Keywords

1.1 Introduction

The ocean is of great importance to earth, not just to coastal nations but also to landlocked communities and countries. The ocean regulates our planet. It produces vast amounts of the oxygen we breathe and acts as a global climate control system by absorbing, storing, and releasing heat and gasses. It is a source of food and essential nutrients such as iodine. It provides the backbone of global transport and trade. Our ocean provides critical economic opportunities and sustainable industries, and contributes to recreation and mental well-being. Covering >70% of the earth’s surface (Kaiser et al., 2005), it is not surprising that the ocean is integral to supporting life on earth, providing us with basic necessities whilst regulating our blue planet.

The coastal and marine environment is crucial for the livelihoods of many inland and coastal communities. In 2005, approximately 2.2 billion people lived within 100 km of coastline. The rapid urbanisation of these areas is causing this figure to double by 2025 (Kaiser et al., 2005). The average population density along coastlines changes rapidly around the globe. On average, globally, the population density is 80 people per km2. However, this rises to 1000 people per km2 in countries such as Egypt and Bangladesh (Kaiser et al., 2005). Many coastal inhabitants depend directly on marine resources for their subsistence or income. More than 3 billion people’s livelihoods (>40% of the global population [World Bank, 2019]) depend directly on coastal and marine biodiversity, whilst the maritime fishing sector, directly or indirectly, employs more than 200 million people (United Nations, 2021).

The economic potential of the ocean is of global importance. It goes further than the fishing industry. The ocean supports a whole range of maritime activities such as shipyards, marine terminals, aquaculture, seafood processing, commercial diving, and marine transportation. The ocean’s contribution to the global economy was predicted, in a pre-COVID-19 projection, to double from US $1.5 trillion in 2010 to US $3 trillion by 2030 (OECD, 2016). The Gross Domestic Product (GDP) of the ocean is of a similar order, estimated at US $2.5 trillion per year (gross marine product) (Hoegh-Guldberg et al., 2015), making the global ocean the words 8th largest economy (World Economic Forum, 2020).

The ocean’s economic importance is recognised through the Blue Economy. The Blue Economy is the “sustainable use of ocean resources for economic growth, improved livelihoods and jobs whilst preserving the health of ocean ecosystem.” The Blue Economy recognises the need to enhance economic development by exploiting marine resources in a sustainable and regenerative way that conserves life-sustaining marine environments. When approached as the Blue Economy, the maritime industries and activities promote the preservation or improvement of livelihoods, social inclusion and economic growth, whilst ensuring environmental sustainability (United Nations, 2019). The ocean’s importance reaches far beyond economic and subsistence. The ocean allows for life on this earth as we know it.

The ocean is a climate regulator and buffer to the current anthropogenic pressures, placing the ocean under the increasing strain of ocean acidification, warming temperatures, decreasing oxygen, and sea-level rise (Bindoff et al., 2019). The diversity of species found in our ocean offer great potential for treatments to combat illness and improve our quality of life. The ocean provides physiological comfort to humans, enhances health and wellbeing, and supports the development of self-efficacy and resilience (Costello et al., 2019). Important in times of increased distress, as seen during the COVID-19 pandemic. A recent study suggests a potential buffer effect of residential proximity to the coast against negative psychological consequences of the COVID-19 pandemic, further supporting the notion that the coast has a positive impact on wellbeing (Severin et al., 2021).

Our ocean is in peril. Overfishing has had a severe impact on fish stocks and ecosystems. Habitats have been degraded, and increasing pollution and climate change further deteriorates entire marine environments. Plastic pollution has entered the ocean by millions of tonnes in the last decades. These threats act as accumulative threats, all of which contribute to rapid biodiversity loss.

Although international conventions provide protection through agreed global cooperation, only 2% of the ocean is protected by marine reserves (Sala et al., 2018). These international conventions include but are not limited to: the international Convention on the Prevention of Marine Pollution by Dumping of Wastes and Other Matter, 1972 (London Convention) and The International Convention for the Prevention of Pollution from Ships, 1973 (MARPOL) and their associated annexes and protocols. Additional regional governance occurs. The seas surrounding Africa are governed through the Barcelona Convention, the Nairobi Convention, the Jeddah Convention and the Abidjan Convention, including its additional protocols on pollution from land-based sources, integrated coastal zone management, sustainable mangrove management, environmental standards and guidelines for offshore oil and gas activities and policy on integrated ocean management. See Chap. 4 and associated figures for details on relevant ocean governance frameworks and their geographical coverage.

