Habitat selection increases the isolating effect of habitat fragmentation on the gopher tortoise

Habitat selection requires choice, which differentiates it from habitat use, and choice, in turn, is dependent upon the responses of organisms to the environmental, social, and other cues that they perceive. Habitat selection by the gopher tortoise (Gopherus polyphemus) was investigated by translocating tortoises and monitoring their movements within two sites in central Florida. The first site supported a stable preponderance of high-quality habitat, and tortoises avoided areas with a dense tree canopy cover caused by fire exclusion. The second site was badly invaded by an introduced weed, and tortoises avoided areas where the weed had formed a dense monoculture. At both sites, individuals appeared to be responding to visual cues to avoid areas that were relatively dark. In landscapes with relatively large amounts of high-quality habitat, this avoidance behavior serves the gopher tortoise well by keeping individuals within the dominant habitat type. In degraded areas, high-quality habitat often becomes increasingly uncommon, and the avoidance behavior exhibited by the tortoises will result in individuals becoming confined to small patches, causing a significant reduction in fitness and hence questioning their long-term survival in such areas. The results from our study show that in order to maintain viable tortoise populations in areas increasingly subjected to human fragmentation and degradation, it is crucial not only to suppress tree canopy cover continually and prevent invasion by exotic weeds, but also to be mindful that the avoidance behavior of the gopher tortoise could prevent individuals from fully occupying a high-quality habitat in response to restoration and management efforts.     

Radioactivity in environmental samples: Calibration standards measurement methods,quality assurance,and data analysis

The numerous environmental radioactivity measurements made by and for the U.S. Environmental Protection Agency (U.S. EPA) include measurements on samples of water, urine, food, milk, and air filters. Calibration standards are listed which are available in the form of water solutions and soils for a wide range of radionuclides. Method validation procedures for U.S. EPA approval include protocol development and single-laboratory and multiple-laboratory evaluation for precision and accuracy. Interlaboratory comparison studies are conducted for both cross-check and performance evaluation samples and involve 295 federal, state, and local laboratories. For water samples, 80%–90% of the participating laboratories are within the control limits for most of the radionuclides measured; however, some problem areas exist, especially for radium-228 and strontium-89 and -90. For milk and food samples, more than 90% of the laboratories are within control limits for cobalt-60 and cesium-137 but some problems exist for the measurement of strontium-90, iodine-131, and potassium-40. For tritium, 91% of the laboratories are within the control limit for water samples and 87% are within the control limits for the urine samples. The laboratory performance for air filter samples shows some problems for gross beta, strontium-90 and cesium-137 measurements.     

Worker training and education in occupational safety and health: A report on practice in six industrialized western nations: Part two of a four-part series

During 1980–1981, a study was conducted of worker training and education in occupational safety and health in Canada, Great Britain, Sweden, France, the Federal Republic of Germany, and the United States. This article is the second in a four-part series of the findings of this study. Part one discussed the genesis of the study and the study design, reported on the training requirements of the occupational safety and health legislation in each of the six countries, and considered the implications of this legislation for worker training and education. Part one also included information on how each country is organized to carry out worker training and education in occupational safety and health. Part two discusses the role perceived for worker training and education as an occupational injury and illness countermeasure and identifies and describes the major components of the occupational safety and health training infrastructure in each country in the study. Part three will report on course design, construction, delivery, evaluation, and costs. Part four will provide synopses of worker training and education for selected subsets of the worker population, e.g., migrant workers, nonorganized workers, employees of small business establishments, and employees of the federal or central government. Worker training and education programs will also be discussed for the following industries: construction, marine cargo handling (longshoring), and petroleum refining and related industries.