Posted: December 25th, 2023

The Hidden Threat of Ship Collisions on Plastic Pollution in the Oceans

The Hidden Threat of Ship Collisions on Plastic Pollution in the Oceans
1. Introduction
1.2 Significance of the Issue
Although there is great concern for the impact of plastic pollution on ocean ecosystems, the direct threats of ship traffic on plastic debris have been vastly overlooked. Vessel strikes, the physical interaction between ships and debris, can potentially increase the fragmentation and bioavailability of plastic debris, making it more harmful to marine life. Despite the fact that vessel strikes are considered one of the main sources of marine debris, the issue of plastic pollution has not yet been integrated into present marine spatial planning approaches and there is indication that it has been somewhat disregarded by the international community (Bryant, 2015). With the expansion of the shipping industry and the continued production and inadequate disposal of plastic materials, it is likely that the debris and the shipping industry will continue to intersect at increasing rates in the upcoming years. Therefore, it is imperative to address the potential issues caused by ship traffic to any future alleviation of plastic pollution in the oceans.
1.1 Background
There are more than five trillion pieces of plastic in the ocean (Cózar et al., 2017). This debris, mostly composed of single-use bags, bottle caps, food wrappers, and foam take-out containers, accumulates on the ocean surface and trails into the vast network of the global shipping industry. A majority of this cargo ship traffic occurs in the Northern Hemisphere, with the majority of traffic at maritime chokepoints such as the Panama and Suez Canals, and into major ports. Due to high-density traffic areas in the vicinity of where much of the plastic debris occupies, it has been documented that ship traffic is indeed correlated with higher density of floating plastic debris (Figure 2), therefore increasing the likelihood of interaction between ships and plastic debris. This has led to a growing concern of how ship traffic might exacerbate the removal of existing debris and potential terrestrial sources into smaller fragments, which are more difficult to track and are more bioavailable to marine organisms (Goldstein et al., 2013), posing increased risks of ingestion and entanglement for various marine species.
1.1 Background
There are two broad categories of plastic sources that contribute runoff and debris to the marine environment: macroplastic and microplastic. Macroplastic originates from both land and ocean and is described as plastic that is larger than 5 mm and is directly visible to the human eye. It includes plastic debris such as single-use bags, water bottles, food packaging, and buoys, all designed for short-term usage and low durability in the environment. This form of macroplastic has a significant threat on marine life within coastal environments. Specific items often become hazardous to marine animals due to resemblance to food items. If large amounts of these plastics are introduced to the marine environment, marine life can readily begin to depend on these products. When these plastics near the end of their life cycles, they begin to break down under solar radiation, losing flexibility and strength. This stage of degradation migrates the plastic into the second category of marine debris, microplastic, before further fragmenting into molecules. High-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene are three specific types of plastic known to fragment quickly.
Conversely, macroplastic can result from ocean-based activities. Abandonment of fishing gear type known as ghost fishing and transport of hull fouling through watercraft are primary sources. Currently, there is limited knowledge on the density of plastic debris in various regions and the time scale required for migration near gyres. We do know, however, that the lifetime of macroplastic in the marine environment can be quite long. If buried in silt, sediment, or sand, it has the potential to degrade into microplastic. In general, plastic material located on the ocean floor has yet to be studied. Calculating the total input of plastic to the marine environment is impossible but increased use of plastics, inefficient or lack of recycling, and improper waste management in coastal regions have guaranteed an increase in the future.
1.2 Significance of the Issue
Finance seems to many as an unmitigated necessary evil for the seaborne shipping of goods; an efficient opportunity cost essential to the survival of industries and their national economies. Consistent with this, it is a common belief that the majority of expenses are poured into new maritime technologies and improved practices in order to maximize profits and, ultimately, the survival of the company. This often unchallenged assumption is not inaccurate when discussing the preventative measures taken against maritime pollution because aside from legislation breaches, the presence of visible and tangible pollutants such as oil and chemical substances are threats to the companies' reputations and purse strings - particularly in today's environmentally conscientious consumer market. It is this consumer pressure and punitive legislations, which in recent times has been known to financially cripple offending companies, that has been so successful in discouraging the dumping of pollutants from cargo and passenger ships. However, when considering the cost allocation of preventing CSO and other forms of marine debris, relative to the hidden threat of ship collisions, a telling discrepancy is revealed.
