Water Pollution's Impact On Animal Life: Counting The Cost

Water pollution is a pressing issue that affects a large number of animals. From marine life to birds, the contamination of water sources poses a significant threat to the survival of various species. The impact of water pollution is evident in the decline of marine animal populations, including whales, sea turtles, and seals. The ingestion of plastic and other pollutants, as well as entanglement in debris, are among the primary causes of harm to these creatures. Additionally, water pollution contributes to the degradation of coral reefs, which are essential for the survival of many sea animals. The issue extends beyond the oceans, as rivers and lakes are also affected, impacting birds, land animals, and even humans.

Plastic pollution

Plastic waste also entangles and strangles many marine animals, including seals, whales, turtles, and birds. Plastic packing bands have been known to strangle seals and sea lions, and abandoned fishing gear and discarded six-pack rings have caused the deaths of seals, whales, turtles, and other creatures.

The impact of plastic pollution extends beyond the immediate harm caused to marine life. Plastic waste can encourage the growth of pathogens in the ocean, increasing the likelihood of disease in organisms that come into contact with it. For example, corals that encounter plastic have an 89% chance of contracting a disease, compared to only a 4% chance for corals that do not.

Additionally, plastic pollution contributes to the creation of dead zones in water bodies. These dead zones are areas where aquatic life cannot survive due to oxygen depletion caused by sewage discharge and fertilizer runoff. While adult fish can usually move to higher-oxygen environments, many crustaceans and shellfish are unable to escape and perish from a lack of oxygen.

The issue of plastic pollution in water is not limited to the oceans; it also affects freshwater ecosystems. Rivers, lakes, and other freshwater sources are polluted by plastic waste, posing threats to the animals that inhabit them.

To address the pressing issue of plastic pollution in water, it is crucial to focus on prevention and waste management. This includes improving waste management systems, promoting recycling, advocating for better product design that considers the short life of disposable packaging, and reducing the manufacturing of unnecessary single-use plastics.

Eutrophication and dead zones

Eutrophication is the process by which a body of water becomes enriched with chemical nutrients, leading to a dense growth of plant life. Eutrophication is often caused by an increase in nitrogen and phosphorus compounds, primarily from agricultural runoff, but also from sewage, emissions, and natural factors. This process depletes oxygen levels in the water, creating "dead zones" where aquatic life cannot survive.

Dead zones are hypoxic (low-oxygen) areas in large bodies of water, typically oceans, but also in lakes and rivers. These zones are characterised by a concentration of dissolved oxygen (DO) below 2 ml of O2/liter. When DO levels fall below this threshold, aquatic flora and fauna are forced to seek out sections of water with higher oxygen levels. Once DO levels decline below 0.5 ml O2/liter, mass mortality occurs, as the water can no longer support aquatic life.

The formation of dead zones is influenced by both natural and anthropogenic factors. Naturally, dead zones can be caused by coastal upwelling, changes in wind and water circulation patterns, long water residence times, high temperatures, and high sunlight penetration. Anthropogenic causes include the use of chemical fertilizers, direct sewage discharge, nutrient discharge from accumulated animal waste, and runoff from sewage, urban land use, and fertilizers.

The effects of eutrophication and dead zones on marine life are significant. The decomposition of aquatic plants in eutrophic systems consumes oxygen, leading to hypoxic or anoxic conditions. This lack of oxygen causes mass mortality among aquatic organisms, particularly crustaceans and shellfish, which are often unable to move to higher-oxygen environments. Additionally, the algal blooms associated with eutrophication can produce toxic algae species that poison aquatic organisms such as seabirds, fish, sea turtles, dolphins, manatees, and sea lions.

The impact of eutrophication and dead zones on marine ecosystems is not limited to the direct effects on oxygen levels and toxicity. Coral reefs, which are vital for many sea animals' survival, are commonly damaged by pollution from oil, trash, fishing nets, and fertilizer, as well as human and animal waste. This degradation of coral reefs contributes to the decline of dependent species, such as the Hawksbill Turtle, whose population has dropped by an estimated 80% in the last 50 years.

Chemical and industrial waste

Industrial Animal Agriculture

Industrial animal agriculture, or factory farming, is a significant source of water pollution. These farms house thousands of animals in a small area, and the waste produced is high in nutrients, including nitrates, which are now the most common contaminant in groundwater aquifers globally. This waste often makes its way into nearby waterways, groundwater, and the ocean, leading to contamination. Factory farms also use antibiotics extensively to treat and prevent infections in their animals, and these antibiotics are ending up in our drinking water.

