Pollution's Chemical Impact On Marine Life

Marine life is under threat from a range of human activities, including pollution. Oceans cover over 70% of the Earth's surface and are home to a diverse range of species, from microscopic algae to blue whales. Marine pollution is a combination of chemicals and trash, most of which comes from land sources. Chemical pollution includes pesticides, herbicides, fertilizers, detergents, oil, industrial chemicals, and sewage. These pollutants can have devastating effects on marine life, altering the ocean's temperature, pH, salinity, and oxygen levels, and disrupting biological processes. For example, excess nutrients from agricultural runoff and wastewater can cause coral bleaching, reduced reproductive rates, and decreased shell integrity in marine invertebrates. Chemical pollution can also lead to the accumulation of toxic substances in the tissues of marine organisms, which can then be passed up the food chain to humans. Plastic pollution is another significant issue, with plastic debris entangling and being ingested by marine animals, and microplastics being consumed by small organisms. Noise and light pollution further contribute to the disruption of marine ecosystems, affecting communication, migration, and reproductive patterns. Addressing marine pollution requires a combination of prevention, cleanup efforts, and regulatory measures to limit the use of harmful substances and plastics.

How does chemical pollution affect the ocean's pH?

The ocean's pH is a measure of how acidic or basic the ocean is. The pH of the ocean is affected by chemical pollution, specifically the absorption of carbon dioxide into the ocean. Carbon dioxide is released into the atmosphere by the burning of coal, oil, and gas. The ocean absorbs some of this carbon dioxide, and when carbon dioxide dissolves in seawater, the water becomes more acidic, and the ocean's pH drops.

Since the industrial revolution, the ocean's pH has dropped from 8.2 to 8.1, and it is expected to drop by 0.3 to 0.4 pH units by the end of the century. This drop in pH is significant because the pH scale is logarithmic, meaning that a drop in pH of 0.1 is actually a 10 times increase in acidity.

The increase in acidity of the ocean has a dramatic impact on marine life. For example, the shells of some animals are already dissolving in the more acidic seawater. The building of skeletons in marine creatures is particularly sensitive to acidity. The more acidic water also has a negative impact on the shells of oysters, mussels, urchins, and starfish.

Chemical pollution in the ocean has multiple negative impacts on marine life. For example, the increase in the absorption of carbon dioxide into the seas causes ocean acidification, which destroys coral reefs, impairs shellfish development, and increases the toxicity of some pollutants. Chemical pollution also threatens marine mammals, fish, and seabirds and accumulates in large mid-ocean gyres. It also breaks down into microplastic and nanoplastic particles containing multiple manufactured chemicals that can enter the tissues of marine organisms, including species consumed by humans.

Chemical pollution in the ocean also has a negative impact on human health. For example, methylmercury and PCBs are the ocean pollutants whose human health effects are best understood. Exposure to these pollutants through the consumption of contaminated seafood can damage brain development, reduce IQ, and increase the risk of autism, ADHD, and learning disorders. Adult exposure to methylmercury increases the risk of cardiovascular disease and dementia.

To prevent chemical pollution, we can reduce our carbon emissions by burning less fossil fuels and finding more carbon sinks, such as regrowing mangroves, seagrass beds, and marshes. We can also transition to a circular economy that creates little waste and focuses on equity rather than endless growth.

What are the effects of chemical pollution on marine wildlife?

Marine life is incredibly diverse, with millions of unique species calling the ocean home. From minuscule plankton to blue whales, the ocean's largest animal, marine life takes thousands of brilliant forms. However, despite the vastness of the oceans, they cannot withstand the amount of chemical pollution produced by human activity.

Chemical Contamination

Chemical contamination, or nutrient pollution, occurs when human activities, such as the use of fertilisers on farms, lead to the runoff of chemicals into waterways that eventually flow into the ocean. This type of pollution includes common man-made pollutants such as pesticides, herbicides, fertilisers, detergents, oil, industrial chemicals, and sewage. These chemicals can have devastating effects on marine life, causing disruptions to their daily lives, including feeding, migratory, and reproductive habits.