The importance of the ocean is emphasised by its role as a climate regulator, a source of food and Blue Economies, all of which have global and regional scales and importance. Due to our physiological, ecological, economic, and psychological dependency on a healthy ocean, ocean protection forms a fundamental part of the United Nations’ Sustainable Development Goals (SDGs). In October 2021, the UN Human Rights Council in Geneva recognised access to a sustainable and healthy environment as a universal right. Inclusion of the ocean in the SDGs (SDG14–“Life below water”) provides global recognition of its importance, and consensus and incentives for protection.

1.2 The Threats the Ocean Faces

The ocean faces cumulative threats from climate change, biodiversity loss, and pollution. With pollution covering chemical pollution, such as nutrient enrichment leading to eutrophication, marine litter, and physical pollution such as the input of light, noise, and heat. The focus of this African Marine Litter Outlook is on marine litter; however, the pollution threats to the ocean are interlinked. They should be considered in relation to each other and in relation to other cumulative pressures on the ocean such as climate change and biodiversity loss.

1.2.1 Marine Litter

Marine litter is “any persistent, manufactured or processed solid material discarded, disposed of or abandoned in the marine and coastal environment” (UNEP, 2006). Though often stated that 80% of marine litter is from land-based sources (GESAMP, 1991; Sheavly, 2005), this number is variable and depends on the location and its pressures. Coastal areas close to urban centres are dominated by litter from land-based litter sources (Ryan et al., 2018). However, the open ocean, islands, and more remote locations show higher proportions of litter from sea-based sources (Ryan, 2020; Ryan et al., 2019). Sea-based sources originate from a wide range of maritime activities, including fishing and shipping related amongst other types of litter. Jambeck et al. (2015) noted that this 80% figure “is not well substantiated and does not inform the total mass of debris entering the marine environment from land-based sources.” The term marine litter encompasses a wide range of materials and sizes (from mega to nano) spread across a variety of compartments (beaches, seafloor, water surface, and water column, etc.), the largest proportion (61–87%) of marine litter consists of plastic (Barboza et al., 2019; Tekman et al., 2019). This percentage indicates weight, irrespective of units, whilst excluding microplastics.

Box 1.1: Size Fractionate and Definitions of Litter

Plastic litter is defined through size classes as macro (>25 mm), meso (5–25 mm), micro (1 μm–5 mm) and nanoplastics (<1 μm) (GESAMP, 2019). Microplastic enters and forms in the environment through primary and secondary sources, respectively. Primary sources are direct inputs such as plastic nurdles, microbeads from personal care products (Carr et al., 2016), and industry abrasives (GESAMP, 2015). Secondary sources of micro and nanoplastics include: industry abrasives (Eunomia, 2017), textile fibres (Browne et al., 2011; Napper & Thompson, 2016), tyre dust as well as fragmentation and degradation of macro and mesoplastics (5–25 mm) (GESAMP, 2019).

1.2.1.1 A Global Perspective of Marine Litter

Following their commercial development in the 1930s (Jambeck et al., 2015), plastic production only grew substantially from the 1950s, with an increase in single-use plastic consumption items and resulting “throw-away” culture in the last two decades—seeing half of the plastic produced since the 1950s was made between 2002 and 2015 (Geyer et al., 2017). Geyer et al. (2017) estimated that, as of 2015, 8.3 billion metric tonnes (MT) of virgin plastic had been produced, with approximately 6.3 billion MT of that becoming waste, of which 79% ended up in landfills or the natural environment. Eriksen et al. (2014) estimate that 250,000 tonnes of plastic are afloat in the ocean. This number excludes items made from polymers which are denser than seawater (which account for roughly 40% of global plastic production by mass) as well as less dense polymers that sink due to biofouling (Fazey & Ryan, 2016; Lobelle & Cunliffe, 2011).

