Ocean Pollution's Impact On The Seafloor: A Hidden Crisis

Ocean pollution is a pressing issue that poses a significant threat to marine ecosystems and the health of our planet. With oceans covering over 70% of the Earth's surface and governing essential processes like weather patterns and air purification, safeguarding them from pollution is crucial. The leading sources of ocean pollution are human activities, with 80% of marine pollution originating from land-based sources. This includes runoff from agricultural activities, septic tanks, vehicles, and industrial operations, among others. One of the significant consequences of ocean pollution is its impact on the seafloor. From plastic debris to acoustic disturbances, human activities are altering the underwater environment, disrupting marine life, and causing far-reaching ecological damage.

Light pollution from coastal cities

Coastal cities leave a significant portion of the seafloor exposed to harmful light pollution. Research by the University of Plymouth, UK, revealed that up to 75% of the seafloor near coastal cities is bathed in artificial light bright enough to impact the surrounding ecosystem. This light pollution can be caused by street lighting and illumination from coastal urban centres, affecting both the sea surface and the seafloor.

The colour of the wavelengths of light shone at the surface also makes a difference in how much reaches the seafloor. Green and blue wavelengths, commonly found in white LED lights, penetrate deeper into the water, with up to 76% and 70% of the seafloor area exposed, respectively. On the other hand, red light reaches less than 1% of the seafloor due to faster attenuation in water.

Light pollution can disrupt the migration and navigation of species that rely on the moon and stars for long-distance travel. It can also affect the circadian rhythms and behaviours of various marine organisms, including crustaceans like copepods, which migrate vertically each day in response to moonlight they can detect over 80 meters below the surface.

As coastal cities continue to expand, with projections of more than a billion people living in coastal areas by 2060, light pollution is expected to increase. The transition from yellow incandescent lights to white LEDs exacerbates the problem due to the higher proportion of blue and green wavelengths in these lights.

To address this issue, researchers are calling for a comprehensive review of the impacts of coastal light pollution to develop mitigation strategies as coastal cities grow. It is important to consider the amount, timing, and colour of artificial light used to minimise its harmful effects on marine ecosystems.

Ocean noise pollution disrupts communication, navigation, and feeding behaviour in marine animals

Ocean noise pollution is a form of environmental pollution caused by human activities, such as commercial shipping, oil exploration, seismic surveys, offshore wind turbine installation, and military sonar. These activities generate unnatural and excessive sound underwater, which can negatively affect marine life.

Marine animals, including dolphins, whales, and fish, use vocalizations to communicate and navigate. Ocean noise pollution can interfere with these natural sounds, disrupting their communication and navigation abilities. For example, increased background noise from cargo ships can emit up to 190 decibels of noise, which is much louder than a plane taking off. As sound travels faster in water than in air, this increased noise level affects marine animals and habitats over a large area.

Ocean noise pollution can also disorientate animals, especially those that rely on echolocation, such as dolphins and toothed whales. Excessive noise can disrupt their echolocation signals, causing them to become disoriented and unable to hunt successfully. Additionally, military sonar and seismic air guns produce high-intensity and excessively loud noises that can send animals into a panic, causing them to ascend too quickly and suffer from decompression sickness or even strand and die.

The impact of ocean noise pollution on the entire marine ecosystem is significant. As ecosystems are interconnected, the effects on one species can indirectly affect another. For instance, if a whale strands on a beach due to sudden, intense noise from human activity, seafloor-dwelling animals that rely on the whale's body for food will lose a crucial food source.

While there are currently no international legal regulations on ocean noise pollution, local governments and individual ports have established their own regulations. However, international institutions like the United Nations Convention on the Law of the Sea (UNCLOS) and the International Maritime Organization (IMO) have begun to address this issue, recognizing the need to prevent and reduce marine pollution from vessels.

Oil spills and other pollutants from human activities impact the health of the ocean

Oil spills and other pollutants from human activities have a detrimental impact on the health of the ocean. The ocean is the endpoint for much of the pollution we produce on land, and human activity is responsible for the majority of marine pollution. Oil spills are a significant concern, with thousands of spills occurring in US waters annually, causing irreversible damage to delicate marine ecosystems. These spills can be caused by boats, airplanes, cars, trucks, and even lawnmowers, and the oil can linger for decades.

In addition to oil spills, other forms of pollution from human activities impact the ocean. Nonpoint source pollution, which occurs as a result of runoff, is a significant issue. This type of pollution includes small sources like septic tanks, vehicles, and boats, as well as larger sources such as farms, ranches, and forest areas. When large areas of land are plowed, the exposed soil can erode during rainstorms, carrying agricultural fertilizers and pesticides into the ocean. This type of pollution can make river and ocean water unsafe for humans and wildlife, leading to beach closures and adverse effects on shellfish-growing waters.