Algal Blooms

The increased concentration of chemicals in the ocean promotes the growth of algal blooms, which can be toxic to marine life and harmful to humans. Nutrient-packed fertilisers applied to farmland often end up in local streams and are eventually deposited into estuaries and bays, triggering massive blooms of algae that rob the water of oxygen, creating dead zones where few marine organisms can survive. Algal blooms also contribute to ocean warming and acidification and can produce toxins that can kill fish, mammals, and birds.

Coral Bleaching

Wastewater pollution, which includes sewage, transports pathogens, nutrients, contaminants, and solids into the ocean, causing coral bleaching and disease and increasing mortality for coral, fish, and shellfish. It can also alter ocean temperature, pH, salinity, and oxygen levels, disrupting biological processes and physical environments essential to marine life. Additionally, herbicides can damage symbiotic algae in coral, affecting photosynthesis and causing bleaching.

Ocean Acidification

The oceans absorb a significant portion of human-caused carbon emissions, which changes the pH of surface waters and leads to acidification. This process is having damaging effects on wildlife, particularly creatures like oysters and corals, which build shells and exoskeletons from calcium particles in seawater. As ocean acidity increases, these particles are more rapidly dissolved, threatening the survival of these animals.

Microplastics

Plastic pollution is another significant issue, with single-use plastics slowly dissolving into microplastics. These tiny plastic particles are consumed by marine organisms, including plankton and whales, and the chemicals are absorbed into their tissues. Microplastics have even been found in corals, which readily ate plastic over food. As larger animals consume smaller organisms containing microplastics, these toxic chemicals migrate up the food chain, eventually becoming part of the human food supply.

In summary, chemical pollution has far-reaching and devastating effects on marine life, disrupting ecosystems and threatening the survival of countless species. From algal blooms and coral bleaching to ocean acidification and microplastic ingestion, the impact of human-caused chemical pollution on marine wildlife is extensive and widespread.

How does plastic pollution affect marine life?

Plastic pollution is a pressing issue that affects all marine life, from birds and turtles to whales and dolphins. It is estimated that marine plastics contribute to the death of more than 100,000 marine mammals each year. The impact of plastic pollution on marine life varies depending on the size of the plastic.

Large plastics, such as fishing gear, six-pack rings, and plastic bottles, can entangle marine mammals and fish, leading to starvation, injury, and increased vulnerability to predators. Discarded fishing nets can also smother and break coral reefs, hindering their healthy growth.

Smaller plastics, ranging from 5-10mm in size, can be mistaken for food by seabirds and other marine species. These plastic fragments can lead to suffocation, starvation, and toxic contamination over time. Microplastics, or plastics smaller than 5mm, are invisible to the naked eye, making them even easier for wildlife to consume. They can adsorb toxins, which then transfer to the fatty tissues of the organisms that ingest them. The long-term impacts of microplastics are still being determined, but they have been found in the placentas of unborn babies and are believed to act as carriers for other harmful toxins.

The impact of plastic pollution on marine life is not limited to direct consumption or entanglement. Plastic debris can also release toxic chemicals into the surrounding environment, affecting the soil and groundwater. Additionally, floating plastics can transport invasive alien species, contributing to biodiversity loss and species extinction.

The accumulation of plastic in the oceans has become a global crisis. With billions of pounds of plastic in the oceans, it is expected to outweigh all the fish in the sea by 2050. The problem is further exacerbated by the durability of plastic, which can take hundreds to thousands of years to degrade. This has led to plastic pollution in even the most remote parts of the planet, from the deepest point of the Mariana Trench to the top of Mount Everest.

How does noise pollution impact marine life?

Noise pollution has had a significant impact on marine life, with human activities such as shipping, boating, and energy exploration causing a constant din in the ocean. This has affected marine animals' ability to communicate, navigate, find food, and reproduce, leading to a rise in mortality risk.

