Hawaii FEP - Western Pacific Fishery Council

eefs are often too slow to keep up with changes in sea level. This was true during the sea levelrises that occurred during the Holocene transgression, and many reefs below this depth drownedduring this period. Coral reef habitat does extend deeper than 30 meters, but few well-developedreefs are found below 50 meters. Many coral reefs are bordered by broad areas of shelf habitat(reef slope) between 50 and 100 meters that were formed by wave erosion during periods oflower sea levels. These reef slope habitats consist primarily of carbonate rubble, algae, andmicroinvertebrate communities, some of which may be important nursery grounds for some coralreef fish, as well as a habitat for several species of lobster. However, the ecology of this habitatis poorly known, and much more research is needed to define the lower depth limits of coralreefs, which by inclusion of shelf habitat could be viewed as extending to 100 meters.The symbiotic relationship between the animal coral polyps and algal cells (dinoflagellates)known as zooxanthellae is a key feature of reef-building corals. Incorporated into the coraltissue, these photosynthesizing zooxanthellae provide much of the polyp’s nutritional needs,primarily in the form of carbohydrates. Most corals supplement this food source by activelyfeeding on zooplankton or dissolved organic nitrogen, because of the low nitrogen content of thecarbohydrates derived from photosynthesis. Due to reef-building coral’s symbiotic relationshipwith photosynthetic zooxanthellae, reef-building corals do not generally occur at depths greaterthan 100 meters (~300 feet; Hunter 1995).Primary production on coral reefs is associated with phytoplankton, algae, seagrasses, andzooxanthellae. Primary consumers include many different species of corals, mollusks,crustaceans, echinoderms, gastropods, sea turtles, and fish (e.g., parrot fish). Secondaryconsumers include anemones, urchins, crustaceans, and fish. Tertiary consumers include eels,octopus, barracudas, and sharks.The corals and coral reefs of the Pacific are described in Wells and Jenkins (1988) and Veron(1995). The number of coral species declines in an easterly direction across the western andcentral Pacific, which is in common with the distribution of fish and invertebrate species. Morethan 330 species are contained in 70 genera on the Australian Barrier Reef, compared with only30 coral genera present in the Society Islands of French Polynesia and 10 genera in theMarquesas and Pitcairn Islands. Hawaii, by virtue of its isolated position in the Pacific, also hasrelatively few species of hard coral (about 65 species in 17 genera) and, more important, lacksmost of the branching or “tabletop” Acropora species that form the majority of reefs elsewherein the Pacific. The Acropora species provide a large amount of complex three-dimensionalstructure and protected habitat for a wide variety of fishes and invertebrates. As a consequence,Hawaiian coral reefs provide limited “protecting” three-dimensional space. This is thought toaccount for the exceptionally high rate of endemism among Hawaiian marine species.Furthermore, many believe that this is the reason certain fish and invertebrate species look andact very differently from similar members of the same species found in other parts of the SouthPacific (Gulko 1998).Coral Reefs of the Hawaii ArchipelagoThe total potential coral reef area in Hawaii (MHI and NWHI) is estimated to be 2,826 squarekilometers within the 10-fathom curve, and 20,437 square miles within the 100-fathom curve,54