1.3 Objectives of the Thesis
The overarching objective of this thesis is to use AIS data to identify the threat of ship strike on large marine animals, especially humpback and right whales which frequent the coastal waters off Eastern Australia. By overlaying predictive models of animal distribution with shipping lanes and traffic density, I aim to ascertain when and where the animals are most at risk. This will enable dynamic management strategies to be implemented, spatially and temporally, to reduce the threat of ship strike on these endangered species. Another key aim of this thesis is to assess the potential impact of proposed LNG developments in the Great Barrier Reef on green turtle populations. By comparing the routing of LNG tankers to and from Gladstone with current vessel traffic through the southern and central reef, I aim to identify high-risk areas for interactions between tankers and sea turtles. Measures to mitigate these interactions will also be discussed.
LNG carriers are amongst the largest and fastest vessels at sea, known to travel in relatively straight lines between source and destination ports. It is often said that if you know where the ships are going, you know where whales are at risk. Although there is currently no specific data available on whale interactions with LNG carriers, it is highly likely that these vessels will cross paths with migrating humpback and minke whales along the Queensland coast. By comparing the temporal and spatial distribution of Queensland whale species with shipping routes of LNG tankers, I aim to confirm the potential risk of ship strike on whales and provide another layer of analysis for marine managers to consider.
2. Understanding Plastic Pollution in the Oceans
Plastic debris comes in all shapes and sizes, but the one factor that most people do not take into consideration is the size of the plastic and how that can affect various marine life. Primarily, the size of the plastic affects the environment in which the marine life thrives. Large plastic debris entangles and kills marine life such as sea turtles and marine mammals. An example of this would be a sea turtle mistaking a plastic grocery bag for a jellyfish. Ingestion of the plastic comes at all sizes and affects various species and is more than often fatal. The larger, more apparent plastic debris can be traced right back to the local beach or coastal recreational area. It is generally associated with packaging, i.e. plastic bags, six-pack rings, fishing line, and bait containers. Some may argue that the small plastic beads found in exfoliating body scrubs and toothpaste can have the most detrimental and long-term effects on the marine environment. These micro-plastics have been found in the digestive tracts of every marine species tested in the laboratory. Hochberg et al (2012) asserted that the ingestion of smaller plastics occurs when an organism like copepods mistake it for food and consume it. This can then be passed on to larger predators and has the potential to bioaccumulate in the digestive tracts of fish and birds.
Marine debris is considered one of the most widespread, persistent, and insidious pollution problems plaguing the world's oceans. One of the main contributors to this marine debris is plastic. According to a report by the UNEP (United Nations Environmental Programme), there are 640,000 tons of abandoned, lost or discarded fishing gear littering the world's oceans. Research from California's "Algalita Marine Research Foundation" suggests that plastic debris outweighs surface zooplankton in the Central North Pacific by a factor of 6:1. Forty-four percent of all seabird species, 22 percent of cetaceans, all sea turtle species, and a growing list of fish species have been documented with plastic in or around their bodies. This phenomenon has been reported in marine species worldwide. These numbers are staggering, and it is no wonder people are calling plastic 'the invisible killer'.
2.1 Sources of Plastic Pollution
Marine litter is a sustained problem in the world's oceans and seas, with plastic making up 60-80% of the total. The origin of the plastic can often be traced back to human activity on land or at sea. Merchant shipping has been serving the needs of the world's communities since humanity began settling by river banks. For over 5000 years, ships have plied their trade across rivers, lakes, and oceans. With modern global trade relying on the import and export of goods, vessels travel to all regions of the world, often taking the shortest course to their destination. This can lead to accidents in the form of groundings, collisions, or damage/loss of containers in storms. Manning a bridge 24 hours a day at sea is a difficult task, and a lapse in concentration can lead to collision with an object, often leading to minor internal or external damage to the vessel that may go unreported. Though no single event involving a vessel may be directly linked to marine pollution, the continued transport of goods across the world's oceans means it is a question of when an accident may occur, not if. Fishing has a documented history dating back some 40,000 years and is an industry that has had a huge impact on marine ecosystems through overfishing, habitat destruction, and use of gear that can result in high levels of researched the fishing accidents. Loss or damage of gear can occur in many ways and is often not reported. Derelict fishing gear is a common and harmful form of marine debris. It is both an economic and ecological problem, with gear continuing to catch fish and crustaceans when left unattended, often in large quantities. Plastic is a popular material for buoys and polystyrene has been used to provide buoyancy to nets. Studies have shown that plastic is the most common type of material associated with marine debris from fishing activity in the Gulf of Mexico and the Mediterranean Sea.
