Sea Creatures: Pollution's Victims And Their Plight

Marine animals are gravely affected by pollution, and the survival of many species is threatened by human activities. The ocean is home to thousands of creatures, from crabs and seals to sea stars and whales. However, human pollution reaches these waterways and the animals that inhabit them. According to the International Union for Conservation of Nature, 9.5 million metric tons of plastic waste end up in the ocean annually, outweighing 63,000 blue whales. This plastic waste includes household trash, runoff from roadways, packaging material, and wastewater.

Plastic pollution is deadly to ocean wildlife, causing slow and painful starvation when ingested and loss of limbs or drowning when entangled in plastic debris. All seven species of sea turtles are affected by plastic pollution, often mistaking plastic bags and clear containers for food. Seabirds, such as pelicans and seagulls, are also impacted, with 80 out of 135 studied seabird species having ingested plastic. By 2050, it is estimated that 99% of seabird species will have ingested plastic.

In addition to plastic, oil spills and agricultural runoff further contaminate the ocean. Oil damages seabirds' feathers, making it difficult for them to stay dry and warm. Predators that consume oiled animals accumulate oil in their bodies, leading to illness over time. Furthermore, increased carbon dioxide in the atmosphere dissolves into the ocean, causing ocean acidification and disrupting the habitats of many fish and plant species.

To protect marine wildlife, it is crucial to address the various sources of pollution and their impacts. Reducing plastic consumption, disposing of plastic waste properly, and improving waste management practices are essential steps toward minimizing the harmful effects of pollution on sea animals.

Sea turtles

Turtles also get entangled in plastic debris, choking them, causing limb loss, and injuring them. They are further affected by ingesting food contaminated by oil or tar balls, which form when crude oil floating in the water degrades. A large percentage of dead hatchlings whose stomach contents have been examined have ingested tar balls.

Research conducted by the Commonwealth Scientific and Industrial Research Organisation (CSIRO) and the University of the Sunshine Coast (USC) found that a turtle had a 22% chance of dying if it ate just one piece of plastic. Once a turtle had ingested 14 plastic items, there was a 50% likelihood that it would die.

Additionally, the degradation of sea turtle habitats due to pollution poses a significant threat. Sea turtle habitats overlap with areas likely to be affected by offshore oil exploration and production. Oil spills from vessels, vessel groundings, offshore oil exploration, and production, as well as the transport and runoff of oil from land-based sources, all contribute to the problem. Oil from spills washes up on beaches, degrading nesting habitats and impacting nests, nesting females, and hatchlings.

Seabirds

The ingestion of plastic has severe consequences for seabirds. It can cause internal damage to various organs, affect their metabolism and endocrine system, and lead to dehydration and poisoning. Plastic ingestion also reduces the volume of the stomach, often resulting in starvation. Additionally, plastic can get entangled in the birds' feathers, affecting their buoyancy and insulation, leading to hypothermia.

Oil pollution is another significant threat to seabirds, especially those that spend a lot of time on the ocean's surface, such as auks, seaducks, and divers. Oil spills can cause mass seabird mortality, and even chronic oil pollution from vessels cleaning their fuel tanks can have a significant impact on seabird populations over time. Oil can damage the waterproofing properties of feathers, leading to hypothermia, and can cause internal damage if ingested.

Overall, the impact of pollution on seabirds is widespread and devastating, with plastic and oil pollution being the most common culprits. The effects of pollution on seabirds highlight the urgent need to address these issues and find solutions to reduce the amount of plastic and oil entering our oceans.

Marine mammals

Ingestion

Once ingested, plastic can cause digestive problems and contaminate the animal with toxins. As marine mammals are at the top of their food chain, the toxins in their food sources accumulate in their bodies, especially in their fatty tissues and breast milk. This can lead to contaminant-induced immunosuppression, endocrine system damage, reproductive malformations, and growth and development issues. It is also linked to a disturbing increase in cancer cases.

Entanglement

Other Types of Pollution

In addition to plastic pollution, marine mammals are also affected by other types of pollution, such as oil spills, industrial pollutants, and agricultural runoff. They are exposed to a wide range of chemical compounds, sewage-related pathogens, and excessive amounts of nutrients that can cause environmental changes.

