Light Pollution's Impact On Marine Life

Light pollution is a growing concern for marine life, with research showing that artificial light can have a profound impact on coastal ecosystems. Marine organisms have evolved over millions of years to rely on natural light cycles, particularly moonlight, to regulate their physiological and biological processes. However, artificial light in coastal cities now threatens to disrupt these natural cycles, with potential consequences for the behaviour and reproduction of marine life.

The effects of light pollution on marine ecosystems are only beginning to be understood, but early research suggests it could be detrimental to a wide range of species, from whales to fish, coral to plankton. With urban development and the increasing use of artificial lighting, particularly energy-efficient LEDs, it is essential to consider the potential harm caused by light pollution and find ways to mitigate its impact on marine life.

Light pollution disrupts marine organisms' hormonal cycles

Light pollution has a detrimental impact on marine life, and it is a growing concern as more people move to cities, increasing light pollution and the number of affected marine ecosystems.

Marine organisms have evolved over millions of years to adapt to natural light, but they now face a deluge of artificial light from human development along the coasts. Moonlight and starlight are essential cues for marine life, and artificial light can easily wash out their glow. This disruption has consequences for their hormonal cycles, inter-species behaviour, and reproduction.

One example is the sea turtle. Artificial light discourages female turtles from coming ashore to lay their eggs, as they seek dark, quiet spots. It also disorients hatchlings, who instinctively move towards inland lights instead of the safety of the moonlight on the water, leading to dehydration or starvation.

Another affected species is coral. Light pollution lowers the rate of photosynthesis in corals, which largely affects the organisms that live in the reefs. Coral reefs are the most diverse marine ecosystems on Earth, so this impact is significant.

The spectral composition of artificial light, particularly the blue and green light components, also has an impact. Blue light, for example, can penetrate to the seafloor and disrupt visually guided ecological processes. Predators that usually feed during the day, such as herring gulls, may be able to see and catch prey that would ordinarily be camouflaged at night, such as marine snails.

Light pollution also affects the gametogenesis cycle of corals, the phase before spawning. Experiments showed that under light-polluted conditions, coral eggs and sperm did not develop.

The very nature of artificial light is changing with the increasing use of LED lighting, which typically emits more short-wavelength light and can penetrate deeper into the water.

Light pollution affects marine reproduction

Light pollution has a detrimental impact on marine life, and its effects on marine reproduction are particularly concerning.

Marine organisms have evolved over millions of years to adapt to natural light sources, such as the moon and stars, and their cycles. However, artificial light from coastal cities now threatens to disrupt the reproductive cycles of various marine species.

One example is coral reefs, which rely on natural light cycles to regulate their physiological and biological processes. Several coral species release their reproductive cells, or gametes, in response to cues from the lunar cycle. Light pollution can mask these natural cues, disrupting the timing of coral reproduction. Research has shown that artificial light can negatively impact the gametogenesis cycle of corals, leading to a collapse in coral reproduction.

Sea turtles are another species affected by light pollution. Female sea turtles prefer dark, quiet spots to lay their eggs, and artificial lighting can deter them from coming ashore. Additionally, hatchlings use moonlight on the water to navigate towards the ocean, but artificial light can disorient them, causing them to head inland and die of dehydration or starvation.

The spectral composition of artificial light also plays a role in its impact on marine reproduction. Green and blue light wavelengths, in particular, have been found to expose a large percentage of the seafloor to light pollution, which can affect the organisms living in coral reefs.

The widespread use of LED lighting further exacerbates the problem. LEDs emit more short-wavelength light, which can penetrate deeper into the water, increasing the exposure of marine life to artificial light.

The effects of light pollution on marine reproduction highlight the urgent need to address this issue. Mitigation strategies, such as reducing the use, duration, and intensity of artificial lighting, especially near coastal areas, can help protect marine ecosystems and ensure the successful reproduction of various marine species.

Light pollution impacts marine inter-species behaviour

Light pollution has a significant impact on marine inter-species behaviour. Marine life has evolved over millions of years to adapt to natural light, but now faces a deluge of artificial light from human development along coasts. This light pollution can easily wash out the moonlight and starlight, which are important cues for marine organisms.

One classic example is the sea turtle. Artificial light discourages female turtles from coming ashore to lay their eggs, as they seek dark, quiet spots. It also disorients hatchlings, causing them to head towards inland lights instead of the safety of the moonlight on the water, leading to their dehydration or starvation.

Light pollution also affects the inter-species behaviour of predators and their prey. For example, daytime predators like the herring gull can now spot prey such as marine snails that would ordinarily be camouflaged at night.

The spectral composition of artificial light, particularly its red, green and blue light components, can also disrupt visually guided ecological processes.

In addition, the impact of light pollution on marine life is not limited to coastal areas. Offshore developments for wind, oil and gas installations are also sources of light pollution that marine animals can encounter.

Light pollution can cause marine dehydration and starvation

Light pollution can have a profound effect on marine life, and new research highlights the need to widen our view to include its impact on coastal marine ecosystems. Marine life has evolved over millions of years to adapt to natural light intensity and patterns, but now faces an ever-increasing flood of artificial light from human development along the coasts.

One classic example of how light pollution can cause marine dehydration and starvation is the case of sea turtles. Artificial light at night is harmful to sea turtles in two ways. Firstly, female sea turtles seeking a dark spot to lay their eggs may avoid lit areas and end up not coming ashore at all. Secondly, and more directly related to dehydration and starvation, is the effect on hatchling sea turtles. After hatching, they are drawn towards inland lights instead of the moon's reflection on the water. This disorientation leads them away from the safety of the ocean, causing them to die of dehydration or starvation.

The issue of light pollution affecting sea turtles is not an isolated incident. A growing body of research shows that marine life is sensitive to artificial light, including extremely low light levels and certain wavelengths, particularly blue and green light. Green light wavelengths can leave up to 76% of the seafloor exposed to light pollution, while blue light wavelengths expose up to 70%. These wavelengths are significant as they can reach and affect a wide range of marine species, from coral reefs to plankton.

The impact of light pollution on sea turtles demonstrates the urgent need to address this issue. Efforts to mitigate light pollution can include reducing the use, duration, and intensity of artificial lighting, especially the use of LED lights, which emit more short-wavelength light and penetrate deeper into the water. Additionally, using red light, which doesn't penetrate as far, and implementing barriers to shield coastlines from artificial light can also help reduce the impact on marine life.

Light pollution lowers the rate of photosynthesis in corals

Light pollution has been proven to have adverse effects on marine life, including corals. Corals are highly photosensitive and are susceptible to light pollution as they are often found in shallow, clear water with high light levels.

A study on the coral species Acropora eurystoma and Pocillopora damicornis found that light pollution caused oxidative stress and impaired photosynthesis. The study revealed that light pollution led to overproduction of reactive oxygen species (ROS) and increased lipid peroxidation (LPO). This resulted in a decrease in the electron transport rate (ETR) and a reduction in chlorophyll and algae density.

Another study on the coral Acropora eurystoma found that light pollution caused a decrease in the photosynthetic efficiency of the corals. The study showed that light pollution disrupted the biological clock of the corals, leading to abnormal cell proliferation and growth.

Light pollution has been shown to impact the physiology and gene expression of corals, affecting their survival and reproductive success. The disruption of natural light cycles by artificial lighting can have far-reaching consequences for coral reefs and the marine ecosystem.

Frequently asked questions