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Polluted Areas (polluted + area)
Selected AbstractsEnvironmental and ontogenetic constraints on developmental stability in the spatangoid sea urchin Echinocardium (Echinoidea)BIOLOGICAL JOURNAL OF THE LINNEAN SOCIETY, Issue 2 2006THOMAS SAUCEDE Spatangoid irregular sea urchins are detritivorous benthic organisms particularly prone to variations of environment, and their mode of growth and plate morphology make them an appropriate model to assess the effects of environmental variations. Two populations of Echinocardium flavescens were sampled in two sites of the Norwegian coast characterized by contrasted environmental conditions. Different morphological descriptors (plate areas, interlandmarks distances, overall size, and shape of the posterior ambulacra) were used to appraise interindividual variations, and fluctuating asymmetry. The comparisons were carried out using classical fluctuating asymmetry (FA) methods, as well as Procrustean approaches. The population suspected to be less influenced by anthropic activities exhibits lower levels of FA for the size parameters (plate surfaces, interlandmarks distances, and centroid size) than the population located in a polluted area. Conversely, it shows higher FA values for the shape parameters (landmarks configuration). Interindividual variations appear to be correlated to FA. Variations are orientated according to the main growth axis of the ambulacra, and their intensity is stronger in the large posterior plates, which are also the youngest. These results are discussed with respect to architectural constraints involved in the sea urchin growth. © 2006 The Linnean Society of London, Biological Journal of the Linnean Society, 2006, 88, 165,177. [source] Stress synergy between drought and a common environmental contaminant: studies with the collembolan Folsomia candidaGLOBAL CHANGE BIOLOGY, Issue 4 2001Rikke Højer Summary The term global change is used predominantly in connection with the global temperature increase and associated changes in weather patterns over the next century. In a broader sense it also covers other anthropogenic impacts on the environment such as habitat fragmentation and pollution. The individual effects of each of these stress types have been extensively studied in the biota. However, organisms will frequently encounter these stress types in combination rather than alone and there is little information available on the effects of stress combinations. Here an examination is made of the interaction between realistic levels of summer drought and a common contaminant of agricultural soil (4-nonylphenol, NP), on a widespread soil invertebrate, the collembolan Folsomia candida. These stress factors were tested individually and in combination using a full factorial design. This approach revealed the existence of highly significant Bliss type synergistic interaction between the two stress types. Thus, exposure to NP significantly reduced the drought tolerance of this organism and, reciprocally, the toxicity of NP (LC50) during realistic summer drought was more than doubled in comparison to the value obtained under optimal soil moisture conditions. Furthermore, it is shown that NP has a detrimental effect on the physiological mechanisms underlying this animal's drought tolerance, thus providing some explanation for the mechanisms involved in the synergy. It is argued that this type of synergy is unlikely to be confined to this particular combination of stresses and thus there is a need to study the interactions between dominant natural stresses and pollution. The most important implication of these results is that some of the effects of global climate changes can be predicted to be most severe in polluted areas. [source] Effects of air pollution on natural enemies of the leaf beetle Melasoma lapponicaJOURNAL OF APPLIED ECOLOGY, Issue 2 2000Elena L. Zvereva Summary 1. ,Air pollution might have differential effects on herbivores and their natural enemies, thus changing population dynamics. Therefore, from 1993 to 1998 we studied mortality caused by parasitoids and predators to the willow-feeding leaf beetle Melasoma lapponica in the impact zone of the Severonikel nickel,copper smelter (Kola Peninsula, north-western Russia). 2. ,Densities of M. lapponica were very low at clean forest sites (below five beetles per 10-min count) but higher in polluted areas (10,340 beetles per count). There were, however, variations between study years. 3. ,Egg predation, mainly by syrphid larvae and zoophagous bugs, was higher at relatively clean sites (55·3%) than at polluted sites (22·2%). Similarly, predation on larvae by zoophagous bugs and wood ants was higher at clean sites (68·4%) than at polluted sites (32·9%). 