The aim of this study was to determine whether the latitudinal distribution of fish species that use estuaries to complete
their entire life cycle has shifted northward as an expected consequence of global warming. The mean latitude of past fish
species distributions found in 1970s’ literature was compared with the mean latitude of distributions today based on fish
density indices collected in 55 tidal estuaries along the Atlantic European seaboard, from Portugal to Scotland. Among the
15 most common species, 11 displayed a positive difference between current and past mean latitudes suggesting a northward
shift of the populations. Using the occurrence of subtropical species in temperate areas as an indicator of water warming,
the northernmost range limit of 10 subtropical species was subsequently focused on. Six of them were recorded up to their
past northern latitudinal limit. These results reinforced the idea that a number of fish species associated to estuaries have
migrated northwards over the last 30 years, possibly due to water warming. These ecological changes can get important managerial
implications, i.e. in the assessment of the ecological status in European directives. 相似文献
Water allocation systems are challenged by hydrologic droughts, which reduce available water supplies and can adversely affect human and environmental systems. To address this problem, drought management mechanisms have been instituted in jurisdictions around the world. Historically, these mechanisms have involved a crisis management or reactive approach. An important trend during the past decade in places such as the United States has been a shift to a more proactive approach, emphasizing drought preparedness and local involvement. Unfortunately, local capacity for drought planning is highly variable, with some local governments and organizations proving to be more capable than others of taking on new responsibilities. This paper reports on a study of drought planning and water allocation in the State of Minnesota. Factors facilitating and constraining local capacity for drought planning were identified using in-depth key informant interviews with state officials and members of two small Minnesota cities, combined with an analysis of pertinent documentation. A key factor contributing to the effectiveness of Minnesota's system is a water allocation system with explicit priorities during shortages, and provisions for restrictions. At the same time, the requirement that water suppliers create Public Water Supply Emergency Conservation Plans (PWSECP) clarifies the roles and responsibilities of key local actors. Unfortunately, the research revealed that mandated PWSECP are not always implemented, and that awareness of drought and drought planning measures in general may be poor at the local level. From the perspective of the two cities evaluated, factors that contributed to local capacity included sound financial and human resources, and (in some cases) effective vertical and horizontal linkages. This analysis of experiences in Minnesota highlights problems that can occur when senior governments establish policy frameworks that increase responsibilities at the local level without also addressing local capacity. 相似文献
The recent crises of BSE and FMD in the United Kingdom have revealed widespread concerns on the part of farmers and consumers about government regulations and handling of animal movements, animal welfare, and food safety. Both crises raised issues of government accountability and the lack of openness in public debate. The issues of democratic process and decision-making were especially strong in relation to the mass slaughter policy of the government to control FMD. This article explores public disquiet about these matters, as expressed through the reports of two public inquiries, and the perceived links between government decision-making and the needs of global agribusiness, to the detriment of family farms and animal welfare. In light of the growing evidence about the environmental and economic costs of agribusiness, the argument is made that strong programs of citizen action, such as the Devon Foot and Mouth Inquiry, that are grounded in an ethical stance on animal welfare can challenge the perspectives of central governments about concepts of cost, efficiency, and safety in agriculture. 相似文献
This work was aimed at finding materials that could be used as alternatives to lichens as air quality monitors since the high natural variability and the large amount of lichen collected are two drawbacks of the use of these organisms. Lichen Flavoparmelia caperata(L.) Hale was exposed in three different forms (transplant, detached from the substratum and as a biomass-ground and homogeneized) and compared to the planetree bark (Platanus hybrida Brot.), exposed as a biomass, and two organic synthetic materials (Chelex(R) 100 resin and cellulose acetate). Materials were exposed for two months in the winter, spring and summer, at three Portuguese coastal cities. The results showed that the airborne accumulations of Cu, Ni, Pb and Sr were partially dependent on the meteorological conditions but mainly dependent on the nature of the exposed material. The standard deviations of the synthetic materials or homogenized biomass were the same or greater than lichen transplants or detached. The accumulation by biological materials, of the four studied elements, was comparable to the lichen transplant accumulation. The replacement of the traditional transplants by the biomass was not considered advantageous, since their preparation is time-consuming. Therefore lichens remain the most suitable in biomonitoring studies. The exposure of detached lichen allows the accurate measurement of the exposed area/volume so it can be useful to relate atmospheric deposition rates with the lichen metal content. The synthetic materials accumulated Cu and Ni and should only be used as an alternative to traditional transplants when these are the elements of interest. 相似文献
The Arctic marine ecosystem is shaped by the seasonality of the solar cycle, spanning from 24-h light at the sea surface in summer to 24-h darkness in winter. The amount of light available for under-ice ecosystems is the result of different physical and biological processes that affect its path through atmosphere, snow, sea ice and water. In this article, we review the present state of knowledge of the abiotic (clouds, sea ice, snow, suspended matter) and biotic (sea ice algae and phytoplankton) controls on the underwater light field. We focus on how the available light affects the seasonal cycle of primary production (sympagic and pelagic) and discuss the sensitivity of ecosystems to changes in the light field based on model simulations. Lastly, we discuss predicted future changes in under-ice light as a consequence of climate change and their potential ecological implications, with the aim of providing a guide for future research. 相似文献
Journal of Material Cycles and Waste Management - Waste water contaminated with inorganic mercury is considered a serious environmental problem, mainly due to the hazardous effects this contaminant... 相似文献