THORN Lighting [Other Lighting Applications]

Northern Australian Coastline

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The Celest lantern has played a variety of roles, but none so unusual as a night light for sea turtles. The Celest lantern has played a variety of roles, but none so unusual as a night light for sea turtles. It’s happening along the beaches of Northern Australia, which not only serve as an important global nesting habitat for four species of vulnerable and endangered marine turtles, but are witnessing a boom in mining activities, typically the stockpiling and shipping of vast quantities of raw materials: bauxite, iron ore, salt etc. Artificial lighting near nesting beaches has a profound negative affect on the breeding process by interfering with the nocturnal behaviours of the turtles*.

Fortunately studies have found that certain wavelengths of artificial light have little affect on marine turtles. Light sources emitting visible energy at high wavelengths (the yellow or red part of the spectrum) have less affect on turtles than low wavelengths (the blue or violet colours). The characteristic monochromatic orange light from the low pressure sodium lamp (SOX) concentrates light at wavelengths of 589 nm and is minimally disruptive to marine turtles, hence Thorn Australia has adapted its linear Celest lantern to take a 55W SOX lamp, thus meeting the demands of local communities and mining companies.

Furthermore by setting the lamp in a highly efficient reflector, the "lighting footprint” is concentrated on the road surface and not towards the beach, glare is reduced and upward light kept below 1 per cent. Finally the use of low wattage lamps reduces the mounting height compared with traditional street lighting schemes and an IP66 seal withstands the salt laden coastal atmosphere.

Other protectionist measures undertaken include limiting the mining operations and their maintenance needs to daylight hours during the nesting season, providing a suitable buffer zone between the beach and the industrial activity, and controlling illumination on loading facilities and onboard ships.

Footnote
*According to the Northern Territory Government’s Environmental Protection Department adult marine turtles known to the shores of the mining leases are disturbed by the presence of lights on the beach when approaching to nest (typically from late October to early March). This may cause them to move to an alternative site or abort the landing attempt. Additionally after egg laying the female turtle will be attracted to lights visible from the beach, which can disorientate their seaward orientation and inadvertently lead them inland, where they become entangled in vegetation or die from exhaustion and dehydration. Likewise hatchling turtles are equally affected after they leave the nest exposing them longer to predators.