ʻOʻopu naniha, like other native Hawaiian gobies, requires intact
stream habitat from headwaters to sea. Learn more.

The native biotic component of Hawaiian streams varies by location, size of stream and extent of disturbance.  Native stream animals typically include gobiid fish, snails, crustaceans and insects.  The five gobiid fish species of Hawaiian continuous perennial streams include 4 endemic species, ‘o‘opu nākea (Awaous stamineus),  ‘o‘opu nopili (Sicyopteris stimpsoni), ‘o‘opu alamo‘o or ‘o‘opu hi‘ukole (Lentipes concolor) and ‘o‘opu okuhe or akupa (Eleotris sandwicensis), and one indigenous species, ‘o‘opu naniha (Stenogobius genivitatus), known also from Samoa.  Other native fish found in Hawaiian streams include aholehole (Kuhlia sandvicensis) and mullet (Mugil cephalus). 

Hawaiian Continuous Perennial Stream, Hanawī, East Maui
Learn more at the State of Hawai'i Aquatic Resources page.

Two endemic decapods comprise the native macro-crustacean fauna, the shrimp ‘ōpae kala‘ole (Atyoida bisulcata) and the prawn ‘ōpae‘oeha‘a (Macrobrachium grandimanus).  Several macro-mollusks are inhabitants of Hawaiian streams,. including hīhīwai, or wī (Neritina granosa), brown wī or hapawai (Theodoxus vespertinus) and several species of Melanoides.  There are in addition, several species of smaller native crustaceans, mollusks and insects in Hawaiian streams.  Nearly all of the stream-related Hawaiian fishes, macro-crustaceans and macro-mollusks require oceanic larval development, followed by upstream migration and maturation.

Threats

Threats to Hawaiian continuous perennial streams include modifications of channel, changes in stream flow by diversion of water, siltation via erosion of disturbed watersheds, direct or indirect pollution of surface or groundwater, and introduction of alien stream animals that either feed on or compete with native species.  Because of the diadromous life cycles of most native stream macrofauna, intact headwaters and upper stream courses with highly modified lower courses and mouths limit all but the most hardy native species.  

Even the most remote and unaltered streams may be invaded by alien species, if those species have oceanic larvae that can disperse between streams or between islands.  Alien prawns, such as the Tahitian prawn (Macrobrachium lar) and Malaysian prawn (M. rosenbergii) are predatory on almost all native stream elements, have an oceanic dispersal phase, and are a particularly difficult problem to address. Other significant alien stream animals include fishes such as cichlids (Cichlasoma spp.), catfish (Clarias fuscus), bass (Micropterus spp.), tilapia (Tilapia spp.), live-bearers, such as mosquitofish (Gambusia affinis), guppies (Poecilia spp.), and swordtails (Xiphophorus, spp.) and the freshwater clam (Corbiculea fluminea)

Protected examples of Hawaiian continuous streams may be found in the Waimanu Estuarine Sanctuary, Pelekunu Preserve of The Nature Conservancy of Hawai‘i, Kīpahulu Valley in the Haleakalā National Park and Waiahuakua Valley in the Hono O Nā Pali Natural Area Reserve.

Two native stream macroinvertebrates: the nerite snail hīhīwai (Neritina granosa) left, and the atyid shrimp 'ōpae kala'ole (Atyoida bisulcata).