Industrial Crop Production

The use of pesticides and fertilizers in modern food production is another contributor to water pollution. When fields are washed by rain, these chemicals are carried into waterways. Additionally, only about 55% of the calories from crops produced globally are consumed directly by humans, while about 36% are fed to animals raised for meat, contributing to the water pollution caused by animal agriculture.

Heavy Metal Contamination

Agricultural practices, including the use of fertilizers, pesticides, manure, and irrigation, contribute to the presence of heavy metals in water. Heavy metal exposure has been linked to various health issues, including weakened bones, liver and lung damage, and cancer.

Pathogen Contamination and Disease Outbreaks

Water pollution caused by industrial animal agriculture can also lead to pathogen contamination and disease outbreaks. Fecal matter from infected animals can transmit diseases such as E. coli and Cryptosporidium to humans and other animal populations.

Algal Blooms and Dead Zones

The waste produced by animal agriculture is rich in phosphorus and nitrogen. When these nutrients enter water bodies, they increase the likelihood and severity of algal blooms. These blooms can create dead zones by depleting the oxygen in the water, leading to mass die-offs of plant and animal species in the affected areas.

Plastic Pollution

Plastic pollution in the oceans is another significant concern, with an estimated one million seabirds and one hundred thousand marine mammals killed by plastic each year. The Great Pacific Garbage Patch, the biggest ocean patch of plastic waste, contains 79 metric tons of plastic. Plastic pollution affects various aquatic mammals, including seals, sea lions, whales, and dolphins, as well as seabirds such as albatrosses and seagulls.

Pesticides and fertilizers

Pesticides are chemicals used to kill or control pests and are applied to protect crops against insects, weeds, fungi, and other pests. They are also used to protect or increase crop yields and the number of times per year a crop can be grown on the same land. Pesticides are potentially toxic to humans and can have both acute and chronic health effects, depending on the quantity and the ways in which a person is exposed.

Pesticides can contaminate water through rainfall, irrigation, and runoff, and can have detrimental effects on wildlife and human health. Pesticides can be transported into bodies of water when runoff, after rainfall, moves through areas that have been sprayed with pesticides. They can also enter water within the soil structure by displacement from absorption sites near water and through treated soil that has moved into the water through soil erosion.

The use of pesticides can have significant effects on water quality due to the extent of farm activities on the landscape, the soil-disturbing nature of those activities, and associated impacts from sediment, nutrients, pesticides, and herbicides. Pesticides can cause soil erosion, nutrient loss, and bacteria from livestock manure, which can all negatively impact water quality.

The effects of pesticide runoff vary widely depending on the type of operation, landscape conditions, soils, climate, and farm management practices. Increased levels of nitrogen and phosphorus from fertilizer and manure can stimulate algal blooms in lakes and rivers, leading to the development of hypoxic (low oxygen) conditions that are harmful to aquatic life. Excessive sedimentation from erosion can overwhelm aquatic ecosystems, smother breeding areas, and degrade coastal and marine ecosystems, including coral reefs. Bacteria and nutrients from livestock and poultry manure can cause beach and shellfish bed closures and affect drinking water supplies. Pesticide runoff to streams can also pose risks to aquatic life, fish-eating wildlife, and drinking water supplies.

Pesticides can have detrimental impacts on weeds and insects, which can indirectly affect crop yield. New pesticides that are more selective and less toxic are being produced to gradually replace older ones.

The use of pesticides can be reduced by adopting soil and water conservation practices, such as nutrient runoff management, tailored methods of tillage and drainage, cover crops, and vegetated buffers.

Marine debris

One of the primary ways that marine debris harms animals is through ingestion. Animals may mistake plastic items for food or accidentally consume them along with their meals. This can lead to intestinal blockages, internal injuries, and starvation. Even when plastic debris does not cause direct physical harm, it can fill up an animal's stomach, leading to a false sense of fullness and depriving them of the necessary nutrients they need to survive. This is particularly prevalent among sea turtles, with research indicating that half of sea turtles globally have ingested plastic. A recent study also found that ingesting just 14 pieces of plastic significantly increases the risk of death for these turtles.

Another significant issue is entanglement, where animals become trapped in derelict fishing lines and nets, packing bands, balloon strings, and other discarded items. Entanglement can cause anything from mild discomfort to severe injuries, infections, and even death. It can restrict movement, making it difficult for animals to feed, and can be fatal for air-breathing creatures like sea turtles, which may drown if they cannot reach the surface to breathe.

The impact of marine debris on wildlife is not limited to the oceans. It also affects freshwater ecosystems, including rivers and lakes. For instance, plastic pollution in the Great Lakes has been found to have some of the highest densities of microplastics recorded.

The scope and severity of the issue call for urgent action to address marine debris and mitigate its harmful effects on marine life.

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