Pacific Science Volume 51, Number 1, 1997

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Pacific Science is a quarterly publication devoted to the biological and physical sciences of the Pacific Region.


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    A New Approach for Analyzing Bird Densities from Variable Circular-Plot Counts
    (University of Hawaii Press, 1997-01) Fancy, Steven G.
    An approach for calculating bird densities from variable circular-plot counts is described. The approach differs from previous methods in that data from several surveys are pooled and detection distances are adjusted as if all distances were recorded by a single observer under a given set offield conditions. Adjustments for covariates that affect detection distances such as observer, weather, time of day, and vegetation type are made using coefficients calculated by multiple linear regression. The effective area surveyed under standard conditions is calculated from the pooled data set and then used to determine the effective area surveyed at each sampling station under the actual conditions when the station was sampled. The method was validated in two field studies where the density of birds could be determined by independent methods. Computer software for entering and analyzing data by this method is described.
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    Radar Study of Seabirds and Bats on Windward Hawai'i
    (University of Hawaii Press, 1997-01) Reynolds, Michelle H. ; Cooper, Brian A. ; Day, Robert H.
    Modified marine surveillance radar was used to study the presence/ absence, abundance, and flight activity of four nocturnal species: Hawaiian darkrumped petrel [Pterodroma phaeopygia sandwichensis (Ridgeway)], Newell's shearwater [Puffinus auricularis newelli (Henshaw)], Band-rumped storm-petrel [Oceanodroma castro (Harcourt)), and Hawaiian hoary bat (Lasiurus cinereus semotus Sanborn & Crespo). Hawaiian seabirds were recorded flying to or from inland nesting colonies at seven sampling sites on the windward side of the island of Hawai'i. In total, 527 radar "targets" identified as petrel or shearwater-type on the basis of speed, flight behavior, and radar signal strength were observed during eight nights of sampling. Mean movement rates (targets per minute) for seabird targets were 0.1, 0.1,0.3, 3.8, 0.9, and 2.2 for surveys at Kahakai, Kapoho, Mauna Loa, Pali Uli, Pu'ulena Crater, and Waipi'o Valley, respectively. Two percent of the petrel and shearwater-type targets detected on radar were confirmed visually or aurally. Flight paths for seabird targets showed strong directionality at six sampling sites. Mean flight speed for seabird targets (n = 524) was 61 km/hr for all survey areas. Peak detection times for seabirds were from 0430 to 0530 hours for birds flying to sea and 2000 to 2150 hours for birds returning to colonies. Most inland, low elevation sampling sites could not be surveyed reliably for seabirds during the evening activity periods because of radar interference from insects and rapidly flying bats. At those inland sites predawn sampling was the best time for using radar to detect Hawaiian seabirds moving seaward. Hawaiian hoary bats were recorded at eight sampling sites. Eighty-six to 89 radar targets that exhibited erratic flight behavior were identified as "batlike" targets; 17% of these batlike radar targets were confirmed visually. Band-rumped storm-petrels were not identified during our surveys.
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    A New Genus and Species of Lizard (Reptilia: Scincidae) from New Caledonia, Southwest Pacific
    (University of Hawaii Press, 1997-01) Sadlier, Ross A. ; Bauer, Aaron M.
    An unusual new lygosomine skink, Simiscincus aurantiacus Sadlier & Bauer, n. sp., is described from a single specimen collected in southern New Caledonia. This species is a member of the Eugongylus group of skinks, but is not readily assignable to any known genus. It has a number of derived characteristics that serve to distinguish it, the most notable of which is the highest number of premaxillary teeth of any scincid. Although its relationships cannot, at present, be established unambiguously, it appears to share affinities with another monotypic endemic New Caledonian genus, Graciliscincus. The discovery of this species highlights the extreme diversity and endemicity of the New Caledonian lizard fauna.
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    The Terrestrial Herpetofauna of the Loyalty Islands
    (University of Hawaii Press, 1997-01) Sadlier, Ross A. ; Bauer, Aaron M.
