Pacific Science Volume 45, Number 3, 1991

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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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    45:3 Table of Contents - Pacific Science
    (University of Hawai'i Press, 1991-07)
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    Fate of Carbaryl, l-Naphthol, and Atrazine in Seawater
    (University of Hawai'i Press, 1991-07) Armbrust, Kevin L. ; Crosby, Donald G.
    The fate of carbaryl, l-naphthol, and atrazine was determined under light and dark conditions in filter-sterilized and raw (unfiltered) seawater. Carbaryl was hydrolyzed in the dark, quantitatively, to l-naphthol with a half-life of 24 hr at pH 7.9 or 23 hr at pH 8.2 (24°C). Naphthol was stable in the dark in sterile seawater, but was degraded to undetectable levels in 96 hr in raw seawater. In artificial sunlight, carbaryl degraded with a half-life of 5 hr and l-naphthol was completely degraded after 2 hr. No further degradation products were observed for either compound. Atrazine was stable under light and dark conditions in sterile seawater; however, in raw seawater, it was degraded by 23% after 96 hr. These data suggest that atrazine may be stable enough in seawater to permit exposure of susceptible marine life, while, in the presence of sunlight, carbaryl and l-naphthol would rapidly dissipate to undetectable levels.
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    Fate of Model Xenobiotics in Calcareous Marine Algae
    (University of Hawai'i Press, 1991-07) Inouye, Laura S. ; Crosby, Donald G.
    Uptake, depuration, and metabolism of p-nitroanisole (PNA) and p-nitrophenol (PNP) were investigated in Halimeda, Padina, and Porolithon species, all of which are calcareous marine algae found in tropical waters . The algae were exposed to filtered seawater solutions of either PNA or PNP in a static system for 24 hr (uptake period), then placed in clean water and allowed to release absorbed chemical and possible metabolites for 24 hr (depuration period). Concentrations of the chemicals were monitored spectrophotometrically, and the water at the end of uptake and depuration was extracted onto a column of Amberlite XAD-4 resin, eluted sequentially with methylene chloride and methanol, and analyzed for metabolites by high-pressure liquid chromatography (HPLC). Results showed that the algae absorb PNA but not PNP. There was no indication that they were capable of metabolizing PNA, except inconsistently, to PNP. However, half of the absorbed PNA remained unaccounted for, and may either have been metabolized to undetected metabolites or bound to tissue macromolecules.
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    Effects of Nutrient Enrichment and Water Motion on the Coral Pocillopora damicornis
    (University of Hawai'i Press, 1991-07) Stambler, Noga ; Popper, Nurit ; Dubinsky, Zvy ; Stimson, John
    Exposure of the hermatypic coral Pocillopora damicornis (Linnaeus) to elevated levels of dissolved inorganic phosphorus did not affect the colony or the zooxanthellae. Exposure to elevated levels of dissolved inorganic nitrogen and inorganic nitrogen + phosphorus led to an increase in algal density, and as a result, to an increase in the chlorophyll concentration. These latter two experimental enrichments slowed skeletal growth rate of the corals, probably because of a decrease in the photosynthetic rate of the algae and perhaps a decrease in the translocation of photosynthetic products from the algae to the coral. The algae probably used the photosynthetic energy for their own increased growth. Experimental manipulation of water motion used in these experiments did not affect the coral or the symbiotic algae.
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    Effects of Two Petroleum Products on Pocillopora damicornis Planulae
    (University of Hawai'i Press, 1991-07) Te, Franklyn Tan
    Pocillopora damicornis planulae were exposed to different concentrations of benzene and gasoline:oil mixtures to determine the lethal concentrations and biological responses of the coral larvae. Bioassay tests with either open or closed static solutions of the test compounds were monitored. Planulae settlement was considered as the visible reaction to the hydrocarbon compound introduced. This study found that corallite formation was significantly influenced by the different concentrations of the test compound, but no clear correlation between concentration of the test compound and rate of corallite formation was ascertained. Mortality was minimal in most of the test concentrations utilized in the experiments.