Plastic production is increasing. Lebreton and Andrady (2019) estimated that production will double within the next 20 years, and plastic waste production to more than double in the same period (Geyer et al., 2017). In addition to increasing plastic production, further economic investment in the industry in America is projected to accelerate virgin plastic production (Borrelle et al., 2020). Globally, waste management systems are not sufficient to safely dispose of or recycle waste plastic (Velis et al., 2017; Wilson & Velis, 2015), resulting in an inevitable increase in plastic pollution entering the environment (Lau et al., 2020).

Increasing awareness of marine litter has led to numerous and varied attempts to quantify the amount of plastic entering our ocean (UNEP, 2020). Lebreton et al.’s (2017) model estimated the amount of plastic waste currently entering the ocean every year from rivers to be between 1.15 and 2.41 million tonnes. Jambeck et al. (2015) proposed that in 2010, 275 million MT of plastic waste was generated in 192 coastal countries, of which 4.8–12.7 million MT entered the ocean. Jambeck et al. (2015) highlighted that population size and quality of waste management systems largely determine which countries contribute to plastic marine litter. Although these numbers are contested, the scale of the issue is not (Ryan, 2020; Vester & Bouwman, 2020).

Lau et al. (2020) modelled different scenarios with all currently feasible interventions, finding that even with immediate and concerted action, 710 million MT of plastic waste will still cumulatively enter aquatic and terrestrial ecosystems between 2016 and 2040. Borrelle et al. (2020) supported their finding that current efforts are insufficient to tackle the plastic waste problem.

Marine litter is symptomatic of more significant issues. First, resource abuse through the unsustainable design, production, and consumption of single-use items. And second, a lack of service delivery and safe management of waste.

1.2.2 Climate Change

Carbon emissions from anthropogenic activities are causing ocean warming, acidification, and oxygen loss within the marine environment. These changes affect marine organisms, ecosystems (Bindoff et al., 2019), and their services. Marine litter is a threat multiplier to the ocean ecosystems already affected by climate change (UNEP, 2021). Marine litter also contributes to climate change through greenhouse gas emissions (Ford et al., 2022; UNEP, 2021) and by reducing the efficiency of the ocean and their ecosystems in storing CO2. Similarly, climate change, through sea level rise, storm surges, and flooding are liking to increase the transport of litter into the marine environment.

1.2.2.1 The Ocean: Carbon Uptake and Storage—Marine Litter’s Role as a Threat Multiplier

The ocean contains the most extensive stock of mobile carbon on earth, containing 50 times more than the atmosphere and 10 times more than the stores in plants and soils combined (Sabine et al., 2004). Through both the physical solubility and biological carbon pump, the ocean helps to buffer anthropogenic climate change through CO2 uptake. The physical solubility pump is the uptake of atmospheric CO2 in surface waters and its transport into the ocean depths through the sinking of denser water. The biological carbon pump is the uptake of CO2 by phytoplankton, and its descend to deeper waters through the sinking of organic debris. Furthermore, the Carbon Dioxide and Carbonate System allows living organisms such as shellfish and corals (as well as phytoplankton and zooplankton) to build their shells or carbonated components from calcium carbonate. Thus, removing carbon from the ocean, further leading to a drawdown of CO2 into the ocean to maintain the carbonate-carbon dioxide balance. Since the industrial revolution, the ocean has acted as a primary net sink (Sabine et al., 2004), taking up 20–30% of anthropomorphic CO2 in the last two decades (Bindoff et al., 2019). Comparing the ocean carbon uptake to the rainforests in the Congo Basin: every year, the global ocean absorbs almost 8 times more carbon than the Congo rainforest (Gruber et al., 2019; Lewis et al., 2009). However, the ocean is nearing the limit of its ability to provide this buffer as increasing temperatures and ocean acidification threaten the efficiency of these systems (Field et al., 2002; Friedlingstein et al., 2006; Fung et al., 2005).

