Fish production and the marine ecosystems of the Scotian Shelf,eastern Canada

Fishery production and food webs have been studied on the Scotian Shelf and upper continental slope along a transect running 270 km SE of Halifax, Canada. The area (TCNAF Division 4W) supports a fishery of roughly 0.15x10⁶ metric tons. Overall primary production of the shelf waters is 102 g C m^-2 year^-1 and of the slope wacers about 128 g C m^-2 year^-1. Demersal fish production (average 4.1 kcal m^-2 year^-1) is highest over the shelf and declines in an offshore direction, while pelagic fish production (average 16 kcal m^-2 year^-1) is highest over the slope and declines in an inshore direction. Hypothetical food webs of these two intergrading ecosystems have been constructed, based on data for primary production, fish catches, and the biomasses of zooplankton and macrobenthos. These lead us to suggest that there are basic differences in food chains and efficiencies between the two ecosystems that account for their differences in production. Although primary production is 17% higher on an average on the Nova Scotian transect than in the North Sea, the apparent zooplankton and macrobenthos production is 31% lower and macrobenthos production may also be lower. Overall fish catch from the Scotian Shelf and slope is about 47% lower per unit area than the catch in the North Sea, despite the fact that the demersal catches are identical. This is accounted for by a much lower overall pelagic catch from the Nova Scotian area, centered in a region that is small compared to the total area. Fish production in different regions cannot be predicted merely on the basis of differences in level of primary production, but must take into account differences in the structure of the ecosystems.     

Handling and Survivorship of African Wild Dog (Lycaon pictus) in Five Ecosystems

Populations of the African wild dog, Lycaon pictus have declined throughout their range in sub-Saharan Africa during the last 20 years. It has been hypothesized that handling of wild dogs led to local extinction of a study population in the Serengeti-Masai Mara ecosystem. In this paper we compare rates of mortality and disappearance in handled ( n = 305) versus unhandled ( n = 135) dogs to test the hypothesis that handling leads to increased mortality of Lycaon . We examine data from five ecosystems in which Lycaon have been handled. Our data show that there is no effect of handling on the longevity of Lycaon in any ecosystem studied. Given these data, a more parsimonious explanation of the decimation of the Serengeti-Mara Lycaon population would be that disease alone was responsible for the population collapse and that researcher handling of Lycaon was correlated with, but not causal to, this mortality.     

黄河包头段不同粒径沉积物分形校正下重金属的吸附研究

推导了分粒级的表面分形维数计算公式,根据推导公式计算了分粒级沉积物的分维值.应用已有的表面分形分维计算公式分别计算了黄河包头段沉积物整体的表面分形分维(1.91)及＜63 μm粒级的分维值(1.36),揭示出黄河水环境的磨蚀和分选2个原因引起黄河包头段沉积物低的分维值.用分形校正吸附模型、Freundlich和Langmuir吸附模型对黄河包头段重金属分粒级沉积物吸附进行了拟合,表明分形校正吸附模型具有较好的适用性,同时揭示分形校正吸附模型与MEA理论结合能更好的对热力学吸附结果进行描述;由吸附结果分析得出4种重金属因粒径引起的吸附量变化程度序列为Cu＞Pb＞Zn≈Cd,初始浓度高的吸附量曲线变化较初始浓度低的曲线变化明显,同时指出Cu、Pb的吸附主要与矿物组成有关,而Zn、Cd的吸附则与吸附剂沉积物空间几何性质(或沉积物表面物理特征)有关.     

The trophic status of two Northern Irish sea loughs

Studies were conducted on nutrient cycling in two coastal embayments; Strangford Lough and Belfast Lough, in order to classify these coastal waters in compliance with the European Union Urban Waste Water Treatment and Nitrates Directives. Analysis of the data suggests that Strangford Lough is nitrogen-limited throughout much of the growing season with chlorophyll-a levels comparable to the open Irish Sea. In contrast, much of Belfast Lough is never nitrogen-limited and, with chlorophyll-a levels at time exceeding 50 μg/l, is exhibiting symptoms of eutrophication.     

Development of a novel passive sampling system for the time-averaged measurement of a range of organic pollutants in aquatic environments