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    Preliminary Observations on Effects of Pesticides Carbaryl, Naphthol, and Chlorpyrifos on Planulae of the Hermatypic Coral Pocillopora damicornis
    (University of Hawai'i Press, 1991-07) Acevedo, Roberto
    Planulae larvae of the reef coral Pocillopora damicornis were exposed to three pesticides in concentrations ranging from 0.01 to 100 ppm. Actively swimming planulae were held in test solutions for 96 hr, after which viability was determined. Carbaryl and l-naphthol in concentrations up to 10 ppm had no effect on the planulae after 96 hr. Chlorpyrifos at levels of 1 ppm and higher resulted in mortality in 50 to 100% of the trials.
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    Mortality and Settlement Success of Pocillopora damicornis Planula Larvae during Recovery from Low Levels of Nickel
    (University of Hawai'i Press, 1991-07) Goh, Beverly P.L.
    Effects on mortality and settlement of Pocillopora damicornis planula larvae during recovery from low levels of Ni++ were investigated. Results indicated that a nickel concentration of 9 ppm over 12 hr was sufficient to cause 50% mortality in larvae 39.6 hr after removal of the toxicant. Settlement in larvae was more sensitive, showing significantly reduced settlement rates from 9 days into recovery, after exposure to I ppm Ni++ at durations of 12-96 hr. It is recommended that coral planula larvae be utilized more extensively in pollution studies.
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    Kinetics of Dark Oxygen Uptake of Pocillopora damicornis
    (University of Hawai'i Press, 1991-07) Newton, P.A. ; Atkinson, M.J.
    Colonies of Pocillopora damicornis were placed in a sealed aquarium in the dark. Water velocity was altered and measured in 10 different experiments. During each experiment, seawater in the aquarium was supersaturated with oxygen (02 ) and then O2 concentration was measured through time until the concentration in the aquarium decreased to 0.3 mg O2 1-1 . Resulting O2 uptake curves were interpreted as a function of water velocity. Rate of O2 uptake fit a hyperbolic equation (d02 /dt = Vm02 /Ks + O2 ) . Maximum uptake rate (Vm ) varied between 0.12 and 0.27 mg O2 1- 1 min " (mean = 0. 18), and the half-saturation constant (Ks ) varied between 0.86 and 2.52 mg O2 1-1. Both Vm and K, did not vary with water velocity, indicating that in these experiments, water motion had little influence on either diffusive boundary layers near the coral tissue or the metabolic rate of O2 uptake. Even supersaturated concentrations of O2 did not completely saturate the uptake capacity of this enzyme system.
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    Behavioral and Ecological Relationships of a Parasite and Its Hosts within a Coral Reef System
    (University of Hawai'i Press, 1991-07) Aeby, Greta S.
    The life cycle of the digenetic trematode Plagioporus sp. includes an intermediate stage that encysts in the scleractinian coral Porites compressa and an adult stage that probably resides in a coral-feeding fish. Coral polyps infected with metacercariae of Plagioporus appear as swollen nodules ranging in color from bright pink to white and have lost their ability to retract into their calices. The polyps' altered appearance and behavior was thought to increase their vulnerability to predation. This study investigated the effect of parasite encystment on coral growth and the effect offish predation on both coral growth and on the parasites' rate of transmission. Parasitized P. compressa showed a 50% reduction in growth when compared to nonparasitized P. compressa. No significant differences were found in growth of corals kept in predator exclusion cages and that of corals left exposed to fish predation in either group, parasitized or nonparasitized. Uncaged parasitized P. compressa showed a marked reduction in number of parasitic cysts, with the infected polyps being replaced by healthy ones. The regeneration of healthy polyps suggests that parasite removal is beneficial to the coral, and the reduction in cyst number suggests that the parasites' rate of transmission was enhanced by exposure of infected corals to fish predation.
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    Reproduction Effort in the Nudibranch Phestilla sibogae: Calorimetric Analysis of Food and Eggs
    (University of Hawai'i Press, 1991-07) Haramaty, Liti
    Phestilla sibogae, a nudibranch living on corals of the genus Porites, is rarely found on the reef at Kaneohe Bay, Hawaii, although Porites compressa is a dominant coral there. This is probably due to massive predation on juveniles and adults. Such predation pressure would force this species to put high effort into reproduction. In this work I found that P. sibogae laid eggs amounting to up to 17% of their body weight each day. Furthermore, based on a 100% conversion efficiency for ingested coral tissue, 51-78% of the calories each individual ate daily were channeled into egg production. Photosynthetic activity of zooxanthellae in the nudibranch's tissue suggests that the algae may provide some of the energy required by the animal's metabolism.
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