ADVERSE ECOLOGICAL EFFECTS ON COMMU

ADVERSE ECOLOGICAL EFFECTS ON COMMUNITIES

Scientists are most concerned about the effects of chemicals and other pollutants on communities. Short-term and temporary effects are much more easily measured than long-term effects of pollutants on ecosystem communities. Understanding the impact of effects requires knowledge of the time course and variability of these short-term changes.
Pollutants may adversely affect communities by disrupting their normal structure and delicate interdependencies. The structure of a community includes its physical system, usually created by the plant life and geological processes, as well as the relationships between its populations of biota.

For example, a pollutant may eliminate a species essential to the functioning of the entire community; it may promote the dominance of undesirable species (weeds, trash fish); or it may simply decrease the numbers and variety of species present in the community. It may also disrupt the dynamics of the food webs in the community by breaking existing dietary linkages between species. Most of these adverse effects in communities can be measured through changes in productivity in the ecosystem. Under natural stresses (for example, unusual temperature and moisture conditions), the community may be unable to tolerate effects of a chemical otherwise causing no harm.

An important facet of biological communities is the number and intensity of interactions between species. These interactions make the community greater than simply the sum of its parts. The community is stronger than its populations, and the ecosystem is more stable than its communities. A seriously altered interaction may adversely affect all the species dependent on it. Even so, some ecosystem properties or functions (such as nutrient dynamics) can be altered by chemicals without apparent effects on populations or communities. Thus, an important part of research in ecological effects is concerned with the relative sensitivity of ecosystems, communities, and populations to chemicals and to physical stresses.

Consider the effects of spraying an orchard with an insecticide when bees and other beneficial insects may be present and vulnerable to the toxicant. This practice is both economically and ecologically unsound, since it would deprive all plants in the area of pollinators and disrupt control of plant pests by their natural enemies. Advanced agricultural practices, such as integrated pest management (IPM), avoid these adverse effects through appropriate timing and selection of sprays in conjunction with non-chemical approaches to insect control.

Effects of chemicals on communities can be measured in laboratory model ecosystem (microcosm) studies, in intermediate sized systems (mesocosms, engineered field systems, open-top plant chambers, field pens), and in full field trials. Thus, data gathered about effects of chemicals on processes and species can be evaluated in various complex situations that reflect the real world.

ADVERSE EFFECTS ON SPECIES

Most information on ecological effects has been obtained from studies on single species of biota. These tests have been performed in laboratories under controlled conditions and chemical exposures, usually with organisms reared in the laboratory representing inhabitants of natural systems. Most tests are short-term, single exposures (acute toxicity assays), but long-term (chronic) exposures are used as well. Although such tests reveal which chemicals are relatively more toxic, and which species are relatively more vulnerable to their effects, these tests do not disclose much about either the important interactions noted above or the role of the range of natural conditions faced by organisms in the environment.
Generally, the effects observed in these toxicity tests include reduced rates of survival or increased death rates; reduced growth and altered development; reduced reproductive capabilities, including birth defects; changes in body systems, including behavior; and genetic changes. Any of these effects can influence the ability of species to adapt and respond to other environmental stresses and community interactions.

Environmental toxicology studies performed on species in the laboratory provide the basis for much of the current regulation of pollutants and have allowed major improvements in environmental quality. However, these tests yield only a few clues to effects on more complex systems. Long-term studies and monitoring of ecological effects of new and existing chemicals released into the environment are needed in order to create understanding of potential adverse ecological effects and their consequences.

SUMMARY

Adverse ecological effects from environmental pollutants occur at all levels of biological organization, but most information about these effects has been obtained with single species. The effects can be global or local, temporary or permanent, or short-lived (acute) or long-term (chronic). The most serious e

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Adverse ECOLOGICAL EFFECTS ON COMMUNITIES

Scientists are concerned Most About the effects of chemicals and pollutants on Other communities. Short-term and temporary effects are much more easily measured than long-term effects of pollutants on ecosystem communities. Impact of Knowledge requires the understanding of the effects and time course of these short-term variability Changes.
Pollutants May adversely affect their communities by disrupting Normal Delicate structure and interdependencies. The physical structure of a Community System includes ITS, usually Created by the Plant Life and Geological processes, as well as the relationships between populations of ITS Biota.

For example, a POLLUTANT May Eliminate a species Essential to the functioning of the entire Community; it may promote the dominance of undesirable species (weeds, trash fish); or it may simply decrease the numbers and variety of species present in the community. It may also disrupt the dynamics of the food webs in the community by breaking existing dietary linkages between species. Most of these adverse effects in communities can be measured through changes in productivity in the ecosystem. Natural under stresses (for example, unusual Temperature and Moisture conditions), the Community May be unable to tolerate effects of a Chemical otherwise causing no harm.

An important facet of Biological communities is the Number and Intensity of interactions between species. These interactions make the community greater than simply the sum of its parts. The community is stronger than its populations, and the ecosystem is more stable than its communities. A seriously altered interaction may adversely affect all the species dependent on it. Even so, some ecosystem properties or functions (such as nutrient dynamics) can be altered by chemicals without apparent effects on populations or communities. Thus, an important Part of Research in Ecological effects is concerned with the Relative sensitivity of ecosystems, communities, and populations to chemicals and to physical stresses.

Consider the effects of spraying an Orchard with an Insecticide when Bees and Other beneficial Insects May be present and. vulnerable to the toxicant. This practice is both economically and ecologically unsound, since it would deprive all plants in the area of pollinators and disrupt control of plant pests by their natural enemies. Advanced Agricultural Practices, such as Integrated Pest Management (IPM), Avoid these adverse effects Through appropriate Timing and selection of sprays in conjunction with non-Chemical approaches to Insect Control.