Though an emerging field of research, marine plastics have been shown to reduce the efficiency of the biological carbon pump by either affecting the survival of zooplankton or by increasing buoyancy of sinking particles (such as faecal pellets or excrement) (Cole et al., 2016; Wieczorek et al., 2019). The biological pump is driven by sinking organic matter, which contains carbon, such as faecal pellets and dead plankton, to the deeper ocean and seafloor, where the carbon becomes trapped. Microplastics reduce feeding, reproductive success, and survival rates in zooplankton (Cole et al., 2015; Lee et al., 2013); this species-level effect may reduce the efficiency of the biological carbon pump. Additionally, when plastic occurs in zooplankton faecal pellets, the pellets become more buoyant, reducing their sinking rates (Cole et al., 2016; Wieczorek et al., 2019). The slower they sink, the more time carbon has to escape back into the upper ocean and atmosphere, thus reducing the efficiency of this sink. Current levels of microplastic ingestion probably have minimal impact on the biological pump. However, under future microplastic concentrations (or in areas with elevated plastic concentrations such as convergent zones), microplastics may have the potential to reduce the efficiency of the biological carbon pump (Wieczorek et al., 2019).

Further effects of plastic on the ocean pumps are theoretical but unknown. These might include interference in light penetration for photosynthesis impacting the biological carbon pump, as well as interfering in the Carbon Dioxide and Carbonate System through smothering of relevant species (e.g., bivalves). Plastic pollution affects microbial biodiversity by altering community composition (Harvey et al., 2020), however, the effects of this are unknown.

1.2.2.2 Marine Ecosystems and Their Services—Marine Litter’s Role as a Threat Multiplier

In addition to the uptake and storage of CO2 by phytoplankton and ocean waters, coastal marine ecosystems play a crucial role in carbon uptake and storage. Mangrove forests, seagrass meadows, and salt marshes all capture and store substantial amounts of organic carbon through net primary production, burial (in detritus and sediment), and export (Duarte, 2017; Duarte et al., 2013; McLeod et al., 2011). In addition to acting as carbon sinks, these ecosystems, and coral reefs form natural coastal defenses (Temmerman et al., 2013), protecting coastal areas from climate-driven rising sea levels and storm surges (Oppenheimer et al., 2019).

In addition, biomass production and water purification are amongst the most essential ecosystem services delivered by the ocean (Karani & Failler, 2020). Efforts to conserve and restore natural carbon sinks will help reduce the impacts of increases in anthropogenic CO2 emissions (Mcleod et al., 2011). Blue Carbon and Ecosystem Services offer an opportunity to develop coastal projects to protect these ecosystems and mitigate climate change (Karani & Failler, 2020).

Key coastal ecosystems are exposed to pollution, reducing their ecosystem services. Harris et al. (2021) found that 54% of mangrove forests are within 20 km of a river that discharges substantial plastic pollution (>1 t year−1), compared to 24% of seagrass meadows, 23% of salt marshes, and 17% of coral reefs. Ecosystem services provided by mangrove forests, seagrass meadows, salt marshes, and coral reefs are outlined in Table 1.1.

Table 1.1 Ecosystem services provided by mangrove forests, seagrass meadows, salt marshes, and coral reefs (Kaiser et al., 2005; Karani & Failler, 2020; Temmerman et al., 2013)
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Coral reefs, and the ecosystem services they provide, are estimated to be worth US $130,000 ha−1 year−1 (Diversitas, 2009). Green and Short (2003) estimated the global value of seagrass meadows services to be US $3.8 trillion, and Costanza et al. (1997) estimated the seagrass meadows to be worth US $19,000 ha−1 year−1. From a biodiversity consideration, mangrove forests and seagrass meadows are two of the most valuable marine habitats in the world, rivalled only by coral reefs in the biodiversity they support (Kaiser et al., 2005).

