Экологические эффекты стрессоров окружающей среды

Аннотация

Regimes of environmental stress are exceedingly complex. Particular stressors exist within continua of intensity of environmental factors. Those factors interact with each other, and their detrimental effects on organisms are manifest only at relatively high or low strengths of exposure—in fact, many of them are beneficial at intermediate levels of intensity. Although a diversity of environmental factors is manifest at any time and place, only one or a few of them tend to be dominant as stressors. It is useful to distinguish between stressors that occur as severe events (disturbances) and those 267 that are chronic in their exposure, and to aggregate the kinds of stressors into categories (while noting some degree of overlap among them). Key words: environmental stress, stressors, chronic stress, acute stress, anthropogenic stress, disturbance, resistance, resilience, ecological integrity Аннотация: Режимы экологического стресса чрезвычайно сложный. Конкретные стрессоры существуют в пределах континуума интенсивности факторов окружающей среды. Эти факторы взаимодействуют друг с другом, и их пагубное воздействие на организмы проявляется только при относительно высокой или низкой интенсивности воздействия – на самом деле, многие из них полезны при промежуточных уровнях интенсивности. Хотя разнообразие факторов окружающей среды проявляется в любое время и в любом месте, только один или несколько из них, как правило, являются доминирующими факторами стресса. Полезно проводить различие между стрессорами, которые проявляются как серьезные события или нарушения, и теми, которые являются хроническими по своему воздействию, и объединяют виды стрессоров по категориям; отмечая при этом некоторую степень совпадения между ними. Ключевые слова: экологический стресс, стрессоры, хронический стресс, острый стресс, антропогенный стресс, нарушение, прочность, устойчивость, экологическая целостность Ecology may be simply defined as the study of the relationships of organisms and their environment. Within that context, the study of environmental influences or factors that affect organisms and ecosystems is a core subject matter. Effects of environmental influences may be exerted at any level of ecology: on individual organisms, populations, communities, echoscopes – landscapes or seascapes, and, ultimately, the biosphere in its entirety. There are also influences on the functions of ecosystems, such as productivity and nutrient cycling. At any particular time or place, the relative importance of those influences can be beneficial, damaging, or inconsequential. The study of environmental factors is an important aspect of ecology because it helps ecologists to better understand the influences that affect, and perhaps even control, the structural and functional attributes of ecosystems and their components. This understanding is of theoretical interest and is also important to the application of ecological knowledge to the resolution of environmental problems. Environmental factors exist as complex regimes of intensities of exposure, which vary on a continuous scale as well as over space and time and also interact with each other. Within the continua of intensity of environmental factors, the range of stressors is marked by a manifestation of detrimental effects on organisms or ecosystem processes at relatively high or low strengths of exposure—in fact, many factors are beneficial at intermediate levels. Although a great diversity of environmental factors are manifest at any time and place, only one or a few tend to be dominant as stressors. Stressors of natural origin have always been part of the environmental context of organisms and ecosystems. Increasingly, however, anthropogenic stressors, those associated with human activities, are exerting an important influence. In fact, anthropogenic stressors are now more pronounced than natural influences over vast tracts of ‗working‘ landscapes and seascapes that are being used to serve human economies, such as in agricultural and urbanized areas. As such, environmental stressors are influences that limit the performance of organisms or of their characteristics at aggregate levels, such as those of a population or community. In the sense meant here, ‗performance‘ of an individual is related to such attributes as its productivity and reproductive fitness relative to its genetic potential. Almost always, the realized performance of an individual is less than would be possible under optimal environmental conditions. Depending on the intensity of a stressor regime, the growth and fitness of organisms may be diminished or even be made nonviable. Because individuals may exhibit genetically based differences in their tolerance of stressors, this aspect of the environmental regime has an influence on the evolutionary dynamics of populations and species. Environmental stressors also affect ecosystems at the larger scales of populations, communities, and echoscopes. In these cases, ‗performance‘