Ethical issues concerning potential global climate change on food production

Burning fossil fuel in the North American continent contributes more to the CO₂ global warming problem than in any other continent. The resulting climate changes are expected to alter food production. The overall changes in temperature, moisture, carbon dioxide, insect pests, plant pathogens, and weeds associated with global warming are projected to reduce food production in North America. However, in Africa, the projected slight rise in rainfall is encouraging, especially since Africa already suffers from severe shortages of rainfall. For all regions, a reduction in fossil fuel burning is vital. Adoption of sound ecological resource management, especially soil and water conservation and the prevention of deforestation, is important. Together, these steps will benefit agriculture, the environment, farmers, and society as a whole.     

Crystallization behavior of predominantly syndiotactic poly(β-hydroxybutyrate)

Predominantly syndiotactic poly(-hydroxybutyrate), syn-PHB, of variable syndioregularity (syndyad fractions 0.59, 0.62, 0.64, and 0.71) and molecular weight was prepared by the dibutyltin dimethoxide catalyzed ring opening of racemic-butyrolactone (BL). The crystallization behavior of the syn-PHB polymers was investigated by DSC and X-ray diffraction analyses. DSC of films after melting and annealing showed at least one, and often two distinct melting transitions occuring over a broad (often 40°C) temperature range. These results indicate that syn-PHB chain segments of variable syndioregularity form crystalline regions with very different thermodynamic stabilities. Maximum degrees of crystallinity for melt annealed 0.64- and 0.71-syn-PHB was observed at an annealing temperature (T _c ) of 30°C. AtT _c values at 45°C and higher, crystallization of relatively lower syndioregular chain segments was apparently excluded to variable degrees dependent onT _c and sample syndiotactic dyad content. After crystallization of syn-PHB samples at elevated temperatures, ambient temperature annealing resulted in an observed lower temperature melting transition at 50°C. This result showed little to no dependence on syn-PHB syndio-regularity andT _c . Both solution precipitated 0.62-syn-PHB and 0.71-syn-PHB have WAXS patterns with poorly resolved crystalline reflections superimposed on amorphous haloes indicating low levels of crystallinity (17% and 25%, respectively) and poorly formed crystals. Isothermal crystallization monitored by DSC showed that the syn- and natural origin PHB showed fastest crystallization rates at temperatures between 50°C and 70°C and 60°C and 90°C, respectively. From the dependence of the higher melting transition onT _c it was determined that the equilibrium melting temperatures for 0.62-syn-PHB (M _n =83,700 g/mol) and a 0.64-syn-PHB (M _n =11,900 g/mol) were 157 and 154°C, respectively. An Avrami analysis of syn-PHB yielded results similar to that found for natural origin PHB indicating that crystal growth occurs by a two-dimensional mechanism.Guest Editor: Dr. Graham Swift, Rohm & Haas.     

A simple procedure to harmonize class boundaries of assessment systems at the pan-European scale

A procedure for a large scale harmonization of assessment systems is delineated. The data collected for the two E.U. co-funded projects STAR and AQEM have been used as a benchmark dataset against which a test dataset derived from Italian standard monitoring programs was compared. A central step in the procedure adopted is the calculation of Intercalibration Common Metrics (STAR_ICMs). For both the benchmark and test datasets, six metrics were calculated, normalized and averaged to obtain an ICM index. The median values obtained for this index within each of the High and Good status classes, as defined within the STAR/AQEM dataset, were compared to the classes defined by the National method applied in Italy before WFD approval. The process of harmonization involved the re-positioning of the boundaries between Italian method quality classes until no more differences were found with the values observed in the STAR/AQEM samples. The re-setting of the Italian assessment boundaries by a step-by-step procedure lead to comparable STAR_ICM index values in the two datasets. Within this example, small refinements of the boundaries between high/good and good/moderate status were sufficient to harmonize the Italian assessment quality classes to the benchmark classification. Once a benchmark dataset is agreed among different countries, the procedure outlined can be easily applied to compare and harmonize assessment systems within and outside Europe. The main scientific and practical advantages of the procedure are listed and commented, especially facing the next steps of the Water Framework Directive Intercalibration process.     

Stable isotopic investigation of physiological and environmental changes recorded in shell carbonate from the giant clam Tridacna maxima

