Pacific Science, vol. 61, no. 1 (2007)

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Introducing a New Series: Biology and Impacts of Pacific Island Invasive Species
David R. Clements and Curtis C. Daehler, 1

Biology and Impacts of Pacific Island Invasive Species. 1. A Worldwide Review of Effects of the Small Indian Mongoose, Herpestes javanicus (Carnivora: Herpestidae)
Warren S. T. Hays and Sheila Conant, 3

The small Indian mongoose, Herpestes javanicus (E. Geoffroy Saint-Hilaire, 1818), was intentionally introduced to at least 45 islands (including 8 in the Pacific) and one continental mainland between 1872 and 1979. This small carnivore is now found on the mainland or islands of Asia, Africa, Europe, North America, South America, and Oceania. In this review we document the impact of this species on native birds, mammals, and herpetofauna in these areas of introduction.

Vegetation History of Laysan Island, Northwestern Hawaiian Islands
J. S. Athens, J. V. Ward, and D. W. Blinn, 17

Paleoenvironmental investigations were undertaken on Laysan Island in the remote Northwestern Hawaiian Islands to investigate its flora before historical observations. Substantial impacts occurred to the island as a result of late nineteenth- and early twentieth-century guano mining, commercial feather collecting, and denudation of vegetation by feral rabbits. An account of Laysan’s historically known vegetation is presented, followed by discussion of results from the investigation of a 16.41-m sediment core from Laysan’s central hypersaline lake. The 7,000-year pollen and seed record, besides indicating the former importance of Pritchardia palms on Laysan, showed the former presence of seven previously unknown taxa, only four of which could be identified. Diatom analysis indicated fresh to brackish lake water during the early Holocene, a finding supported by the mollusk assemblage. Diatom diversity gradually decreased over time until there is a near monoculture, with types indicating a gradual increase of salinity. Hypersaline conditions were first recognizable near the top of the sequence with the appearance of Artemia zooplankton. Generally wetter conditions seem to have characterized the island before about 5,150 yr B.P., with drier conditions thereafter. The pollen record also suggests two possibly very brief periods of much drier conditions, conceivably related to El Niño–Southern Oscillation episodes.

Avifauna of Lehua Islet, Hawai‘i: Conservation Value and Management Needs
Eric A. VanderWerf, Ken R. Wood, Chris Swenson, Maya LeGrande, Heather Eijzenga, Ronald L. Walker, 39

We conducted surveys from 2002 to 2005 and compiled historical information on the avifauna of Lehua Islet, Hawai‘i, to assess its conservation status and management needs. Thirty-five bird species have been observed on Lehua since 1931, including 18 seabirds endemic or indigenous to the Hawaiian Islands, one resident indigenous waterbird, six migratory waterbirds, and 10 alien land birds. We observed 29 of these species during surveys from 2002 to 2005, 13 of which had not been recorded on the islet previously. Over 25,000 pairs of eight seabird species were documented to breed on Lehua, including previously unknown breeding colonies of Black-footed Albatross (Phoebastria nigripes) and Laysan Albatross (P. immutabilis), and the largest breeding colonies of Brown Booby (Sula leucogaster) and Red-footed Booby (S. sula) in the Hawaiian Islands. Remains of a Newell’s Shearwater (Puffinus auricularis newelli) chick and a Band-rumped Storm-Petrel (Oceanodroma castro) chick were found, demonstrating that those species have nested on the islet and probably still do. The nesting season varied among species, with most species breeding from March to August, and at least one species breeding in every month. Predation by alien Polynesian rats (Rattus exulans) and Barn Owls (Tyto alba) is the most serious threat to nesting seabirds on Lehua. Sediment beneath a Barn Owl roost contained hundreds of bones from a variety of bird species, including Brown Noddy (Anous stolidus), which has been extirpated from the islet. Feral rabbits (Oryctolagus cuniculus) are suppressing vegetation that could provide additional nest sites for Red-footed Boobies and help prevent erosion and burying of seabird burrows. The most urgent management needs on Lehua are eradication of alien Polynesian rats, alien Barn Owls, and feral rabbits. Rocky offshore islets like Lehua may become increasingly important in seabird conservation because their small size makes it more feasible to manage threats, and because they are less likely to be affected by increases in sea level associated with climate change.

