Pollution's Impact On Aquatic Life: Understanding The Threat

Water pollution has devastating effects on aquatic animals. It is caused by human activities such as industrial waste, sewage, and agricultural activities. These activities introduce harmful substances such as chemicals, waste, plastic, and other pollutants into bodies of water, degrading water quality and making it toxic. Aquatic animals are directly affected by these pollutants, which can cause physical harm, deformities, and even death. Oil spills, for example, can lead to the death of countless fish and birds. Additionally, water pollution can reduce oxygen levels in the water, creating dead zones where aquatic life cannot survive. Pollutants can also impact the food chain, with predators consuming contaminated prey, leading to a knock-on effect. Furthermore, plastic waste can attract other contaminants, making it even more dangerous when ingested by marine life. The effects of water pollution on aquatic animals are far-reaching and pose a significant threat to their survival.

Sewage and wastewater

Sewage is defined as the waste liquids and solids usually carried away by sewers. Wastewater includes sewage and liquids from industrial, agricultural, and urban sources. Domestic wastewater includes human and animal waste, as well as water from activities like washing and bathing. Industrial wastewater includes pulp, paper, petrochemicals, chemicals, salts, and acids. Agricultural wastewater contains contaminated groundwater, pesticides, and fertilisers. Urban wastewater is a mix of domestic and industrial wastewater, sewage, and rainwater.

Wastewater also introduces biological hazards such as bacteria, fungi, parasites, and viruses, which can cause diseases such as E. coli, typhoid fever, salmonella, cholera, and shigellosis. These microorganisms further deplete oxygen levels in the water as they break down sewage.

In addition, sewage and wastewater contain drugs, hormones, antidepressants, and other chemicals that can affect the reproductive development of fish and amphibians. Heavy metals such as lead, mercury, cadmium, and arsenic can accumulate in fish tissues, reaching toxic levels as they are consumed by larger animals, including humans.

Wastewater also contributes to litter in aquatic ecosystems, with plastics making up 70% of this litter. This plastic litter is ingested by aquatic organisms, causing harm and even death. Overall, sewage and wastewater have severe impacts on aquatic life, disrupting ecosystems and causing widespread harm to various species.

Oil spills

Sea turtles are vulnerable to oil at all stages of life. They can inhale oil fumes and swallow oil when breathing at the ocean surface in or near oil slicks. Fish important to recreational and commercial fishers, including bluefin and yellowfin tuna, are also impacted. Oily water damages the gills of fish and makes it harder for them to get enough oxygen. Oil can also kill fish eggs and can be detrimental to the growth of young fish.

Marine mammals, such as bottlenose dolphins, spend a lot of time near the surface of the water, where oil floats, putting them at high risk during oil spills. They can be exposed through breathing in the oil, eating oiled food, or swimming through it, all of which can lead to devastating health issues.

Birds, once oiled, cannot regulate their body temperature or use their feathers for insulation against water and cold weather, which can lead to death by hypothermia. Oiled birds can also die from dehydration and exhaustion.

Plastic pollution

Plastic waste in water bodies has severe consequences for aquatic animals. They often mistake plastic for food, which then causes internal blockage and leads to starvation. Plastic waste can also cause external and internal injuries, reducing the ability of aquatic animals to swim and fly. In addition, plastic waste can get entangled around the bodies of aquatic animals, causing them to suffocate or become more vulnerable to predators.

The impact of plastic pollution is not limited to aquatic animals; it also affects humans. Microplastics have been found in human blood and placentas and in food and drinks, including tap water, beer, and salt. Several chemicals used in plastic production are known to be carcinogenic and can cause developmental, reproductive, neurological, and immune disorders.

To address the issue of plastic pollution, it is essential to reduce plastic production, phase out harmful subsidies, eliminate products and chemicals of concern, improve waste management systems, and adopt strong national plans and rigorous reporting and compliance mechanisms.

Radioactive substances

The effects of radiation exposure on marine animals are similar to those on humans. There is a slight increase in the risk of cancer, and radiation can interfere with reproduction. However, according to some experts, the ocean has a "'tremendous capacity' for diluting radiation," and the levels of artificial radioactivity are lower than the amount of natural radioactivity, which poses no threat.

Eutrophication

Oxygen Depletion and Hypoxia

The excessive growth of algae due to increased nutrient availability can lead to oxygen depletion in the water. When the algae die and decompose, they are broken down by microbes, which consume large amounts of oxygen. This can result in hypoxic or anoxic "dead zones" where most organisms cannot survive due to the lack of oxygen. Fish kills are a direct consequence of this, especially for fish species that require high levels of dissolved oxygen.

Algal Blooms

Increased Turbidity and Sedimentation

Changes in Biodiversity and Biota

The high competition for resources and predator pressure in eutrophic systems result in a decrease in species diversity. The dominant biota changes, with certain fish species becoming more or less dominant depending on nutrient levels and ecosystem productivity.

Impact on Human Activities

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