Species richness of the genus Molgolaimus (Nematoda) from local to ocean scale along continental slopes

This study investigated the distribution of Molgolaimus species (Nematoda) at different hierarchical spatial scales and observed the turnover of species along bathymetrical transects and among transects in two separate geographical regions. Samples from six transects (200–2000 m) from the Southern Oceans (SO) and four bathymetric transects (50–2000 m) from the Western Indian Ocean (WIO) were compared. Of the 30 species recorded, only one was common to both regions. WIO had higher local species richness than the SO. In both regions, the local scale was the greatest contributor to the total species richness. In the SO, there was no difference between species turnover at the different spatial scales, however, in the WIO, the turnover along bathymetrical transects was higher than among separated transects. For the particular genus studied, the evidence suggests that the study area in WIO has more widespread species and was better sampled, while the SO has many restricted species and it is most probably characterized by different biogeographical provinces. At the ocean scale (i.e. WIO versus SO), evolutionary histories may have strongly influenced nematodes species composition, while at local and regional scales, ecological processes are probably promoting species co‐existence and speciation. The high co‐existence of certain species at local scale is partially explained by species preference for different sediment layers.     

Meiofauna and macrofauna community structure in relation to sediment composition at the Iberian margin compared to the Goban Spur (NE Atlantic)

Meiofauna and macrofauna communities and several sediment characteristics were compared between a slope situated far from the coast (Goban Spur) and two transects across the Iberian Margin with steep slopes and close to the shore. The northern Galician transect (off La Coruña) was situated in an area subjected to wind-induced upwelling events. The western Galician transect was also subjected to upwelling, was additionally influenced by outflows of water rich in organic matter from the Rías Bajas. This transect also included the Galicia Bank. Macrofauna density decreased exponentially from the shelf edge (154 m) to the abyssal plain (4951 m) and different communities occurred on the shelf, the upper- and lower slope and on the abyssal plain. Apart from two extremely low-density stations on the Iberian Margin, there were no significant differences in the meiofauna between the Goban Spur and the Iberian Margin. Along the La Coruña-transect a station where meiofaunal densities were low occurred at a depth of 1522 m, where the sediment was characterised by having a high median-grain size, ripple structures, a low C_org and total N content. There were relatively high numbers of macrofaunal filter-feeders but low numbers of crustaceans, indicating a high current velocity regime. On top of the Galicia Bank (˜770 m) the sediment consisted mainly of shells of pelagic foraminifers, and had low contents of C_org and N. The macrofauna was dominated by filter-feeding and carnivorous taxa. At both these stations meiofauna densities were low. Meiofauna densities and community structure differed between the Goban Spur and the Iberian Margin. Meiofauna densities on the Galician shelf were more than double those on the Goban Spur shelf. The two deep stations on the La Coruña transect and the deepest station on the Galicia Bank transect all contained meiofaunal densities that were higher than found at similar depths off the Goban Spur. The meiofaunal densities were inversely correlated with %CaCO₃ content and, excluding the shelf stations, were positively correlated with both %C_org and total N at the Iberian Margin. Neither upwelling nor the enriched outflows from the rias affected the macrofauna, but meiofaunal densities were greatly enhanced.     

“Amount effect” of water isotopes and quantitative analysis of post‐condensation processes

A numerical model is proposed that describes the interaction between raindrops and water vapour near the planetary boundary layer to explain the “amount effect”. This model relates the intensity to the isotopic composition of precipitation. The model resolves raindrop sizes, and explicitly includes: (1) the isotopic equilibration time of raindrops that is drop‐size dependent; (2) raindrop transit times through the atmosphere; and (3) the evolution of the isotopic composition of vapour at various rain rates. At high rain rate, the precipitation through a layer is less equilibrated with the vapour because the isotopic equilibration time is long compared to the fast transit time, and there is a preponderance of large drops, which take longer to equilibrate. The δ¹⁸O of vapour in the lower atmosphere becomes lower as a result of the interaction with these raindrops of low δ¹⁸O, and the degree of depletion of ¹⁸O is higher when precipitation rates are high. The model reproduces time‐series observations of isotopic composition of precipitation in Japan, and a vapour replenishment rate is inferred by either advection or evaporation of about 5% of the precipitation rate. The results could be the basis for a new parameterization of the isotopic equilibration for different precipitation types and rates in General Circulation Models (GCMs). When the model is applied to a GCM, this parameterization is important for places where precipitation occurs at cold temperatures (<15 °C). Copyright © 2007 John Wiley & Sons, Ltd.     