2.2 Impact on Marine Life
Poorly understood and under-reported, the impact of plastic particles on marine life is undergoing close scrutiny by scientists worldwide. The greatest concerns lie around entanglement and ingestion. Plastic is found in the stomachs of virtually all species of marine species including those so important to humans. Entanglement is a largely unreported and often unnoticed occurrence, with fishing gear making up the majority of cases. Effects can be long term and often fatal. Ingestion of plastic debris can be mistaken for food, and because plastic can be very difficult for organisms to excrete, it can result in blockage of the digestive tract. Starvation and gut impaction follow, with animals effectively consuming a diet of plastic. It is estimated that 80% of the plastic that enters the oceans from land-based sources sinks, with the other 20% being washed out to sea from ships and platforms.
2.3 Current Efforts to Address Plastic Pollution
Research and documentation on the current status of plastic pollution is one of the approaches to educating the general public and policy makers on the severity of the problem. Scientists like Kara Lavendar Law are sailing the oceans on research vessels studying the extent of plastic pollution in various parts of the world. Studies such as this are essential in providing not only a solid knowledge base on the issue, but also the empirical evidence needed to inspire governmental action. Furthermore, efforts are being made to study the most effective means of cleaning up the mess. Engineers from the British company Ironsides are designing new ships aimed at collecting and disposing of plastics at sea, and several organizations are looking into recycling essay service research papers owl the vast amount of plastic debris.
Many international and local organizations have been working on raising awareness and finding ways to effectively reduce the plastic entering the oceans. Project AWARE (a non-profit organization mobilizing divers to protect the ocean one dive at a time) and the Surfrider Foundation are just two examples of environmental organizations that are actively working towards finding ways to combat marine debris. The United Nations Environment Programme has also been active in combating marine debris by addressing the issue in international waters. Such organizations are finding ways to implement national and international policies to reduce plastic input into the oceans.
3. Ship Collisions: A Hidden Contributor to Plastic Pollution
Plastic pollution is a sea of concerns of growing interest to NGOs, researchers, and policymakers. Not a soul who has researched on this topic would fail to be despondent at the state of the blow, for it is a malady the size of the Great Pacific Garbage Patch. Predictions are that thousands of aquatic life forms from sea turtles to marine mammals will suffocate or otherwise perish from this affliction. The main victims, however, possessing a predisposition to the consumption of plastics of any size, are sea birds.
Petrels, puffins, and albatrosses, to name a few, have been found with stomachs crammed full of plastic waste. The result often being fatal. One case involving a dead baby albatross found on a beach in Hawaii graphically personifies the scourge of oceanic plastic pollution.
One of the most insidious effects of plastic ingestion is the concentration of toxic chemicals in the bodies of aquatic organisms. Most of the pollutants in the ocean today stick to the surface of the plastic, so when an organism ingests the plastic, it also ingests the pollutants. High concentrations of these chemicals can have effects on reproductive capabilities, immune systems, and alter hormone levels. Effects which will undoubtedly pass up the food chain to impact human health.
