Habitats of Tubicolous Polychaetes from the Hawaiian Islands and Johnston Atoll

Abstract

Forty-seven species of tube-building polychaetes, belonging to the families Spionidae, Chaetopteridae, Sabellariidae, Terebellidae, Sabellidae, and Serpulidae, were collected from the Hawaiian Islands and Johnston Atoll. Eight different habitat types or zones were distinguished, each having a characteristic polychaete fauna. The tidepools of rocky shores support up to 20 species, including the only tubeincubating spirorbine found in Hawaii, Spirorbis marioni. Two of the three known Hawaiian chaetopterids, the large fan worm Sabel/astarte sanctijosephi, and 13 serpulid species occur on reef platforms that lack lush coral growth. Four species of algae were found with associated polychaetes. The greatest number of species was associated with Dictyosphaeria cavernosa, which provides suitable habitats for cryptic and sessile organisms. Live coral heads and the subtidal, fringing reefs apparently have an impoverished tube-worm fauna. Spirobranchus giganteus is the only living serpuline associated with live corals. The hard parts of mobile crustaceans and gastropods reveal a diverse invertebrate fauna, and the species composition of the associated polychaetes reflects that of the surrounding environment. Boat harbors and lagoons have a typically rich fauna due to the introduction of benthic invertebrates on the bottoms of boats. Such habitats remain reservoirs of introduced species, which are important in the geographical distribution of tube worms within the islands. Mercierella enigmatica and other euryhaline polychaetes are found in brackish waters. The unique anchialine pond systems of lava flows on Maui and Hawaii have discrete polychaete faunas and physical characteristics influenced by a freshwater lens. Six serpulids and a sabellariid were dredged from depths of 200 to 600 meters off Oahu and Molokai.