Pacific Science Volume 58, Number 1, 2004

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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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    Temporal Variation in Forest Bird Survey Data from Tutuila Island, American Samoa
    (University of Hawai'i Press, 2004-01) Freifeld, Holly B. ; Solek, Chris ; Tualaulelei, Ailao
    Avian census data from tropical Pacific islands often are limited to brief, one-time surveys. These efforts yield information about species' presence and distribution but reveal little about variation in abundance through time. This variation may be important for refining and optimizing survey methods and, in turn, assessing habitat preferences, population status, activity patterns, or the impact of disturbance on the abundance and distribution of island birds. The objective of this study was to determine if intra- or interannual patterns exist in the recorded abundance of resident land birds. Forest birds on Tutuila Island, American Samoa, were surveyed each month from 1992 to 1996 at 35 stations on six transects distributed around the island. We used multiple regression techniques to determine that seasonal patterns in detected abundance exist in several species, most notably the Purple-capped Fruit-dove, Ptilinopus porphyraceus, and the Wattled Honeyeater, Foulehaio carunculata. Intraannual patterns may be associated with seasonally variable vocalizations or with concentrations of birds at particular resources. Interannual trends in abundance were not islandwide for any native species during the study period; they were localized and as such may be attributable to small-scale changes in habitat rather than to overall changes in population size. The results of this study, especially that the abundance of nonmigratory island birds is seasonally variable, reinforce the importance of year-round monitoring in the study and conservation of Pacific birds.
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    Survey and Estimates of Commercially Viable Populations of the Sea Cucumber Actinopyga mauritiana (Echinodermata: Holothuroidea), on Tinian Island, Commonwealth of the Northern Mariana Islands
    (University of Hawai'i Press, 2004-01) Trianni, Michael S. ; Bryan, Patrick G.
    A survey was conducted in 1997 to assess commercially viable populations of the surf redfish, Actinopyga mauritiana, and establish a harvest quota for those populations on the island of Tinian. A simple random sampling approach was employed using circular plots as samples. Outer reef flat and reef slope habitats were sampled, producing a total of 333 samples over a 2-month period, with a preharvest population estimate of 71,034. A harvest quota of 17,893 surf redfish was established due to stock depletions on both Rota and Saipan, uncertainty of the density required to ensure successful reproduction of the species, and high degree of uncertainty in the population estimates. It was determined that a stratified sampling approach utilizing either simple proportional or optimal allocation would have resulted in more precise estimates, and these approaches are favored for any future survey work. Population estimates should be revised when more accurate estimates of A. mauritiana habitats become available.
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    Annotated Checklist of the Fishes of Wake Atoll
    (University of Hawai'i Press, 2004-01) Lobel, Phillip S. ; Lobel, Lisa K.
    This study documents a total of 321 fishes in 64 families occurring at Wake Atoll, a coral atoll located at 190 17' N, 1660 36' E. Ten fishes are listed by genus only and one by family; some of these represent undescribed species. The first published account of the fishes of Wake by Fowler and Ball in 1925 listed 107 species in 31 families. This paper updates 54 synonyms and corrects 20 misidentifications listed in the earlier account. The most recent published account by Myers in 1999 listed 122 fishes in 33 families. Our field surveys add 143 additional species records and 22 new family records for the atoll. Zoogeographic analysis indicates that the greatest species overlap of Wake Atoll fishes occurs with the Mariana Islands. Several fish species common at Wake Atoll are on the IUCN Red List or are otherwise of concern for conservation. Fish populations at Wake Atoll are protected by virtue of it being a U.S. military base and off limits to commercial fishing.
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    Mineralogical Variation in Shells of the Blackfoot Abalone, Haliotis iris (Mollusca: Gastropoda: Haliotidae), in Southern New Zealand
    (University of Hawai'i Press, 2004-01) Gray, Blair E. ; Smith, Abigail M.
    The New Zealand blackfoot abalone, Haliotis iris Gmelin, is among the few gastropods that precipitate both calcite and aragonite in their shells. The location, composition, and thickness of these mineral layers may affect color, luster, and strength of the shell, which is locally important in jewelry manufacture. Skeletal mineralogy and shell structure of H. iris from three southern New Zealand locations were determined using X-ray diffractometry, scanning electron micrography, and mineral staining. In H. iris an outer calcitic layer is separated from an inner aragonitic surface by both calcified and noncalcified organic layers running longitudinally through the shell. Skeletal mineralogy within individual shells varies from 29 to 98% aragonite, with older shell having significantly higher aragonite content than young sections. Variation within populations ranges from 40 to 98% aragonite, and among three populations from 34 to 98% aragonite. Shell thickness, too, varies within individual shells from 0.2 to 4.2 mm, with a significant positive relationship with age. Within population variation in shell thickness ranges from 2.1 to 5.4 mm, with no significant difference in shell thickness variation among populations. The high degree of variability within and among individual shells suggests that it is essential to test replicate samples from individual mollusk shells, especially when they have complex bimineral structure.
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