3.1 Overview of Ship Collisions
Ship collisions are an inherent risk in maritime transport and entail serious safety and financial consequences. However, ships can also be a source of plastic pollution. An understanding of the scale of the problem is conjectural, but if we are to appreciate the magnitude of the issue and to assess the impact of any remedial actions, it is important to try and quantify the amount of plastics that could be introduced to the oceans from collisions. At present, knowledge of the types and quantities of plastics on board ships is limited. In general, most of the information on plastics at sea is derived from studies of floating plastic debris, particularly from the Pacific, Atlantic and Indian oceans. Given that ship collisions occur all over the world, it is reasonable to assume that all types of plastic are at risk from becoming marine debris, depending on the nature and location of the collision. This includes plastics in the form of single resin pellets, especially prevalent in Japan, which are transported around the world for the manufacture of plastic products. Data on the densities of plastic debris in the ocean are also sparse, but the distribution patterns of plastics released from ships will depend on the type and size of plastic involved and the location and nature of the collision. High density plastics are likely to sink, especially if they are fouled by marine organisms, and are thus not relevant to surface drift studies. This can have acute benthic impacts in ecologically sensitive areas, such as seagrass beds and coral reefs. Plastics released in less severe collisions in open ocean areas are most likely to become part of the surface drift as with general ocean litter, where they may be transported over great distances before washing up on beaches. So while we can speculate that different types of plastic released from ship collisions have different fates, the final resting places of these plastics may be very difficult to track and assess.
3.2 Factors Leading to Ship Collisions
Human error and failure of navigational equipment are obvious and direct causes of ship collisions. Causes such as neglect, lack of education, and fatigue fall under this category and also lead to an element of complacency in ship operation, especially in familiar areas. A paper written by Tetsuo in 2005 describes that some mariners in coastal countries that have little exposure to the technology and methods of modern Western navigation continue to rely on traditional techniques of coastal piloting and celestial positioning. This, along with a cultural resistance to and neglect of modern technology, is a major factor in the high concentration of shipping incidents in the Asian region. Failure of equipment presents more of an indirect cause of collision, and Michael in 1998 documents how the increase in automation, although positive in reducing the chance of collision due to human error, may lead to or intensify collisions caused by equipment failures due to lack of watchfulness and testing. Step written in 2018 has shown how it is difficult to prove direct relations between human error and collisions, but studies have demonstrated that minor human errors and/or lateness in correcting them were most likely affected by additional complicating factors like adverse weather or strong currents and have led to the collision.
Weather can cause a variety of problems for ships, including visibility reduction, increased sea states, and in the case of extreme weather, structural damage to the ship. One of the major effects of poor weather is strong currents, and this is now seen to be a major factor in ship collisions. In 2001, the MV Willy grounded onto the ecologically sensitive Jacob's Rock in the Delaware River. The National Transportation Safety Board investigation found that the pilot's decision to continue the voyage despite predictions of thick fog, reduced visibility, and dangerously high tides was a major contribution to the incident. High winds and rain can turn trivially submerged rocks or reefs into serious hazards to navigation, and ships that might otherwise have passed without incident have been set upon a collision course due to adverse weather conditions.
3.3 Consequences of Ship Collisions on Plastic Pollution
Plastic pollution has become a pervasive and permanent pollutant in the world's oceans, and it has been estimated that a range of between 60% and 80% of marine debris originates from land-based sources. The discharge of plastic at sea from ships has been relatively well studied. Items commonly discarded will include plastic packaging, sacks, and fishing gear. Regular deck maintenance to remove fouling organisms and organisms accumulated within sea chests may result in large quantities of microplastics entering the sea through the abrasion of antifouling paints and other polymer-based materials. However, the loss of cargo is perhaps the most significant source of direct plastic input at sea from ships. Significant losses of containerized cargo will occur during a major shipping disaster, and while the environmental impact of sunken containers is related to their contents, it is worth noting that certain plastic products may be virtually indestructible and last centuries in the marine environment. An example would be the millions of plastic resin pellets being transported around the world as a base material for the plastic manufacturing industry.
Even in the absence of direct collisions and groundings, boats and ships can disturb sediments, resulting in the resuspension of contaminated sediments and increased turbidity. This can have a detrimental impact on benthic habitats and associated fauna and flora, while the increased turbidity can inhibit the growth of phytoplankton and result in a cascade effect through marine food webs. High-speed craft such as jet skis can cause a disproportionate amount of damage relative to the amount of fuel they consume, and in some cases have been responsible for significant damage to coral reefs. Erosion due to the wake from larger vessels can occur in shallow coastal areas with significant impacts on geomorphology and habitat structure.
