Lecture 1

Question 1

what is a marine mammal?

Answer 1

must meet all characteristics of all mammals:
- breathe air through lungs
- warm-blooded
- have hair/fur (at some point in their lives)
- produce milk to nurse their young

Question 2

what 3 taxonomic orders did marine mammals evolve from?

Answer 2

1) cetacea (whales, dolphins, porpoises)
2) carnivora (fin-footed: seals, sea lions, walrus, polar bears, sea otters)
3) sirenia (manatees and duogongs)

Question 3

what are 6 characteristics of marine mammals?

Answer 3

1) not all are closely related
2) form a habitat-based group of animals associated with water
3) feed at different trophic levels
4) occur from freshwater to open-ocean ecosystems
5) found across most latitudes
6) important component of ecosystem structure and function

Question 4

what is marine mammal ecotoxicology?

Answer 4

the study of the exposure, accumulation, and effects of contaminants in marine mammals

Question 5

what is the definition of toxicology?

Answer 5

study of adverse effects of chemical, biological, or physical substances on living organisms

Question 6

what is a toxicant?

Answer 6

a synthetic, human-made, toxic chemical

Question 7

what is a toxin?

Answer 7

poisons produced within living cells or organs of plants, animals, and bacteria (eg. biotoxins)

Question 8

what is a contaminant?

Answer 8

a substance that is present where it should not be, but is not necessarily harmful

Question 9

what is a pollutant?

Answer 9

a substance that causes pollution and adverse effects on an organism or an environment

Question 10

all _____ are _____, but not all _____ are _____

Answer 10

pollutants, contaminants, contaminants, pollutants

Question 11

what are 2 examples of toxic substances that can be produced by both natural and anthropogenic activities? how are they produced?

Answer 11

1) polycyclic aromatic hydrocarbons (PAHs): produced by the combustion of organic matter through ordinary processes (eg. forest fires) and human activities (eg. combustion of coal for energy production and cigarette smoking)
2) arsenic (metal): largely appears in groundwater as a natural contaminant, but also enters groundwater from other sources

Question 12

any substance can be toxic if:

Answer 12

it is present at a specific dose and under specific conditions

Question 13

what is environmental toxicology?

Answer 13

focuses on the effects of toxic substances on human health and individual organisms within the environment

Question 14

what is ecotoxicology?

Answer 14

sub-discipline of environmental toxicology and ecology, integrates the effects of stressors across all levels of biological organization, from molecular to whole communities to ecosystems

Question 15

what is the aim of ecotoxicology?

Answer 15

to protect all non target species

Question 16

why is ecotoxicology required for predicting real world effects?

Answer 16

because most marine mammals are exposed to complex mixtures of chemicals

Question 17

what are the characteristics of the biomolecular scale?

Answer 17

• elucidating molecular mechanisms of toxicity
• can study the molecular mode of toxic action
• eg. omics signature - changes in RNA, proteins, and metabolites = biomarker

Question 18

what are the characteristics at the cells and tissues scale?

Answer 18

• toxicant-induced changes in cells and tissues
• reflect a cell’s failure to remain viable in the presence of a toxicant or ability to maintain homeostasis
• eg. histological assessment - necrosis, inflammation = biomarker

Question 19

what are the characteristics at the whole organism scale?

Answer 19

• effects to individuals are used to make inferences about contaminant impacts on individuals fitness, and indirectly on populations and communities
• eg. mortality, development, growth, reproduction, behaviour, physiology, and bioenergetics
• acute (4 days or shorter) vs. chronic (longer than 10% of an individual’s lifespan) exposures

Question 20

what are the characteristics at the population scale?

Answer 20

• studies may focus on vital rates
• birth, death, stage change, migration rate
• apply demographic models based on these vital rates to predict consequences to the populations (eg. drop in the population growth rate)

Question 21

what are the characteristics at the community scale?

Answer 21

• explores the consequences of contaminant exposure and movement of contaminants within ecological communities. usually done to assess risk or define remediation action for a contaminated system or site
• bioindicators applied = sensitive species, or species richness or diversity metric

Question 22

what are the characteristics of the ecosystem scale?

Answer 22

• vary widely in both spatial and temporal scales
• ecosystem modelling is usually applied to an easily definable ecosystem such as a contaminated lake or watershed
• fate and movement of the contaminant are then modelled or measured using an extensive sampling program

Question 23

what is a mode of action?

Answer 23

identification of key and obligatory steps, the broader process or understanding by which a contaminant produces an effect
eg. modulating immune response

Question 24

what is the mechanism of action?

Answer 24

more detailed understanding at biochemical and molecular level. specific biochemical interactions through which a chemical produces its effect on an individual
eg. binding to a specific receptor

Question 25

what is the adverse outcome pathway?

Answer 25

toxicological construct that connects mechanistic information to apical endpoints. links a molecular initiating event (such as receptor binding) to the adverse outcome (such as reproductive impairment) via key events

Question 26

what are the steps in the toxicological process?

Answer 26

source - exposure pathways - intake/uptake - internal dose - biological effective dose - effects

Question 27

what are the characteristics of 6PPD-quinone?

Answer 27

- 6PPD is a parent compound added to tires to reduce tire wear - 6PPD released from tire rubber is converted by the ozone to 6PPD-Q - 6PPD-Q is a toxic compound in road runoff that is responsible for mass mortalities of adult coho salmon - juvenile coho are three orders of magnitude more sensitive to 6PPD-Q than other pacific salmonoids

Question 27

what is an example of variability of toxicity between species?

Answer 27

chlorpyrifos (organophosphate (OP) insecticide) is 200x more toxic to aquatic arthropods compared to fish. the most sensitive aquatic groups to OP insecticides are insects and crustaceans. other aquatic animals have the same toxicological receptor, but the toxicity is reduced

Question 28

why does sensitivity differ among species?

Answer 28

1) toxicokinetics (differences in uptake and metabolism) - uptake, excretion, metabolism, and distribution of environmental contaminants within the body of organisms 2) toxicodynamics (differences at toxicological receptor) - what contaminants do physiologically, biochemically, molecularly

Question 29

why are test species used?

Answer 29

there is not enough time nor resources to test all potentially impacted species, so environmental risk typically considers the more sensitive species

Question 30

what are the characteristics of surrogate test species? (6)

Answer 30

- well known biology and physiology - available in all seasons of the year - easy to work with and maintain in a library - yield toxicological results that are representative or more sensitive than other species - may be important to the ecosystem of concern OR may not occur in the ecosystem and is just selected based on sensitivity - alternatives to a surrogate test species include in vitro approaches - cell lines