    The terrestrial herpetofauna of the Loyalty Islands, New Caledonia, is reviewed. This is the first comprehensive account of the reptile fauna of these islands since Roux's monograph on the region in 1913 and is based on recent collections made in August 1987 and a review of the collections made by Roux and Sarasin and housed in the Naturhistorisches Museum, Basel. Seventeen species of lizards and two species of snakes (one boid and one typhlopid) occur in the Loyalty Islands. Approximately half the lizard species are endemic to the New Caledonia/Loyalty Islands region, but only one, Emoia loyaltiensis (Roux), is endemic to the Loyalties alone. The remaining lizard species have widespread distributions throughout the Pacific. Most widespread species also occur on mainland New Caledonia, but several (Gehyra vorax Girard, Emoia cyanura [Lesson], and Candoia bibroni [Dumeril & Bibron]) do not.
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    Sea-Floor Geology of a Part of Mamala Bay, Hawai'i
    (University of Hawaii Press, 1997-01) Hampton, Monty A. ; Torresan, Michael E. ; Barber, John H Jr.
    We surveyed the sea-floor geology within a 200-km2 area of Mamala Bay, off Honolulu, Hawai'i, by collecting and analyzing sidescan sonar images, 3.5kHz profiles, video and still visual images, and box-core samples. The study area extends from 20-m water depth on the insular shelf to 600-m water depth in a southeast-trending trough. The sidescan images depict three principal types of seafloor material: low-backscatter natural sediment, high-backscatter drowned carbonate reef, and intermediate-backscatter dredged-material deposits. Cores indicate that the natural sediment is muddy sand, composed of carbonate reef and microfauna debris with some volcanic grains. Vague areal trends in composition are evident. The dredged material comprises poorly sorted, cobble- to clay-size mixtures of reef, volcanic, and man-made debris, up to 35 cm thick. Dredged-material deposits are not evident in the 3.5-kHz profiles. In the sidescan images they appear as isolated, circular to subcircular imprints, apparently formed by individual drops, around the periphery of their occurrence, but they overlap and coalesce to a nearly continuous, intermediate-backscatter blanket toward the center of three disposal sites investigated. We did not observe noticeable currents during our camera surveys, but there is abundant evidence of sediment reworking: symmetrical and asymmetrical ripples in the visual images, sand waves in the 3.5-kHz profiles and side-scan images, moats around the reefs in 3.5-kHz profiles, winnowed dredged material in the visual images, and burial of dredged material by natural sediment in cores. Most current indicators imply a westerly to northwesterly transport direction, along contours or upslope, although there are a few areas of easterly indicators. Internal waves probably drive the transport; their possible existence is implied by measured water-column density gradients.
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    Notes on Juvenile Hawksbill and Green Turtles in American Samoa
    (University of Hawaii Press, 1997-01) Grant, Gilbert S. ; Craig, Peter ; Balazs, George H.
    Both hawksbill [Eretmochelys imbricata (L.)] and green turtles [Chelonia mydas (L.)] occur in American Samoa. Three distinct size classes were encountered in the region in both species: hatchlings <5 cm in length, juveniles 30-70 cm long, and adult females ≥77.5 cm long. Recaptures of flipper-tagged juvenile hawksbill turtles demonstrated short-distance homing movements and high growth rates (4.5 cm/yr CCL [curve of the carapace length]).
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    Reproductive Biology of the Green Turtle (Chelonia mydas) at Tern Island, French Frigate Shoals, Hawai'i
    (University of Hawaii Press, 1997-01) Niethammer, Kenneth R. ; Balazs, George H. ; Hatfield, Jeff S. ; Nakai, Glynnis L. ; Megyesu, Jennifer L.
