The Sustainability of Subsistence Hunting in the Neotropics

Hunting is an important component of native subsistence strategies in Amazonia. It is also a serious threat to biodiversity in some areas. We present data on the faunal harvests of two native Neotropical subsistence hunting peoples, Machiguenga bow-hunters and Piro shotgun hunters of Peru. The rate of annual harvest per square kilometer of catchment is estimated and compared to rates of sustainable harvest calculated by Robinson and Redford (1991). We used indicators of prey abundance to test for the depletion of species that hunters killed in numbers greater than what the model predicts to be sustainable. As predicted, we found the strongest evidence for local depletion of the large primates at the Piro site. The woolly monkey ( Lagothrix lagothricha) harvest at the Machiguenga village and the deer ( Mazama americana) and collared peccary (Tayassu tajacu) harvests at both sites were not predicted to be unsustainable and we found no evidence for depletion. Machiguenga bow hunters killed spider monkeys (Ateles paniscus) in quantities that were slightly above what the model predicted to be sustainable, yet we found no evidence for depletion. Differential species vulnerability, catchment size, and consumer population size could be important factors in determining sustainability.     

Transport of cadmium and other metals in the blood of the bivalve mollusc Mercenaria mercenaria

The distribution of metals (Ba, Cr, Cu, Fe, Mn, Ni and Zn) in the blood plasma and the circulating hemocytes was determined for a eulamellibranch bivalve, the quahog Mercenaria mercenaria (L.), collected from a relatively clean site at Falmouth, Massachusetts, USA. Whole blood volume was an exponential function of quahog length (Y=5.71×10^-5 X^3.0678; Y=ml of whole blood; X=mm length). Of this volume, 1.2±0.3% ( ) was attributable to blood cells. Total metal content (g metal, or g metal normalized per g of whole blood) was much higher in blood plasma than in hemocytes. In quahogs exposed in the laboratory to 100 ppb ¹⁰⁹Cd, 93.0% of the total accumulated blood Cd was in the plasma rather than in the circulating hemocytes (7.0%), irrespective of the length of exposure (1 h to 31 d). Less than 5% of the plasma Cd was either Cd²⁺, small inorganic Cd complexes or bound to organic molecules with a molecular weight smaller than 1 000. Cadmium was primarily bound to high molecular weight protein(s) (>60 000 daltons) within the plasma. This plasma protein-Cd complex has a low affinity constant (approximately 10⁴ M ^-1), indicating non-specific Cd binding, although the capacity for Cd-binding in the plasma is great (as high as 200 g Cd per ml of plasma). Blood plasma may be far more important in metal transport than has previously been realized.     

Genotypic differences in brood rearing in honey bee colonies: context-specific?

Summary Three experiments were performed to determine whether brood care in honey bee colonies is influenced by colony genetic structure and by social context. In experiment 1, there were significant genotypic biases in the relative likelihood of rearing queens or workers, based on observations of individually labeled workers of known age belonging to two visually distinguishable subfamilies. In experiment 2, no genotypic biases in the relative likelihood of rearing drones or workers was detected, in the same colonies that were used in experiment 1. In experiment 3, there again were significant genotypic differences in the likelihood of rearing queens or workers, based on electrophoretic analyses of workers from a set of colonies with allozyme subfamily markers. There also was an overall significant trend for colonies to show greater subfamily differences in queen rearing when the queens were sisters (half- and super-sisters) rather than unrelated, but these differences were not consistent from trial to trial for some colonies. Results of experiments 1 and 3 demonstrate genotypic differences in queen rearing, which has been reported previously based on more limited behavioral observations. Results from all three experiments suggest that genotypic differences in brood care are influenced by social context and may be more pronounced when workers have a theoretical opportunity to practice nepotism. Finally, we failed to detect persistent interindividual differences in bees from either subfamily in the tendency to rear queen brood, using two different statistical tests. This indicates that the probability of queen rearing was influenced by genotypic differences but not by the effect of prior queen-rearing experience. These results suggest that subfamilies within a colony can specialize on a particular task, such as queen rearing, without individual workers performing that task for extended periods of time.     

