Duration and characteristics of metal price cycles

This paper addresses the fluctuations in real metal prices: are they simply random variations or do they display some degree of cyclicality? This study identifies peaks and troughs in the inflation adjusted prices for 14 metals, using monthly average data from January 1947 through December 2007. Duration dependence testing, which is performed on the expansions, contractions, and full cycles, finds many cases in which the duration of these phases are not purely random and have some degree of cyclicality. Additional characterization show that contractions generally persist longer than expansions (in contrast to macroeconomic cycles) that long-term real prices have been trendless, and that the amplitude of price changes over the phases has little regularity. For those performing this type of analysis, the appendices explain the procedures for dating turning points and assessing duration dependence.     

Unavailability of polynuclear aromatic hydrocarbons from coal particles to the eastern oyster

The accumulation by oysters of polycyclic aromatic hydrocarbons (PAH) from coal dust entering the estuarine environment has been postulated in the vicinity of coal transfer operations. Oysters Crassostrea virginica were exposed to coal dust plus 15 day leachate at concentrations of 10 mg litre(-1) and 1 mg litre(-1) coal dust for 28 days in a flow-through test system. Potential effects of the exposures were measured by comparing the uptake of PAH and the growth of the exposed animals versus control groups. Oysters sampled at 7, 14 and 28 days did not exhibit an increase in PAH body burden over control animals provided the guts were first purged of particulates. Even at the high test concentrations (10 mg litre(-1)), no effect of the exposure on shell growth was observed.     

Effects of high temperature and CO2 on intracellular DMSP in the cold-water coral Lophelia pertusa

Significant warming and acidification of the oceans is projected to occur by the end of the century. CO₂ vents, areas of upwelling and downwelling, and potential leaks from carbon capture and storage facilities may also cause localised environmental changes, enhancing or depressing the effect of global climate change. Cold-water coral ecosystems are threatened by future changes in carbonate chemistry, yet our knowledge of the response of these corals to high temperature and high CO₂ conditions is limited. Dimethylsulphoniopropionate (DMSP), and its breakdown product dimethylsulphide (DMS), are putative antioxidants that may be accumulated by invertebrates via their food or symbionts, although recent research suggests that some invertebrates may also be able to synthesise DMSP. This study provides the first information on the impact of high temperature (12 °C) and high CO₂ (817 ppm) on intracellular DMSP in the cold-water coral Lophelia pertusa from the Mingulay Reef Complex, Scotland (56°49′N, 07°23′W), where in situ environmental conditions are meditated by tidally induced downwellings. An increase in intracellular DMSP under high CO₂ conditions was observed, whilst water column particulate DMS + DMSP was reduced. In both high temperature treatments, intracellular DMSP was similar to the control treatment, whilst dissolved DMSP + DMS was not significantly different between any of the treatments. These results suggest that L. pertusa accumulates DMSP from the surrounding water column; uptake may be up-regulated under high CO₂ conditions, but mediated by high temperature. These results provide new insight into the biotic control of deep-sea biogeochemistry and may impact our understanding of the global sulphur cycle, and the survival of cold-water corals under projected global change.     

Lack of sampling site variation in chorion villus biopsy as assessed by DNA,enzymatic, morphological and cytogenetical analyses

A study of villus samples from eight random sites on five electively aborted chorion sacs was performed to determine any significant differences in yield, quality and composition of DNA, iduronate sulphate sulphatase activity and karyoptype status. The villi were also examined for their histological characteristics (e.g. stem, intermediate or terminal villi) and for HCG and BGP immuno-reactivities. The overall findings indicated no significant site to site variations in any of the parameters studied. It is therefore proposed that any villus should be equally suitable for prenatal diagnosis.     

A method for the detection of non-random associations among flocking birds and its application to sanderlings Calidris alba wintering in N.E. England

Summary Indices of association are frequently used in studies of social behaviour. Observed association indices may be compared with those obtained from computer randomizations of the data in order to test whether any two individuals in a population tend to occur together more than would be expected by chance. Data for individually-identifiable colour-ringed sanderlings Calidris alba are presented to illustrate the importance of the assumptions on which such null models are built. When each individual was given an equal chance of appearing in each flock associations differed from those expected by chance. But when the different numbers of times that each individual occurred at the study site were taken into account associations were not different from those expected by chance. Hypotheses relating association levels to a number of factors were tested. None of the factors examined had significant and appreciable effects on association levels. In particular, there was no evidence for sanderlings moving around in stable groups. Taking into account the different distributions of different individuals, the population of birds present on any day represented a random sample from the population of birds seen during the winter. Correspondence to: G. Roberts     

