Every year, more than 10 million tonnes of plastic enter the world’s oceans annually (Jambeck et al. 2015). As of 2014, over 5 trillion counts of plastic, weighing over 260 thousand tonnes, float over our oceans (Erikson et al., 2014). Not only is this figure certainly significantly higher now, but most of the plastic in our oceans is also out of sight from the surface, with most (97%) of the plastic that ends up in our oceans being reported to be on the sea floor (Eunomia, 2016). These plastics can be broadly classified into 4 categories, based on their size– namely macroplastics, mesoplastics and microplastics (Thushari & Senevirathna, 2020) (Figure 1). In marine and coastal environments, the high salinity of seawater intensifies the degradation and fragmentation (by various physical, chemical and biological processes) of larger pieces of plastics into microplastics (plastics less than 5mm in diameter) (Browne et al., 2011; Wang et al., 2018). As such, microplastics are the most abundant form of MPP, and can be extensively found across all layers of the ocean (Thompson, 2015; Thushari & Senevirathna, 2020).

Figure 1: Classification of plastic litter based on their size. (Loganathan, 2022)

Negative Impacts of Marine Plastic Pollution (MPP) on the environment

I’m sure many of us are familiar with or have at least heard of the numerous adverse ecological impacts that plastic pollution can have on marine biodiversity, as well as on human health. Firstly, the ingestion and entanglement of macroplastic fragments pose significant risks for marine and coastal organisms. Gall and Thompson (2015) recorded that over 208 species have experienced problems related to the accidental ingestion of macroplastic fragments, while a further 243 species have been entangled by these fragments. While the ingestion and entanglement of plastics by marine organisms are not always lethal, they can result in many other sub-lethal effects, such as the loss of mobility, reduced food intake and decreased growth (Gall and Thomspon, 2015). Figure 2 highlights some of the effects on marine and coastal organisms, due to ingestion and entanglement. 

 

Figure 2: Effects of plastic ingestion and entanglement by marine and coastal organisms. a) Plastics ingestion by a blue shark; b) Attachment on plastic debris by Goose Barnacle; c)Partial cover of macroplastic pollutants on Rock Oyster; d)Entanglement of nestling in a synthetic plastic string. (Thushari & Senevirathna, 2020).

Similarly, being similar to the feeding matter of many organisms, microplastics are also often ingested by many marine organisms (Browne et al., 2007; Wright, 2013). Such microplastics are highly toxic, as not only do they contain toxic chemicals (e.g. Bisphenol-A, monomers, oligomers, flame retardants etc), but they also absorb surrounding persistent toxic chemical substances such as Persistent Organic Pollutants (POPs)– often by-products of industrial processes, that are resistant to biodegradation (e.g. dioxins and various industrial chemicals) (Thushari & Senevirathna, 2020). Such ingestion of microplastics often results in the chemical bioaccumulation of toxic chemicals in organisms throughout the food chain. The subsequent consumption of such seafood by humans poses significant health effects (Cole et al., 2013). 

Is the shipping industry a major contributor to marine plastic pollution? 

In the preceding section, we delved into the various adverse effects of MPP. However, as the focus of this blog is on the polluting impacts of the shipping industry, in the following section, I aim to investigate whether the shipping industry is a substantial contributor to MPP.

According to Annex V of the International Convention for the Prevention of Pollution from Ships (MARPOL) (Entered into force in 1978 and signed by 156 states, representing 99.42% of the world’s shipping tonnage), merchant ships are prohibited from disposing of any garbage into the sea, and instead, dispose it only at ports. Additionally, ships are also required to prepare and implement Garbage Management Plans (International Chamber of Shipping, n.d.). According to the International Chamber of Shipping (ICS), discharge from MPP from ships is “very rare”. 

However, based on a report published by Eunomia (2016), while they have indeed identified land-based coastal pollution to be the biggest source of MPP, contributing around 9 million tonnes per annum (Mtpa), at-sea sources still accounted for 1.75Mtpa, of which litter from shipping activities contributed to 0.60Mtpa. Land-based inland pollution contributes 0.5Mtpa and microplastics (<5mm) contribute to the remaining 0.95Mtpa. Figure 3 highlights the various sources of MPP, as well as their eventual sinks. 

Figure 3: Source and sinks of Marine Plastic Pollution (MPP). (Eunomia, 2016).

