High powered lights scare turtles away from the beaches. (I Baran)

The bright lights of distraction

Biological studies indicate that it is likely that turtles attempt to return to the same beaches from which they emerged as hatchlings. However, it's known that when a female is ready to lay eggs she will survey the coastline for some tim e before venturing ashore. A turtle will invariably choose quiet darkened beaches in favour of areas where there is disturbance.

Strong beach front lighting will immediately deter pregnant females from coming ashore even if the beach is ideal for nesting. Instead, a turtle will seek out alternative sites which, although less disturbed, may be less suitable for heal thy egg development. In Cyprus and Greece, for example, it has been witnessed that loggerhead turtles avoiding illuminated hotel fronts have tended to nest in unsuitable areas where their eggs may be destroyed by flooding at high tides. I n other instances turtles may repeatedly be 'turned back' from their chosen nesting beach by light and noise until they may lose their eggs altogether. In Laganas bay on Zakinthos researchers have reported large numbers of eggs laying on the sea bed after they have been dropped by females. Disturbance from light and noise is a particular problem where late night bars and restaurants are located on the beach front.

Instead of heading out to sea these hatchlings in Florida were attracted by the lights of a nearby apartmant building. (N Wu)

Light is also a major distraction to newly hatched turtles since they are programmed to respond to light when they emerge from nests at night. Under natural conditions the lightest part of the beach is the point where the surf reflects th e moon and the stars, a phenomenon which automatically leads hatchlings to the sea. Unfortunately electric lights from bars and hotels are a stronger attraction than moon light, drawing hatchlings away from the sea and further up onto the shore. The longer a hatchlings spends on the beach the more energy it wastes, and the more susceptible it becomes to predators and the effects of the sun.

In Zakinthos, Greece, loggerhead hatchlings have become so disorientated by lights they've been found more than a kilometre from the sea front crawling along streets. In North Carolina, beach front swimming pools that are lit by night hav e been found to trap hundreds of hatchlings annually in their chlorine rich water.

Turtle friendly tourism

Hotels and resort planning authorities can do a lot to reduce light pollution merely by repositioning and shading light sources so they are not directed towards the sea.

Many beaches are still illuminated by lights pointing straight out to sea; these should be removed as a matter of urgency from any areas where turtles are likely to nest.

Research in the United States and in Costa Rica has found that a turtle's sensitivity to illuminations is dependant on the wave length of light. White mercury vapour lamps emitting short-wave light were shown to significantly reduce the number of nesting females, while yellow low pressure sodium vapour lamps emitting long-wave light had no effect. The widespread adoption of this type of lighting in areas where illumination is essential would significantly reduce disturb ance to turtles.