Growth and reproductive rates of Littorina rudis from three contrasted shores in North Wales,UK

Data are presented on growth and reproductive rates of Littorina rudis Maton from 3 contrasted habitats: a sheltered saltmarsh, a moderately sheltered boulder shore and an exposed cliff face. Growth was fastest in L. rudis from the moderately sheltered boulder shore, followed closely by snails from the sheltered saltmarsh. Growth was much slower and the asymptotic size much less in L. rudis from the exposed cliff face, this being attributed to the reduced time available for foraging caused by longer and more erratic periods when the substratum dries out. Eggs extracted from the brood chambers of the saltmarsh L. rudis took about 72 d to hatch in the laboratory at 10°C. No seasonal trend was detected in the percentage of sexually mature snails, which fluctuated erratically round about 54 to 99% in each population. Similarly, the ratio of females: males fluctuated erratically about 1.0. The number of eggs and embryos held in the brood chamber peaked in May–June and birth rates (release of young from the brood chamber) peaked in July-August. Following a lull in August, the brood chamber contents were maintained at moderately high levels throughout the winter, whereas the birth rates declined to very low levels. These differences in the seasonal cycle of brood chamber contents and birth rates were probably caused by seasonal differences in embryological development rate and in the propensity of the young to leave the brood chamber. Fecundity increased with parental size and, because of this, the smaller, slower growing exposed-shore L. rudis had much lower potential fecundities than L. rudis from the other shores. However, the size-specific fecundity of the exposedshore L. rudis was about 1.7 times that of L. rudis on the more sheltered shores. This difference was apparently not attributable to smaller young or to a greater capacity of the brood chamber in the exposedshore L. rudis, and must therefore have been caused by higher rates of egg production. 18% of mature females from the boulder shore and 5% of those from the cliff face were oviparous, having a jelly gland in place of the brood chamber.     

An empirical test of biases in the rapid visual technique for species-time censuses of reef fish assemblages

For an assemblage of fishes inhabiting a warm temperate, rock reef near San Diego, California (USA), a series of censuses were made based on frequency of occurrence and standard numerical counts. These data were then compared with a parallel study based on the rapid visual technique (RVT) of Jones and Thompson (1978). Because the RVT ranks abundances according to frequency of encounter and disregards variations in the spatial distributions of different species, the method overemphasizes the importance of widespread albeit rare fishes but under-emphasizes patchy although abundant species. The discussion considers the relative merits of the RVT method for characterizing assemblages of fishes on temperate rock reefs and on tropical coral reefs.     

A critical compilation of Henry's law constant temperature dependence relations for organic compounds in dilute aqueous solutions

A comprehensive compilation of published studies reporting directly measured experimental determinations of Henry's law constant (HLC) temperature dependence relationships for organic compounds in dilute, non-saline aqueous solutions under ambient conditions was conducted. From this effort, 55 such studies (covering 204 organic compounds) were identified, critically reviewed, summarized and discussed. Of the 204 compounds, 57 were studied in more than one investigation. For the 57 'multi-studied' compounds, relatively good agreement (averaging within 20-30%) was found between the results from different investigations. Given such results, a 'consensus' relationship (i.e., an average temperature dependence relation) was generated for each of the multi-studied compounds. Overall, considering relations established for 197 of the 204 compounds investigated (the results for the other 7 compounds being excluded due to poor correlation coefficients), the average slope of the temperature dependence line was found to correspond to an increase in HLC values by a factor of 1.88 (i.e., an 88% increase) per 10 degrees C rise in temperature (thermodynamically equivalent to an average enthalpy of volatilization of 47 kJ/mole). The associated range found for the temperature dependence slope corresponds to an increase in HLC values by a factor ranging from 1.12 to 3.55 (i.e., a 12-255% increase) per 10 degrees C rise (equivalent enthalpy of volatilization range: 8-93 kJ/mole). The wide range of slope values found indicates that serious errors may result if one applies the commonly cited 'rule of thumb' that HLC values double per 10 degrees C rise in temperature to a specific compound. In light of this finding, when faced with a lack of data, a prudent course for practitioners to take appears to be conducting a laboratory study to determine the exact temperature dependence for the compound(s) of interest.