Molecular Systematics of the Endangered O‘ahu Tree Snail Achatinella mustelina: Synonymization of Subspecies and Estimation of Gene Flow between Chiral Morphs
Brenden S. Holland, Michael G. Hadfield, 53

The single-island endemic O‘ahu tree snail Achatinella mustelina Mighels, 1845 is an endangered species with dimorphic shell chirality, persisting in small populations restricted to upper-elevation native forest in the Wai‘anae Mountains. We used an intraspecific molecular phylogeny (n = 21 populations) to evaluate the validity of subspecies, most of them introduced by Welch in 1938 on the basis of shell characters, by determining whether the nominal subspecies examined correspond to detectable molecular partitions and to examine the possibility that opposing shell chirality acts as a reproductive isolating mechanism. We mapped the nominal subspecies and shell chiralities onto a mitochondrial DNA (mtDNA) phylogram based on 86 cytochrome c oxidase I gene fragments and the extant range of the species. Although clear genetic breaks and haplotype clusters with well-defined boundaries exist and correspond to topographic features, each of the five monophyletic clades in the gene tree contains multiple supposed subspecies, haplotypes are shared between different subspecies, and none of the 13 nominal subspecies exhibits monophyly. Furthermore the mtDNA clades in the gene tree do not correspond to observed patterns in shell chirality, and both chiralities occur in all clades. Thus, the subspecies are not taxonomically valid and have no relevance for conserving genetic diversity, and chirality differences do not appear to impart a reproductive barrier in this species. Therefore, all subspecies of A. mustelina are herein synonymized.

Diversity and Biogeography of the Scleractinian Coral Fauna of Easter Island (Rapa Nui)
Peter W. Glynn, Gerald M. Wellington, Bernhard Riegl, Donald B. Olson, Eric Borneman, Evie A. Wieters, 67

Three surveys at Easter Island (Rapa Nui) spanning the period 1999–2005, and examination of private and museum collections, have revealed a depauperate zooxanthellate scleractinian fauna. Collections were all made off island shelf exposures, from tide pools to 70 m with scuba, and by dredging to 100 m. With synonymies, reassignments, and two new records in the families Pocilloporidae and Faviidae, the Easter Island coral fauna now comprises 13 species. Pocilloporid and poritid coral abundances were generally high on all island shelves protected from southern swells. A cluster analysis of the coral fauna relationships of 19 south, central, and far-eastern Pacific sites indicates a strong affinity between those of Easter Island and the far-eastern Pacific equatorial region (e.g., Colombia, Ecuador, Panamá, and the Galápagos Islands). The precipitous drop in coral species richness from the Pitcairn Island group (61 species) to Easter Island suggests the presence of a dispersal barrier between these two remote southeastern Pacific areas, separated by ~1,800 km of deep ocean waters. Consideration of the surface circulation based on satellite-tracked surface drifters confirms this conclusion. Surface currents are from east to west along the topography on which Easter and Sala-y-Gómez Islands sit, suggesting a substantial barrier to recruitment from the west.

The Crinoid Fauna (Echinodermata: Crinoidea) of Palau
Charles G. Messing, 91

Taxonomic revisions and a recent survey using scuba place the number of shallow-water (<50 m) crinoid species known from Palau at 22. Five are new records: Clarkcomanthus littoralis, Comanthus suavia, Alloeocomatella pectinifera, Oxycomanthus comanthipinna, and O. exilis. A submersible survey (to 310 m) recovered five additional new records, four of which are the first representatives of their families from Palauan waters: Eudiocrinus venustulus (Eudiocrinidae), Glyptometra sp. (Charitometridae), Cosmiometra belsuchel Messing, n. sp. (Thalassometridae), and Porphyrocrinus verrucosus (Phrynocrinidae), the first stalked crinoid recorded from Palau. Two of the three specimens of the latter have regenerating crowns, suggesting that this species may be subject to substantial predation or an unstable environment.

Feeding Preferences of Acanthaster planci (Echinodermata: Asteroidea) under Controlled Conditions of Food Availability
Morgan S. Pratchett, 113

Feeding preferences of the crown-of-thorns sea star, Acanthaster planci (L.), were studied in a series of laboratory-based feeding trials wherein sea stars were provided with equal availability of six different coral species. The order in which corals were consumed was then used to ascertain feeding preferences. Crown-of-thorns sea stars exhibited strong and consistent feeding preferences across replicate feeding trials. The most readily eaten coral species was Acropora hyacinthus, followed by A. gemmifera, A. nasuta, A. formosa, Stylophora pistillata, Montipora undata, and Pocillopora damicornis. Crown-of-thorns sea stars also consumed Goniopora lobata, Fungia fungites, Goniastrea retiformes, and Pavona cactus but only after all Acropora and Montipora (Family Acroporidae) as well as Pocillopora and Stylophora (Family Pocilloporidae) were eaten. The least preferred corals were Favites abidita, Porites lobata, Symphyllia recta, Echinopora horrida, and Porites cylindrica. Of these, P. cylindrica was never eaten in any of the feeding trials in which it was offered. Observed feeding preferences substantiate findings from previous studies, where corals from the families Acroporidae and Pocilloporidae were preferred over all other corals. Further research is required to assess the underlying basis of feeding preferences of A. planci, but this study confirms that these starfish readily distinguish between different corals and have innate preferences for certain species. Still, most corals were eventually consumed, showing that when food is limited (during population outbreaks) A. planci is likely to consume virtually all different coral species, causing extreme devastation to coral reef ecosystems.

