Hawaii FEP - Western Pacific Fishery Council

Figure 10: Benthic EnvironmentSource: WPRFMC 2005b3.3.2.1 Intertidal ZoneThe intertidal zone is a relatively small margin of seabed that exists between the highest andlowest extent of the tides. Because of wave action on unprotected coastlines, the intertidal zonecan sometimes extend beyond tidal limits due to the splashing effect of waves. Vertical zonationamong organisms is often observed in intertidal zones, where the lower limits of some organismsare determined by the presence of predators or competing species, whereas the upper limit isoften controlled by physiological limits and species’ tolerance to temperature and drying(Levington 1995). Organisms that inhabit the intertidal zone include algae, seaweeds, mollusks,crustaceans, worms, echinoderms (starfish), and cnidarians (e.g., anemones).Many organisms in the intertidal zone have adapted strategies to combat the effects oftemperature, salinity, and desiccation due to the wide-ranging tides of various locations.Secondary and tertiary consumers in intertidal zones include starfish, anemones, and seabirds.Marine algae are the primary produces in most intertidal areas. Many species’ primaryconsumers such as snails graze on algae growing on rocky substrates in the intertidal zone. Dueto the proximity of the intertidal zone to the shoreline, intertidal organisms are important fooditems to many human communities. In Hawaii, for example, intertidal limpet species (snails)such as `opihi (Cellana exarata) were eaten by early Hawaiian communities and are still apopular food item in Hawaii today. In addition to mollusks, intertidal seaweeds are alsoimportant food items for Pacific islanders.3.3.2.2 Seagrass BedsSeagrasses are common in all marine ecosystems and are a regular feature of most of the inshoreareas adjacent to coral reefs in the Pacific Islands. According to Hatcher et al. (1989), seagrassesstabilize sediments because leaves slow current flow, thus increasing sedimentation of particles.The roots and rhizomes form a complex matrix that binds sediments and stops erosion. Seagrassbeds are the habitat of certain commercially valuable shrimps, and provide food for reefassociatedspecies such as surgeonfishes (Acanthuridae). Seagrasses are also important sources52