BIO3082 Lecture Notes - Lecture 21: Polychlorinated Biphenyl, Persistent Organic Pollutant, Chronic Toxicity
Lecture 21 – Pollution and Bioremediation
Major Types of Pollution that Affect Biota
• Human development results in pollution
• Pollution describes the introduction of harmful contaminants into the natural
environments
o Substances (organic and inorganic)
o Energy (light, heat, noise)
• Current levels are unsustainable → causing local and global losses in
biodiversity
o Affecting 21% IUCN-listed threatened species
• Light and noise pollution
o Light pollution – from urban settlements
▪ Causes fatal attractions for many species
▪ Disrupts circadian rhythms
▪ Affects predator-prey detection
o Noise pollution
▪ E.g. whale beachings
• Solid pollution
o Plastics, aluminium, lead, glass
• Liquid pollution
o Oil, pesticides, metal ions, chlorinated solvents
• Gaseous pollution
o CO, SO2, NO2, mercury vapour
• Marine pollution affects organisms
o Physical effects from plastic and glass pollution:
▪ Entanglement, suffocation, abrasion and digestive blockages
o Sublethal chemical affects
▪ Long-term effects on growth, behaviour and reproduction
▪ E.g. herbicide atrazine and antidepressant fluoxetine
o Lethal chemical effects
▪ Chemicals cause acute or chronic toxicity: heavy metals,
petroleum compounds, organochloride pesticides and
polychlorinated biphenyls
Examples of how Pollution Causes Acute and Chronic Toxicity
• 1989: 42 million litres of crude oil was released from oil tanker in Alaska
o Affected 2000 km of pristine coastline
o Exxon Valdez Oil Spill
• Acute toxicity
o Oil spill caused mass short-term mortality
▪ Of seabirds, sea mammals, benthic invertebrates, fish and
macroalgae
▪ Wiped out 250,000 seabirds and killed 40% of sea otter
population
▪ Oiling of fur and feathers lead to death from smothering,
drowning, ingestion, or hypothermia due to loss of insulating
capacity
• Chronic toxicity – long-term
o Mortality caused by persistence of oil and byproducts
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o Chronic exposure has killed harlequin duck and sea otter individuals
▪ Senstiive as they feed on benthic invertebrates that live in areas
where oil and its byrpdoucts often remain high
o Delayed effects of sublethal doses on reproduction and development
▪ Salmon and herring populations have declined due to
sensitivity of their eggs to oil byproducts
▪ Levels of 1 ppmv can be toxic
▪ Abnormal development and reproduction
• Pesticide use is unsustainable
o Resulted in significant increases in food quantity and quality
worldwide but they are pollutants affecting biodiversity
▪ Over 95% of pesticide residues have off-target effects
o Causes >50 million bird deaths in US annually
o Frogs chance sex in response to atrazine, honeybee colony collapses →
pollination failure
Terms ‘Bioaccumulation’ and ‘Bioremediation’
• Bioremediation: use of organisms to neutralise sites contaminated with
pollution
o Examples: using bacteria to degrade organic contaminants and using
plants to detoxify metal-contaminated soils
• Toxicity due to pesticide bioaccumulation
o Organochloride insecticide DDT – devastating ecological effects
▪ DDT (organic pollutant) causes long-term toxicity by persistin
in environments and bioaccumulating through food chains
o Residues from the organic pollutant has bioaccumulated through the
food chain
▪ Hydrophobic nature of compound → accumulates inside
organisms rather than being excreted
▪ Internal concentration increases with each trophic level in food
chain
o Effects most felt on birds, which suffer from direct toxicity and
reduced reproductive success due to eggshell thinning
o DDT-induced decline and recovery of peregrine falcon
▪ Banned DDT in 1972, facilitated population recovery for
multiple species
Examples of how Pollution Affects Behaviour and Reproduction
Case Study: Pollution from endocrine-disrupting compounds affects reproductive
behaviour of fish species
• Endocrine disrupting chemicals (EDCs)
o Natural or synthetic compounds: pharmaceueticals, pesticides, plastic
softeners, personal care products
o Disrupts the production, release, transport and metabolism of natural
hormones
▪ Can bind to hormone receptors
o Main source: wastewater treatment, agriculture and industry
• Female snails produce male organs
• Behaviour
o Good early-warning signal of chemical pollutants
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