Long-Term Changes in the Avifauna of Barro Colorado Island, Panama, a Tropical Forest Isolate

Since its isolation from the mainland more than 85 years ago, 65 bird species have disappeared from Barro Colorado Island, Panama. Because of these extinctions the island is often used as a model for the study of faunal relaxation, or loss of species through time. The most recent survey of the island's bird community was completed in 1970. Between June 1994 and May 1996 I surveyed the island and observed 218 species, including 5 species never before recorded. Three relatively sedentary species have experienced severe population declines since Willis's 1970 survey and may be on the brink of disappearing from the island. Willis estimated 500 Slate-colored Grosbeaks ( Pitylus grossus ), whereas I found only two pairs of this conspicuous midstory-dwelling finch. Two cotingas—Speckled Mourner ( Laniocera rufescens ) and Rufous Piha ( Lipaugus unirufus )—have declined by 85–95%. I did not locate any individuals of 36 other species that were present during the 1970s. Most (21) of these are uncommon aquatic or nocturnal species, which I may have missed during my surveys, or are rare to uncommon edge species that probably move frequently to and from the island. Seven species, however, are primarily inhabitants of second-growth forest and have been lost probably because of continuing successional maturation of the forest, including changes in land use around the laboratory clearing. Seven forest-dwelling species disappeared during the 1970s and have not recolonized. I detected only one sedentary forest-dwelling species, Great Currasow ( Crax rubra ), that previously had been reported as missing from the island. The nearly complete lack of recolonizations by such forest-interior species suggests that local extinction from tropical forest isolates may be extremely persistent. Tropical forest reserves as small as Barro Colorado Island (1600 ha) may not preserve high levels of regional avian diversity over long periods of time.     

Climate change and sustainable development: realizing the opportunity

Manifold linkages exist between climate change and sustainable development. Although these are starting to receive attention in the climate exchange literature, the focus has typically been on examining sustainable development through a climate change lens, rather than vice versa. And there has been little systematic examination of how these linkages may be fostered in practice. This paper examines climate change through a sustainable development lens. To illustrate how this might change the approach to climate change issues, it reports on the findings of a panel of business, local government, and academic representatives in British Columbia, Canada, who were appointed to advise the provincial government on climate change policy. The panel found that sustainable development may offer a significantly more fruitful way to pursue climate policy goals than climate policy itself. The paper discusses subsequent climate change developments in the province and makes suggestions as how best to pursue such a sustainability approach in British Columbia and other jurisdictions.     

Best management practices to prevent cross-media transfers during soil cleanup

Cleanup activities often focus on the initial and final concentration levels of contaminants. What happens in-between, during implementation of treatment technologies, has raised major concerns by several environmental groups. To address this issue, the U.S. Environmental Protection Agency (EPA) has undertaken the task of developing a guidance that would identify the potential for cross-media transfer during implementation of various soil treatment technologies and recommend best management practices (BMPs) to prevent or control these cross-media transfers. The soil treatment technologies have been grouped into seven major categories in this effort. This article provides some details of the seven soil treatment technology groups and the general BMPs recommended in the draft BMP guidance document. One case history of existing control practices is also presented in this article and compared with the recommended BMPs.     

Model testing using data on 131I released from Hanford

The Hanford test scenario described an accidental release of 131I to the environment from the Hanford Purex Chemical Separations Plant in September 1963. Based on monitoring data collected after the release, this scenario was used by the Dose Reconstruction Working Group of BIOMASS to test models typically used in dose reconstructions. The primary exposure pathway in terms of contribution to human doses was ingestion of contaminated milk and vegetables. Predicted mean doses to the thyroid of reference individuals from ingestion of 131I ranged from 0.0001 to 0.8 mSv. For one location, predicted doses to the thyroids of two children with high milk consumption ranged from 0.006 to 2 mSv. The predicted deposition at any given location varied among participants by a factor of 5-80. The exercise provided an opportunity for comparison of assessment methods and conceptual approaches, testing model predictions against measurements, and identifying the most important contributors to uncertainty in the assessment result. Key factors affecting predictions included the approach to handling incomplete data, interpretation of input information, selection of parameter values, adjustment of models for site-specific conditions, and treatment of uncertainties.     

Modelling the biochemical degradation of solid waste in landfills

This paper describes the concept of a generic spatially distributed numerical model that has been developed to contain and link sub-models of landfill processes in order to simulate solid waste degradation and gas generation in landfills. The model includes the simulation of the transport of leachate and gases, and the consolidation of the solid waste. The structure of the model consists of linked discrete constant volume elements. The paper outlines the theoretical background that provides the framework to contain the numerical procedures that make up the model. Details are also given of the approach to the modelling of the chemistry and microbiology of solid waste degradation.