Pacific Science Volume 29, Number 2, 1975

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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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    Trace Element Geochemistry of Biogenic Sediments from the Western Equatorial Pacific
    (University of Hawai'i Press, 1975-04) Burnett, William C.
    Twenty-seven surface samples of biogenic sediment, including radiolarian, nannofossil, and foraminiferal oozes from the Western Equatorial Pacific have been analyzed for potassium, magnesium, iron, rubidium, strontium, barium, chromium, cobalt, nickel, copper, and zinc by rapid instrumental techniques. Interelement associations have been evaluated with the use of a computer-compiled matrix of correlation coefficients. The variables considered include elemental determinations, water depth, and percentage of calcium carbonate. The associations calcium carbonate: strontium, potassium: rubidium, and barium: nickel: copper may all be explained with regard to their mode of entry into the sediment. The data indicate that organic fixation of metals is a significant process during the deposition of Pacific Equatorial sediments, whereas contributions from other sources, i.e., sorbed cations on the surfaces of clay~ and coprecipitation with iron or manganese oxides, are effectively masked in most cases by high rates of biogenous deposition.
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    Function of the Dimorphic Eyes in the Midwater Squid Histioteuthis dofleini
    (University of Hawai'i Press, 1975-04) Young, Richard Edward
    The squid Histioteuthis dofleini, like other members of the family Histioteuthidae, has a large left eye and a small right eye. The large eye points in a dorsal posterior direction while the squid typically orients at an oblique angle with the arms downward. The large eye, as a result, points vertically upward. The small eye appears to be directed ventrolaterally. This squid occurs primarily at depths of 500 to 700 m during the day where it is exposed to low levels of downwelling light. Presumably the large eye utilizes this faint downwelling light while the smaller eye utilizes bioluminescent light.
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    Systematics and Distribution of Callianassa (Crustacea, Decapoda, Macrura) from Port Phillip Bay, Australia, with Descriptions of Two New Species
    (University of Hawai'i Press, 1975-04) Poore, Gary C.B.
    Two new species of Callianassa are described from Port Phillip Bay subtidal sediments. Their systematic position and their status within the genus are briefly discussed. The distribution of the four species known from Port Phillip Bay correlates with that of sediment type and depth. C. arenosa n. sp. was distributed on silty sand sediments and was most dense between 13-19 m depth. C.limosa n. sp. was most dense (over 1,000 individuals per m2) on silty clay sediments below 15 m. C. ceramica Fulton & Grant occurred at low densities on sandy sediments less than 10m depth and has previously been reported from intertidal muddy flats along with C. australiensis (Dana).
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    Petrolisthes zacae Haig, 1968 (Crustacea, Decapoda, Porcellanidae): The Development of Larvae in the Laboratory
    (University of Hawai'i Press, 1975-04) Gore, Robert H.
    The larval development of Petrolisthes zacae Haig, 1968, an eastern Pacific species of porcellanid crab that inhabits mangrove forests, is completely described and illustrated. Development consists of a prezoeal stage, two zoeal stages, and a megalopal stage. The zoeae and megalopae of P. zacae are quite similar to those of P. armatus but can be distinguished from the latter by several morphological features. The larvae of P. zacae are compared to those of both Atlantic and Pacific P. armatus, wherein the close relationship exhibited by the larvae of all three forms reaffirms that already noted for adults of the two species.
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    Fecundity and Length at First Spawning of the Hawaiian Anchovy, or Nehu (Stolephorus purpureus Fowler) in Kaneohe Bay, Oahu
    (University of Hawai'i Press, 1975-04) Leary, Daniel F. ; Murphy, Garth I. ; Miller, Marlyn
    Fecundity, length at first spawning, and spawning seasonality of Stolephorus purpureus were determined by examining preserved ovarian eggs and fish captured throughout a 4-year period. Fecundity was estimated from the number of eggs in the most advanced ovarian mode after it was determined that all these eggs hydrated and were spawned. Fecundity (Y) was related to fish weight (X) by the hyperbolic function, Y = X/(0.0049-0.0033X). According to this relationship, a fish having a weight equal to the mean for the population contains 566 eggs/g of fish weight. Large variations in fecundity from year to year were attributed primarily to environmental factors whose influence on reproduction by Stolephorus purpureus has not been studied. Length frequencies of ovarian eggs were bimodal, but the smaller modes remained stationary regardless of the position of the larger modes. This was interpreted as evidence that individual fish spawned only once per year. From data on egg length versus fish length it was estimated that fish were first capable of spawning when 35 mm (standard length); the smallest fish observed to contain hydrated eggs was 37.8 mm. Captured fish containing hydrated eggs were rare, 1.1 percent of 1,735 adult females examined. Spawning occurred year around but the incidence was higher during the spring and summer than during the remainder of the year.
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