The aragonitic shell of the photosymbiont-bearing bivalve Tridacna maxima contains a record of the physiological and environmental changes the organism has experienced during its lifetime. This record is preserved as chemical and microstructural variations throughout the shell. Stable isotopic analyses of oxygen (¹⁸O/¹⁶O) and carbon (¹³C/¹²C) in shell carbonate were combined with growth increment studies to interpret the shell record of specimens collected from the Rose Atoll (Lat. 14°31S; Long. 168°10W) in April 1982. The seasonal water temperature cycle is recorded in the oxygen isotopic signature of the clams, permitting the recognition of annual cycles in the ¹⁸O profile. The total number of these cycles corresponds to the age of a specimen, while the cycle length is a measure of the yearly growth rate. Large-amplitude cycles, reflecting year-round calcification, characterize the early portion of the growth record. With the onset of sexual maturity and slower growth at an age of approximately ten years, the cycles decrease in amplitude and become more erratic. During this later growth phase calcification is limited to the cooler months of the year, perhaps in response to a re-ordering of energy priorities between growth and gametogenesis. A growth curve developed from the ¹⁸O profile indicates rapid juvenile shell growth followed by slower growth thereafter producing a lifespan of several decades. Carbon isotopic analyses of T. maxima were compared to analyses of the symbiont-barren gastropod Terebra areolata collected from the same locality in April 1984. A 2 depletion in the ¹³C composition of T. maxima shell carbonate is attributed to a symbiontenhanced metabolic rate and an increased flow of isotopically light, respired CO₂ into the carbon pool used in calcification. Such a depletion may prove useful in identifying the presence of photosymbionts in extinct species of fossil mollusks.     

Modeling seed dispersal distances: implications for transgenic Pinus taeda.

Predicting forest-tree seed dispersal across a landscape is useful for estimating gene flow from genetically engineered (GE) or transgenic trees. The question of biocontainment has yet to be resolved, although field-trial permits for transgenic forest trees are on the rise. Most current field trials in the United States occur in the Southeast where Pinus taeda L., an indigenous species, is the major timber commodity. Seed dispersal distances were simulated using a model where the major determinants were: (1) forest canopy height at seed release, (2) terminal velocity of the seeds, (3) absolute seed release, and (4) turbulent-flow statistics, all of which were measured or determined within a P. taeda plantation established from seeds collected from wild forest-tree stands at the Duke Forest near Durham, North Carolina, USA. In plantations aged 16 and 25 years our model results showed that most of the seeds fell within local-neighborhood dispersal distances, with estimates ranging from 0.05 to 0.14 km from the source. A fraction of seeds was uplifted above the forest canopy and moved via the long-distance dispersal (LDD) process as far as 11.9-33.7 km. Out of 10(5) seeds produced per hectare per year, roughly 440 seeds were predicted to be uplifted by vertical eddies above the forest canopy and transported via LDD. Of these, 70 seeds/ha traveled distances in excess of 1 km from the source, a distance too great to serve as a biocontainment zone. The probability of LDD occurrence of transgenic conifer seeds at distances exceeding 1 km approached 100%.     

Vertical distribution of Calanus finmarchicus and C. helgolandicus in relation to the development of the seasonal thermocline in the Celtic Sea

The geographical distribution and annual mean abundance of Calanus finmarchicus (Gunnerus) and C. helgolandicus (Claus) in the northern North Atlantic Ocean were shown in relation to the seasonal and annual fluctuations of abundance of the species in the Celtic Sea from 1960 to 1981. These congeneric copepods, although showing allopatric distributions over most of their geographical range, have sympatric distributions in the Celtic Sea where they dominate the dry weight biomass of the plankton throughout the year. The two species respond differently to the development of the seasonal thermocline and halocline by taking up different vertical distributions in the water column. C. finmarchicus occurred in the colder, more saline water below the thermocline, while C. helgolandicus occurred in the warmer, less saline water above the thermocline. This behaviour is postulated as a mechanism by which these morphologically similar copepods more fully exploit the resources of their temporally and spatially heterogeneous environment and also minimise interspecific competition. The species have the same foraging techniques and are able to exploit the same size spectrum of particulates. The vertical depth strata in which the populations are found for most of the year in the Celtic Sea means that both species exploit the diatom bloom in early spring but, thereafter, C. helgolandicus grazes on the daily production of the autotrophs in the euphotic zone while C. finmarchicus, below the thermocline, has to rely for its food on sedimenting particulates (whole cells, detritus and faecal material). The isolating mechanisms whereby these two populations partition the habitat in the Celtic Sea are discussed.     

Aquatic litter, management and prevention—the role of measurement

Methodology of litter management has many forms and increasingly measurement is linked to management. By providing measured profiles of the quality of litter types, trends in the input of new items can be assessed and prevention programmes directed more effectively to sources. Developing methodologies and their application to management cover three main areas.

Viable embryogenesis of the winter flounder Pseudopleuronectes americanus from - 1.8° to 15°C

Pseudopleuronectes americanus spawns in late winter near New York, and its eggs may be found in shallow water under ice at temperatures below the usual freezing point of vertebrate tissues. Survival and duration of development at a variety of constant temperatures were recorded for artificially fertilized eggs in the laboratory. Many eggs hatched into normal larvae after 2 months at the lowest temperature tried,-1.8°C. The upper lethal temperature was about 15°C. There was a linear relation between log time and temperature in the minimum mortality range (0° to 10°C), with a Q₁₀ of about 4.8.