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  • 1. Artificial Night Lighting and Sea Turtles (by Michael Salmon) Reconciliation Ecology
  • 2. Main Points
    • Marine Turtles- nesting and hatching
    • Photopollution- affects of artificial lights on turtles
    • How Photopollution also affects migratory birds
  • 3. Marine Turtles
    • In danger because of direct and indirect human activity
      • Directly by egg and adult harvesting
      • Indirectly by incidental capture by fisheries, habitat modification and degradation
    • Artificial lights are a major problem for marine turtle reproduction
    • (Habitat modification)
      • photopollution
  • 4. Sea Turtle Nesting
    • Process is much the same for all species
      • Female emerges from the water
      • Move onto beach up to a location between the dune vegetation and high
      • tide wrack
      • Female digs an egg chamber
      • Drops soft shelled eggs into chamber
      • Covers eggs with sand
      • Scatters surface sand to hide nest
      • Finally, female returns to the sea
  • 5. Females
    • Reach sexual maturity in 10-50 years depending on species
    • Nesting occurs 2-8 times in a season
    • After completing a nesting cycle, it may take 2-5 years for females to accumulate enough energy to travel to the nesting beach again and lay eggs
      • Nesting beach can be adjacent to feeding grounds or hundreds of kilometers away
    • Reproductive life spans can exceed 40 years
  • 6. Hatchlings
    • Eggs incubate for about 50 days
    • After hatching they dig almost to the surface, then wait for the sands to cool
    • When night falls they make a mad dash for the ocean
    • They swim non-stop for 24-36 hours to reach “nursery areas”
    • Only 1 of every few thousand will survive to maturity
  • 7. Seafinding
    • Process of locating the ocean from the nest
    • Accomplished by visual cues
    • Hatchlings scan 180 º wide areas close to the horizon
      • Turn away from areas that are dark and elevated
      • Move towards areas that are flatter, lower, and bright
      • Depending on the environment, cues can be equally important, or one cue may be more important than the other
  • 8. The Effects of Artificial Lighting on Females
    • White light repels turtles
    • “ Dose dependent” - some nesting will still occur if levels are low enough, but not in great numbers
    • Presence of lighting is now becoming a major factor in nesting location choice
      • Nesting sites normally chosen for their remoteness, low wave energies, proximity to favorable oceanic currents, and absence of predators
    • As humans continue to modify more
    • and more habitat, nesting will become
    • more concentrated on the few
    • remaining “dark” beaches
  • 9. Consequences of Concentrated Nesting due to Human Lighting
    • Spatial concentration will attract predators (both marine and terrestrial) and increase hatchling mortality rates
    • Destruction of nests due to over crowding
      • Females that come to nesting site after others may destroy other nests while creating their own
    • Microbial blooms due to larger numbers of dead eggs
    • Increases the probability of chance events destroying nests
      • Local storms, hurricanes, etc.
  • 10. Effects of Lighting on Hatchlings
    • Lighting keeps hatchlings from locating the sea
    • Results in disorientation or misorientation
      • Disorientation: crawl for hours in circuitous paths
      • Misorientation: crawl away from ocean toward lighting
    • Thousands die annually in Florida alone
      • Exhaustion, predators, entanglement in vegetation, dehydration, crushed by cars
  • 11. Hatchling Orientation as Effected by Light
  • 12. Why does Artificial light have this affect ?
    • The physiological changes responsible for the break down in normal orientation systems is unknown
    • It may be that lighting results in directional cues that misinform hatchlings
  • 13. Difference Between Natural & Artificial Light
  • 14. Artificial Light
    • Differences between artificial light and natural light result in pathological behavior
    • Directness of light is major factor in causing abnormal behavior
      • Increasing illumination in the background diminishes effect
    • Laws have been passed to regulate/restrict lights around nesting beaches
      • Nesting is slowly increasing
    • New threat from lights farther inland
  • 15. Photopollution
    • In the U.S., 30% of outdoor lighting is wasted by illuminating the atmosphere
    • Costing an estimated $1.5 billion in wasted electricity
  • 16. Photopollution Also Affects Migratory Birds
    • Every year about 90,000 migratory birds die in New York City
    • Lights confuse and blind birds causing them to collide with the buildings
      • New York started a Lights Out NY campaign in 2005
      • Empire State Building and Chrysler Building dim their lights
    • Asking the Public to:
    • From September 1 to October 31st
    • Tall buildings (40 stories or more):
      • Turn off decorative lighting on the upper stories by midnight and leave lights off until daylight.
      • Tenants on the upper floors are encouraged to turn out lights or draw blinds by midnight.
    • Low buildings (with extensive glass exteriors along Hudson River and East River):
      • Turn off exterior lighting by midnight and leave lights off until daylight.
      • Turn off interior lighting or draw blinds by midnight.
    • This campaign saves birds and money
      • For a building with 2.5 million square feet of floor space, turning off the lights after midnight would conserve more than 750,000 kilowatts and save approximately $120,000 this fall.
  • 17. Photopollution Also Affects Migratory Birds
    • Chicago was the first U.S. city to initiate a Lights Out Campaign
      • Buildings dim their lights 5 months of the year
      • It is estimated that this program saves 10,000 migratory land birds each year
    • Other cities that have similar programs
      • Boston
      • New York City (as discussed)
      • Baltimore
      • Minneapolis
      • San Francisco
      • Denver
      • Detroit
      • Indianapolis
  • 18. Management Solutions
    • Turn off unnecessary lights
    • Reduce wattage to the minimum required for function
    • Redirect and focus lighting so it only reaches the ground or areas where it is intended
    • Eliminate all upward-directed decorative lighting
    • Use alternative light sources where possible and practical
    • In any new construction, incorporate the latest light management technology
  • 19. The End Citations Salmon, M. 2003. Artificial Night Lighting and Sea Turtles . Biologist, 50 (4): 163-168. Richard. 2010.