Mineral consumption in the UK, 1945–1980: A statistical analysis

Trends in the UK consumption of 12 metallic and 19 non-metallic minerals are examined for the period 1945–1980. Comparisons are drawn between these trends and developments in per capita GDP, total world consumption and UK mineral processing capacity. Although the consumption of most minerals has shown a tendency to stagnate or decline in recent years, taking the post-war period as a whole the consumption of non-metallics has displayed a faster and more sustained growth than that of metallics; thus their share of the total value of minerals consumed in the UK has increased significantly.     

THE DEFINITION AND MEASUREMENT OF MINERAL CONSUMPTION

The concept of mineral consumption is considered in the context of a (metallic) commodity's progression from mine to manufacture and reasons are advanced as to why consumption is best measured at the point referred to as the “first processing stage.” Two methods for measuring consumption at this stage, one direct (“reported consumption”) and one deductive (“apparent consumption”), are described and the merits and drawbacks of the methods discussed. The article concludes with a brief review of the existing statistics on worldwide mineral consumption and suggests that there is the scope, and the need, for improvement. Dans cet article, la notion de la consommation minérale est envisagée dans le cadre de l'acheminement du minerai (métallique) de la mine à l'usine de transformation. II donne les raisons pour lesquelles la consommation peut se mesurer le mieux au niveau de la “phase de première transformation.” A ce stade, l'article décrit deux méthodes permettant de mesurer cette consommation: l'une directe (la consommation déclarée) et l'autre supposée (la consommation apparente). Les avantages et les inconvénients des méthodes y sont aussi discutés. En conclusion, l'article passe brièvement en revue les statistiques existantes sur la consommation minérale mondiale et suggère que la possibilité ainsi que le besoin d'amélioration se font sentir dans ce domaine. El concepto de consumo de minerales se examina dentro del contexto de la progresión del producto desde la mina a la manufactura y se sostiene que dicho consumo se mide mejor en la “etapa de primer procesamiento.” Se describen dos métodos para medir el consumo en esta etapa, el método directo (consumo reportado) y deductivo (consumo aparente). Se discuten las ventajas y desventajas de estos métodos. El artículo concluye con una revisión breve de las estadísticas existentes del consumo de minerales a nivel mundial y sugiere que existe la necesidad y la posibilidad para mejorarlas.     

Thermal behaviour of a small spider (Araneae : Araneidae : Araneinae) on horizontal webs in semi-arid Western Australia

Summary The solar orientation response of a small spider (gen. nov.: Araneae: Araneidae: Araneinae) is examined at a semi-arid location in tropical Western Australia. The spiders rest beneath horizontal dome-shaped webs close to the ground surface on spinifex (Triodia sp.). The spiders are small (c. 5 mm long) and robust, being only twice as long as wide. Spider orientation, elevation, wind velocity, radiation and wet and dry bulb temperatures together with spider and egg-sac temperatures were measured throughout the day. The spiders orientated their long axis to the solar azimuth through much of the day and postured to the solar elevation; in so doing they tracked the apparent movement of the sun throughout the day with considerable precision, far exceeding that of other spiders studied. Stepwise regression indicated that the solar position was the most important environmental factor associated with the posturing and orientation. The variance in the orientation of the population was associated with a suite of environmental variables related to wind velocity and temperature. Spider (abdominal) temperature had a curvilinear relationship with ambient temperature, with a plateau at c. 35° C, whereas egg-sac temperature had a strictly linear relationship with ambient temperature. Stepwise regression indicates that both the spider and egg-sac temperatures are related mainly to net radiation and ambient temperature. The spiders can alter the incident radiation to which they are exposed by c. 2.2 times which represent the limits of the exposed silhouette area between full dorsal sunlight and the posterior (or anterior) aspect. Under hot conditions the spiders posture and orientate such that the long axis of the body is orientated abdomen towards the sun.     

Awareness and convenience are important in increasing conference sustainability

Conference organizers are increasingly making efforts to reduce resource use at conferences, yet few responsibilities are placed on attendees. We hosted an ecology conference and offered attendees a discount if they took a sustainability pledge agreeing to reduce their resource use at the conference. In a post-conference survey, 83% of respondents reported fulfilling the pledge, but 62% indicated that convenience was the biggest obstacle impeding their ability to continue the pledge during and after the conference. We found great willingness by attendees to reduce resource use at and beyond our conference, and facilitating their participation was an important part of our success.     

Population dynamics of naturalised Manila clams <Emphasis Type="Italic">Ruditapes philippinarum</Emphasis> in British coastal waters

The Manila clam Ruditapes philippinarum was introduced to Poole Harbour (lat 50°N) on the south coast of England in 1988 as a novel species for aquaculture. Contrary to expectations, this species naturalised. We report on individual growth patterns, recruitment, mortality and production within this population. On the intertidal mudflats the abundance of clams (>5 mm in length) varied seasonally between 18 and 56 individuals m⁻². There appear to be two recruitment events per year and there were 6 year classes in the population. A mid-summer decline in abundance was partly due to increased mortality but probably also a result of down-shore migration in response to high water temperatures and the development of anoxic conditions. A winter fishery removes c 75% of clams of fishable size (maximum shell length ≥40 mm) and c 20% of the annual production. The fishery depresses the maximum age and size attained by the clams but appears to be sustainable. Clam mortality due to factors other than fishing is highest in late-winter to early spring. The growth of the clams is intermediate in comparison with many published studies but remarkably good given their intertidal position. As on the coasts of the Adriatic Sea, where the clam is also non-native, the Manila clam has thrived in a shallow, eutrophic, lagoon-like system on the English coast. While the Poole Harbour population is currently Europe’s most northerly reported self-sustaining, naturalised population, given forecasts of increasing air and sea temperatures it might be expected that this species will eventually spread to more sites around the coasts of Northern Europe with associated economic and ecological consequences.