    We monitored nesting of the green turtle (Chelonia mydas Linnaeus) on Tern Island, French Frigate Shoals, in the Northwestern Hawaiian Islands from 1986 through 1991. Egg oviposition occurred between 26 April and 20 October. Nesting peaked between mid-June and early August. Hatchlings emerged between 8 July and 27 December. Hatchling emergence peaked between mid-August and early October. Mean incubation period was 66.0 (range 53-97) days. Mean clutch size was 92.4 (range 33-150) eggs. Mean hatching success was 78.6% when averaged over success of individual nests and 81.1% when calculated as percentage of total number of eggs. Natural hatchling emergence was 71.1 %, based on percentage of total number of eggs. Live and dead hatchlings were found when nests were excavated and accounted for 10.0% of the eggs. Incubation periods tended to be longer in early and late portions of the season than in midseason, and incubation periods tended to decrease the farther inland the nest was situated from the high tide line. Maximum hatching success occurred at an incubation length of 66.7 days. Other trends indicated that nesting peaked near 5 July when conditions produced a near optimal incubation period for yielding maximum hatching success.
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    Ammolabrus dicrus, A New Genus and Species of Labrid Fish from the Hawaiian Islands
    (University of Hawaii Press, 1997-01) Randall, John E. ; Carlson, Bruce A.
    Ammolabrus dicrus is described as a new genus and species of labrid fish from O'ahu, Hawaiian Islands. It is characterized by: dorsal rays IX,12; anal rays III,12; all fin spines flexible; caudal fin small and forked; upper jaw strongly protrusible; a pair of small, forward-projecting, outcurved canine teeth anteriorly in upper jaw, and a smaller pair of outward-projecting canines at front of lower jaw; a single row of very small conical teeth on about anterior half of side of jaws; no canine tooth at comer of mouth; pharyngeal teeth small, none as molars; body elongate, the depth 4.2-4.45 in standard length (SL); scales thin and rhomboidal, 27 in longitudinal series; lateral line interrupted (last one or two scales of dorsoanterior series without a pore); no median predorsal scales; median prepelvic scales 3; anterior third of prepelvic region naked; 2 small scales dorsally on opercle, and an oblique series of 5 partially embedded scales behind eye; adults pale with a dark blotch on side of body above outer third of pectoral fin. Occurs over open sand substrata, often in small, swift-swimming schools; specimens collected from 7 to 18 m, the largest 94 mm SL; feeds on zooplankton. The new genus appears to be most similar to Novaculichthys.
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    Biodiversity and Biogeography of Benthic Marine Algae in the Southwest Pacific, with Specific Reference to Rotuma and Fiji
    (University of Hawaii Press, 1997-01) N'Yeurt, ADR ; South, G.R.
    Occurrence and distribution of various species of benthic marine algae in Fiji and Rotuma were investigated, with the resulting floras being subjected to comparison indices (Jaccard) both between themselves and with respect to other neighboring floras in the Southwest Pacific. The Rotuman flora was found to be rather impoverished (106 species) with respect to the Fijian flora (314 species), and the Nauruan and Rotuman flora were most similar, as were the Fijian and Micronesian floras. Dispersal mechanisms for algae in the region were considered, with special attention to the major ocean currents. These currents tend to favor movements of algal species from more northerly locations toward Fiji, and dispersal in the opposite direction seems unlikely. This is assumed to explain the similarities of the Rotuman flora with the Nauruan and Micronesian floras. Peculiar distribution patterns of algae were examined, with one species (Meristotheca procumbens P. Gabrielson & Kraft) being found in Rotuma, Lord Howe Island, and New South Wales (Australia), but not in intervening localities. Ecological and geographical factors are invoked to explain this, although unavailability of detailed checklists from many sites in the region impedes an accurate biogeographical analysis.
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    Why Sailing Sea Animals Have Mirror Images
    (University of Hawaii Press, 1997-01) Woodcock, Alfred H.
    The worldwide distribution of Physalia physalis (L.) (the Portuguese man-of-war), a wind-propelled jellyfish-like animal on sea-surface waters, is a much discussed but poorly understood phenomenon. The radically different courses sailed by the two mirror-image forms of this organism appear to result from simply their need for maximum dispersion by the winds on the earth's warmer seas. Study reveals, however, that the two forms of P. physalis sail different mirror-image courses and gain separate access to upwelling, diverging sea-surface waters that probably contain their major food. These courses are sailed without obvious steering efforts by the animals. Thus the wind-induced pattern of motion of the waters appears to have markedly influenced the animal's form and sailing courses. Their behavior apparently results from their natural involuntary use of steering effects of two wind induced surface-water motions.
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