Early life history of the congrid eels gnathophis habenatus and G. incognitos in New Zealand waters

Larvae (leptocephali) of Gnathophis habenatus (Richardson, 1848) and G. incognitas Castle, 1963 occur off Castlepoint throughout most of the year (not sampled December‐February), In general they are smallest in late summer (March) and ilargest in mid‐spring (October‐November), with metamorphosis to the juvenile in early summer of the year of spawning. The two species therefore have a larval life of approximately 10 months. The early life of these two species in Australian waters, and of G. capensis (Kaup) off southern Africa, agrees well with these observations. Eel eggs collected in the East Cape region of New Zealand and tentatively identified as those of Gnathophis confirm the spawning times (March—April) suggested by the sizes of leptocephali.     

Sea surface ichthyoplankton off southeastern New Zealand,summer 1977–78

Plankton samples from the Chatham Rise, Pukaki Rise, and Campbell Plateau provided information on the young stages of a number of poorly known New Zealand fish species, and on the presence of a large spawning area of barracouta, Thyrsites atun, over the Mernoo Bank, The Chatham Rise was more important as a spawning area than the areas further south.     

Comparing an estimate of seabirds at risk to a mortality estimate from the November 2004 Terra Nova FPSO oil spill

On 21 November 2004, about 1000 barrels of crude oil were accidentally released from the Terra Nova FPSO (floating production, storage and offloading) onto the Grand Banks, approximately 340 km east-southeast of St. John's, Newfoundland. We estimated the number of vulnerable seabirds (murres (Uria spp.) and dovekies (Alle alle)) at risk from this incident by multiplying observed densities of seabirds with the total area covered by the slick, estimated at 793 km(2). A mean density of 3.46 murres/km(2) and 1.07 dovekies/km(2) on the sea surface was recorded during vessel-based surveys on 28 and 29 November 2004, with a mean density of 6.90 murres/km(2) and 13.43 dovekies/km(2) combining those on the sea and in flight. We calculated a mean of 9858 murres and dovekies were at risk of being oiled, with estimates ranging from 3593 to 16,122 depending on what portion of birds in flight were assumed to be at risk. A mortality model based on spill volume was derived independently of the risk model, and estimated that 4688 (CI 95%: 1905-12,480) birds were killed during this incident. A low mortality estimate based strictly on spill volume would be expected for this incident, which occurred in an area of relatively high seabird densities. Given that the risk and mortality estimates are statistically indistinguishable, we estimate that on the order of 10,000 birds were killed by the Terra Nova spill.     

Dust transport near electron beam impact and shadow boundaries

When the moon enters the plasma sheet of the earth, high energy electron fluxes are incident upon the lunar surface. Some regions are in the shadow of these fluxes due to topographic features. Large electric fields were found at similar shadow boundaries created by the electron beams incident upon an obstacle in the laboratory. Potentials on the beam-illuminated surface follow beam energies and were negative relative to potentials on the shadowed surface. Charged dust particles in the beam-illuminated region were observed to move into the shadow due to these electric fields. The oblique incidence of the electron fluxes upon craters can lead to a portion of the crater surface in the beam-illumination and another portion in the shadow. Dust particles on the slopes of the craters can thus experience large electric fields and transport downhill to fill the bottom of the craters. This mechanism may contribute to the formation of dust ponds observed by the NEAR-Shoemaker spacecraft at Eros, and might be at work on the lunar surface as well. In the laboratory, we used electron fluxes with energies up to 90 eV to bombard an insulating half-pipe. An angle of incidence was chosen so that the impact occurred on farside of the slope and left the bottom and the nearside slope in the shadow. Dust particles on the beam-illuminated slope moved down along the surface toward the bottom of the half-pipe and hopped to the bottom as well, while particles on the shadowed slope remained at rest.     

DXL: a sounding rocket mission for the study of solar wind charge exchange and local hot bubble X-ray emission

The Diffuse X-rays from the Local galaxy (DXL) mission is an approved sounding rocket project with a first launch scheduled around December 2012. Its goal is to identify and separate the X-ray emission generated by solar wind charge exchange from that of the local hot bubble to improve our understanding of both. With 1,000 cm² proportional counters and grasp of about 10 cm² sr both in the 1/4 and 3/4 keV bands, DXL will achieve in a 5-min flight what cannot be achieved by current and future X-ray satellites.     

