L8: Effects on Individuals

Question 1

Sublethal Effects

Answer 1

Occur at concentrations or doses below those producing death
Include changes in physiology, growth, reproduction, behaviour, etc.
Diminish an individual’s fitness
More difficult to measure, likely more important in ultimate consequences
Sublethal effects can have lethal consequences

Question 2

Sublethal exposures to contaminants effect on physiology of animals

Answer 2

Includes respiration, metabolism, excretion, ion regulation, osmoregulation, bioenergetics (e.g. gill ventilation increases in fish exposed to metals)

Question 3

Sublethal exposures to contaminants effect on physiology of plants

Answer 3

Includes studies on root growth, respiration, transpiration, nitrogen or carbon fixation, chlorophyll content, photosynthesis (e.g. PCBs decrease photosynthesis in plants)

Question 4

Immunology

- what aspects do contaminants affect?

Answer 4

Responsiveness of immune system (timing, magnitude) 
Cellular responses (lymphocyte and phagocyte production)
Humoral responses (antibody)

Question 5

Growth

- how is it measured/compared?

Answer 5

Easy to measure, integrates suite of biochemical and physiological effects into one quality associated with individual’s fitness

Length or height
Mass
Changes in length or mass over time (growth rates)
Condition (mass of organism relative to its length)

Question 6

Behavioural toxicology definition

Answer 6

contaminant effects on animal and plant activities

Most often measured in lab

Question 7

Why is Behavioural toxicology underused in ecotoxicology?

Answer 7

1. Believed to be difficult to study objectively, may generate biased data
2. Behaviours and behavioural data highly variable
3. Difficult to extrapolate from lab to field studies

Some feel that behaviours more sensitive than other endpoints, effects occur at lower concentrations

Question 8

Tadpole Study (pH & Al)

• mortality
• Al conc/ Na conc
• growth
• swimming speeds

Answer 8

Greater aluminum conc in water =elicit lethal response in lower pH

In lower pH, aluminum uptake into body was greatest
Low pH & Al known to disrupt Na+ and Cl- regulation in fish/tadpoles:
Increased aluminum conc and decreased pH=lower Na conc within the body

High aluminum conc=decreased growth relative to control (pH 7) in tadpoles in lower pH

Reduced swimming speeds relative to controls in lower pH & greater aluminum conc