A new sampling system has been developed for the measurement of time-averaged concentrations of organic micropollutants in aquatic environments. The system is based on the diffusion of targeted organic compounds through a rate-limiting membrane and the subsequent accumulation of these species in a bound, hydrophobic, solid-phase material. It provides a novel and robust solution to the problem of monitoring in situations where large temporal fluctuations in pollutant levels may occur. Accumulation rates are regulated by choice of diffusion-limiting membrane and bound solid-phase material and have been found to be dependent on the physico-chemical properties of individual target analytes. Two separate prototype systems are described: one suitable for the sampling of non-polar organic species with log octanol/water partition coefficient (log P) values greater than 4, the other for more polar species with log P values between 2 and 4. Both systems use the same solid-phase material (47 mm C18 Empore disk) as a receiving phase but are fitted with different rate-limiting membrane materials (polysulfone for the polar and polyethylene for the non-polar analytes). The two systems complement each other and together can be used for sampling a wider range of organic analytes than generally possible using current passive sampling techniques. Calibration data are presented for both devices. In each case, linear uptake kinetics were sustained, under constant conditions, for deployment periods of between 1 and 9 days. The effects of water temperature and turbulence on sampling rates have been quantitatively assessed. The performance of the system was further investigated by means of field exposures for one and two weeks in marine environments where calibrated samplers were used to determine the time-averaged concentrations of the polar biocides diuron and irgarol 1051. The quantitative results obtained using the passive sampler were compared with those obtained using spot sampling.     

Compliance with ivory trade regulations in the United Kingdom among traders

Global demand for elephant ivory is contributing to illegal poaching and significant decline of African elephant (Loxondonta africana) populations. To help mitigate decline, countries with legal domestic ivory markets were recommended by the Convention on International Trade in Endangered Species of Wild Fauna and Flora to close domestic markets for commercial trade. However, implementing stricter regulations on wildlife trade does not necessarily mean compliance with rules will follow. Using an online questionnaire, we examined the relationship between self-reported compliance with ivory trade regulations among 115 ivory traders in the United Kingdom and 4 dimensions (control, deterrence, legitimacy, and social norms) hypothesized to influence compliance with conservation regulations. Although most traders supported regulations, a large number did not always check that they comply with them when trading objects containing ivory. The main factors influencing compliance with ivory trade regulations were traders’ ability to comply and their perceptions of the regulations and punishments to deter illegal trade. These findings demonstrate the utility of conservation criminology to improve wildlife trade regulations and identify opportunities to reduce illegal ivory entering the market in the United Kingdom. Compliance could be improved by clearer regulations that facilitate easier detection of illegal ivory products and stronger prosecution of violations.     

Qualitative impact evaluation of a social marketing campaign for conservation

Social marketing campaigns use marketing techniques to influence human behavior for the greater social good. In the conservation sector, social marketing campaigns have been used to influence behavior for the benefit of biodiversity as well as society. However, there are few evaluations of their effectiveness. We devised an approach for evaluating the influences of social marketing campaigns on human behavior and conservation outcomes. We used general elimination methodology, a theory-driven qualitative evaluation method, to assess the long-term impacts of a 1998 Rare Pride campaign on the island of Bonaire that was designed to increase the population of the Lora (Amazona barbadensis), a threatened parrot. We interviewed stakeholder groups to determine their perceptions of the drivers of the changes in the Lora population over time. We used these data to develop an overall theory of change to explain changes in the Lora population by looking at the overlap in hypotheses within and between stakeholder groups. We then triangulated that theory of change with evidence from government reports, peer-reviewed literature, and newspapers. The increase in the Lora population was largely attributed to a decrease in illegal poaching of Loras and an associated decrease in local demand for pet Loras. Decreases in poaching and demand were likely driven by a combination of law enforcement, social marketing (including the Rare campaign), and environmental education in schools. General elimination methodology helped show how multiple interventions influenced a conservation outcome over time. There is a need for evidence-based evaluations of social marketing interventions to ensure that limited resources are spent wisely.     

Calibration of the Chemcatcher passive sampler for the monitoring of priority organic pollutants in water

An integrative passive sampler consisting of a C18 Empore disk receiving phase saturated with n-octanol and fitted with low-density polyethylene diffusion membrane was calibrated for the measurement of time-weighted average concentrations of hydrophobic micropollutants, including polyaromatic hydrocarbons and organochlorine pesticides, in water. The effect of temperature and water turbulence on kinetic and thermodynamic parameters characterising the exchange of analytes between the sampler and water was studied in a flow-through system under controlled conditions. It was found that the absorption of test analytes from water to the sampler is related to their desorption to water. This allows for the in situ calibration of the uptake of pollutants using offload kinetics of performance reference compounds. The sampling kinetics are dependent on temperature, and for most of the tested analytes also on the flow velocity. Sampler-water partition coefficients did not significantly change with temperature.     

Cost-benefit analysis in the selection of efficient multipollutant strategies

Pollution control efforts are motivated by the desire to protect human health and the environment. Often, those efforts involve selecting among multiple options for attaining air quality objectives. For example, state and local decision-makers must choose the mix of control strategies for meeting the requirements of the National Ambient Air Quality Standards (NAAQS) and the Regional Haze Rule. We demonstrate that including assessments of the human health and environmental benefits when evaluating alternative strategies may help decision-makers to identify multipollutant attainment strategies that achieve greater net benefits than would accrue under strategies optimized for cost alone. This paper presents a conceptual framework that decision-makers could use to choose among alternative multipollutant control strategies, accounting for the benefits and the costs of different types and locations of emissions reductions.