Mangrove forests and salt marshes trap plastics (Martin et al., 2020; Yao et al., 2019), creating a harsh environment where fragmentation occurs, leading to increased microplastic quantities in their respective biota (Deng et al., 2021; Yao et al., 2019). Seagrass meadows are within close proximity to rivers discharging substantial amounts of plastic pollution (Harris et al., 2021). They grow in naturally sheltered areas, and plastics have been found to settle on their above-ground structure (de Smit et al., 2021; Seng et al., 2020). Seagrass meadows and coral reefs both act as significant microplastic sinks, facilitating the accumulation and burial of microplastics along with sediment, thus removing them from the pelagic food chain (de Smit et al., 2021). Research on the ingestion and impact of these plastics on these ecosystems is in its infancy (Seng et al., 2020). Plastic pollution has been linked with a decline in coral health and increased coral disease such as white syndromes (Lamb et al., 2018; Reichert et al., 2018). Mangrove forest health (tree density, survival, and tree size) is significantly affected by plastic pollution. Plastic directly and indirectly causes mangrove degradation, thus reducing ecological functioning and ecosystem services (Suyadi & Manullang, 2020). Although macroplastics alter seagrass architecture and may prevent vertical rhizome growth (Menicagli et al., 2021), additional effects of plastic pollution on seagrass meadows are largely unknown (Bonanno & Orlando-Bonaca, 2020). Similarly, the impact of plastic pollution on salt marshes is undetermined.

Marine litter provides additional habitats for a range of species. The colonisation of marine litter affects dispersion rates and life-history traits of rafting species. This can lead to increased introduction and colonisation of invasive species; for example, plastics foster the spread of non-native macroalgae in seagrass meadows, thus increasing their vulnerability to invasion.

Marine litter affects the health and growth of seagrass meadows, mangroves, and corals and, therefore can affect the carbon uptake in these ecosystems. Identifying and addressing the sources of marine litter is paramount in mitigating climate change (McLeod et al., 2011).

1.2.2.3 Climate Change—Plastic Production’s Role

The production and management of plastics also contribute to climate change as every stage of the plastic lifecycle releases greenhouse gas emissions (Ford et al., 2022; Shen et al., 2020). The two main forms of energy used by the plastics processing industry are electricity and natural gas. Plastic production includes both direct and indirect greenhouse gas emissions. Direct emissions include the combustion of fuel, such as at a plastics processing facility. Indirect emissions would include fossil-fuel-powered electricity used in plastics processing. With plastic production increasing globally (Geyer et al., 2017), we utilise more fossil fuels in plastic manufacture, thus contributing to climate change. In addition to overuse, the mismanagement of plastic waste and the loss of this resource from a potential circular economy, driving raw material extraction and production, exacerbating climate change (Masnadi et al., 2018; Shen et al., 2020).

1.2.2.4 Marine Litter—Climate Changes as a Threat Multiplier

Flooding and sea-level rise associated with climate change and global warming will increase the quantities of plastics washed into the ocean every year. In Africa, where poor waste management systems are common, flood water and runoff water from rain are the main pathways through which plastics are introduced into the ocean. Climate change is likely to compound the marine litter issue through increases in sea level, storm events, flooding, and displacement of human settlements leading to issues around the safeguarding and provision of waste management services.

Coastal areas are most vulnerable to the impact and risks associated with sea-level rise in relation to climate change (Lam et al., 2012; World Risk Report, 2018). Global warming and associated climate change and climate variabilities pose huge potentials for disruption of the marine ecosystem globally, with the African continent as no exception. In fact, climate change is, and will, affect the world disproportionately, with Africa being one of the areas disproportionately affected (IPCC, 2019), with climate change further aggravating the physical, biological, social, and economic stress that currently exists in Africa’s coastal areas. Climate change could ultimately lead to loss and fragmentation of marine habitats and biodiversity, and especially negative stresses to fishing, aquaculture, food production, and food security in many African coastal cities and settlements. Many African cities are low-lying and are very susceptible to flooding that could become severe in sea-level rise due to climate change. The UN-HABITAT (2008) report has identified many African coastal cities as being at risk in this regard. The coastal settlements of the several small island countries of the African continent are also at high risk. Landfills, or dumpsites positioned near beaches (e.g., Strandfontein and Witsand, Western Cape, South Africa) lie within the zone of projected sea-level rise and are at risk of being breached. In addition, plastic currently buried in beaches will be released into the sea as storm surges and rising sea levels scour coastal areas (Ryan, 2020). Ongoing efforts at mitigation and adaptation to climate change, promoted and supported by international treaties, have achieved very little to mitigate these risks to Africa’s coastal cities.

