Environmental Impacts of Brazil's Tucuruí Dam: Unlearned Lessons for Hydroelectric Development in Amazonia

Brazil's Tucuruí Dam provides valuable lessons for improving decision-making on major public works in Amazonia and elsewhere. Together with social impacts, which were reviewed in a companion paper, the project's environmental costs are substantial. Monetary costs include costs of construction and maintenance and opportunity costs of natural resources (such as timber) and of the money invested by the Brazilian government. Environmental costs include forest loss, leading to both loss of natural ecosystems and to greenhouse gas emissions. Aquatic ecosystems are heavily affected by the blockage of fish migration and by creation of anoxic environments. Decay of vegetation left in the reservoir creates anoxic water that can corrode turbines, as well as producing methane and providing conditions for methylation of mercury. Defoliants were considered for removing forest in the submergence area but plans were aborted amid a public controversy. Another controversy surrounded impacts of defoliants used to prevent regrowth along the transmission line. Mitigation measures included archaeological and faunal salvage and creation of a “gene bank” on an island in the reservoir. Decision-making in the case of Tucuruí was virtually uninfluenced by environmental studies, which were done concurrently with construction. The dam predates Brazil's 1986 requirement of an Environmental Impact Assessment. Despite limitations, research results provide valuable information for future dams. Extensive public-relations use of the research effort and of mitigation measures such as faunal salvage were evident. Decision-making was closely linked to the influence of construction firms, the military, and foreign financial interests in both the construction project and the use of the resulting electrical power (most of which is used for aluminum smelting). Social and environmental costs received virtually no consideration when decisions were made, an outcome facilitated by a curtain of secrecy surrounding many aspects of the project. Despite improvements in Brazil's system of environmental impact assessment since the Tucuruí reservoir was filled in 1984, many essential features of the decision-making system remain unchanged.     

Selective Breeding Programs for Rare Alleles: Examples from the Przewalski''s Horse and California Condor Pedigrees

As extinction due to loss of habitat grows more imminent for a wide variety of species, population management has been recognized as an important means toward species survival and recovery in the wild. Genetic management practices generally seek to preserve population variation at the level of the genome. It has been proposed, however, that such efforts should instead be directed to specific loci harboring alleles with particular selective benefits. This strategy may in fact result in greater loss of variation in the rest of the genome, potentially threatening population viability. Pedigrees of Przewalski's horse ( Equus prezewalskii ) and the California Condor ( Gymnogyps californianus ) were used to evaluate a "rare kinship" management strategy in which a single individual known to carry a unique allele is repeatedly bred to mates chosen by mean kinship in order to increase the frequency of the rare allele. This strategy led to increased population mean kinship and reduced gene diversity and founder genome equivalents relative to a no-management control pedigree and performed considerably worse than a pedigree managed for mean kinship. Reduced success in the breeding program can be directly attributed to significant deviations of founders' representations from their respective target values. As a result, a strategy for increasing the frequency of rare alleles cannot be generally recommended for management of captive populations. Under strict conditions, however, limited use of this strategy may be applicable only if used for a short time under careful monitoring by pedigree analysis. Even if these conditions are met, managing by a more conventional method such as mean kinship is preferable. These results illustrate the utility of thoughtful analysis of pedigree information to successful population management.     

A review of adaptive cluster sampling: 1990–2003

Adaptive cluster sampling (ACS) is an adaptive sampling scheme which operates under the rule that when the observed value of an initially selected sampling unit satisfies some condition of interest, C, other additional units in some pre-defined accompanying neighborhood are also added to the sample. In turn, if any of these additional units satisfy C, then their corresponding unit neighborhoods are added to the sample as well, and so on. This process stops when no additional units satisfying C are encountered. This paper will provide a review of the major developments and issues in ACS since its introduction by Thompson (1990) [Journal of the American Statistical Association, 85, 1050–1059].     