Laboratory chalcopyrite oxidation by Acidithiobacillus ferrooxidans: Oxygen and sulfur isotope fractionation

Laboratory experiments were conducted to simulate chalcopyrite oxidation under anaerobic and aerobic conditions in the absence or presence of the bacterium Acidithiobacillus ferrooxidans. Experiments were carried out with 3 different oxygen isotope values of water (δ¹⁸O_H2O) so that approach to equilibrium or steady-state isotope fractionation for different starting conditions could be evaluated. The contribution of dissolved O₂ and water-derived oxygen to dissolved sulfate formed by chalcopyrite oxidation was unambiguously resolved during the aerobic experiments. Aerobic oxidation of chalcopyrite showed 93 ± 1% incorporation of water oxygen into the resulting sulfate during the biological experiments. Anaerobic experiments showed similar percentages of water oxygen incorporation into sulfate, but were more variable. The experiments also allowed determination of sulfate–water oxygen isotope fractionation, ε¹⁸O_SO4–H2O, of ~ 3.8‰ for the anaerobic experiments. Aerobic oxidation produced apparent ε_SO4–H2O values (6.4‰) higher than the anaerobic experiments, possibly due to additional incorporation of dissolved O₂ into sulfate. δ³⁴S_SO4 values are ~ 4‰ lower than the parent sulfide mineral during anaerobic oxidation of chalcopyrite, with no significant difference between abiotic and biological processes. For the aerobic experiments, a small depletion in δ³⁴S_SO4 of ~? 1.5 ± 0.2‰ was observed for the biological experiments. Fewer solids precipitated during oxidation under aerobic conditions than under anaerobic conditions, which may account for the observed differences in sulfur isotope fractionation under these contrasting conditions.     

Iron isotope fractionation during microbially stimulated Fe(II) oxidation and Fe(III) precipitation

Interpretation of the origins of iron-bearing minerals preserved in modern and ancient rocks based on measured iron isotope ratios depends on our ability to distinguish between biological and non-biological iron isotope fractionation processes. In this study, we compared ⁵⁶Fe/⁵⁴Fe ratios of coexisting aqueous iron (Fe(II)_aq, Fe(III)_aq) and iron oxyhydroxide precipitates (Fe(III)_ppt) resulting from the oxidation of ferrous iron under experimental conditions at low pH (<3). Experiments were carried out using both pure cultures of Acidothiobacillus ferrooxidans and sterile controls to assess possible biological overprinting of non-biological fractionation, and both SO₄²⁻ and Cl⁻ salts as Fe(II) sources to determine possible ionic/speciation effects that may be associated with oxidation/precipitation reactions. In addition, a series of ferric iron precipitation experiments were performed at pH ranging from 1.9 to 3.5 to determine if different precipitation rates cause differences in the isotopic composition of the iron oxyhydroxides. During microbially stimulated Fe(II) oxidation in both the sulfate and chloride systems, ⁵⁶Fe/⁵⁴Fe ratios of residual Fe(II)_aq sampled in a time series evolved along an apparent Rayleigh trend characterized by a fractionation factor α_{Fe(III)aq-Fe(II)aq} ∼ 1.0022. This fractionation factor was significantly less than that measured in our sterile control experiments (∼1.0034) and that predicted for isotopic equilibrium between Fe(II)_aq and Fe(III)_aq (∼1.0029), and thus might be interpreted to reflect a biological isotope effect. However, in our biological experiments the measured difference in ⁵⁶Fe/⁵⁴Fe ratios between Fe(III)_aq, isolated as a solid by the addition of NaOH to the final solution at each time point under N₂-atmosphere, and Fe(II)_aq was in most cases and on average close to 2.9‰ (α_{Fe(III)aq-Fe(II)aq} ∼ 1.0029), consistent with isotopic equilibrium between Fe(II)_aq and Fe(III)_aq. The ferric iron precipitation experiments revealed that ⁵⁶Fe/⁵⁴Fe ratios of Fe(III)_aq were generally equal to or greater than those of Fe(III)_ppt, and isotopic fractionation between these phases decreased with increasing precipitation rate and decreasing grain size. Considered together, the data confirm that the iron isotope variations observed in our microbial experiments are primarily controlled by non-biological equilibrium and kinetic factors, a result that aids our ability to interpret present-day iron cycling processes but further complicates our ability to use iron isotopes alone to identify biological processing in the rock record.