Age and Growth of the Finescale Triggerfish, Balistes polylepis (Teleostei: Balistidae), on the Coast of Mazatlán, Sinaloa, Mexico
Ithandehui Barroso-Soto, Emerita Castillo-Gallardo, Casimiro Quiñonez Velázquez, Ramón E. Morán-Angulo, 121

To estimate the weight-length relationship, determine age, and describe growth of the finescale triggerfish, Balistes polylepis Steindachner, 1876, 552 specimens were measured and weighed, and 318 first dorsal spines were collected from the artisanal catch in Mazatlán, Sinaloa, Mexico, between October 2000 and October 2001. Fish ranged between 16 and 53 cm in total length (TL), and distribution was biased toward small sizes. Age was assigned according to the number of opaque-hyaline bands in spines, identifying seven age groups (1–7), with age groups 2, 3, and 4 jointly representing over 80% of the collection. The von Bertalanffy model was adequately fitted to the age-TL data and accounted for 91% of the variation in TL. Parameters were estimated as TL = 55:8 cm; K = 0.17 yr -1, and t0 = 1:7 yr. The total weight (TW) of the finescale triggerfish ranged between 75 and 2,200 g, and the TW-TL relationship showed a negative allometric growth (b = 2:7). These results are the first reported for age and growth of this species.

Laboratory Observations of Reproduction in the Deep-Water Zoarcids Lycodes cortezianus and Lycodapus mandibularis (Teleostei: Zoarcidae)
Lara Annette Ferry-Graham, Jeffrey C. Drazen, Veronica Franklin, 129

The first observations of reproduction and associated behaviors in captive bigfin eelpout, Lycodes cortezianus, and pallid eelpout, Lycodapus mandibularis, are reported here. One Lycodes cortezianus pair produced 13 transparent and negatively buoyant eggs that were approximately 6 mm in diameter. These were laid on a hydroid-covered rock. The development period was about 7 months, and the young that emerged were approximately 2 cm in total length. An additional captive pair also exhibited mating behavior as the male repeatedly nudged the female and the pair produced a burrow under a sponge; however the male died before any mating. Two gravid female Lycodapus mandibularis were captured and laid between 23 and 46 eggs that were about 4 mm in diameter. These were released on the sandy substrate after the females moved the sand about the tank, and the eggs were negatively buoyant. These eggs were all unfertilized. Additional burrowing behavior was observed from other captive individuals, but no eggs were subsequently produced. Taken together, our observations suggest that burrowing or use of other protective structures is a reproductive behavior of central importance to zoarcids. Contrary to some earlier hypotheses, even midwater species likely return to the sediment to burrow and/or deposit eggs. This behavior means that field data regarding reproduction in this family will continue to be difficult to obtain, and the contribution of further study in laboratory situations should not be underestimated.

Redescription of Yirrkala gjellerupi, a Poorly Known Freshwater Indo-Pacific Snake Eel (Anguilliformes: Ophichthidae)
John E. McCosker, David Boseto, Aaron Jenkins, 141

Yirrkala gjellerupi (Weber & de Beaufort, 1916), unknown since the brief and unfigured original description of the holotype from New Guinea, is herein diagnosed, described, and illustrated, based on specimens recently captured in a Fijian freshwater stream. Other eels collected there and nearby include Anguilla megastoma, A. obscura, Lamnostoma kampeni, and an unidentified moringuid. Living far from the sea is very atypical for an adult ophichthid.

New Species of Extinct Rails (Aves: Rallidae) from Archaeological Sites in the Marquesas Islands, French Polynesia
Jeremy J. Kirchman, David W. Steadman, 145

We examined 53 bones of rails (Rallidae), previously referred to Gallirallus n. spp., from archaeological sites on four islands in the Marquesas Islands, French Polynesia. We describe three new, extinct, flightless species of Gallirallus: G. roletti (Tahuata), G. gracilitibia (Ua Huka), and G. epulare (Nuku Hiva). Two bones from Hiva Oa, although probably representing another extinct species of Gallirallus, are regarded as an inadequate basis for describing a species. At first human contact, the genus Gallirallus probably included many scores if not hundreds of flightless species on islands from the far western Pacific (Okinawa, Philippines, Halmahera) eastward across most of Oceania. As currently understood, the Marquesas Islands represent the eastern range limit of Gallirallus.