Another form of pollution from human activities is chemical discharges from factories and raw sewage overflow from water treatment systems. These pollutants contribute to algal blooms and aquatic dead zones, further degrading the health of the ocean. Additionally, noise pollution from shipping, seismic air gun surveys, and pile driving can disrupt communication, navigation, and feeding behavior in marine animals.

Light pollution is another often overlooked form of pollution from human activities that can impact the ocean. Artificial light from coastal cities and towns can reach the seafloor, affecting light-sensitive marine organisms. This type of pollution has the potential to disturb ecosystems and impact the behavior of marine creatures, such as tiny crustaceans called copepods, which migrate vertically each day in response to moonlight.

Overall, human activities have a significant impact on the health of the ocean, and it is crucial to address these issues to protect delicate marine ecosystems.

Plastic pollution entangles marine life and is ingested by fish, whales, turtles, and seabirds

Plastic pollution is a pressing issue that poses a grave threat to marine life. The oceans, covering over 70% of the Earth's surface, are home to a diverse range of species, from microscopic algae to the majestic blue whale. However, human activities have led to the contamination of these waters with plastic waste, endangering the very creatures that dwell within. One of the most insidious forms of ocean pollution is plastic, which entangles and is ingested by marine organisms, wreaking havoc on their health and survival.

Plastic pollution in the ocean takes various forms, from discarded fishing gear and six-pack rings to microplastics, which are plastic particles smaller than 5mm in size. These microplastics are invisible to the naked eye, making them easily consumable by marine life. Larger plastics can entangle marine mammals and fish, impeding their movement and leading to starvation, injury, and increased vulnerability to predators. Discarded fishing nets can also smother and damage coral reefs, disrupting the delicate balance of these ecosystems.

Marine species, including fish, whales, turtles, and seabirds, often mistake plastic for food. This ingestion of plastic can lead to fatal consequences, such as suffocation and starvation. For example, plastic bags can resemble jellyfish, a staple food source for leatherback turtles, and fishing nets can be mistaken for edible seaweed. Additionally, microplastics have the ability to adsorb toxins, which then transfer to the fatty tissues of the organisms that ingest them, leading to toxic contamination.

The impact of plastic pollution on marine life is devastating and far-reaching. It is estimated that marine plastics contribute to the death of more than 100,000 marine mammals annually, with 81 out of 123 marine mammal species known to have ingested or become entangled in plastic. All seven species of sea turtles are affected by plastic pollution, and research indicates that half of the sea turtles worldwide have ingested plastic. Furthermore, plastic debris has been found in the stomachs of seabirds, leading to the deaths of over a million seabirds each year.

The consequences of plastic pollution extend beyond the immediate harm to marine life. As plastic breaks down into smaller pieces over time, it becomes increasingly challenging to retrieve from the ocean. Microplastics can be ingested by smaller organisms, such as molluscs, and accumulate in the food chain, ultimately reaching humans through the consumption of contaminated seafood. This bioaccumulation of toxic chemicals poses a significant threat to both marine ecosystems and human health.

Ocean acidification threatens the survival of shellfish and other marine life

Ocean acidification is a significant threat to marine life, and it is caused by excess carbon dioxide (CO2) from the atmosphere dissolving into the ocean, forming carbonic acid. This chemical shift reduces the availability of carbonate ions, which are essential for many marine organisms to build their shells and skeletons. As atmospheric CO2 levels rise due to human activities like fossil fuel combustion, the ocean absorbs about 30% of the emitted CO2, accelerating acidification.

Organisms that produce calcium carbonate structures, such as corals, sea urchins, sea snails, oysters, mussels, clams, and pteropods (tiny snails eaten by fish and whales), are affected by ocean acidification. As the ocean becomes more acidic, these animals have to spend extra energy repairing or thickening their shells and exoskeletons, which can negatively impact their growth and reproduction. This can have knock-on effects in the food chain, potentially affecting other animals that rely on them for food, including humans.

Ocean acidification also poses a significant threat to shell-forming species, including shellfish, corals, and certain plankton. With the decrease in carbonate ions, it becomes increasingly challenging for these organisms to maintain and build their shells, leaving them more vulnerable to predation and environmental stressors. The impacts on the shellfish industry are already being observed, with oyster hatcheries experiencing high mortality rates and weakened shell structures.

Additionally, ocean acidification can alter the sensory abilities and behaviour of fish, making it difficult for them to navigate, find food, and evade predators. These changes can have cascading effects on marine ecosystems, altering predator-prey dynamics and threatening the resilience of marine life.

The effects of ocean acidification are far-reaching, and it is crucial to address this issue through collective action and innovative research. By volunteering with marine conservation organizations and reducing personal carbon emissions, individuals can actively contribute to monitoring and advocacy efforts, safeguarding the health of our oceans for future generations.

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