4. ,In contrast to predation, mortality caused by the parasitoid flies Megaselia opacicornis (Phoridae) and Cleonice nitidiuscula (Tachinidae) was lower at clean sites (12·3%) than at polluted sites (35·3%). Total parasitism levels increased significantly with pollution load. 5. ,Total mortality caused by natural enemies was higher at clean sites (93·7%) than at polluted sites (79·4%) due to higher predation rates, which may partly explain increased leaf beetle density within the smelter's impact zone. The effects of predators in clean forests were confirmed by the extinction of adults of M. lapponica introduced to one of the forest sites. 6. ,Although some individual sources of mortality appeared to be density dependent (direct or inverse), the joint effect of all natural enemies was not. 7. ,Our data show that a decrease in predation can contribute to increased leaf beetle density at polluted sites. However, the overall effects of natural enemies in this case were not sufficient to account for all density variations between sites. To our knowledge this is the first study to assess how pollution affects the partitioning of mortality in herbivorous insects between predators and parasitoids. [source] Impacts of increased nitrogen supply on Norwegian lichen-rich alpine communities: a 10-year experimentJOURNAL OF ECOLOGY, Issue 3 2005ELI FREMSTAD Summary 1Species cover was tested during a 10-year fertilization experiment in the low-alpine Cetrarietum nivalis community and the middle-alpine Phyllodoco-Juncetum trifidi community in the Dovre mountains of south-central Norway. Nitrogen was added at 7, 35 and 70 kg N ha,1 year,1, with the highest dose corresponding to approximately 3.5 times the annual deposition in south-west Norway. 2Both communities are dominated by lichens (Cladonia spp. and Cetraria spp., respectively), have a patchy structure and are ,conservative' as regards species content. 3Lichens, which showed a decrease in cover and size, and after some years developed discoloured thalli, are the best organisms for monitoring changes in alpine vegetation that is exposed to increased nitrogen deposition. The most sensitive species in Cetrarietum nivalis appeared to be Alectoria nigricans and Cetraria ericetorum, but more abundant species (Cladonia mitis, C. stellaris and Cetraria nivalis) are likely to be more reliable indicators. Cetraria delisei seems to be a reliable indicator species for monitoring in Phyllodoco-Juncetum trifidi. 4Fertilization had no significant effect on the vascular plants (dwarf shrubs and a few graminoids) in either community, except for Festuca ovina, the cover of which increased slightly. 5Nitrogen pollution may affect oligotrophic, alpine communities differently, depending on their species composition and horizontal structure (patchiness). 6It is suggested that other factors, such as climate, soil properties and community structure, may be more important than long-range nitrogen pollution for determining species composition and species cover in many of the oligotrophic, alpine communities in southern Norway. However, in lichen-rich communities, critical loads have already been exceeded in the most polluted areas of south-west Norway. [source] Genomic pattern of adaptive divergence in Arabidopsis halleri, a model species for tolerance to heavy metalMOLECULAR ECOLOGY, Issue 9 2009CLAIRE-LISE MEYER Abstract Pollution by heavy metals is one of the strongest environmental constraints in human-altered environments that only a handful of species can cope with. Identifying the genes conferring to those species the ability to grow in polluted areas is a first step towards a global understanding of the evolutionary processes involved and will eventually improve phytoremediation practices. We used a genome-scan approach to detect loci under divergent selection among four populations of Arabidopsis halleri growing on either polluted or nonpolluted habitats. Based on a high density of amplified fragment length polymorphism (AFLP) markers (820 AFLP markers, i.e. ~1 marker per 0.3 Mb), evidence for selection was found for some markers in every sampled population. Four loci departed from neutrality in both metallicolous populations and thus constitute high-quality candidates for general adaptation to pollution. Interestingly, some candidates differed between the two metallicolous populations, suggesting the possibility that different loci may be involved in adaptation in the different metallicolous populations. [source] | ||||||||||