The consequences and effects of ship collisions often go beyond direct hull and engine damage. Plastic pollution can result from the very obvious discharge of plastics at sea associated with derelict and sunken vessels. However, the picture is far more complex and insidious. Any hard substrate in the marine environment, including ship hulls, provides a surface to which other debris and marine organisms can attach. Ships can essentially act as vectors, transporting alien species on their hulls from one part of the world to another. A recent but as yet unquantified impact is the transport of hard substrate fouling communities from one part of the ocean to another, potentially resulting in a loss of biodiversity at some sites and an increase at others. Hard substrates including shipwrecks also represent a long-term source of microplastic production through the breakdown of larger items.
3.4 Case Studies of Ship Collisions and Plastic Pollution
On the 10th of August 2006, the cargo ship MV Hyundai Advance dropped anchor in the San Francisco Bay. Just minutes after dropping anchor, the anchor dragged across the bottom of the ocean, hit an underwater oil pipeline, and caused an oil spill from the damaged pipeline. Approximately 5000 gallons of oil were released into the ocean, which affected many marine mammals, such as seals and sea lions. One year after this incident, a research was conducted by the National Marine Mammal Foundation, and they discovered an unusually high number of seals and sea lions sick and dying from a mystery disease. These mammals were found malnourished and lethargic, and my research writing edu birdie online slowly died. Upon necropsy of the dead animals, it was discovered that the brain was the most affected organ, and a high number of domoic acid poisoning cases were related to the brain damage. Domoic acid is a neurotoxin that affects the brains of marine mammals and birds, and it is produced by algal blooms. High amounts of this toxin can cause long-term effects and ultimately death. In hypothesis, it was said that the cause of the oil spill was actually an indirect contribution to the effect of domoic acid on the marine mammals. Due to the damage of the pipeline, the oil spill led to a decrease in the quality of the seawater near the affected animals and an increase in domoic acid levels inside the seals' food source. This is because the oil traveled two miles north of the Golden Gate Bridge, and at that exact same time in 2006, there was a major event of harmful algal blooms in the ocean in northern California. An increase in distribution of the algal bloom and higher levels of domoic acid inside the bodies of affected mammals led to long-term effects that the mammal populations are still recovering from today. This case directly relates the effects of ship accidents to plastic pollution. MV Hyundai Advance's accident is one of many ship accidents to this day that leave a large long-term effect on marine biology.
4. Mitigating the Impact of Ship Collisions on Plastic Pollution
The first attempt at an international regulation for preventing marine pollution was implemented by the United Nations Environmental Programme (UNEP) in 1972 with the Convention for the Prevention of Marine Pollution by Dumping from Ships and Aircraft. This then led to MARPOL and in 1973, the International Maritime Organization (UN body responsible for the safety and security of shipping and the prevention of marine pollution), began to look at the effects of all forms of marine pollution and not just pollution by dumping. This brought about a more detailed consideration of the relationship between shipping and pollution which eventually led to MARPOL 73/78, the international convention that has more than any other instrument, contributed to the significant reduction of pollution. In particular, MARPOL has addressed pollution from ships into the marine environment, both by accidents or operational mishaps, and from routine practices. Of the concerned accidents referred to above, the most significant is that of oil pollution from ships. Since oil pollution has a range of short and long-term effects on the marine environment, the measures taken to prevent it have had obvious benefits for the prevention of pollution by other substances and plastics.
4.1 International Regulations and Policies
Ships can emit plastic indirectly through inadequate sewage and waste disposal, but it is the loss of cargoes and fishing gear and damage from ship traffic that are the most significant sources of sea-based marine plastic. These are issues that are more commonly associated with the accidental pollution of the sea, rather than direct littering. If the UN IMO definition of marine pollution as "any substance that man deliberately or inadvertently introduces into the marine environment" is considered, then there is a responsibility for accidental plastics to be classed as marine pollution regardless of their source.
