How Dugongs Suffer From Pollution's Harmful Effects

Dugongs, also known as 'sea cows', are marine mammals that feed on seagrass in shallow coastal waters. Their survival is threatened by human activities, including pollution, which can take various forms. Water pollution, caused by inadequate treatment of sewage and industrial waste disposal, as well as pesticide and nutrient runoff, can destroy seagrass habitats, leading to dugong population decline. Noise pollution from boating activities can interfere with their communication and navigation, while plastic pollution can result in entanglement, ingestion, and toxic exposure. Oil spills and land reclamation also pose significant dangers to dugongs and their habitats. Conservation efforts are crucial to protect dugongs and their sensitive seagrass ecosystems from the detrimental impacts of pollution.

Dugongs are vulnerable to getting tangled in fishing nets

Dugongs are vulnerable marine mammals that are threatened by human activities. One of the most significant threats to their survival is entanglement in fishing nets. Dugongs can easily get tangled in gillnets or other nets set for different species, making them unintended victims of fishing operations. This problem is exacerbated by the lack of alternative livelihood options for rural coastal communities, leading to over-exploitation of marine resources and the use of destructive fishing practices.

Dugongs, also known as "sea cows", are closely related to elephants and share a similar appearance to manatees. They are the only exclusively herbivorous marine mammal, feeding almost exclusively on seagrass. Seagrass meadows, found in shallow coastal waters, are the primary feeding areas for dugongs and are vital for their survival. Unfortunately, these ecosystems are constantly threatened by human activities such as bottom trawling, chemical use, and untreated sewage disposal, which directly damage the seagrass and reduce its availability for dugongs.

The incidental capture of dugongs in fishing nets is a significant issue. Between 2005 and 2010, 56 dugongs were caught in nets, and only one of the 51 found alive was released. This practice is particularly common in Least Developed Countries, where poverty is high and communities depend on natural resources for survival. The over-exploitation of marine resources in these areas leads to the use of destructive harvesting practices, further endangering dugongs and their habitats.

To address these threats, a multi-faceted strategic approach is necessary. Conservation planning must include objectives to develop alternative livelihoods for coastal communities, improve public understanding of dugongs and their habitats, and encourage the adoption of sustainable fishing practices. By reducing the demand for marine resources and increasing awareness, the risk of dugongs being entangled in fishing nets can be mitigated, and their populations can recover.

Additionally, it is important to reduce the impact of other human activities on seagrass ecosystems. This includes addressing pollution from coastal development and industrial activities, as well as the effects of climate change. By protecting seagrass meadows and reducing pollution, we can help ensure the survival of dugongs and the stability of the marine ecosystems they support.

Boat strikes and noise pollution

Dugongs are vulnerable to boat strikes and noise pollution, which can have significant impacts on their populations and behaviour. Boat strikes, or collisions with boats and watercraft, are a growing concern for dugong conservation. Dugongs are slow-moving and tend to float near the water's surface, making them susceptible to strikes by boats, especially in shallow waters. The risk of boat strikes is higher in areas with a high density of both dugongs and vessels, such as near ports and in coastal regions. Additionally, boat speed plays a crucial role, with faster boats posing a greater risk of collision. Studies have suggested new boating routes and speed limits to minimise these strikes while considering the needs of boaters as well.

Boat engines and propellers create underwater noise pollution, which can interfere with dugongs' communication, navigation, and foraging behaviours. Noise pollution can lead to disorientation and stress in dugongs, disrupting their ability to attract mates, communicate with their young, and feed effectively. This disruption can have long-term consequences for their breeding and feeding cycles, potentially affecting the health and stability of dugong populations.

The presence of boats and boat traffic can also cause disturbance and displacement of dugong populations. Dugongs have been observed moving away from areas with high boat traffic, seeking quieter sanctuaries. This displacement may lead to a reduction in their feeding grounds and can impact their energy intake and overall health. While the direct impact of boat traffic on dugong feeding behaviour has been deemed relatively low in some studies, the increasing boat traffic in many regions remains a concern for conservationists.

To mitigate the impacts of boat strikes and noise pollution on dugongs, conservation efforts focus on assessing and managing risks. This includes studying the distribution and movements of both dugongs and boats, particularly in areas where their paths overlap. By understanding these patterns, conservationists can propose alternative boating routes and speed restrictions to reduce the likelihood of strikes and minimise noise pollution. Additionally, raising awareness among boaters and operators about the presence of dugongs and the importance of quiet waters can help foster a collective sense of responsibility for dugong conservation.

