By SoniaJ.Rowley Refugia in the ‘twilight zone’: discoveries from the Philippines O of teries the mys- to penetrate has enabledus technology using advanced closed-circuit submersible. However, exploration shallow tojustifythecostofadeep-sea ous forconventional SCUBAandtoo sible oroverlooked, beingtooprecari- mesophotic reefs were largelyinacces- recent technologicaladvances, such environmental disturbances.Until and positedtoactasrefugia against priority ecosystems(e.g.IUCN) MCEs are classifiedasconservation ‘mesophotic coralecosystems’ (MCEs). between 40and200mare termed ate and/orexacerbatenaturalprocesses. ashumanimpactsacceler- particularly responses toenvironmental change, geographical distributionsare species determining biodiversity andbio- the region. Nevertheless, centralto and migrationfrom withinoroutside generating hypothesesofspeciation much controversy andinvestigation such diversity remains thesubjectof per geographicalarea. Theoriginof number ofislands(more than7,100) due toithavingamongthehighest the Philippine archipelago largely Triangle, ismostnotablethroughout considered atitspeakwithintheCoral environments. Coralreef biodiversity, Coral reefs inthe‘twilight zone’ continuously shapedcoralreef geological sealevel changeshave ver themillennia, perpetual we are caughtinpeace As inquisitiveexplorers and exhilaration Leptoseris, low-light habitatsthroughout members ofthezooxanthellate genus Hawai’i whichare oftendominatedby such patternsduplicatedinotherareas? surrounding habitatsifatall,andare are theybeneficiallyconnectedtothe present, how dotheysurvive, time. What faunaandeven flora are tion relationships over geological and theevolution ofstructure–func- questions ofpersistence,polyphyly, discovered, theyalsoholdthekeysto and interactionsjustwaitingtobe species,behaviours a myriadofnew in time.Not onlydoMCEsharbour reefs are back akintobeingtransported mesophotic reef before us. To methese attenuation ofthedeepslopeand exhilaration between theenticing explorers we are caughtinpeaceand is notwithoutrisks.Asinquisitive away from thebustleofshallows, the Batangas region ofthePhilippines. characterize mesophoticreefs within and todiscover, documentand Poseidon nextgenerationrebreather; team wastwofold:totest-pilotthe sion astheBishop Museum rebreather by theSeaverported Institute, ourmis- of acollaborative research teamsup- these little-studiedreefs. Here, aspart With theexception ofreefs within Descending todepthsunexplored, the Pacific are typicallycharac- terized by gorgonian sea fans, soft sea fans,soft corals, corals, sponges sponges and and Science letters

black corals, the majority of which are depth. The swim bladders of sampled unknown to science. The Philippines fish are vented with needles as we are no exception; on this trip alone ascend (the notorious ‘Pyle’ stop). At we have discovered at least seven new the surface, specimens are catalogued fish and 20 new gorgonian species at and preserved, whilst digital imagery is depth, the latter providing substrate systematically documented for immedi- for fish to lay their eggs. Our diving ate dissemination in the web-based experience tells us that it is at around archive Explorers Log. The discovery 80 m depth that the of the twilight zone is not exclusive— Images: Opposite: A typical mesophotic drops, a shelf emerges, and where such everyone can immediately enjoy! assemblage from the Solomon Islands with characteristic ‘twilight’ assemblages Are shallow reefs being seeded by the deep-reef Griffis’ AngelfishApolem - begin to be found. Dynamic sea-level deep reefs? Are certain taxa habitat spe- ichthys griffisi. Carlson & Taylor 1981. This changes produce extreme variations in cialists or bathymetric migrators? These page, from top left: Chromis n. sp.. Plectran- shallow water habitats of up to 80–100 questions remain to be elucidated, thias n.sp.. Dr. Luiz Rocha with the pinecone m, with these deeper reefs remaining but when they are, key evolutionary fishMonocentris sp.. Mesophotic reefs of gorgonians in the Philippines. Mesophotic relatively unchanged, and less than mechanisms facilitating survival over reefs of gorgonians in Fiji. Dr. Brian Bowen. 50% species overlap with shallow taxa. geological time will undoubtedly be The PI team: Brian Greene, David Pence, Therefore, gorgonian corals and reef unveiled. So even though as humans Dr. Richard Pyle, Joshua Copus, Dr. Sonia fish are key taxonomic groups within we are challenged to save habitats Rowley, Robert Whitton, with Poseidon deep-reefs with some taxa spanning from their ongoing destruction, prototypes and Inspiration . considerable depths (e.g. 5–2,000 m). ‘twilight’ reefs of refugia may likely At depths greater than 100 m we replenish many of their inhabitants. work against time, determined by the Dr. Sonia Rowley (soniajrowley@ ratio between the saturation of our gmail.com) is an invertebrate mortal tissue with dissolved gas and zoologist at the Bernice Pauahi Bishop Museum, and the University the safety gas that we carry. Yet no of Hawai’i, USA. part of what we encounter is lost; all Funding and collaborations: digital imagery is synchronized with Bernice Pauahi Bishop Museum, the rebreathers’ advanced electronics, Hawai’i, USA; Hawai’i Institute of capturing time, depth and specimen , Hawai’i, USA information. I continue to collect California Academy of Sciences, gorgonians as we ascend—intrigued by California, USA; Seaver Institute, their dynamic patterns of diversity with California, USA

Spring 2014 | The Marine Biologist 19