Pacific Science Volume 25, Number 2, 1971
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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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ItemThe Zoogeographic Relationships of Fanning Island Inshore Fishes(University of Hawai'i Press, 1971-04)
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ItemThe Littoral Marine Molluscs of Fanning Island(University of Hawai'i Press, 1971-04)
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ItemEcologic Observations on an Estuarine Environment at Fanning Atoll(University of Hawai'i Press, 1971-04)Salinity variations observed in an inlet and tidal flat on Fanning Atoll ranged from 7.8 to 42.3 %. Water temperatures varied from 25.1 C to 39.70 C. Daytime oxygen concentrations indicated that water at all stations was supersaturated. There are numerous estuaries on Fanning. Although distinct physical regions may be recognized within the estuaries, the distribution of organisms over these regions was found not to be comparable from estuary to estuary. Most of the fauna of the estuarine environment on atolls appears to be derived from euryhaline, high intertidal, or supratidal species of the lagoon shore.
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ItemSedimentation and Coral Reef Development in Turbid Water: Fanning Lagoon(University of Hawai'i Press, 1971-04)Lack of light and excessive sediment deposition rates are factors limiting coral reef development. The presence of very turbid water and muddy bottom does not mean, however, that coral growth is prohibited. Fanning Lagoon has a turbid water area (visibility, 2 m) and a clear water area (visibility, 10 to 15 m). Both areas have a muddy bottom. Because of the shallow depth and the light-scattering effect of the suspended CaC03, relative light intensity at the bottom is greater than 5 percent. The cleaning mechanism of the corals is sufficient to handle the deposition of sediment. Live corals cover 62 percent of the clear-water area and 31 percent of the turbid. Reefs in the turbid water are ecologically different from the ones in clear water, but they are still living reefs. Ramose corals make up 55 percent of the individuals in the turbid water and only 10 percent of those in the clear water. This difference is reflected in the structure of the reefs; those in clear water are massive and steep-sided, while those in the turbid water have gentler slopes and are more open with sediment infill. Fanning Lagoon is an example of penecontemporaneous formation of reef and intervening muddy sediment with bathymetric relief never more than 8 m.
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ItemNote on the Planktonic Primary Production in Fanning Island Lagoon(University of Hawai'i Press, 1971-04)A single series of representative observations indicates that both the productivity and standing crop of phytoplankton in Fanning Lagoon are much greater than reported in the lagoons of other Pacific atolls. Productivity, as measured by the radiocarbon method, averaged 9.29 mg C/m^3/hr, while chlorophyll a averaged 0.548 µg/liter. Phytoplankton, principally dinoflagellates with some diatoms and coccoid blue-greens, averaged 12.6 X 10^4 cells/liter. The relative richness of this lagoon compared with others appears to be due to the greater availability of nutrients which, in turn, is caused by the unique geographic features of the atoll.
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ItemOrganic Carbon Budget of Fanning Island Lagoon(University of Hawai'i Press, 1971-04)The concentrations of total and particulate organic carbon in the waters of Fanning Island Lagoon are high and fairly uniform throughout, averaging 1.68 mg/liter and 80 µg/liter, respectively. Phytoplankton and reefs in the lagoon produce 7.8 X. 10^4 kg of organic carbon daily, giving a turnover time of only 11 days for organic carbon. Only 0.4 percent of the daily production is lost from the lagoon by tidal exchange, the remainder is respired by organisms in the lagoon. Fanning Lagoon is a rich and unique environment which, because of its low flushing rate of about 230 days, has little effect on the surrounding ocean.
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ItemFlux of Suspended Calcium Carbonate (CaCO3), Fanning Island Lagoon(University of Hawai'i Press, 1971-04)A plume of turbid, CaCO3-laden water (0.24 mg/liter) is expelled from English Harbor, Fanning Atoll, on outgoing tides. On incoming tides, the concentration is 0.36 mg CaCO3/liter. At the two other passes of the atoll, incoming CaCO3 concentrations also are higher than outgoing concentrations. Lagoon waters contain 1 mg CaCO3/liter in the clear central portion of the lagoon and 4 mg CaCO3/liter elsewhere. Offshore concentrations out of the plume area are 0.03 mg CaCO3/liter. The lagoon and plume CaCO3 material is reef-derived detritus (aragonite and high-Mg calcite). Offshore CaCO3 particles are primarily coccoliths (low-Mg calcite). During a 24-hour survey 10 tons of suspended CaCO3 were transported into the lagoon. It is likely that the English Harbor plume represents little or no sediment loss from the lagoon. The plume debris is interpreted to be material produced on the outside fringing reefs, sucked into the lagoon on incoming tides, and subsequently expelled. Production of CaCO3 in the lagoon may be filling the lagoon faster than sea level is rising.
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ItemTides and Currents in Fanning Atoll Lagoon(University of Hawai'i Press, 1971-04)As part of the Fanning Island Expedition 1970, selected physical studies were conducted in the atoll lagoon. The major effort was the measurement of volume, salt, and heat transports through the three main atoll openings over a 24-hour period. In addition, lagoon and ocean tides were recorded, and a cursory survey was made of circulation in a small, reef-enclosed pond within the lagoon.
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ItemFanning Island Expedition-1970(University of Hawai'i Press, 1971-04)
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ItemSome Chemical Features of Lavas from the Manu'a Islands, Samoa(University of Hawai'i Press, 1971-04)The lavas of the Manu'a Islands have chemical compositions typical of oceanic island alkali lavas. They have rare earth abundances with chondrite normalized lanthanum:ytterbium ratios around 10 and ytterbium concentrations about 2.2 ppm. Strontium concentrations are greater than 400 ppm and within the range of strontium values for Hawaiian alkalic lavas. Potassium:rubidium ratios are generally between 300 and 400 but three samples have potassium: rubidium ~700, suggesting heterogeneity of source materials. The 87strontium: 86strontium ratios average 0.7046 ± .0003, and are the highest known for oceanic islands. Low pressure differentiation is controlled by olivine and plagioclase. These lavas were segregated from a normal oceanic upper mantle at >40 km depth and the percentage of partial melting was in the range of 3 to 7 percent. The chemical composition of the probable original magma is estimated using combined trace element, major element, and partition coefficient data.