Pacific Science Volume 47, Number 2, 1993

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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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    Anomalous Orographic Rains of O'ahu (Hawai'i) Revisited: An Over-sea Origin Indicated
    (University of Hawaii Press, 1993-04) Woodcock, Alfred H.
    The first study of anomalous orographic rains of O'ahu, Hawai'i, utilized the average daily amounts and shower frequency characteristics as an indication of where they were first formed. In this renewed study I show that the rain rates, rather than the amounts and shower frequency, are more appropriate for revealing rain origin. Hourly amounts at gage sites alined about parallel and normal to the winds are graphically presented. The graphs reveal that many of the rains, although concentrated over the island, apparently originated as light rains over the windward sea along a crosswind line, intensifying as the wind-borne overcast of cumulus clouds was carried inland. This finding adds further support to early suggestions of an over-sea origin of many of O'ahu's orographic rains. It is hypothesized that all of these anomalous rain lines, and perhaps the trade-wind cumulus showers as well, originate upwind of the island. The idea could be readily tested experimentally.
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    Effects on the Animal Community of Dislodgment of Holdfasts of Macrocystis pyrifera
    (University of Hawaii Press, 1993-04) Vasquez, Julio A.
    Effects of natural dislodgment of holdfasts of Macrocystis pyrifera (L.) C. Agardh on the associated holdfast community were studied during a 110-day period. Six holdfasts were collected at the beginning of the study and analyzed to determine the abundance of major taxa at time O. Forty-four holdfasts were detached from the rocky substrate and suspended on three midwater buoys to simulate natural dislodgment and drift in the kelp forest. The most abundant taxa associated with attached and drift holdfasts were decapod crustaceans, mollusks, polychaetes, ophiuroids, echinoids, asteroids, isopods, and amphipods. Only amphipods and isopods increased significantly in density in drift holdfasts during the experimental period. All other invertebrate taxa showed a decrease in abundance during the 3-month experiment.
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    Temporal Variability of the Nutrient Environment on Davies Reef in the Central Great Barrier Reef, Australia
    (University of Hawaii Press, 1993-04) Ayukai, Tenshi
    Nutrient concentrations were measured at a fixed station in the lagoon of Davies Reef, the central Great Barrier Reef, Australia, monthly between January and December 1990. The day-to-day variation in nutrient concentration inside and outside the lagoon was determined in May. The average dissolved inorganic nitrogen (DIN) (sum of N03 , N02 , and NH4 ) concentration for the pooled data in each of 11 monthly observations ranged between 0.34 and 1.84 uM. There was only a two-fold variation in average P04 concentration. Average Si04 concentration showed a magnitude of variation similar to that of DIN concentration. DIN concentration was significantly higher in the lagoon than in the surrounding open water, suggesting that the significant DIN flux results from internal sources. There were no clear inside-outside differences in P04 and Si04 concentrations. N:P ratios in the lagoon were usually < 16: 1, suggesting the possibility of N limitation. However, the ratios became> 16: 1 under low wind conditions, when the exchange of lagoon water was restricted and the contribution of the internal DIN flux to the nutrient budget increased. Si was usually available in excess of the growth requirement of diatoms (Si: N > 1: 1), but occasional decreases in relative Si availability resulted in occurrence of a high number of dinoflagellates.
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    Checklist of the Coastal Fishes of Lord Howe, Norfolk, and Kermadec Islands, Southwest Pacific Ocean
    (University of Hawaii Press, 1993-04) Francis, Malcolm P.
    A checklist of coastal fishes includes 433 species from Lord Howe Island, 254 from Norfolk Island, and 145 from the Kermadec Islands. Tropical and subtropical species dominate all three faunas, but the proportion of tropical species decreases, and the proportion of subtropical species increases, from west to east. Subtropical species are the most abundant individual fishes at all three islands. Only 4.6% of the combined fauna is endemic, with individual island endemism even lower (1.2-2.1 %). The fish faunas of the three islands appear to have originated mainly by larval dispersal from Australia and the Coral Sea. Evidence for present-day dispersal is discussed. Faunal relationships among the subtropical islands of the western, central, and eastern South Pacific are examined. In the South Pacific as a whole, there is a high positive correlation between coastal fish diversity and hermatypic coral diversity.
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    Further Additions to the Fish Faunas of Lord Howe and Norfolk Islands, Southwest Pacific Ocean
    (University of Hawaii Press, 1993-04) Francis, Malcolm P. ; Randall, John E.
    New fish records are reported from subtropical Lord Howe Island (34 species) and Norfolk Island (35 species). Most of the new records are based on few individuals of widespread tropical species. The new records increase the known coastal fish faunas to 433 species at Lord Howe Island and 254 at Norfolk Island.
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