Climate change and its resulting influences on environmental degradation, water stress, and food security impact urbanisation plans (IPCC, 2019; Niang et al., 2014). Waste management systems that are already under pressure through population growth and rapid urbanisation (UNEP, 2018b), will be strained further due to climate change.

1.2.3 Depletion of Fish Stocks

Overfishing and the resulting depletion of fish stocks is a global issue, with the average state of global fish stocks being poor and declining (Costello et al., 2016). Overfishing has ecological, social, and economic effects.

1.2.3.1 Contributions of Marine Litter to Overfishing

Abandoned, lost, or otherwise discarded fishing gear (ALDFG) is a recognised issue of marine litter from sea-based sources—fisheries specifically. With much of it being synthetic, ALDFG contributes to marine litter, with an estimated 0.6 MT of ALDFG entering the marine environment as litter in 2015 (UNEP, 2018a). Once lost at sea, ALDFG continues to fish. This is referred to as “ghost fishing” and has detrimental impacts on fish stocks and potential impacts on endangered species and benthic environments. The scale of the issue of ghost fishing and its impacts on fish stocks has not been fully quantified. Please see Chap. 3 for more details on the impact of ALDFG.

1.2.4 Pollution

Marine litter and plastic are not the only form of pollution threatening coastal and marine environments; chemical pollution and nutrient enrichment leading to eutrophication are also pollution threats. Chemical pollution covers toxic metals, persistent organic pollutants (POPs), and crude/refined petroleum oil. Nutrients input into rivers and coastal water could result in eutrophication.

Marine litter can act as a threat multiplier to existing chemical and nutrient pollutants. Firstly, by containing additional chemicals. Secondly, by sorbing and transporting chemicals between compartments, areas, and species.

1.2.4.1 Other Pollutants—Marine Litter’s Role as a Threat Multiplier

Plastic has been identified as a vector for toxic chemicals. Plastics contain and leach additives such as colourants, plasticisers, lubricants, and flame retardants into the environment (Rochman et al., 2019).

Plastic particles may also sorb and accumulate chemicals from their surroundings, including POPs and heavy metals (Näkki et al., 2021). These chemicals are then transported with the plastics across environmental compartments where they may be released, or the toxic plastic may be ingested by marine organisms. The net contribution of plastic ingestion to bioaccumulation of contaminants by marine organisms is likely to be small compared to the uptake of contaminants directly from the water itself (Bakir et al., 2012; Koelmans et al., 2016). However, the multi-stressor effect does still need to be considered (see details in Chap. 3).

1.2.4.2 Other Pollutants—Nutrient Enrichment

Nutrient enrichment of coastal and marine waters is the primary cause of eutrophication that leads to the formation of algal blooms. Eutrophication leads to hypoxic and anoxic conditions in water, extreme turbidity, and a threat to marine life (Malone & Newton, 2020). Nutrient input to the marine environment is primarily derived from land-based sources, mainly through stormwater runoffs from agricultural land where fertilisers are applied. Nutrients are also derived from the discharge of untreated sewage and industrial/domestic wastewater into river courses. As such, there is a similarity with plastic input sources. In Africa, due to the poor state of water and sanitation facilities (Yasin et al., 2010), a significant proportion of the nutrient input originates from sewage disposal. Several eutrophic coastal areas or death zones now affect countries around the African continent, namely Côte d’Ivoire, Egypt, Ghana, Kenya, Mauritius, Morocco, Nigeria, Tanzania, Tunisia, Senegal, and South Africa (Diaz et al., 2011). These might also be hotspots for plastic pollution. Solving the stormwater and wastewater treatment issue would thus reduce pollution from nutrients, sewage, and plastic.

1.3 Africa’s Oceanographic Position

As shown in Fig. 1.1a, the African continent is surrounded by the Atlantic Ocean, Indian Ocean, Mediterranean Sea, and the Red Sea. Off the continent’s coast are various islands associated with the continent and included in this Outlook. The upwelling linked to the colder Benguela and Canary Currents drive the productivity seen off West Africa. The warmer currents of the east coast of Africa are significant as they bring oceanic water from countries in south-east Asia, which is important for the long-distance drift of marine litter (Duhec et al., 2015; Ryan, 2020; Ryan et al., 2021)–which is covered in detail in Chap. 2.

