Monitoring and Assessment of Marine Pollution

Question 1

Measuring toxicity - whta are the three measurements?

Answer 1

Median Lethal Time (LT50) or LTm)

• –The time taken at the specified concentration of toxin for 50% of the test organisms to die.

Median Lethal Concentration or DOSE (LD50 or LDm)

• –The concentration of the toxin required to produce mortality of 50% of the test organisms after a specified time period (usually) 96 hours (e.g. 96h LD50).
• –Time period varies, may be as low as 2 hours for planktonic organisms or larvae.

Effective Concentration

• –If end point is some condition other than death, then is termed an effective concentration (EC) or effective dose (ED).

Question 2

Define bioaccumulation and biomagnification

Answer 2

•Bioaccumulation

–Substances that are not metabolised may accumulate in the body

•Biomagnification

–If contaminants accumulate in the body of a prey organism, then the predator will receive an enriched dose, thus levels of bioaccumulating substances tend to increase up the food chain

Question 3

What is a bioindicator?

Answer 3

A bioindicator is an anthropogenically-induced response in biomolecular, biochemical, or physiological parameters that has been causally linked to biological effects at one or more of the organism, population, community, or ecosystem levels of biological organization.

Question 4

What levels can pollution effect?

Answer 4

•Sub-organism level:

–Molecular, subcellular, cellular, tissue level

–Molecular profiling ‘omics’ (Veldhoen et al., 2012)

•Level of the individual:

–gross morphology, behaviour, reproductive success

• Level of population : recruitment, mortality
• Presence/absence of indicator species
• Level of community - relative abundance of species

Question 5

Nuclella as a bioindicator

Answer 5

Nucella lapillus

• No planktonic larval stage in life cycle
• Young emerge directly from egg capsules laid on shore
• Extremely low concentrations: of TBT

–females develop a penis, but are still fertile

•Higher concentrations:

–penis enlarges

–vas deferens becomes convoluted and blocks genital pore (sterility)

• Highest concentrations can result in death
• Indicator at the tissue level and the population level

Question 6

Imposex in dogwhelks

Question 7

Criteria for selecting abioindicator

Answer 7

Specificity

•Biological response is specific to the stressor of interest and not to other environmental stressors

Monotonicity

•The magnitude of the biological response should reflect the intensity and duration of the stressor of interest

Variability

•Biological responses should be consistent at a range of spatial and temporal scales. Ideally, there should be low background variability although a change in variance can itself be used as an indicator of an impact

Practicality

•Measurements of biological responses should be cost effective, easy to measure, non-destructive and observer independent

Relevance

•Biological response should be ecologically relevant and important in public perception to assist communication

Question 8

what are the potential uses of bioindicators?

Answer 8

• Identify contaminant exposure
• Help to identify the mechanisms of toxicity
• Provide early warning of impending environmental change
• Provides early indications of early environmental recovery and remediation
• Important in linking cause (stressor) to ecologically relevant effects
• Can be incorporated into ecological risk assessment