Calcite patchiness in Lake Constance as viewed by LANDSAT-TM

Calcite precipitation is a phenomenon occuring in most hardwater lakes world-wide. On May 5th, 1990, a whiting in Lake Constance was observed by LANDSAT for the first time. Physical, chemical and biological ground data sets prove that the observed structures are caused by calcite precipitation. This satellite observation provides information about the patchiness of calcite crystals suspended in the surface water of the lake western basin.     

Low-cost long-term monitoring of global climate forcings and feedbacks

We describe the rationale for long-term monitoring of global climate forcings and radiative feedbacks as a contribution to interpretation of long-term global temperature change. Our discussion is based on a more detailed study and workshop report (Hansenet al., 1993b). We focus on the potential contribution of a proposed series of inexpensive small satellites, but we discuss also the need for complementary climate process studies and ground-based measurements. Some of these measurements could be made inexpensively by students, providing both valuable climate data and science educational experience.     

Comparative urbanization project for the Asian pacific region

This short article outlines the objectives, organization, research frame and content areas of a comparative urbanization project which will start in 1981. The project involves a total of nine national teams each of which is composed of three or more experts from the fields of urban geography, city and regional planning, demography, development economics and other related disciplines. One unique feature of the project is that each of the countries covered will be researched on by its own local researchers. And, the organizer tries to get at least one government official involved, in his personal capacity, as a team member, to get better insight and interpretation of official policies and objectives regarding urbanization. The responsible persons of the national teams and the time table of the project have also been included in this article.     

Two examples of uranium associated with organic matter

Precambrian carbonaceous material from Cluff, Saskatchewan (Canada), and samples of Late Carboniferous material from Arlit (250 km NNW of Agadès, Niger), were studied by high resolution transmission electron microscopy and energy dispersive X-ray analysis. The Cluff sample is very rich in uranium, whereas those from Arlit are poorer. An intact organo-uranium complex is the major component of the Cluff sample, the carbon and oxygen content of which are high. Uraniferous fragments show very small molecular orientation, whereas those that are uranium-free present a statistical long range preferred orientation. The carbonaceous material of Arlit is entirely free of uranium and behaves as any other humic poorly evolved material; it acquires a small molecular orientation on heat treatment. Uranium was found associated with titaniferous illite in the form of poorly crystallized UTi₂O₆ (Brannerite). The formation of brannerite is attributed to a topotactic transformation of clay particles containing adsorbed organic matter. Clay yields TiO₂; organic matter is the source of UO₂. Destruction of clay leads to release of organic matter, free of uranium, which undergoes diagenesis.     

A diatom model for inferring sea level change in the coastal waters of Hong Kong

Diatoms were identified and enumerated from surface sediments of 25 sites in Double Haven, Hong Kong. The relationship between diatom species distribution and 14 environmental variables was examined using Detrended Correspondence Analysis (DCA) and Canonical Correspondence Analysis (CCA). Water depth was identified as the most important environmental variable influencing the distribution of diatoms in Double Haven. Subsequently a Weighted Average (WA) calibration model was developed to infer water depth. The reliability of the model was evaluated by the error of prediction (RMSE_boot= 3.479) and the correlation (r ²= 0.7342) between observed and diatom-inferred values. This predictive calibration model has the potential to infer past sea level change in Hong Kong and the adjacent coastal areas.     

Identifying and Removing the Silences of Roma Culture in Polish School Texts

The Roma are the largest and, some scholars would argue, the most marginalized group in Europe, an observation evident in an examination of school texts for Polish children. Using the concept of the “geographies of silence,” we discuss the nature of text and graphical silences and the reasons behind the paucity of text, photo, and map coverage. We conclude by presenting photos that could be used in future texts to better inform Polish youth about a much-neglected part of their culture.