Impact on Communication and Navigation

Marine mammals, such as whales, dolphins, and porpoises, are highly dependent on sound for their survival. They rely on sound to communicate, locate mates and prey, navigate, and defend their territories. Noise pollution from ships, construction, and sonar devices interferes with their ability to detect acoustic signals, leading to changes in behaviour and social interactions. It can also cause hearing loss, especially in marine mammals, as they are already facing the pressure of climate change and overfishing.

Altered Behaviour and Migration

Foreign sounds can disrupt the natural behaviour of marine mammals, causing them to move away from noisy areas, adjust their activities to avoid certain times of day, or increase their anti-predatory behaviour. For example, humpback whales have been observed simplifying their vocal calls in response to increased ship noise, which may reduce the effectiveness of their communication. Additionally, noise pollution can delay the migration of whales, leading to entrapment in ice and subsequent death.

Physiological and Reproductive Effects

Noise pollution has been shown to cause physiological stress in many fish species, with increased cortisol levels and other biochemical stress indicators. This stress can lead to reduced nest care in fish, impacting brood survival. It can also impair their risk assessment abilities, making them more vulnerable to predators. In addition, noise pollution can negatively impact reproduction in marine life. For example, cod exposed to noise produced eggs with higher cortisol levels, resulting in a 40% lower fertilization rate and a 50% decrease in viable egg productivity. Similarly, reduced communication in whales and dolphins due to noise can hinder their reproduction.

Food Web Disruption

Noise pollution has disrupted the marine food web, affecting both prey and predator species. For example, seismic airguns used in oil and gas exploration emit noise blasts of up to 260 decibels every 10 to 15 seconds, damaging the ears of fish and causing mass strandings of giant squid with extensive internal organ damage. Additionally, a single airgun blast can kill a large part of the zooplankton, the base of the marine food web, within a radius of 1.2 kilometres.

Ecosystem-Level Consequences

Noise pollution has impacted the ocean ecosystem as a whole, affecting reproduction, feeding, nutrient cycling, and water filtration. For instance, noise-induced stress in clams compromised their ability to mix upper sediment layers, impairing their feeding and nutrient availability for other organisms. Furthermore, plankton's ability to take up carbon dioxide is hindered, exacerbating the climate crisis.

How does light pollution affect marine life?

Light pollution is a growing concern for marine life, particularly in coastal areas where urban development is exposing marine ecosystems to artificial light. This has various physiological and behavioural consequences for the organisms that inhabit these waters.

Marine life has evolved over millions of years to adapt to natural light intensity and patterns, but now faces a deluge of artificial light from human development along the coasts. Moonlight and starlight are important cues for marine organisms, and their glow can be washed out by artificial light. This disrupts hormonal cycles, inter-species behaviour, and reproduction.

For example, artificial light negatively affects sea turtles in two ways. Firstly, female turtles seeking a dark spot to lay their eggs may avoid lit areas and not come ashore at all. Secondly, hatchlings, which naturally head towards moonlight on the water, are drawn towards inland lights and subsequently die of dehydration or starvation.

Light pollution also impacts the gametogenesis cycle of corals, the phase before spawning. Experiments in the Gulf of Aqaba, one of the world's most light-polluted areas, found that coral eggs and sperm did not develop under high light pollution conditions. On a physiological level, corals exposed to light pollution also exhibited increased stress.

The spectral composition of artificial light is another concern. Green light wavelengths leave up to 76% of the seafloor exposed to light pollution, while blue light wavelengths leave up to 70% exposed. Blue light, in particular, can penetrate right down to the seafloor and has been linked to retina damage and sleep disturbances in humans.

Light pollution also affects the daily migration of zooplankton, a key part of the marine food chain. Research in the Arctic has observed that zooplankton move away from artificial light, even at depths of at least 200 metres.

The impact of light pollution on marine life is an emerging field of study, and the full scope of its consequences is yet to be fully understood. However, it is clear that artificial light poses a significant threat to marine ecosystems, and efforts to reduce light pollution and mitigate its impacts are essential to protect marine life.

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