Destruction of seagrass habitats

Dugongs are highly dependent on the presence and health of seagrass habitats within coastal and nearshore areas. Seagrass meadows are underwater areas dominated by various species of seagrasses, which serve as the primary feeding areas for dugongs. These meadows are typically found in calm, shallow waters, estuaries, lagoons, and inlets. The largest population of dugongs lives off the coast of Australia, in the warm Indian Ocean. Dugongs are also found off the western coast of Madagascar, along the east coast of Africa, in the Red Sea, the Persian Gulf, around the Indian subcontinent, and in the western Pacific from southern Japan to northern Australia.

Seagrass meadows are highly effective at capturing and storing carbon, and their removal or damage has major environmental implications. They are important natural carbon sinks, with an average of around 14 kg of carbon per square meter buried in their sediments. Seagrass meadows can influence hydrodynamics by reducing current velocity, dissipating wave energy, and stabilizing the sediment, contributing to the protection of whole shorelines and the health of other ecosystems.

However, seagrass meadows are threatened by various human activities, including coastal development, pollution, and the destruction of seagrass meadows. Seagrass loss rates are comparable to those of mangroves, coral reefs, and tropical rainforests, making seagrass meadows one of the most threatened ecosystems on Earth. Among the major causes of seagrass loss are direct impacts from coastal development and dredging activities, as well as indirect impacts from declining water quality. Other human activities that contribute to seagrass destruction include eutrophication, land erosion, mechanical damage due to dredging, seining, boat mooring, and anchoring.

Boat propellers in shallow water can impact the roots, stems, and leaves of seagrasses, creating long, narrow furrows devoid of vegetation. This type of damage, known as propeller scarring, can take years to heal and can completely destroy seagrass beds if it is severe or repeated. Additionally, derelict or abandoned fishing gear and vessels can impact seagrass habitats by settling on the bottom and shading out the seagrass, as well as eroding and scouring the plants.

Hunting and illegal poaching

Dugongs are hunted and poached for their meat and oil. In some Asian cultures, dugong meat is considered a luxury food with aphrodisiac properties. Dugongs have been hunted to near-extinction in some countries, including Indonesia, Singapore, and Cambodia. While dugong hunting is illegal in most places, it is legal but heavily regulated in Australia.

The illegal wildlife trade is a lucrative business, with high-profit margins and high prices paid for rare species. Poor rural communities often turn to poaching due to a lack of alternative livelihood options. Wildlife crime is run by dangerous international networks that traffic animals and their parts, similar to the trade of illegal drugs and arms. Some networks are also linked to terrorist organizations.

The incidental and deliberate capture of dugongs in artisanal fisheries is one of the most serious and widespread threats to their survival. Dugongs can easily get tangled in gillnets or caught in traps set for other species, making them unintentional victims of fishing operations. The overfishing of fish species that graze on seagrasses can also indirectly harm dugongs by disrupting the balance of the ecosystem.

To address the threat of unsustainable hunting and poaching of dugongs, a multi-faceted strategic approach is necessary. This includes incorporating poverty alleviation into conservation planning, developing alternative livelihoods for rural coastal communities, improving public understanding of dugongs and their seagrass habitats, and implementing strict deterrents and laws to protect dugong populations.

Climate change and extreme weather

Dugongs, or 'sea cows', are strictly marine mammals that feed almost exclusively on seagrass. They are found in the warm coastal waters of the Indian and western Pacific Oceans, with the largest population off the coast of Australia in the Indian Ocean.

Dugongs are vulnerable to a range of human activities, including pollution, which directly threatens their survival. Climate change and extreme weather events are significant factors in the declining health of dugong populations. As oceans are affected by rising temperatures and climate change, dugongs are impacted through the loss and degradation of their seagrass habitats.

Seagrass meadows are highly effective carbon sinks, capturing and storing carbon. They are sensitive ecosystems that are threatened by pollution and destructive human activities. Pollution, including untreated sewage, agricultural runoff, and industrial waste disposal, directly damages seagrass meadows. Climate change exacerbates these issues, as rising temperatures and extreme weather events further degrade seagrass habitats. Natural disasters such as cyclones, storm surges, and tsunamis contribute to the destruction of seagrass ecosystems.

Additionally, dugongs are vulnerable to the indirect effects of climate change and extreme weather. For example, bottom trawling and other destructive fishing practices can damage seagrass meadows and disrupt the ecosystems that dugongs rely on. Climate change can intensify these practices, as warming oceans and extreme weather can lead to overfishing and increased pressure on marine resources, ultimately harming dugong habitats.

The combination of direct and indirect impacts of climate change and extreme weather makes dugongs highly vulnerable. Their survival depends on the preservation and conservation of seagrass ecosystems, which are under constant threat. To protect dugongs, it is crucial to address the root causes of climate change and mitigate the effects of extreme weather events on their fragile habitats.

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