Fig. 1.1
An African map indicates river plastic inputs, a large marine ecosystem with temperature speed and population density.figure 1figure 1figure 1figure 1

a Africa’s oceanographic context showing major currents, LMEs, country population densities, as well as the major river systems and the river’s plastic inputs. b Africa’s key oceanic ecosystems—salt mashes. c Africa’s key oceanic ecosystems—seagrass meadows. d Africa’s key oceanic ecosystems—mangrove forests. e Africa’s key oceanic ecosystems—coral reefs

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Africa has 30,500 km of coastline, with 70% of Africa’s 54 countries containing coastlines. The African Large Marine Ecosystems (LMEs) include 33 coastal and 5 Island states (Clarke et al., 2020) and 1.3 billion people as of 2019 (UNDESA, 2019). LMEs are highly biodiverse areas of ocean extending from estuaries to the edge of continental shelves or to the outer boundaries of major currents. Due to the high levels of land-sourced nutrients, these are the world’s most productive ocean areas, where most (about 90%) of the world’s fish catch is caught. Global LMEs provide essential ecosystem services (US $3 trillion globally) (“LME Hub,” 2021). These areas face high levels of degradation due to pollution (including but not limited to marine litter), overfishing, and climate change. See Sects. 1.2.1, 1.2.2, 1.2.3 and 1.2.4 for more detail.

There are 7 LMEs around Africa: Canary Current LME, Mediterranean Sea LME, Red Sea LME, Somali Coastal Current LME, Agulhas Current LME, Benguela Current LME, and Guinea Current LME (Sherman et al., 2011). These LMEs are determined by their currents, most of which are transboundary in nature (Fig. 1.1a). African LMEs are richly endowed with both living and non-living resources including unrivalled natural beauty, and abundant fisheries (Satia, 2016). All of the African LME’s have potential for sustainable economic growth (AU-IBAR, 2019a). Governed by strong upwelling systems, the Benguela and Canary currents rank second and third in the world, respectively, in primary productivity (Lutjeharms & Bornman, 2010).

Africa’s LMEs contain ecosystems critical to carbon storage and coastal protection, such as, mangroves forests, seagrass meadows, salt marshes, and coral reefs (Fig. 1.1b–e) (see Sect. 1.2.2 for more details). Their current value is estimated to match the average monetary value of carbon uptake and storage of US $130,000 per km2 of mangrove forests, salt marshes, and seagrass meadows (Karani & Failler, 2020). The Guinea Current LME has some of the world’s largest mangrove ecosystems (FAO, 2007; UNEP, 2007), and all the eastern LMEs contain coral reefs (Fig. 1.1a–e).

1.3.1 Africa’s Blue Economy

Leaders across Africa recognised the importance of the Blue Economy as an area of future inclusive and sustainable economic growth. The African Union Inter-African Bureau for Animal Resources (AU-IBAR) has developed the Africa Blue Economy Strategy (Karani & Failler, 2020), which outlines the following key sectors (AU-IBAR, 2019a):

  1. i.

    Fisheries, aquaculture, and ecosystems conservation,

  2. ii.

    Shipping, transportation, and trade,

  3. iii.

    Sustainable energy, extractive minerals, gas, and innovative industries,

  4. iv.

    Environmental sustainability, climate change, and coastal infrastructure,

  5. v.

    Governance, Institutions, and social actions.

Inland water masses (e.g., Lake Victoria, Lake Malawi, Lake Tanganyika, etc.) and significant rivers (Fig. 1.1a) are included in the Blue Economy in Africa due to their importance for inland fisheries and transport. The Africa Blue Economy Strategy integrates existing global and African strategies, policies, and initiatives (AU-IBAR, 2019a).

In 2019, Africa had a combined GDP of US $2.6 trillion (International Monetary Fund, 2019). The Blue Economy in Africa in 2018 created 49 million jobs (Fig. 1.2a) and was valued at US $296 billion (11% of the total combined GDP) (Fig. 1.2a, b). Pre-COVID-19 projections estimated these numbers would increase to a value of US $405 billion and 57 million jobs by 2030 (AU-IBAR, 2019a).

