Pacific Science, Volume 64, Number 4, 2010

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    Origins and Nature of Vessels in Monocotyledons. 12. Pit Membrane Microstructure Diversity in Tracheary Elements of Astelia.
    (Honolulu, University of Hawaii Press, 2010-10) Carlquist, Sherwin ; Schneider, Edward L.
    Xylem of stems and roots of three species of Astelia, a monocot with relatively unspecialized xylem, was examined with scanning electron microscopy (SEM) to better understand structural conditions intermediate between tracheids and vessel elements. Both macerations and hand-sectioned material were studied. Tracheary elements of roots of Asteliaceae can be characterized as tracheids with some degrees of transition to vessel elements. Pit membrane remnants, which take the form of pores, reticula, or threads, are present commonly in end walls of tracheary elements of roots of Astelia. Stems of Astelia have tracheids with less-conspicuous porosities in the pit membranes of end walls than those of roots. Sectioned materials show that the porose (reticulate) cellulosic layers of the primary wall, which is embedded in a matrix of amorphous material, can be exposed to various degrees by the sectioning process; the cellulosic network faces the lumen, and the amorphous material is the compound middle lamella. Astelia shows stages of transition between vessel elements and tracheids. These character expressions relate to occupancy of moist habitats (Astelia) with steady availability of moisture during the year. There appears to be little difference between a terrestrial species (A. chathamica) and the scandent/epiphytic species A. argyrocoma and A. menziesiana in terms of tracheary element microstructure, suggesting that habitat is more important than habit as a determinant of tracheary element microstructure and the degree to which lysis of pit membranes occurs. Freehand sectioning of ethanol-fixed materials, as in earlier studies in this series, provides a reliable way of observing pit membrane/ perforation structure when viewed with SEM. Astelia is one of several monocots that demonstrate the difficulty of discriminating between tracheids and vessel elements.
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    Marine Benthic Algae of Johnston Atoll: New Species Records, Spatial Distribution, and Taxonomic Affinities with Neighboring Islands.
    (Honolulu, University of Hawaii Press, 2010-10) Tsuda, Roy T. ; Abbott, Isabella A. ; Vroom, Peter S. ; Fisher, Jack R.
    Forty-five of the 107 species of marine benthic algae collected during 2004 and 2006 NOAA cruises to isolated Johnston Atoll and two additional species from earlier collections represent new species records. Total number of algae is now increased to 189 species: 26 species of cyanobacteria ( blue-green algae), 105 species of red algae, 15 species of brown algae, and 43 species of green algae. The macroalga Caulerpa serrulata and the epiphyte Lomentaria hakodatensis were the most widely distributed species at Johnston Atoll based on frequency of occurrence at 10 of 12 stations and 8 of 12 stations, respectively, during the 2004 NOAA cruise. Despite the atoll’s isolation, the parasitic red alga Neotenophycus ichthyosteus and the cyanobacterium Borzia elongata are the only endemic algal species on Johnston Atoll. Nonmetric multidimensional scaling analyses indicate that taxonomic affinities of Johnston Atoll lie between French Frigate Shoals and Wake Atoll. In terms of atolls, biodiversity of the marine flora of Johnston Atoll (i.e., 189 species) is surpassed only by the 256 algal species of the much-larger and better-studied Enewetak Atoll in the Marshall Islands.
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    Review of Crocodile (Reptilia: Crocodilia) and Dugong (Mammalia: Sirenia) Sightings in the Federated States of Micronesia.
    (Honolulu, University of Hawaii Press, 2010-10) Buden, Donald W. ; Haglelgam, John
    Three confirmed occurrences of crocodiles, one identified as Crocodylus porosus (two others presumed C. porosus), and four occurrences of the dugong, Dugong dugon, are recorded for the Federated States of Micronesia. The records of a crocodile and a dugong on Eauripik Atoll and a dugong on Kosrae are reported in the literature for the first time. On geographic grounds, the crocodiles and dugongs recorded from Yap State, in the western part of the FSM, probably pertain to vagrants from Palau, approximately 450 km to the southwest, whereas those recorded from the eastern islands (Pohnpei and Kosrae) are more likely to have originated from populations in the Bismarck Archipelago and Solomon Islands area, approximately 1,500 km to the southwest, rather than from Palau, which is a much greater distance to the west.
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    Records of Great White Sharks (Carcharodon carcharias) in New Caledonian Waters.
    (Honolulu, University of Hawaii Press, 2010-10) Tirard, Philippe ; Manning, Michael J. ; Jollit, Isabelle ; Duffy, Clinton ; Borsa, Philippe
    The occurrence of great white sharks (Carcharodon carcharias) in New Caledonia is documented from 30 observation events (sightings or captures or forensic examination of wounds) made between 1943 and 2009, involving 34 individual sharks. Nine of the observation events concerned animals caught on lines set for deep-sea fishes, five were encounters with scuba divers or snorkelers, and one was a fatal attack on a surfer; two other observations included great white sharks feeding on whale carcasses; two were from pop-up archival transmitting tag records that monitored individuals tagged in the Chatham Islands, New Zealand; one was a forensic identification from wounds sustained by another large shark; and seven were fortuitous sightings from boats. Nearly all observations were of solitary sharks. Observation events were concentrated in the southern lagoon of New Caledonia or along its barrier reef. They occurred from July to March, with most records in September and November, coinciding with a peak of occurrence of large cetaceans.
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    Impacts of Recreational Divers on Palauan Coral Reefs and Options for Management.
    (Honolulu, University of Hawaii Press, 2010-10) Poonian, Chris ; Davis, Patricia Z.R. ; McNaughton, Colby Kearns
    Recent growth in the popularity of recreational scuba diving has generated concerns about resulting impacts to coral reefs, particularly in locations such as the Republic of Palau, a world-renowned dive destination with rapidly increasing numbers of visitors. Divers were observed in-water at three of the most visited dive sites in the Rock Islands–Southern Lagoon Area: German Channel, Ngerchong, and Big Drop-off. Dive guides were interviewed about diver impacts at German Channel and Ngerchong. Divers’ contact rates with hard coral ranged from 0.87e0.27 to 2.98e0.59 contacts diver_1 10 min_1 (meaneSEM). Three instances of obvious physical damage were observed. Holding and fin contacts were the most common potentially damaging behaviors of divers, particularly those with cameras or gloves. Guides identified natural impacts (63% of respondents) and divers (34% of respondents) as the primary causes of damage to coral. Proactive management is essential to mitigate any negative impacts of recreational diving on coral reefs and to ensure resilience against other increasing threats. Long-term monitoring of dive sites, controls on the use of gloves and underwater photography, and training of guides are suggested to minimize damage caused by divers to coral reefs in Palau and elsewhere.