Pollution Flashcards
What can ecological light pollution include
Ambient light (eg sky glow)
Direct illuminance from the source (eg street lights)
(astronomical light pollution can reduce number of visible stars, tall lighted structures can be collision hazard)
potential ecological impacts of light pollution
Behaviour- sleep, orientation, foraging, mating
Physiological- stress, metabolism
Reproductive/fitness of pops- survival, nesting success, recruitment, phenology
Interactions- completion, predation, pollination, dispersal, herbivory
Community structure and ecosystem function- diversity, productivity
impacts vary among organisms and light sources
Artificial lights emit a variety of wavelengths
LEDs have a broad wavelength spectrum, with a particularly big peak at the lower wavelength- this is how they affect a broad range of organisms. The short peak wavelength of white light LEDs coincides with sensitivity of melatonin response and invertebrate behaviours to light
eg spiders affected by relatively low intensity of light
Light pollution and behaviour
Disorientation results from ambient illumination (light incidence on objects in an environment)
Attraction/repulsion in response to light sources themselves resulting from how bright they are
Foraging, expansion of foraging time- the nighttime niche
Territoial singing in birds- the night time niche
Eg sea turtles- hatchlings particularly effected b abroad wavelengths of light so can become disorientated. Could be light bouncing off water or actual light itself. Would normally go toward starlight off water but urban lights are much brighter so they get confused.
Effect of light on marine plankton
Both direct and indirect ski glow can increase depths of coastal marine invertebrate activity. Sea plankton are sensitive to small changes in short wavelength light bc this time of light goes furthest into the water. They show sensitivities by movement. Light affects depths at which behaviours are triggered- implications for community and ecosystem dynamics
Pollination and light
Night lights can have varying effects on moth pollination with effects on community networks. Effects can spill over into unlit regions. eg the lit region may have an increase in moth abundance. Other effects:
Concentration effect- moth had higher abundances in lit, strong interactions incr, weaker lost
Ecological trap- moths attracted up to light, some weaker interactions lost (between plant and bug), may have decreased flower visiting activity
Disruption effect- moth behaviour disrupted around light (decr flower visiting activity)
Preferential disruption effect- behaviour of a subset of moth spp disrupted ( eg larger spp), decreased flower visiting activity by some spp
Dispersal and light
Light might repel important seed dispersers in tropical systems eg fruit bats in costa rica. Lit/dark choice experiments clearly show preference for the dark. Bats feed on epiphytes, light might repel this bat from fulfilling its dispersal role and could work with other bat spp
In wild pops, fruit were harvested from a greater percentage of unlit piper plants than lit.
After sunset, fruit was harvested >3 hours in lit, compared to 90mins in unlit. Lower foraging frequency and longer delay may impact on forest successional dynamics in heavily lit, unfragmented areas.
Effect of light at night on plants - phenology
Using light data from satellite images and controlled for urban heat island effects and background temperatures. Looked at bud burst. Compared four different spp that opened at different times.
In brighter areas bb advanced by 7.5 days. Stronger effects for later budding spp. Even more pronounced when excluding large urban areas
Light may also affect growth and reproduction, top down effects of predators and herbivores on plants and bottom up effects on herbivores and invertebrates, effects varying with light colour
Number of inflorescences lower with lighting on greater birds foot trefoil. Consistent effect of lighting with herbivores present. Aphid abundance lower with amber lighting in August only. Limited evidence of bottom up effects. Aphids prefer to feed on inflorescences, so if less reproduction for plants the they’ll be affected- experiment type kevin gaston boxes in field?
Mitigating the effects of light pollution
Buffer zones to reduce light levels in core protected areas. Ambient light may still be an issue. We would limit artificial lighting and urban development - could be around national parks.
Light reduction and shielding- focussed light sources downward pointing, hooded lights. Conflict of interests (safety) could turn off for periods of time. Even focussed light sources can disorientate/attract/repel at a local scale
Technological solutions eg make light have longer wavelength. In turtle areas could make light shredder. Seen evidence of huge reduction in disoriented hatchlings.
Challenges to understanding the effects of light
Confounding factors- european robins in urban areas might sing at night. This was initially thought to be a shift to the ‘nighttime niche’ bc higher levels of light. But evidence suggests the shift may be due to noise pollution. Birds sing at night so they can be heard (sound interferes with communication). Can see correlation with noise and signing so this is thought to be more likely. Fitness benefit to shifting to night
Sound pollution in PA
Researchers found that 63 percent of all U.S. protected lands are exposed to manmade noise that is at least as twice as loud as ambient sounds from natural sources like wind
Potential ecological effects of sound
Behaviour - sleep, foraging, mating (communication)
Physiology - stress, metabolism,
Reproduction/fitness of the pop - survival, nesting success
Interactions- competition, predation, pollination
Community structure and ecosystem function - ?
A lot of the work focusses on individual animals, a lot less on community structure and impacts
Sources of sound pollution
Intentional (aquatic)
- seismic exploration (prospecting for prescence of oil, vessels emit high pressure sound that is absorbed into seabed)
- harassment devices- eg in fisheries, might want to repel predators of fish using sound devices
Unintentional
- industry eg pile deriving to create foundations and mining, oil wells, compression of gases out of terrestrial gas wells
- transport
- construction
- forestry and mining
How can sounds manifest below water
As pressure (sound waves) or as particle movement
Animals hear either or both forms
Can be short wave (0-8KHz)
Or long wave (90-200KHz)
This coincides with hearing freq and communication freq in multiple taxa. Noise pollution in most cases leads to some sort of response. Almost all cases for invertebrates
sound and behaviour and reproduction of birds
Gas extraction sites either with or without gas compressors
Measured
- survival
- predation (particularly by brood predator spp)
- number of nest predators
Found
- survival lower in control (no noise)
- Greater predation in control,
- Higher rate of nest predators in control sites
Noise repels predator species. Another study found nesting species richness lower in noisy sites. Different spp composition at sites,
spp present in noisy and quiet had higher nesting success in noisy
