The utilization of an intertidal salt marsh creek by larval and juvenile fishes: Abundance,diversity and temporal variation

The utilization of an intertidal salt marsh creek in South Carolina during January 1977 was determined by sampling every third ebb tide for 13 days. All fishes leaving the creek during that period were captured in a channel net. This procedure produced a time-series of samples which permitted analysis of the fish community occupying the intertidal creek at all times of day and night. A total of 14,730 larval, juvenile, and adult fishes comprising at least 22 species in 16 families were collected. The most common larval and juvenile fishes wereLeiostomus xanthurus, Mugil spp.,Myrophis punctatus leptocephali,Lagodon rhomboides, Paralichthys spp., andMicropogon undulatus. Catch sizes for all species varied widely between samples. No diurnal-nocturnal pattern in catches was evident forL. xanthurus, Mugil spp.,L. rhomboides andM. undulatus. M. punctatus was taken in large numbers only when the flood tide occurred during the day, while moreParalichthys spp. larvae were taken in late afternoon-evening flood tide samples. The most common invertebrate,Palaemonetes pugio, was taken in large quantities only in late afternoon-night flood tide samples. Three diversity indices were computed for each sample. Values for all indices varied widely between successive samples. The results emphasize a high degree of utilization of the intertidal creek habitat by larval and juvenile fishes. The diurnal-nocturnal activity patterns of some species, and the wide variation in catch size of the other species can permit use of the intertidal salt marsh habitat with reduced competition for available space and energy.     

A high-quality monthly pan evaporation dataset for Australia

A high-quality monthly pan evaporation dataset of 60 stations has been developed for monitoring long-term pan evaporation trends over Australia. The quality control process involved examination of historical station metadata together with an objective test comparing candidate series with neighboring stations. Identified points of discontinuity were located, including installations of bird guards, site relocations and changes in exposure. Appropriate inhomogeneity adjustments have been applied using established methods to produce the first homogeneous pan evaporation dataset for Australia. Analysis of these data reveals that Australian annual mean pan-evaporation shows large interannual variability with no trend over the 1970–2005 period. Previous studies using unadjusted data have shown a decline in pan evaporation, highlighting the importance of checking data for homogeneity before drawing conclusions about long-term trends. A strong inverse correlation is evident between all-Australian means of pan evaporation and rainfall, while a moderate positive correlation is found between pan evaporation and mean temperature. The positive correlations between mean temperature and pan evaporation that exist on the interannual time scales are not reflected in the long-term trends, highlighting that the mechanisms that are responsible for variations on the short and longer time scales are different. This result cautions against the expectation that large changes in potential evaporation are a natural consequence of global warming.     

深海锰结核中螺旋状超微生物化石的发现及其意义

对东太平洋深海瘤状锰结核透射电的系统观察和分析表明，瘤状锰结核的包壳，即奇异叠层石的建造者米级的螺旋状微生物、螺旋状微生物体的菌落呈圆盘状至不规则分枝状，菌落主下陷，营养菌丝体呈辐射状从中央向周围生长，营养菌丝体的束宽度为１７－６０ｎｍ，呈双分叉。生殖菌丝体由粗细不等的螺旋状丝体组成。螺旋状丝体的宽度３－２５ｎｍ，长度为３６－２００ｎｍ。螺环宽度为２－４ｎｍ、螺旋状生殖丝体分太、孢囊呈球形，深陷于     

Temperature increase and respiratory performance of macroinvertebrates with different tolerances to organic pollution

Respiration rates (mg O₂ g^?1 AFDW h^?1) of Leuctra hippopus, Sericostoma personatum, Helodes minuta, Gammarus pulex and Asellus aquaticus were studied across an oxygen gradient at 2.8 and 6.3 °C, corresponding to an expected 3.5 °C increase in Danish winter stream temperature. Species were selected from the Danish Stream Fauna Index (DSFI), representing an expected hierarchy of tolerance towards water quality degradation. We expected that low-ranking, tolerant species (i.e. indicators of bad water quality) would have the capacity to regulate their oxygen uptake relatively independently of oxygen availability (oxy-regulators) and high-ranking, sensitive species (i.e. indicators of good water quality) would be less able to do so (oxy-conformers). For all species respiration rate was higher (although non-significantly) at 6.3 °C. The species’ oxy-regulatory capacity did not consistently reflect their DSFI ranking. As expected, and in accordance with its DSFI ranking, A. aquaticus had the highest oxy-regulatory capacity with the ability to regulate O₂ uptake until an oxygen saturation of only 20%, which did not change with increasing temperature, emphasizing the robustness of A. aquaticus towards changes in the environment. S. personatum, H. minuta and G. pulex revealed no oxy-regulatory capacity. In contrast, the plecopteran L. hippopus did display an unexpected oxy-regulatory capacity. Though an increase in temperature changed L. hippopus’ capacity to oxy-regulate (the critical limit increased from 32.5 to 43.5% oxygen), respiration rates did not change significantly in spite of the temperature increase. This result contradicts the general belief that stoneflies, because of their affinity to well oxygenated habitats, are conformers. Our findings call for further studies on the respiratory conformer–regulator concept and its role as an eco-physiological trait for bio-assessment.     

