Hawaii FEP - Western Pacific Fishery Council

1976). Off Oahu, many submarine terraces that otherwise would be suitable habitat for blackcorals are covered with sediments. In the MHI, the lower depth range of Antipathes dichotomaand A. grandis coincides with the top of the thermocline (ca. 100 m; Grigg 1993).Pink, bamboo, and gold corals all have planktonic larval stages and sessile adult stages. Larvaesettle on solid substrate where they form colonial branching colonies. The length of the larvalstage of all species of precious corals is unknown. Like other cnidarians, black corals have lifecycles that include both asexual and sexual reproduction. Asexual reproduction (budding) buildsthe colony by adding more living tissue that, in turn, secretes more skeleton. Regular growthrings laid down as the skeleton thickens can be used to estimate the age of the colony. Sexualreproduction involves the production of eggs and sperm to create young that can disperse andsettle new areas. Polyps are either male or female, but a single colony may be hermaphroditic,with both male and female polyps. The larval stage, called a planula, can drift with currents untila suitable surface is found. Once the larva settles, it metamorphoses into a polyp form andsecretes skeletal material that attaches it to the seafloor. Then it begins budding, creating morepolyps that will form a young colony. Asexual reproduction can also occur naturally byfragmentation of branch ends. In one Hawaiian species that have been studied (A. dichotoma),the colony may grow about 2.5 inches (6.4 cm) per year. Reproductive maturity may be reachedafter 10 to 12 years and reproduction may occur annually. A large six-foot (1.8 m) tall coral treeis estimated to be between 30 and 40 years old; a colony life span may be 70 years. Some speciesmay live even longer 22 .On Hawaii's deep reef slopes and throughout the world, black corals host unique communities ofmarine life. Their tree-like colonies create habitat for crustaceans, bivalves, and fish. Each coralmay host a different combination of species. Some residents are commensals --dependentpartners that live only on the black coral. Many species in this deep reef community are new toscience. The habitat sustaining precious corals is generally believed to be in good condition.However, an alien species called snowflake coral, Carijoa riisei, has recently begun smotheringnative deep reef sea life including precious corals. 23 In 2001 deepwater surveys in the AuauChannel found a maximum impact between 70-110 m where more than 50 percent of blackcorals had snowflake coral overgrowth (Khang and Grigg 2005). A second survey in 2006reexamined conditions in the Auau Channel and found that the impact of snowflake corals hadnot worsened and it was possible that conditions in some areas had stabilized or improved. Thisled researchers to conclude that the ecological impact of snowflake coral on black corals mayhave stabilized or possibly abated slightly (Khang 2007).To reduce the complexity and the number of EFH identifications required for individual speciesand life stages, the Council designated EFH for precious coral assemblages. The species complexdesignations are deep- and shallow-water complexes (see Table 28). The designation of thesecomplexes is based on the ecological relationships among the individual species and theirpreferred habitat.The Council considered using the known depth range of individual PCMUS to designate EFH,but rejected this alternative because of the rarity of the occurrence of suitable habitat conditions.22 http://www.waquarium.org/MLP/root/pdf/MarineLife/Invertebrates/Cnidarians/BlackCoral.pdf23 http://www.cop.noaa.gov/ecosystems/coralreefs/features/fs-2005-12-12-cr.html181