Where does MPP from the shipping industry originate from then? 

An insight into one source of MPP from the shipping industry– shipping container spills, is provided in a recent paper by Saliba et al. (2022). Citing the World Shipping Council, they highlight that an annual average of 1382 containers, equivalent to 13,820t of consumer packaged goods (CPG) are lost at sea yearly (World Shipping Council, 2020, as cited in Saliba et al, 2022). 

While this represents only a small percentage of the estimated 0.60Mtpa of MPP that is contributed by the shipping industry, MPP from shipping container spills is nonetheless a noteworthy source of MPP. This is especially so as Saliba et al. (2022) have, in their review of maritime governance in the North Sea, highlighted the inadequacy of current legal and policy instruments, as well as mechanisms, to hold MPP polluters liable for the environmental damage that they have caused by shipping container loss. 

The next section, using examples from the North Sea, highlight a few of the identified policy gaps, where current systems and processes in place at global and regional governance levels fail to hold polluters accountable for MPP. 

Global Level: The absence of the need to declare the loss of containers at sea

As identified by Saliba et al. (2022), under the International Convention for the Prevention of Pollution from Ships (MARPOL)– which is the main global convention covering the prevention of pollution of the marine environment by ships from operational or accidental causes– there is an absence of a compulsory system to report lost shipping containers at sea or to determine the total number of containers/goods lost. This has led to the lack of reporting of shipping container losses. 

An example is the Ever Laurel case in 1992, where when a shipping container vessel– The Ever Laurel, owned by the Evergreen Marine Corporation, and transporting children’s bath toys from Hong Kong to Washington– had over 29,000 floating plastic toys fall overboard into the Central Pacific Ocean (Ebbesmeyer et al., 2007). This has resulted in various MPPs (in the form of children’s bath toys) continuing to wash ashore along various coasts of the Pacific Ocean (as far as the British Isles), even many years later. However, as the spill was neither reported by the Ever Laurel nor witnessed by others, the identity and cause of the spill were only revealed many years later by journalists. 

Regional (European Union & North Sea): Absence of specific legislation to address MPP as a result of accidental container loss

The European Union has adopted several directives to ensure offences of MARPOL can be prosecutable under criminal law. The ‘Protection of the Environment through Criminal Law’ (Directive 2008/99/EC), mandates the prosecution of states for causing harm to the quality of water, animals, and plants (European Union, 2016). Additionally, the ‘Environmental Liability Directive’ (ELD) (DIrective 2004/35/CE), which adopts the Polluter Pays Principle, covers the prevention and mitigation of environmental damage caused by the discharge of hazardous and noxious substances (HNS) (The European Parliament and the Council of the European Union, 2004). 

However, Saliba et al. (2022) have, through interviews, identified some policy gaps that render these directives ineffective in dealing with MPP from shipping container losses. Firstly, plastic is excluded from the HNS list. Additionally, although the ELD mandates polluters to finance the restoration of damaged nature to its original state, it has been challenging to apply it in previous maritime oil spills, such as the Torrey Canyon and Amoco Cadiz incidents, due to insufficient baseline data of the conditions of the affected environment. Applying this to MPP in the context of container spills, it becomes challenging to hold responsible parties liable for the harm caused to nature and its ecosystem services. This is because states would need to demonstrate the extent of ecological damage caused by the plastic spill, based on baseline conditions. 

The exclusion of MPP is not limited to the ELD. Another example is In the main regional agreement present in the North Sea to unify efforts the pollution– The Convention for the Protection of the Marine Environment of the North-East Atlantic (OSPAR Convention). While the OSPAR convention requires states to ensure incidents of container spills are reported, it does not consider MPP to be damaging to the environment and is not listed as a noxious pollutant. 

Conclusion

In conclusion, while MPP has adverse ecological impacts on marine biodiversity, as well as on human health, Saliba et al. (2022) have, in their review of marine governance at various levels, found a lack of systems and processes in place to hold polluters of MPP by shipping container loss accountable. This, therefore, brings to light, the difficulty in enforcing compensation for the damage that MPPs have on the ecosystem. Ultimately, a concerted effort is needed by all stakeholders (international organisations, governments, shipping industry),  to address the issue of MPP by shipping container loss. This can start with MARPOL mandating the need to report all shipping container losses. 

References

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