EVSC30006 Lecture Notes - Lecture 8: Light Pollution, Ecological Trap, Melatonin
1 Jun 2018
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LECTURE 8: NOISE & LIGHT POLLUTION
• Anthropogenic noise & artificial light at night are widespread & pervasive in cities
• Altered regimes affect animals:
o Changing diurnal & seasonal patterns of behaviour
o Influence foraging success & predation risk
o Disorient migrating animals
o Alter hormonal & reproductive cycles
o Hinder acoustic communication
ECOLOGICAL LIGHT POLLUTION
• Includes all types of light pollution from artificial sources that disrupts natural cycles of light & dark
o Wide ranges of animals affected, important for behaviour
• Urban Sky Glow: brightening of night sky due to artificial lighting
• Insects die when flying around lights, some bats cross light others don’t
o Hypothesised that bats outcompeted by those who prefer light
• Birds:
o Night-migrating birds that rely on constellations being disrupted
o Migrate prematurely or breed early – think spring is coming early
• Attraction & Disorientation: turtle hatchlings, insects (polarised light pollution), frogs, nocturnally migrating birds, bats
• Polarised light pollution: asphalt roads reflect partially linearly polarised light, attracts aquatic insects that detect
water = ecological trap
• Blue light – disrupts production of melatonin – comes from LED lights
ANTHROPOGENIC NOISE
• Acoustic communication plays key role in social behaviour
• Acoustic interference: when background noise reduces the length a noise can travel
• Masked thresholds: threshold at which you can hear a signal within the background noise
• Active Space: distance a signal can be received by a pulse receiving animal
• Fish and whales affected by boats
• Frogs: calling louder & at higher frequencies
o Relationship between body size & call frequency
o Bigger frogs have deeper calls – better breeding success & reproduction as can communicate in urban
environment
Effects on Birds
• Changes to singing & calling behaviour: timing, pitch, amplitude, structure of vocal signals
• Difficulty attracting & maintaining mates = lower breeding success
• Reduced abundance
• Mornington Peninsula: birds changing frequency of song according to frequency of traffic noise
Document Summary
Lecture 8: noise & light pollution: anthropogenic noise & artificial light at night are widespread & pervasive in cities, altered regimes affect animals, changing diurnal & seasonal patterns of behaviour. Influence foraging success & predation risk: disorient migrating animals, alter hormonal & reproductive cycles, hinder acoustic communication. Includes all types of light pollution from artificial sources that disrupts natural cycles of light & dark: wide ranges of animals affected, important for behaviour, urban sky glow: brightening of night sky due to artificial lighting. Insects die when flying around lights, some bats cross light others don"t: hypothesised that bats outcompeted by those who prefer light. Birds: night-migrating birds that rely on constellations being disrupted, migrate prematurely or breed early think spring is coming early, attraction & disorientation: turtle hatchlings, insects (polarised light pollution), frogs, nocturnally migrating birds, bats. Polarised light pollution: asphalt roads reflect partially linearly polarised light, attracts aquatic insects that detect water = ecological trap.
