Stress occurs when pressures exceed resources. It can be caused by environmental stressors like noise, crowding, air pollution, extreme temperatures, and natural disasters. Environmental stressors exert influence on individual organisms and entire ecosystems. They can be physical, like fires and pollution, thermal like heat, or biological, through interactions between organisms. Managing stress requires addressing the balance between pressures and available resources.
4. S=P R
• Stress occurs when the pressure
is greater than the resource.
5. STRESSES
• A state of mental or emotional strain or tension
resulting from adverse or demanding
circumstances.
6. STRESSOR
• A stressor is a chemical or biological agent,
environmental condition, external stimulus
or an event that causes stress to an organism.
An event that triggers the stress response
may include: environmental stressors (hypo
or hyper-thermal temperatures, elevated
sound levels, over-illumination,
overcrowding).
7. ENVIRONMENTAL STRESSORS
• Stressors that are found in our surroundings
are called environmental stressors.
Everyday life is full of environmental
stressors that cause minor irritations. If you
use an alarm clock to wake up, the loud
noise from your alarm is an environmental
stressor. Extreme temperatures are also
environmental stressors and can lead to
discomfort.
8. ENVIRONMENTAL STRESSORS
• Other common environmental stressors include:
• Noise
• Crowding
• Air quality
• Colours
• Tornadoes and other natural disasters
• War and other manmade disasters
• Light
• Insects
9.
10. ENVIRONMENTAL STRESSORS
• Environmental stress refers to physical, chemical, and
biological constraints on the productivity of species and on
the development of ecosystems. When the exposure to
environmental stressors increases or decreases in intensity,
ecological responses result. Stressors can be natural
environmental factors, or they may result from the activities
of humans. Some environmental stressors exert a relatively
local influence, while others are regional or global in their
scope. Stressors are challenges to the integrity of
ecosystems and to the quality of the environment.
11. ENVIRONMENTAL STRESSORS
• Species and ecosystems have some capacity to
tolerate changes in the intensity of environmental
stressors. This is known as resistance, but there are
limits to this attribute, which represent thresholds
of tolerance. When these thresholds are exceeded
by further increases in the intensity of
environmental stress, substantial ecological changes
are caused.
12.
13. ENVIRONMENTAL STRESSORS
• Recent research has linked extreme temperatures, crowding,
and noise with increased levels of discomfort and
aggression. Studies have also shown that crime rates are
higher during those hot summer days. Different colours can
raise or lower your stress levels. For example, green is often
associated with life and growth and is known to reduce
tension and anxiety. Exposure to light can improve your
mood and decrease fatigue, while prolonged exposure to
darkness can interfere with sleep patterns and lead to
symptoms of depression.
14. Environmental stressors can be grouped into
the following categories:
• Physical Stress
• Wildfires
• Pollution
• Thermal Stress
• Radiation Stress
• Climatic Stress
• Biological Stress
15. CATEGORIES
• Physical stress refers to brief but intense exposures
to kinetic energy. This is a type of ecological
disturbance because of its acute, episodic nature.
Examples include volcanic eruptions, windstorms,
and explosions.
• Wildfire is also a disturbance, during which much
of the biomass of an ecosystem is combusted, and
the dominant species may be killed.
16. CATEGORIES
• Pollution occurs when chemicals are present in
concentrations large enough to affect organisms and thereby
cause ecological changes. Toxic pollution can be caused by
gases such as sulfur dioxide and ozone, by elements such as
arsenic, lead, and mercury, and by pesticides such as DDT.
Inputs of nutrients such as phosphate and nitrate can
influence productivity and other ecological processes,
causing a type of pollution known as eutrophication.
17. CATEGORIES
• Thermal stress occurs when releases of heat influence
ecosystems, as happens in the vicinity of natural hot-water
vents on the ocean floor, and near industrial discharges of
heated water.
• Radiation stress is associated with excessive loads of
ionizing energy. This can occur on mountain tops where
there are intense exposures to ultraviolet radiation, and in
places where there are exposures to radioactive materials.
18. CATEGORIES
• Climatic stress is associated with excessive or
insufficient regimes of temperature, moisture, solar
radiation, and combinations of these. Tundra and
deserts are examples of climatically stressed
ecosystems, while tropical rainforests occur under a
relatively benign climatic regime.
• Biological stresses are associated with the diverse
interactions that occur among organisms of the
same or different species.
