Sea Turtles' Battle: Surviving Pollution's Deadly Impact

Sea turtles have existed for over 150 million years, but their time in the ocean is now under threat due to plastic pollution. Plastic affects sea turtles at every stage of their lives, from hatchlings crawling through plastic on their way to the ocean, to adult turtles mistaking plastic for food. The impact of plastic pollution on sea turtles is devastating, with thousands dying each year from ingestion of or entanglement in marine debris. In addition to plastic, other forms of pollution such as oil spills, chemical runoff, and light and noise pollution also have severe effects on sea turtle populations.

Plastic ingestion

Sea turtles are affected by plastic at every stage of their lives. They crawl through plastic on their way to the ocean as hatchlings, swim through it while migrating, and crawl back through it as adults.

Research has shown that a turtle has a 22% chance of dying if it eats just one piece of plastic. The likelihood of death increases with the amount of plastic consumed, and once a turtle has 14 plastic items in its gut, there is a 50% chance of death. This ingestion of plastic can also cause malnutrition and reduced growth rates, as it affects their ability to digest actual food.

Hatchlings and young turtles are particularly vulnerable to plastic ingestion as they have not yet developed the same level of discernment as adult turtles when it comes to their food choices.

The presence of plastic in the ocean and on beaches has severe consequences for sea turtles, with an estimated 52% of all sea turtles worldwide having ingested plastic. This plastic pollution, combined with other threats such as entanglement and habitat destruction, has contributed to a noticeable decrease in global turtle population numbers.

Entanglement in plastic

Sea turtles are affected by plastic at every stage of their lives. Entanglement in plastic waste is a daily threat and one that can have fatal consequences. From the moment they are born, turtles face the risk of injury or death due to plastic pollution.

Turtles can get entangled in plastic waste on the beach, in the ocean, and underwater. This waste includes lost fishing nets, plastic twine, nylon fishing line, six-pack rings, plastic packaging straps, plastic balloon string, kite string, and discarded anchor lines. These items can cause choking, limb loss, and other injuries, and can even result in death. The risk of entanglement is not limited to adult turtles; hatchlings and young turtles are also vulnerable as they make their way to the ocean.

Research has shown the severe impact of plastic entanglement on sea turtles. A study by the University of Exeter found that 91% of turtles entangled in discarded fishing gear died. Another study by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the University of the Sunshine Coast (USC) revealed that a turtle had a 22% chance of dying if it ingested just one piece of plastic.

The issue of entanglement is not limited to a specific location but is a global concern. A recent survey found evidence of sea turtle entanglement in over 43 countries. It is estimated that more than 1,000 turtles die each year due to entanglement in plastic, and this number is likely an underestimate as many dead turtles are never recovered.

The impact of plastic entanglement on sea turtles is a serious issue that requires attention and action. By reducing plastic waste and disposing of it properly, we can help mitigate the risks that sea turtles face and contribute to their conservation.

Oil pollution

Oil spills and urban runoff of chemicals and fertilizers through drains and rivers from cities may contribute to up to 36% of all marine pollution from oil. Oil pollution tends to accumulate along the food chain and therefore affects the sensitive habitats that sea turtles depend on, such as seagrass beds, mangroves, and coral reefs. These habitats are critical for the development of young sea turtles and provide feeding and nesting grounds for adult turtles.

On a larger scale, oil from offshore spills concentrates along convergence zones, which are important areas for the growth of young sea turtles. Oil can also accumulate on nesting beaches, impacting nests, adult female turtles, and hatchlings. Sea turtles may be directly or indirectly exposed to oil pollution, and the buildup of pollutants in their tissues over time can lead to immune suppression and various health issues, including gastrointestinal ulceration and organ damage.

It is important to address oil pollution and other forms of marine pollution to protect sea turtle populations and maintain the health of marine ecosystems. Reducing oil consumption, advocating for stricter regulations on offshore drilling, and improving waste disposal methods can help mitigate the impacts of oil pollution on sea turtles.

Light and noise pollution

Light Pollution

Sea turtles are extremely sensitive to light. Unfiltered lights in coastal areas can disorient hatchlings, causing them to move inland and away from the ocean, where they face dehydration, predation, or death by vehicles or drowning. Artificial lighting also deters adult female turtles from nesting, as they instinctively seek out dark areas to lay their eggs.

The use of turtle-friendly lighting fixtures and sources can help mitigate these issues. Turtle-friendly lights are designed to be pointed downward, limiting the spectrum of light emitted and minimising the impact on turtles. The use of low-pressure sodium-vapour lighting (LPS) or red lights, which emit a narrow portion of the visible light spectrum, can also reduce light pollution's effects on turtles.

Noise Pollution

Turtles are vulnerable to hearing loss from excess underwater noise, which can be caused by passing ships and offshore construction. This noise pollution can induce temporary hearing loss, making turtles less able to detect sounds in their environment, including warnings of approaching predators. It may also lead to permanent hearing loss or auditory damage.

Fertilizer and chemical runoff

The nutrients in fertilizer, such as nitrogen and phosphorus, act as food for algae, causing them to multiply rapidly when present in high concentrations. This leads to the formation of thick mats on the water's surface, which can be green, blue, or even red. These algal blooms are known for their toxic effects, producing toxins that can cause skin and respiratory irritation and impair liver or kidney function in humans. When dogs swim in algae-infested waters, they are also at risk of illness and death.

Additionally, eutrophication caused by fertilizer runoff can lead to oxygen depletion in the water. As the algae consume and use up the available oxygen, there is less left for fish and other aquatic organisms, leading to sickness and death. This can create dead zones in bodies of water, such as the famous example in the northern Gulf of Mexico, where many animals can no longer survive.

Furthermore, the nutrients in fertilizer can promote seaweed growth. Seaweed, a large form of algae, responds to the excess nutrients in the same way as algae, overgrowing its aquatic environment and choking out other organisms by consuming the resources they need to thrive.

To address the issue of fertilizer and chemical runoff, education and public involvement are crucial. People can follow local codes enforcing fertilizer bans near waterways, opt for natural compost instead of chemical fertilizers, buy organically produced food and products, and support policies and regulations that aim to reduce pollution.

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