Marine litter has been a concern of many countries for over three decades, with numerous international, regional, and national initiatives aimed at tackling the problem. Before assessing the laws and policies designed to reduce marine plastic from ships, it is important to look at whether ships could be considered a significant source of marine plastic. Surprisingly, shipping has long been exonerated from taking responsibility for its plastic emissions into the sea. For example, in the United Nations International Maritime Organization (UN IMO) report on marine debris in 2005, it was stated that there was insufficient information to establish whether or not marine plastics are primarily land-based or sea-based sources. Also, the quantities and sources of marine plastic are uncertain, and the effects are predominantly aesthetic. All of which serve to downplay the severity of the issue.
4.2 Technological Solutions
Technological solutions to reduce the impact of ship collisions on plastic pollution are numerous and diverse. Some are technological fixes for ships that reduce the likelihood or consequences of collisions, while others focus on improving the situational awareness of coastal and port authorities to prevent such incidents occurring, or to trace and understand shipping dynamics and the fate of plastic in the ocean. The MarineLitterTrac project is developing a system based on buoyant drifters equipped with satellite tracking beacons which can follow the same routes as plastics in the ocean. This will enable validation of models of plastic distribution and eventual fate and assist in prediction and early warning of areas where plastic waste is likely to be concentrated, minimising the risk of collision for ships unwittingly taking these routes. The drifters will be made from biodegradable materials to avoid creating a secondary source of pollution should they be lost. The EU funded SMARTOCEAN project seeks to develop a new generation of cost-effective, compact, integrated, real-time subsea and surface monitoring systems for marine resources and environment, with particular focus on fisheries and aquaculture and protection of the environment. These systems are intended to provide a better understanding of the distribution of marine activity and its interaction with vulnerable marine ecosystems, and therefore contribute to improved governance and sustainable management of marine resources. A spin-off of this work would be improved knowledge of the complex and dynamic distribution and fate of plastics in the marine environment and development of techniques to predict areas of high plastic concentration and collision risk for shipping. At the level of the shipping industry itself, operational advances or changes that can reduce collision risk are often most practical if they can be clearly linked with economic or practical benefit. Slight alterations to shipping routes or changes in speed can decrease the risk of collision with debris, which is particularly the case for large uncharted fields of debris such as the 'Great Pacific Garbage Patch'. Knowledge of the location of this and other high debris areas is very beneficial for ships to plan avoidance strategies, and thus research improving the quality and accessibility of global information on plastic distribution is of significant value.
4.3 Collaboration and Awareness Initiatives
Global awareness of the issue of ship strikes is not consistent across stakeholder groups. While some shipping industry professionals are aware of the potential for strikes and have adopted mitigation strategies, many others do not recognize the scale of this issue and its potential impacts to the environment and their livelihoods. Create change within the shipping industry and other stakeholder groups will require a comprehensive outreach and education strategy delivered through a variety of media to increase knowledge and awareness of the issue of marine vessel/animal collisions. An understanding of the perceptions and norms of various stakeholder groups concerning this issue would be helpful for targeted message development.
Effective collaboration and information sharing can help to support and encourage isolated initiatives and prevent duplication of efforts (thereby maximizing efficiency of resource allocation). Would-be collaborators face serious barriers to the exchange of ideas and findings, often due to competition for funding. Forging collaboration among ship strike mitigation projects will require a shared forum for information exchange and development of a strategic plan to encourage the complementary nature of various initiatives. Increased investment in this type of leadership is essential.
As ship strikes continue to be a significant threat to marine use - as outlined in previous sections - initiatives geared toward raising awareness of the issue and generating collaboration among a variety of stakeholders are increasing in both number and visibility. An assessment of the available and emerging initiatives provides an understanding of the current state of mitigation efforts and highlights potential windows of opportunity for addressing ship strikes. Awareness initiatives and collaboration efforts were identified through an extensive web search, literature review, and personal communication with experts and managers in the field of marine conservation. A surprising number of independent efforts are currently underway. However, these efforts often operate in isolation from one another indicating the absence of a coordinated global strategy to address this issue.

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Tags: Plastic Pollution, Ship Collisions, The Hidden Threat of Ship Collisions on Plastic Pollution in the Oceans