Artificial Night Lighting and Sea Turtles (by Michael Salmon)

Reconciliation Ecology

Main Points

• Marine Turtles- nesting and hatching

• Photopollution- affects of artificial lights on turtles

• How Photopollution also affects migratory birds

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

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

FemalesFemales

Reach sexual maturity in 10-50 years depending Reach sexual maturity in 10-50 years depending on specieson species

Nesting occurs 2-8 times in a seasonNesting occurs 2-8 times in a season After completing a nesting cycle, it may take 2-5 After completing a nesting cycle, it may take 2-5

years for females to accumulate enough energy years for females to accumulate enough energy to travel to the nesting beach again and lay eggsto travel to the nesting beach again and lay eggs Nesting beach can be adjacent to feeding grounds or Nesting beach can be adjacent to feeding grounds or

hundreds of kilometers awayhundreds of kilometers away Reproductive life spans can exceed 40 yearsReproductive life spans can exceed 40 years

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

Seafinding

• Process of locating the ocean from the nest• Accomplished by visual cues• Hatchlings scan 180º 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

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 moreand more habitat, nesting will become more concentrated on the few remaining “dark” beaches

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.

Effects of Lighting on HatchlingsEffects of Lighting on Hatchlings Lighting keeps hatchlings from locating the Lighting keeps hatchlings from locating the

seasea Results in disorientation or misorientationResults in disorientation or misorientation

Disorientation: crawl for hours in circuitous Disorientation: crawl for hours in circuitous pathspaths

Misorientation: crawl away from ocean toward Misorientation: crawl away from ocean toward lightinglighting

Thousands die annually in Florida alone Thousands die annually in Florida alone Exhaustion, predators, entanglement in Exhaustion, predators, entanglement in

vegetation, dehydration, crushed by carsvegetation, dehydration, crushed by cars

Hatchling Orientation as Effected by Light

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

Difference Between Natural & Artificial Light

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

Photopollution• In the U.S., 30% of outdoor lighting is

wasted by illuminating the atmosphere • Costing an estimated $1.5 billion in

wasted electricity

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.

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

Management SolutionsManagement Solutions

1.1. Turn off unnecessary lightsTurn off unnecessary lights2.2. Reduce wattage to the minimum required for Reduce wattage to the minimum required for

functionfunction3.3. Redirect and focus lighting so it only reaches Redirect and focus lighting so it only reaches

the ground or areas where it is intendedthe ground or areas where it is intended4.4. Eliminate all upward-directed decorative Eliminate all upward-directed decorative

lightinglighting5.5. Use alternative light sources where possible Use alternative light sources where possible

and practicaland practical6.6. In any new construction, incorporate the latest In any new construction, incorporate the latest

light management technologylight management technology

The EndCitations

Salmon, M. 2003. Artificial Night Lighting and Sea Turtles. Biologist, 50 (4): 163-168.

Richard. 2010. http://www.treehugger.com/files/2010/08/audubon-lights-out-campaign-save-migratory-birds-this-fall.php

http://lightsout.audubon.org/