methods in US Waters in Frontiers in Ecology and the Environment.

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