Long-Term Landscape Change and Bird Abundance in Amazonian Rainforest Fragments

Abstract:  The rainforests of the Amazon basin are being cut by humans at a rate >20,000 km²/year, leading to smaller and more isolated patches of forest, with remaining fragments often in the range of 1–100 ha. We analyzed samples of understory birds collected over 20 years from a standardized mist-netting program in 1– to 100-ha rainforest fragments in a dynamic Amazonian landscape near Manaus, Brazil. Across bird guilds, the condition of second growth immediately surrounding fragments was often as important as fragment size or local forest cover in explaining variation in abundance. Some fragments surrounded by 100 m of open pasture showed reductions in insectivorous bird abundance of over 95%, even in landscapes dominated by continuous forest and old second growth. These extreme reductions may be typical throughout Amazonia in small (≤10 ha), isolated fragments of rainforest. Abundance for some guilds returned to preisolation levels in 10- and 100-ha fragments connected to continuous forest by 20-year-old second growth. Our results show that the consequences of Amazonian forest loss cannot be accurately described without explicit consideration of vegetation dynamics in matrix habitat. Any dichotomous classification of the landscape into "forest" and "nonforest" misses essential information about the matrix.     

Effects of Road Clearings on Movement Patterns of Understory Rainforest Birds in Central Amazonia

Abstract:  The impacts of potential linear barriers such as roads, highways, and power lines on rainforest fauna are poorly understood. In the central Brazilian Amazon, we compared the frequency of local movements (≤300 m long) of understory birds within intact forest and across a 30- to 40-m-wide road over a 2-year period. Rainforest had regenerated along some road verges, to the extent that a nearly complete canopy was formed in some areas, so we also assessed whether this facilitated bird movement. Movement data were determined from 1212 recaptures of 3681 netted birds at six study sites. The road significantly inhibited total bird movement across roads at five of the six sites. Bird foraging guilds varied in their responses to the road and different ages of regrowth. Movements of frugivorous and edge and gap species were not inhibited at any site, whereas most forest-dependent insectivores (mixed-species flocks, terrestrial species, and army-ant followers) had markedly inhibited road-crossing movements, except at sites with extensive regrowth. Solitary understory species were especially vulnerable, rarely crossing even roads overgrown by tall regrowth. For sensitive species, road-crossing movements were inhibited because individuals tended to avoid both edge-affected habitat near the road and the road clearing itself. Our results suggest that even narrow roads with low traffic volumes can reduce local movements of many insectivorous birds in Amazonia.     

Wildlife Loss through Domestication: the Case of Endangered Key Deer

Abstract:  Wildlife extinction represents the ultimate failure of wildlife conservation. It has many causes, some of them natural, but is increasingly tied to anthropogenic factors. Wildlife loss via domestication, however, is rarely considered. We evaluated the potential for inadvertent domestication of wildlife by determining the effect of feeding and watering on Key deer ( Odocoileus virginianus clavium ) density, group size, and distribution. Key deer sightings were significantly higher in areas (42 ha) surrounding the households that provided food and water (0.18 deer/m;  n = 8   ) than in randomly selected areas (0.03 deer/m;  t = 3.82, 14  df, p = 0.002   ). Average distance to a household providing food and water decreased logistically as group size increased, and large groups (>2 individuals each) were observed more frequently in areas where food and water were provided (27.5%) than in the randomly selected areas (7.5%). The incidence of large groups outside feeding areas (7.5%), however, was similar to the incidence of large groups during early urbanization (5.1%; 1968–1973). Our results suggest illegal feeding caused changes in density, group size, and distribution indicative of domestication. Because fresh water and food were primary selective pressures for Key deer before illegal feeding and watering, genetic changes may occur in the future. For those who value "wildness" in wildlife, domestication of wildlife species is a serious problem that must be addressed.     