Heat Flux in the Coastal Zone

Various difficulties with application of Monin–Obukhov similarity theory are surveyed including the influence of growing waves, advection and internal boundary-layer development. These complications are normally important with offshore flow. The transfer coefficient for heat is computed from eddy correlation data taken at a mast two kilometres off the Danish coast in RASEX. For these coastal zone data, the thermal roughness length shows no well-defined relation to the momentum roughness length or roughness Reynolds number, in contrast to previous theories. The variation of the momentum roughness length is dominated by wave state. In contrast, the thermal roughness length shows significant dependence on wave state only for small values of wave age where the mixing is apparently enhanced by wave breaking. The development of thin internal boundary layers with offshore flow substantially reduces the heat transfer and thermal roughness length but has no obvious influence on momentum roughness length. A new formulation of the thermal roughness length based on the internal boundary-layer depth is calibrated to the RASEX data. For the very stable case, the turbulence is mainly detached from the surface and existing formulations do not apply.As an alternative to adjusting the thermal roughness length, the transfer coefficient is related directly to the stability and the internal boundary-layer depth. This avoids specification of roughness lengths resulting from the usual integration of the non-dimensional temperature function. The resulting stability function is simpler than previous ones and satisfies free convection similarity theory without introduction of the gustiness factor. The internal boundary layer also influences the moisture transfer coefficient.     

Hard X-ray observations of PSR J1833−1034 and its associated pulsar wind nebula

PSR J1833−1034 and its associated pulsar wind nebula (PWN) have been investigated in depth through X-ray observations ranging from 0.1 to 200 keV. The low-energy X-ray data from Chandra reveal a complex morphology that is characterized by a bright central plerion, no thermal shell and an extended diffuse halo. The spectral emission from the central plerion softens with radial distance from the pulsar, with the spectral index ranging from  Γ= 1.61  in the central region to  Γ= 2.36  at the edge of the PWN. At higher energy, INTEGRAL detected the source in the 17–200 keV range. The data analysis clearly shows that the main contribution to the spectral emission in the hard X-ray energy range is originated from the PWN, while the pulsar is dominant above 200 keV. Recent High Energy Stereoscopic System (HESS) observations in the high-energy gamma-ray domain show that PSR J1833−1034 is a bright TeV emitter, with a flux corresponding to ∼2 per cent of the Crab in 1–10 TeV range. In addition, the spectral shape in the TeV energy region matches well with that in the hard X-rays observed by INTEGRAL . Based on these findings, we conclude that the emission from the pulsar and its associated PWN can be described in a scenario where hard X-rays are produced through synchrotron light of electrons with Lorentz factor  γ∼ 10⁹  in a magnetic field of ∼10 μG. In this hypothesis, the TeV emission is due to inverse-Compton interaction of the cooled electrons off the cosmic microwave background photons. Search for PSR J1833−1034 X-ray pulsed emission, via RXTE and Swift X-ray observations, resulted in an upper limit that is about 50 per cent.     

Validation of the ozone + tetramethylethylene reaction using an atmospheric pressure flow reactor/ion trap mass spectrometer

This paper demonstrates the performance of a new design of atmospheric pressure flow-tube reactor coupled with an ion trap mass spectrometer. The reactor is designed for studying gas-phase reactions with reaction times in the range from 0.2 to 2 s. The system provides a simple, fast and robust method for introducing the reactant mixtures and for identifying the products of gas-phase reactions. As a practical example of application, we used the flow reactor to study the reaction of O₃ with 2,3-dimethyl-2-butene. Good agreement was obtained between the flow tube results and previously reported studies for the identification of major products and measurement of their yields. This design has the potential to be used to study the atmospheric ozonolysis reactions of unsaturated species at realistic pressures and temperatures.     

Scattering in the radiation source and the fundamental-harmonic hypothesis

A model for the radiation source for type III solar radio bursts which includes random density fluctuations is reviewed. This methodology is applied to the burst of 28 September, 1973, 03:19 UT which is an archetype fundamental-harmonic pair. It is found that for scattering inhomogeneities consistent with those necessary to explain the observed sizes of the sources, it is impossible to amplify fundamental radiation in a source with a spatially uniform energy density in plasma waves; i.e., it is impossible to interpret this burst as a fundamental-harmonic pair from such a source. However, the supposed fundamental has fine structure similar to type IIIb bursts and since it is very difficult to explain these features except as fundamental radiation, it is concluded that there must be small clumps of intense plasma waves in the source which allow the fundamental to be amplified. These results are also applied to the hectometric burst of 19 July, 1971 for which a steep rise in brightness is observed between 10 and 50 R ₀. It is argued that the most plausible explanation of this rise is that the density inhomogeneities become sufficiently weak to allow the fundamental to be amplified in this range.The National Center for Atmospheric Research is sponsored by the National Science Foundation.     

Crustal seismic structure beneath the West Philippine Sea, 17°–18° North

Crustal seismic structures beneath the West Philippine Sea are determined by using explosive sources (0.5–108.6 kg) and ocean bottom seismometers to measure refracted compressional waves. Total crustal thicknesses are shown to be thinner in the eastern part of the ocean basin, approaching only 3.5 km. Crustal thinning toward the east is consistent with the Palau Kyushu Ridge being a remnant transform fault connecting the Central Basin Ridge and the Kula Pacific Ridge in the past. A velocity-depth inversion from the westernmost refraction profile indicates the upper transitional crust layer to have strong velocity gradients which gradually decrease with depth; the lower crust is characterized by a nearly constant velocity gradient. The western part of the ocean basin is also shown to have more typical oceanic thicknesses, as is found in deep ocean basins of the Pacific. Spectral energy models using WKBJ synthetic seismograms suggest that there is a sharp seismic discontinuity between the crust and moho in the western part of the basin. Predicted water depths for the West Philippine Basin using an age-depth relation and corrected for an isostatic response to the measured crustal thicknesses, are still 300 meters shallower than observed depths. The depth anomaly can not be fully reconciled by thinner crust in the eastern part of the basin. This observation implies that a deeper seated anomaly is present beneath the West Philippine Basin.