Water Pollution: A Deadly Threat To Marine Life

Water pollution is a pressing global issue, and marine animals are bearing the brunt of it. From plastic waste to chemical contaminants, human activity is wreaking havoc on aquatic ecosystems. Marine mammals, seabirds, fish, and other sea creatures are suffering the consequences, with physical harm, habitat destruction, and interference in their natural behaviours threatening their very existence.

The impact of water pollution on marine life is extensive and devastating. It is essential that we understand the effects of our actions on these vulnerable creatures and take steps to mitigate the damage.

Plastic ingestion

The ingestion of plastic can cause digestive problems, leading to starvation and even death. In 2019, a whale was found washed up with 40kg of plastic in its stomach, and a pregnant pygmy sperm whale was found stranded on a beach near Melbourne with a stomach clogged with ingested plastic. Sea turtles are also particularly vulnerable, with all seven species of sea turtles from the Atlantic and Pacific Oceans and the Mediterranean Sea found to have traces of microplastics in their gut. A recent study of loggerhead sea turtles in the Mediterranean found that almost half of the turtles examined had consumed some type of plastic, with one turtle ingesting a shocking 67 pieces.

The threat of plastic ingestion is not limited to larger marine animals. A recent study of mussels sourced from UK waters found that 100% of samples contained microplastic pieces. Microplastics are also consumed by fish, with over two-thirds of 500 fish species studied found to have consumed plastic. As microplastics are invisible to the naked eye, they are easily consumed by wildlife. They also have the ability to absorb toxins, which can then be transferred to the fatty tissues of the organisms that ingest them.

The issue of plastic ingestion is further compounded by the fact that plastic does not biodegrade. Once plastic enters the ocean, it can be carried by waves and storms to even the most remote reaches, where it accumulates and breaks down into smaller and smaller pieces. This makes retrieving plastics from the ocean extremely difficult, and the problem will only continue to grow unless measures are taken to prevent plastic from entering the ocean in the first place.

Entanglement in plastic

Fishing nets, in particular, can smother and break coral reefs, hindering their healthy growth. Marine mammals, such as whales, dolphins, and porpoises, are highly susceptible to entanglement in ghost fishing gear, with an estimated 300,000 individuals dying from this issue annually. This equipment, including ropes, nets, and pots, is often discarded or abandoned at sea, posing a severe risk to a variety of marine life, from large whales to small crabs.

The impact of entanglement can be devastating, leading to drowning, deep cuts in the skin, and deadly infections. Rare species, such as the humpback dolphin, have been observed with marine debris tightly wrapped around their bodies, affecting their health and mobility.

Additionally, entanglement in plastic can cause digestive problems in marine animals. For example, turtles often mistake plastic bags for jellyfish, their staple diet. Ingesting plastic bags can create a false sense of fullness, leading to starvation.

Oil spills

• Marine mammals: These animals, such as sea otters and bottlenose dolphins, spend a lot of time near the surface of the water, where oil floats, putting them at high risk. They can be exposed to oil through inhalation, ingestion of oiled food, or swimming through it, leading to severe health issues.
• Birds: Once oiled, birds cannot regulate their body temperature or use their feathers for insulation against water and cold weather, which can lead to hypothermia and death. Oiled birds can also die from dehydration and exhaustion.
• Sea turtles: Sea turtles like the endangered Kemp's ridley turtle are vulnerable to oil at all life stages. They can inhale oil fumes and swallow oil when breathing at the ocean surface in or near oil slicks.
• Fish: Oil spills can damage the gills of fish, making it difficult for them to get enough oxygen. Oil can also kill fish eggs and impair the growth of young fish, making them unsafe for human consumption.

Noise pollution

Anthropogenic noise pollution from ships, seismic surveys, explosions, construction, and sonar devices has turned the once peaceful ocean environment into a loud, chaotic place. This type of pollution interferes with the key life functions of marine animals and can even cause death. Very loud noises can cause panic, leading to decompression sickness and tissue damage from gas bubble lesions. It can also lead to hearing loss, which can be fatal when sound is a crucial tool for survival.

To reduce noise pollution in the marine environment, policies are needed to mitigate propeller noise from ships and reduce the sounds of sonar equipment, seismic air guns, pile driving, and construction. Quieter technologies must also be developed to help improve the ocean soundscape and enable the recovery of marine life.

Chemical pollution

One of the primary concerns of chemical pollution is the direct harm it causes to marine organisms. Contaminants like heavy metals, oil spills, and pesticides can be ingested by fish and other aquatic creatures, leading to deformities and reproductive issues. For example, oil spills can suffocate fur-covered mammals and birds, impairing their ability to move freely, maintain body temperature, and feed. Additionally, toxic chemicals can accumulate in smaller fish, which are then consumed by larger predators, allowing contaminants to move up the food chain and eventually reach humans.

Furthermore, chemical pollution has long-term environmental and health implications. Microplastics, for instance, can break down into smaller particles, attracting and absorbing toxins. These microplastics are then ingested by marine animals, transferring toxins into their fatty tissues. The accumulation of these toxins in the food chain can have detrimental effects on human health, leading to diseases such as cancer, cardiovascular issues, reproductive disorders, and Alzheimer's.

The impact of chemical pollution on marine animals is evident in various studies. Research on otters in England and Wales revealed the presence of PFAS (per- and polyfluoroalkyl substances) in their bodies, indicating the widespread existence of these chemicals in the environment. Harbour porpoises in the UK have experienced a 41% increased risk of infectious diseases due to chemical accumulation, becoming a leading cause of death for this species. Additionally, young grey seal pups in Scotland were found to have accumulated harmful chemicals in their blubber within the first 18 days of life, impacting their chances of survival in their initial year at sea.

Overall, chemical pollution poses a severe threat to marine animals, affecting their health, behaviour, and ability to reproduce. Addressing this issue is crucial to prevent further environmental degradation and protect the biodiversity of our oceans.

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