Effects of chemicals on communities Can be measured in Laboratory Model Ecosystem (microcosm). studies, in intermediate sized systems (mesocosms, engineered field systems, open-top plant chambers, field pens), and in full field trials. Thus, effects of chemicals About Data gathered on species and processes Can be evaluated in Various Complex Situations that Reflect the Real World.

EFFECTS ON SPECIES adverse

effects Most information on Ecological Studies has been obtained from on single species of Biota. These tests have been performed in laboratories under controlled conditions and chemical exposures, usually with organisms reared in the laboratory representing inhabitants of natural systems. Most tests are short-term, single exposures (acute toxicity assays), but long-term (chronic) exposures are used as well. Although such tests reveal which chemicals are relatively more toxic, and which species are relatively more vulnerable to their effects, these tests do not disclose much about either the important interactions noted above or the role of the range of natural conditions faced by organisms in the environment. .
Generally, the effects observed in these tests include reduced toxicity or Survival Rates of Increased Death Rates; reduced growth and altered development; reduced reproductive capabilities, including birth defects; changes in body systems, including behavior; and genetic changes. Any of these effects Can influence the ability of species to Adapt and Respond to Other Environmental stresses and Community interactions.

Environmental toxicology Studies performed on species in the Laboratory provide the basis for much of the current Regulation of pollutants and have allowed Major Improvements in Environmental quality. . However, these tests yield only a few clues to effects on more complex systems. Long-term Studies and Monitoring of Ecological effects of New and existing chemicals Released Into the Environment are Needed in Order to create understanding of potential adverse Ecological effects and their Consequences.

SUMMARY

Adverse Ecological effects from Environmental pollutants occur at all levels of Biological Organization, but. most information about these effects has been obtained with single species. The effects can be global or local, temporary or permanent, or short-lived (acute) or long-term (chronic). The most serious e

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ADVERSE ECOLOGICAL EFFECTS ON COMMUNITIES.Scientists are most concerned about the effects of chemicals and other pollutants on communities. Short-term and temporary. Effects are much more easily measured than long-term effects of pollutants on ecosystem communities. Understanding the impact. Of effects requires knowledge of the time course and variability of these short-term changes.Pollutants may adversely affect communities by disrupting their normal structure and delicate interdependencies. The structure. Of a community includes its, physical system usually created by the plant life and geological processes as well, as the. Relationships between its populations of biota.For example a pollutant, may eliminate a species essential to the functioning of the entire community; it may promote the. Dominance of undesirable species (weeds trash, fish); or it may simply decrease the numbers and variety of species present. In the community. It may also disrupt the dynamics of the food webs in the community by breaking existing dietary linkages. Between species. Most of these adverse effects in communities can be measured through changes in productivity in the, ecosystem. Under natural stresses (for example unusual temperature, and moisture conditions), the community may be unable to tolerate. Effects of a chemical otherwise causing no harm.An important facet of biological communities is the number and intensity of interactions between species. These interactions. Make the community greater than simply the sum of its parts. The community is stronger than its populations and the, ecosystem. Is more stable than its communities. A seriously altered interaction may adversely affect all the species dependent on, it. Even so some ecosystem, properties or functions (such as nutrient dynamics) can be altered by chemicals without apparent. Effects on populations or communities. Thus an important, part of research in ecological effects is concerned with the relative. Sensitivity, of ecosystems communities and populations, to chemicals and to physical stresses.Consider the effects of spraying an orchard with an insecticide when bees and other beneficial insects may be present and. Vulnerable to the toxicant. This practice is both economically and ecologically unsound since it, would deprive all plants. In the area of pollinators and disrupt control of plant pests by their natural enemies. Advanced, agricultural practices. Such as integrated pest management (IPM), avoid these adverse effects through appropriate timing and selection of sprays. In conjunction with non-chemical approaches to insect control.Effects of chemicals on communities can be measured in laboratory model ecosystem (microcosm), studies in intermediate. Sized systems (mesocosms engineered systems, field, plant, open-top chambers field pens), and in full field trials, Thus,. Data gathered about effects of chemicals on processes and species can be evaluated in various complex situations that reflect. The real world.ADVERSE EFFECTS ON SPECIES.Most information on ecological effects has been obtained from studies on single species of biota. These tests have been. Performed in laboratories under controlled conditions and chemical exposures usually with, organisms reared in the laboratory. Representing inhabitants of natural systems. Most tests, are short-term single exposures (acute toxicity assays), but long-term. (chronic) exposures are used as well. Although such tests reveal which chemicals are relatively, more toxic and which species. Are relatively more vulnerable to their effects these tests, do not disclose much about either the important interactions. Noted above or the role of the range of natural conditions faced by organisms in the environment.Generally the effects, observed in these toxicity tests include reduced rates of survival or increased death rates; reduced. Growth and altered development; reduced, reproductive capabilities including birth defects; changes in, body systems including. Behavior; and genetic changes. Any of these effects can influence the ability of species to adapt and respond to other environmental. Stresses and community interactions.Environmental toxicology studies performed on species in the laboratory provide the basis for much of the current regulation. Of pollutants and have allowed major improvements in environmental quality. However these tests, yield only a few clues. To effects on more complex systems. Long-term studies and monitoring of ecological effects of new and existing chemicals. Released into the environment are needed in order to create understanding of potential adverse ecological effects and their. Consequences.SUMMARY.Adverse ecological effects from environmental pollutants occur at all levels of, biological organization but most information. About these effects has been obtained with single species. The effects can be global or local temporary or permanent or,,, Short-lived (acute) or long-term (chronic). The most serious e.