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661.
The structuring and organizing effects of apex predators on ecosystems are becoming increasingly well documented. The enhancement of kelp forests via sea otter predation on herbivorous sea urchins is among the earliest and best known examples. This study provides evidence for direct and indirect trophic interactions among sea otters, predatory sea stars, and filter-feeding mussels (Mytilus trossulus) and barnacles (Semibalanus cariosis). In western Massacre Bay at Attu Island (173°E, 53°N), subtidal transects showed sea star body size and biomass density declined markedly between 1983 and 1994 as sea otters reinhabited this area. Mussels and barnacles translocated from the rocky intertidal zone to shallow subtidal habitats to assess loss rates from sea star predation showed lower mortality rates after the arrival of sea otters. Prey mortality rates in subtidal caged controls were consistently low and similar to those of intertidal controls in both years. These findings elucidate a trophic pathway by which sea otters can influence ecosystems separate from the well-known sea otter/sea urchin/macroalgae cascade. 相似文献
662.
N. N. Nemova E. P. Ieshko O. V. Meshcheryakova N. V. Il’mast L. V. Anikieva D. I. Lebedeva M. V. Churova O. P. Sterligova Ya. A. Kuchko 《Russian Journal of Ecology》2012,43(4):323-327
The population structure and biological parameters of the European whitefish, Coregonus lavaretus (L.), have been analyzed in a technogenically polluted water body. The biochemical state of the whitefish and the fauna and morphology of helminths parasitizing them have been assessed. It is shown that the species composition of the fish, plankton, benthos, and parasite faunas of this water body are depleted and the morphological parameters of common fish parasites are altered. It is noted that, in addition to adaptive rearrangements in biochemical metabolism, the whitefish from the transformed water body are characterized by a reduction in the level of protein synthesis in muscles and the rate of aerobic energy metabolism in the liver and muscles. 相似文献
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V. A. Romanenkov J. U. Smith P. Smith O. D. Sirotenko D. I. Rukhovitch I. A. Romanenko 《Regional Environmental Change》2007,7(2):93-104
The Model of Humus Balance was used to estimate the influence of climate effects and changing agricultural practices on carbon
(C) levels in soddy–podzolic soils in the Russian Federation for the years 2000–2050. The model was linked with a spatial
database containing soil, climate and farming management layers for identification of spatial change of C sequestration potential.
Analysis of relationships between C, soil texture and climate indicated that compared with a business-as-usual scenario, adaptation
measures could increase the number of polygons storing soil organic carbon (SOC) by 2010–2020. The rate of possible C loss
is sensitive to the different climate scenarios, with a maximum potential for SOC accumulation expected in 2030–2040, thereafter
decreasing to 2050. The effect is most pronounced for the arid part of the study area under the emission scenario with the
highest rate of increase in atmospheric CO2 concentration, supporting findings from the dynamic SOC model, RothC. C sequestration during the study period was permanent
for clay and clay loam soils with a C content of more than 2%, suggesting that C sequestration should be focused on highly
fertile, fine-textured soils. We also show that spatial heterogeneity of soil texture can be a source of uncertainty for estimates
of SOC dynamics at the regional scale.
Figures in color are available at 相似文献
668.
Trends in plant cover synanthropization along a plain-foothills-mountains gradient have been revealed in the reserve. Characteristics of plant communities in anthropogenically disturbed habitats, centers of concentration of anthropophytes and apophytes, and pathways of their migration are described. 相似文献
669.
Nelzair A. Vianna Daniel Gonçalves Flavia Brandão Roberta P. de Barros Gilberto M. Amado Filho Rodrigo O. Meire João Paulo M. Torres Olaf Malm Argemiro D’Oliveira Júnior Leonardo R. Andrade 《Environmental science and pollution research international》2011,18(3):416-427
Purpose
The aims of this paper were to quantify the heavy metals (HM) in the air of different sites in Rio de Janeiro (RJ) and Salvador (SA) using Tillandsia usneoides (Bromeliaceae) as a biomonitor, and to study the morphology and elemental composition of the air particulate matter (PM) retained on the Tillandsia surface. 相似文献670.