Endosulfan acute toxicity and histomorphological alterations in Jenynsia multidentata (Anablepidae,Cyprinodontiformes)

Toxicity tests using adult specimens of Jenynsia multidentata were carried out during 96 hours in order to determine the lethal concentration (LC50) of endosulfan. Histological alterations were determined in gills and liver. Gill damage was quantified as secondary lamellae thickness. The 96 hr LC50 values were significantly different between males (0.719 μ g.L^{? 1}) and females (1.317 μg.L^{? 1}). The sex difference was attributed to the dimorphism in the lipid content in females (2.16%) and males (1.79%). Histological alterations in gills included hypertrophy and lifting of the epithelium of the secondary lamellae and aneurisms. These alterations caused a significant increase of the secondary lamellae thickness in treatment versus control fish. Finally, reversible histological alterations (such as hydropic degeneration and dilation of sinusoids) were observed in the liver of exposed fish as well as an irreversible change such as necrosis at the highest concentrations.     

Post-disaster recovery dilemmas: challenges in balancing short-term and long-term needs for vulnerability reduction

Following disasters, governments often clamor to quickly reduce risk, rebuild communities and restore permanence. The pressure to urgently address complex, difficult decisions can result in reactive policies that may increase long-term vulnerability of affected populations. Sri Lanka in the aftermath of the 26 December 2004 tsunami represents such an example: a hastily designed coastal buffer zone policy has incited massive relocation of affected populations and resulted in social, economic and environmental problems that threaten the well-being of poor coastal communities. We review the impacts of this policy from its inception, days after the tsunami hit the island, until its revision, approximately 10 months following the disaster. We then apply a framework to conceptualize the components of vulnerability within Sri Lanka's coastal, human–environment system and to identify where post-disaster policies should focus to reduce vulnerability of coastal populations more effectively. From this analysis, it is apparent that the buffer zone policy gave disproportionate attention to reducing exposure to future tsunamis and, subsequently, did not address the critical social, economic and institutional factors that influenced sensitivity to the hazard. Post-disaster policies aimed at sustainable re-development should be informed by an analysis of the components of vulnerability that comprise a system and how these can be most effectively influenced during the separate short-term and long-term phases of rebuilding.     

A multiobjective programming framework for integrating timber and wildlife management

This article describes a multiobjective programming (MOP) framework for integrating timber and wildlife management. The framework allows for the simultaneous consideration of timber and wildlife objectives. Management strategies are defined in terms of management regimes consisting of a time-identified and site-specific schedule of activities. A MOP model is described and demonstrated using an integrated planning example involving a forest managed for timber production and a variety of wildlife species.     

Analysis of the eastern Pacific yellowfin tuna fishery based on multiple management objectives

Vector optimization techniques were used to generate arbitrary segments of a policy frontier for a dynamic yellowfin tuna (Thunnus albacares) fishery model assuming fixed technology and considering four policy objectives: minimizing dolphin mortality, minimizing incidental catch (all species except dolphins), maximizing sustainable yield, and minimizing biological risk for the yellowfin tuna stock. Results show that along the policy frontier: (1) reducing incidental dolphin mortality increases the incidental catch of other species in a nonlinear way; (2) yield increases (subject to a biomass precautionary level) can only be obtained at the expense of higher levels of dolphin mortality and incidental catch; (3) biological risk increases as the level of tunas caught increases, but this increase depends on the type of fishery (longline fishing and three different modes of purse-seining: log-sets, dolphin-sets or school-sets) that dominates the fishing effort; (4) there is an indirect relationship between the dolphin mortality levels and those of biological risk; (5) there is a direct relationship between the incidental catch levels and biological risk. Catch obtained with dolphin-sets dominates the Pareto-optimal solutions with highest dolphin mortality levels but is associated with lower biological risk, whereas catch obtained with log-sets dominates in Pareto-optimal solutions with higher incidental catch and higher biological risk. In general, trade-offs or shadow prices among objectives are not linear, indicating that marginal costs vary along the policy frontier. Results of the trade-off analysis may provide useful information for decision-makers and other policy actors. Complete information about the preferences of the decision-makers regarding the objectives is necessary to recommend a specific management policy.     

Effects of zinc oxide nanoparticles on growth and antioxidant enzymes of Capsicum chinense

Abstract

The effects of suspensions of zinc oxide nanoparticles at concentrations between 100 and 500?mg L^?1 on germination of Capsicum chinense seeds and vigor of plants were evaluated using a randomized complete design with four replications, resulting in increased germination and improved development of lengths of plumule and radicle. The activities of peroxidase, catalase and ascorbate peroxidase were determined, showing that at all concentrations the activities of the former two enzymes were increased, whereas the activity of the latter was reduced at 500?mg L^?1. Pretreatments of seeds with ZnO nanoparticles can improve germination and development of seedlings and the activities of antioxidant enzymes.     

Conflicting Frames about Ownership and Land Use Drive Wildfire Ignitions in a Protected Conservation Area

The creation of protected conservation areas may result in protracted conflicts between stakeholders. In this study we examine the drivers of anthropogenic wildfire ignitions in the National Park of “los Alerces” (NPA) in Patagonia, Argentina. The NPA was established in 1937 to protect the native “andino-patagónico” forests from wildfires as well as preserving its scenic beauty and native flora and fauna. At the time of its creation state authorities prohibited all extractive human activities in the “intangible”—fully protected—“National Park” section, while other regulated extractive and ecotourism activities were allowed to continue in the “Natural Reserve” section in an effort to accommodate the historical entitlements of the displaced populations of “pobladores” (settlers) that had been living in the NPA for over a century. Here we interviewed the main stakeholder groups—“pobladores”, forest rangers and administrators, ecolodge owners and angler club members—to identify the drivers of wildfire ignitions in the park. Wildfires have been singled out by state authorities as the main threat to the NPA though considerable scientific uncertainty exists regarding their complex ecological effects. This study argues, based on the human and biophysical system data collected, that two conflicting cultural frames exist within the NPA that provide the necessary backdrop for understanding the drivers of wildfire ignitions. In turn, these findings raise puzzling dilemmas for the main theoretical approaches that have been used to inform and design conflict management strategies in protected conservation areas.     

Agriculture and elevation are the main factors for Pampasic stream habitat and water quality

Streams of the Pampasic plain in Southeastern South America are ecosystems affected by both water pollution and habitat alteration mainly due to agricultural activity. Water quality is influenced by the quality of habitats and both depend on land use and watershed morphology. The objective of this study was to determine the relationship between the variables of four factors: (1) the morphology of the watershed, (2) land use in the watershed, (3) river habitat, and (4) water quality of wadeable streams in Uruguay, as well as to determine the most representative variables to quantify such factors. We studied 28 watersheds grouped into three ecoregions and four principal activities, which generated seven zones with three to five streams each. Correlations between the variables of each factor allowed reducing the total number of variables from 57 to 32 to perform principal component analyses (PCA) by factor, reducing the number of variables to 18 for a general PCA. The first component was associated with water quality and elevation. The second was associated with the stream and watershed size, the third with habitat quality, and the fourth to the use of neighboring soils and objects in the channel. Our results indicate that agricultural intensity and elevation are the main factors associated with the habitat and water quality of these lowland streams. These factors must be especially considered in the development of water quality monitoring programs.