Ch 8a Flashcards
What are sublethal effects
include responses to doses or concentrations below those resulting in somatic death
Toxin levels that have sublethal effects in the lab that may result in the organisms death in nature is known as…
ecological mortality - described as the reduction of organism fitness in the ecosystem that results in death due to a toxin exposure
True or false: Sterility can be considered ecological death
TRUE
How can sublethal effects be minimized by animals that are mobile ?
by avoidance of contaminated areas
What is Selyean stress
- distinguished from cellular stress response (heat shock, SOS response)
- initial stages are the “flight or Fight” response
- specific set of physiological responses which make up the boys attempt to reestablish or maintain homeostasis when under the influence of a stressor
True or False: reactions that are specific to a given insult such as metallothionein production in response to metal exposure IS and example of Selyean stress.
FALSE
What are the three phases in the physiological response to resist change or regain homeostasis
- Alarm reaction (flight or fight)
- Adaptation reaction
- Exhaustion phase
Describe what happens in the body with the Alarm reaction
- short term response
- heat rate, blood pressure increase
- Release of adrenaline, reduced blood supply to digestive system, increased blood supply to skeletal muscle
Describe what happens in the body with the adaptation reaction
- longer term response to persistent stressor
- enhanced tissue level response like enlarged adrenal glands, or shrinkage of thymus, lymph nodes, spleen, or appearance of gastric ulcers
Describe what happens in the body with the Exhaustion phase
Long term exposure may result in the stressor exceeding the individuals ability to maintain homeostasis, may eventually lead to death
why is growth often used as a parameter for sublethal effects ?
Because it can be considered to integrate various biochemical and physiological events
Whats and issue with using growth as a parameter for sublethal effects?
It does not usually show underlying cause for the growth effects
- ex: fish growth decreases under acidic conditions
List 8 possible causes of growth effects
- lack of food
- dealing with stress therefore less energy put into growth
- osmotic regulation problems
- Excretion of dissolved metals
- Interference with growth hormones
- Respiration problems due to increased mucus in the gills
- Difficulty feeding
- Tissue damage (acid burns)
Give 2 examples where growth results are more complex
- toxin exposure resulting in higher growth rate but decreased longevity
- Later compensatory growth may mask toxin effects
Sometimes a very low concentration of toxin can actually increase growth compared to the control, explain why & give an example
Its a nonspecific response called hormesis, may result form overcompensation to low levels of stressors. In some cases can result from the toxin acting as a nutrient at low concentrations
- ex: copper in the copepod data
