As mentioned in the previous post, light pollution poses great threat to different species on earth. In assessing the impacts of light pollution in cities, it becomes ever so important to look beneath the surface and into marine waters to understand just how immense the effects of light pollution are. In this and the following posts, we will be looking at how light pollution may impact different kinds of marine creatures such as sea turtles, fish, corals and invertebrates.
Light pollution from artificial light in coastal settlements affects sea turtles in three main ways:
- How they choose where to lay their eggs
- How they return to sea after they nest
- How their offsprings navigate to sea after they are hatched
Unlike the past, these nocturnal creatures have to now fight for their rights on the beach to nest, more often than not losing the battle against increasing tourists and built facilities such as hotels that encroach these beaches. Artificial light from these infrastructures deter female sea turtles from emerging from the sea to the shore to nest.
Image 1. False Crawls by sea turtles
Because of artificial light onshore, female sea turtles often head back to the ocean where she will lay her eggs while swimming or go to another beach in search for another nesting spot. This return trip to the sea is also known as false crawls.
Even if the female sea turtles have successfully laid their eggs, their offspring are not spared from the effects of artificial light. In their attempt to navigate the ocean, these hatchlings often turn toward the brightest direction. Ideally, the moonlight that reflects off the surface of the ocean will lead the young back in the right direction. However light from the coastline has interfered with the hatchlings’ vision and navigation back to the waters, leading them away from the ocean and into coastal settlements which further decreases their already slim chance of survival.
However not all is bleak as conservation groups like The Sea Turtle Conservancy (STC) are constantly helping darken coastal settlements based on three basic principles of keeping light low, keeping it shielded and keeping it long. Click on the video below which will give you a quick glimpse of the efforts to reduce the impacts of light pollution on sea turtles!!
Aside from the gory and heart breaking pictures of plastic bags and straws that have harmed large numbers of turtles around the world, perhaps more attention should also be paid on impacts of light pollution on a life cycle of sea turtles, which impacts not only the current generation of turtles but its future offsprings to come.
Stay tuned for more!
Jean
References:
- Witherington, B., & Martin, E. (2003). Understanding, Assessing, and Resolving Light-Pollution Problems on Sea Turtle Nesting Beaches. Fl. Mar. Res. Inst. Tech. Rep. TR-2
- Sea Turtle Conservancy https://conserveturtles.org/information-sea-turtles-threats-artificial-lighting/
- Verutes, G., Huang, C., Estrella, R., & Loyd, K. (2014). Exploring scenarios of light pollution from coastal development reaching sea turtle nesting beaches near Cabo Pulmo, Mexico. Global Ecology and Conservation 2, 170-180. Retrieved from https://www.sciencedirect.com/science/article/pii/S2351989414000274
- Sea Turtle Conservancy: Guardians of the Night: Reducing Light Pollution on Sea Turtle Nesting Beaches https://www.youtube.com/watch?v=R5ID9MU1bCQ&feature=youtu.be
- https://news.usc.edu/144389/usc-scientist-database-reduce-effects-of-led-light-on-animals/ (image cover)