Coral reefs

Impacts of Land-Based Pollution on Coral Reefs

The expansion of human populations and development in coastal areas poses a significant threat to coral reefs. As the landscape is altered through coastal development, deforestation, and agricultural runoff, the health of coral reefs is jeopardised. This includes activities such as:

• Failed septic systems releasing nutrients and pathogens.
• Coastal development and impervious surfaces leading to sedimentation and toxins.
• Stormwater runoff carrying sediment, toxins, nutrients, and pathogens.
• Deforestation contributing to sedimentation.
• Oil and chemical spills releasing toxins.
• Road construction causing sedimentation.
• Agriculture adding excess nutrients and sediments.

How Pollution Affects Coral Reefs

Pollution from these land-based sources can impede coral growth and reproduction, disrupt ecological functions, and cause disease and mortality in sensitive species. Here are some of the specific ways pollution impacts coral reefs:

• Sedimentation: Sediment deposited on reefs can smother corals, interfering with their feeding, growth, and reproduction.
• Excess Nutrients: While nutrients are beneficial for marine ecosystems, corals are adapted to low nutrient levels. Excess nutrients can lead to excessive algae growth, blocking sunlight and consuming oxygen needed by corals for respiration. This can result in an ecosystem imbalance and support the growth of pathogenic microorganisms.
• Pathogens: Bacteria and parasites from inadequately treated sewage, stormwater, and livestock pen runoff can cause disease in corals, especially when combined with other environmental stressors.
• Toxic Substances: Metals, organic chemicals, and pesticides found in industrial discharges, sunscreens, runoff, mining activities, and landfill runoff can affect coral reproduction, growth, feeding, and defensive responses. Pesticides, for instance, can harm the symbiotic algae that corals depend on, leading to bleaching.
• Trash and Microplastics: Plastic bags, bottles, and discarded fishing gear can snag on corals, blocking sunlight and harming reef organisms. Degraded plastics and microplastics can be consumed by corals and other reef animals, causing digestive blockages and potentially introducing toxins.

Global Threats to Coral Reefs

In addition to local threats, coral reefs also face global challenges, primarily from increased ocean temperatures and changing ocean chemistry. As atmospheric temperatures rise, seawater temperatures increase, stressing corals and potentially causing them to expel the microscopic algae they depend on for food. This results in coral bleaching, where corals lose their coloration, leaving them vulnerable to infectious diseases.

Furthermore, ocean acidification, caused by the uptake of carbon dioxide from the atmosphere, reduces the availability of dissolved salts and ions necessary for coral growth. If acidification becomes severe, coral skeletons may even dissolve.

Clams and oysters

Clams are highly effective at filtering water, removing nitrogen, and sequestering carbon. A single littleneck-sized clam can filter up to 4.5 gallons of seawater per day, improving water clarity and promoting the growth of important seagrasses. Additionally, clams can remove 0.09 grams of nitrogen per clam and store 2.76 grams of atmospheric carbon per clam. These ecosystem services provided by clams have been recognised in studies, such as the University of Florida's examination of the environmental benefits of the state's hard clam aquaculture industry.

However, clams are susceptible to the detrimental effects of pollution. As filter feeders, clams can inadvertently ingest microplastics and other pollutants present in the water. These contaminants can accumulate in their tissues and shells, leading to potential toxic effects. Moreover, clams are sensitive to changes in water chemistry, such as ocean acidification caused by elevated carbon dioxide levels. This can hinder their larval development and growth, threatening their survival and disrupting the balance of marine ecosystems.

Oysters, another type of bivalve mollusc, are also significantly impacted by pollution. They are filter feeders, straining seawater through their gills to feed on algae and plankton. This process helps clarify the water and provides better access to sunlight for seagrasses. However, when oysters are farmed in polluted waters, they can retain toxins and pollutants, potentially becoming toxic themselves.

Oyster farming practices can have additional environmental impacts. The controlled mating process in oyster farms can increase the risk of disease spread among populations, and the introduction of oyster spat can bring invasive species into ecosystems. Moreover, the machinery and structures used in oyster farming can physically disturb seabeds, alter tidal patterns, and negatively affect local marine life.

In conclusion, clams and oysters are highly sensitive to pollution and other human activities that impact their habitats. Their filter-feeding nature makes them vulnerable to ingesting pollutants, and changes in water chemistry can hinder their growth and survival. Additionally, oyster farming practices can have unintended consequences, including the spread of diseases and the introduction of invasive species. Therefore, it is crucial to address these issues and implement sustainable practices to protect and conserve these valuable species and the ecosystems they support.

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