Local Participation in Natural Resource Monitoring: a Characterization of Approaches

Abstract: The monitoring of trends in the status of species or habitats is routine in developed countries, where it is funded by the state or large nongovernmental organizations and often involves large numbers of skilled amateur volunteers. Far less monitoring of natural resources takes place in developing countries, where state agencies have small budgets, there are fewer skilled professionals or amateurs, and socioeconomic conditions prevent development of a culture of volunteerism. The resulting lack of knowledge about trends in species and habitats presents a serious challenge for detecting, understanding, and reversing declines in natural resource values. International environmental agreements require signatories undertake systematic monitoring of their natural resources, but no system exists to guide the development and expansion of monitoring schemes. To help develop such a protocol, we suggest a typology of monitoring categories, defined by their degree of local participation, ranging from no local involvement with monitoring undertaken by professional researchers to an entirely local effort with monitoring undertaken by local people. We assessed the strengths and weaknesses of each monitoring category and the potential of each to be sustainable in developed or developing countries. Locally based monitoring is particularly relevant in developing countries, where it can lead to rapid decisions to solve the key threats affecting natural resources, can empower local communities to better manage their resources, and can refine sustainable‐use strategies to improve local livelihoods. Nevertheless, we recognize that the accuracy and precision of the monitoring undertaken by local communities in different situations needs further study and field protocols need to be further developed to get the best from the unrealized potential of this approach. A challenge to conservation biologists is to identify and establish the monitoring system most relevant to a particular situation and to develop methods to integrate outputs from across the spectrum of monitoring schemes to produce wider indices of natural resources that capture the strengths of each.     

Dynamics of Hybridization and Introgression in Red Wolves and Coyotes

Abstract:  Hybridization and introgression are significant causes of endangerment in many taxa and are considered the greatest biological threats to the reintroduced population of red wolves ( Canis rufus ) in North Carolina (U.S.A.). Little is known, however, about these processes in red wolves and coyotes ( C. latrans ). We used individual-based simulations to examine the process of hybridization and introgression between these species. Under the range of circumstances we considered, red wolves in colonizing and established populations were quickly extirpated, persisted near the carrying capacity, or had intermediate outcomes. Sensitivity analyses suggested that the probabilities of quasi extinction and persistence of red wolves near the carrying capacity were most affected by the strength of two reproductive barriers: red wolf challenges and assortative mating between red wolves and coyotes. Because model parameters for these barriers may be difficult to estimate, we also sought to identify other predictors of red wolf population fate. The proportion of pure red wolves in the population was a strong predictor of the future probabilities of red wolf quasi extinction and persistence. Finally, we examined whether sterilization can be effective in minimizing introgression while allowing the reintroduced red wolf population to grow. Our results suggest sterilization can be an effective short-term strategy to reduce the likelihood of extirpation in colonizing populations of red wolves. Whether red wolf numbers are increased by sterilization depends on the level of sterilization effort and the acting reproductive barriers. Our results provide an outline of the conditions likely required for successful reestablishment and long-term maintenance of populations of wild red wolves in the presence of coyotes. Our modeling approach may prove generally useful in providing insight into situations involving complex species interactions when data are few.     

Effect of Local Cultural Context on the Success of Community‐Based Conservation Interventions

Abstract: Conservation interventions require evaluation to understand what factors predict success or failure. To date, there has been little systematic investigation of the effect of social and cultural context on conservation success, although a large body of literature argues it is important. We investigated whether local cultural context, particularly local institutions and the efforts of interventions to engage with this culture significantly influence conservation outcomes. We also tested the effects of community participation, conservation education, benefit provision, and market integration. We systematically reviewed the literature on community‐based conservation and identified 68 interventions suitable for inclusion. We used a protocol to extract and code information and evaluated a range of measures of outcome success (attitudinal, behavioral, ecological, and economic). We also examined the association of each predictor with each outcome measure and the structure of predictor covariance. Local institutional context influenced intervention outcomes, and interventions that engaged with local institutions were more likely to succeed. Nevertheless, there was limited support for the role of community participation, conservation education, benefit provision, and market integration on intervention success. We recommend that conservation interventions seek to understand the societies they work with and tailor their activities accordingly. Systematic reviews are a valuable approach for assessing conservation evidence, although sensitive to the continuing lack of high‐quality reporting on conservation interventions.