Distinguishing between effects of natural and anthropogenic environmental factors on ecosystems is a fundamental problem in environmental science. In river systems the longitudinal gradient of environmental factors is one of the most relevant sources of dissimilarity between communities that could be confounded with anthropogenic disturbances. To test the hypothesis that in macroinvertebrate communities the distribution of species' sensitivity to organic toxicants is independent of natural longitudinal factors, but depends on contamination with organic toxicants, we analysed the relationship between community sensitivity SPEAR(organic) (average community sensitivity to organic toxicants) and natural and anthropogenic environmental factors in a large-scale river system, from alpine streams to a lowland river. The results show that SPEAR(organic) is largely independent of natural longitudinal factors, but strongly dependent on contamination with organic toxicants (petrochemicals and synthetic surfactants). Usage of SPEAR(organic) as a stressor-specific longitude-independent measure will facilitate detection of community disturbance by organic toxicants.
Thermal stress, food poisoning, infectious diseases, malnutrition, psychiatric illness as well as injury and death from floods, storms and fire are all likely to become more common as the earth warms and the climate becomes more variable. In contrast, obesity, type II diabetes and coronary artery disease do not result from climate change, but they do share causes with climate change. Burning fossil fuels, for example, is the major source of greenhouse gases, but it also makes pervasive physical inactivity possible. Similarly, modern agriculture's enormous production of livestock contributes substantially to greenhouse gas emissions, and it is the source of many of our most energy-rich foods. Physicians and societies of medical professionals have a particular responsibility, therefore, to contribute to the public discourse about climate change and what to do about it.
ReprintIn: Ugeskr Laeger. 2008 Aug 25;170(35):2667-818761852
A selective approach may be used in an ecological study where the aim is to choose a subset of units of analysis (UAs) and produce interpretations about a population of interest (PI) based solely on those UAs. The results for the PI will be reliable if that population is concentrated in the selected UAs and rare in other UAs. This article presents a graphical tool that helps determine whether these conditions are satisfied.
Data on the Inuit and Métis ancestry populations from the 1996 Census of Canada are used for illustrative purposes. Based on a classification statistics table, a concentration-coverage curve can be created for a given PI. The shape of the curve indicates whether it is possible to choose a threshold that will yield both adequate concentration and adequate coverage of the PI.
The concentration-coverage curve shows that, among Aboriginal peoples living in rural areas, the Inuit population is classifiable, but the Metis population is not.
This method can be applied to any ecological study focussing on the proportion of individuals sharing a single characteristic defined by a binary variable.
Depletion of stratospheric ozone over the Antarctic has been re-occurring yearly since 1974, leading to enhanced UV-B radiation. Arctic ozone depletion has been observed since 1990. Ozone recovery has been predicted by 2050, but no signs of recovery occur. Here we review responses of polar plants to experimentally varied UV-B through supplementation or exclusion. In supplementation studies comparing ambient and above ambient UV-B, no effect on growth occurred. UV-B-induced DNA damage, as measured in polar bryophytes, is repaired overnight by photoreactivation. With UV exclusion, growth at near ambient may be less than at below ambient UV-B levels, which relates to the UV response curve of polar plants. UV-B screening foils also alter PAR, humidity, and temperature and interactions of UV with environmental factors may occur. Plant phenolics induced by solar UV-B, as in pollen, spores and lignin, may serve as a climate proxy for past UV. Since the Antarctic and Arctic terrestrial ecosystems differ essentially, (e.g. higher species diversity and more trophic interactions in the Arctic), generalization of polar plant responses to UV-B needs caution.
Despite global occurrence of several perfluorinated compounds (PFCs) the potential ecological effects of such substances on natural populations are not known. In endangered lesser black-backed gulls (Larus fuscus fuscus) on the Norwegian Coast, the blood concentrations of PFCs were as high as legacy organochlorines (OCs), and here we examined whether PFCs show associations similar to those of OCs to factors potentially affecting population growth, by evaluating relationships between contaminant concentrations and demographic parameters (reproductive performance and the probability of adults returning between breeding seasons). PFCs were not adversely associated with demographic parameters, while the most persistent OCs; notably PCB and p,p'-DDE, were adversely associated with early chick survival, and adult return rate. This study thus suggests that when the concentrations of PFCs and OCs are of similar magnitude in a gull population, OCs are more likely to cause adverse ecological effects.
Department of Archaeology & Natural History, Research School of Pacific and Asian Studies, Australian National University, Canberra, Australian Capital Territory 0200, Australia. firstname.lastname@example.org
Philos Trans R Soc Lond B Biol Sci. 2007 Feb 28;362(1478):219-28
In the highlands of New Guinea, the development of agriculture as an indigenous innovation during the Early Holocene is considered to have resulted in rapid loss of forest cover, a decrease in forest biodiversity and increased land degradation over thousands of years. But how important is human activity in shaping the diversity of vegetation communities over millennial time-scales? An evaluation of the change in biodiversity of forest habitats through the Late Glacial transition to the present in five palaeoecological sites from highland valleys, where intensive agriculture is practised today, is presented. A detailed analysis of the longest and most continuous record from Papua New Guinea is also presented using available biodiversity indices (palynological richness and biodiversity indicator taxa) as a means of identifying changes in diversity. The analysis shows that the collapse of key forest habitats in the highland valleys is evident during the Mid - Late Holocene. These changes are best explained by the adoption of new land management practices and altered disturbance regimes associated with agricultural activity, though climate change may also play a role. The implications of these findings for ecosystem conservation and sustainability of agriculture in New Guinea are discussed.
Cites: Asia Pac Viewp. 2001;42(2-3):209-1819170258
The extent of remediation of contaminated industrial sites depends on spatial heterogeneity of contaminant concentration and spatially explicit risk characterization. We used sequential Gaussian simulation (SGS) and indicator kriging (IK) to describe the spatial distribution of polycyclic aromatic hydrocarbons (PAHs), pH, electric conductivity, particle aggregate distribution, water holding capacity, and total organic carbon, and quantitative relations among them, in a creosote polluted soil in southern Sweden. The geostatistical analyses were combined with risk analyses, in which the total toxic equivalent concentration of the PAH mixture was calculated from the soil concentrations of individual PAHs and compared with ecotoxicological effect concentrations and regulatory threshold values in block sizes of 1.8 x 1.8 m. Most PAHs were spatially autocorrelated and appeared in several hot spots. The risk calculated by SGS was more confined to specific hot spot areas than the risk calculated by IK, and 40-50% of the site had PAH concentrations exceeding the threshold values with a probability of 80% and higher. The toxic equivalent concentration of the PAH mixture was dependent on the spatial distribution of organic carbon, showing the importance of assessing risk by a combination of measurements of PAH and organic carbon concentrations. Essentially, the same risk distribution pattern was maintained when Monte Carlo simulations were used for implementation of risk in larger (5 x 5 m), economically more feasible remediation blocks, but a smaller area became of great concern for remediation when the simulations included PAH partitioning to two separate sources, creosote and natural, of organic matter, rather than one general.