Fig. 1.2
2 pie charts illustrate employment generated by the blue economy. The centre of each chart has a map of Africa written, 49 million jobs and 57 million jobs respectively. The highest in the top chart is for coastal tourism with 24, followed by fisheries with 13. Coastal tourism is highest in the second chart with a value of 28 and fisheries at 14.7.figure 2

a The value of the Blue Economy (marine and freshwater) in employment terms in 2018 and pre-COVID projection for 2030. b The value of the Blue Economy (marine and freshwater) in monitory terms in 2018 and pre-COVID projection for 2030. The size of the graph represents the relative size of Blue Economy

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African countries have vast LMEs (Satia, 2016), which are attractive to coastal and marine tourism (Karani & Failler, 2020). Thus, within Africa, tourism is the highest value sector of the Blue Economy, both in jobs and monetary terms, now (24 million jobs, US $85 billion) and in the future (28 million jobs, US $135 billion in 2030) (Fig. 1.2a, b).

With large African oil and gas reserves (Satia, 2016), the extractive industry, mining and quarrying, including oil and gas production (Fig. 1.2b) are second after tourism in terms of monetary value (respectively US $56 billion and US $80 billion, in 2018). However, they contribute substantially less towards job creation (Fig. 1.2a) (0.16 million jobs in 2018 and projected to grow to 1.2 million jobs in 2030). Their development can also substantially negatively affect the growth of three of the other sectors of the Blue Economy, that being (i) Fisheries, aquaculture, and ecosystems conservation, (ii) Environmental sustainability, climate change, and coastal infrastructure, and (iii) Governance, Institutions, and social actions, as well as impact climate change.

The African LMEs are some of the most productive globally, with the fisheries sector (Fig. 1.2a, b) employing many people (13 million jobs and 14.7 million jobs in 2018 and 2030, respectively) (AU-IBAR, 2019a). It is noted that (certainly in West Africa) the industrial fisheries are captured mainly by foreign companies, with most of the fish destined for export (Belhabib et al., 2018). African fisheries are overexploited by European and Chinese fleets, with substantial economic losses to Africa. For example, China and Europe pay as little as 4 and 8% of the landed value, respectively, to access West African fishing grounds (Belhabib et al., 2015). Underreporting and illegal practices occur across both fleets. Underreporting impacts local economies and sustainability directly as it hides over-fishing, threatening the long-term sustainability of fishing stocks (Belhabib et al., 2015).

Aquaculture (Fig. 1.2a, b) is currently relatively small, contributing less than 3% globally (Halwart, 2020). The aquaculture industry in Africa is valued (Fig. 1.2b) at US $2.77 billion in 2018 and is projected to expand to US $5.1 billion in 2030 (AU-IBAR, 2019a). Aquaculture employed 1.2 million people in 2018 and is projected to increase to 1.6 million people by 2030 (Fig. 1.2a).

With increasing populations, growing economies (UNEP, 2018b; United Nations, 2020), and trade agreements, port calls, and shipping are expected to grow at a constant rate. Current infrastructure capacity is insufficient to deal with current waste in ports, raising concerns around waste management for future growth (Maes & Preston-Whyte, 2022). Ecosystem services, including blue carbon produced by coastal, marine, and aquatic ecosystems are expected to progressively increase in value as conservation efforts expand. Education and research will follow the same pattern due to a growing demand for knowledge, especially in areas of deep-sea mining, offshore exploration, and climate change mitigation and adaptation (Fig. 1.2a, b) (AU-IBAR, 2019a).

1.4 Marine Litter—A Growing Problem in Africa

Given the present and potential importance of the Blue Economy to Africa, any threat to it, especially to tourism, should be considered a priority. Marine litter is one such threat. The 2019 African Ministerial Conference on the Environment (Durban, South Africa) emphasised the need to address plastic pollution, with all 54 member states supporting a declaration calling for global action on plastic pollution (de Kock et al., 2020). If unchecked, the increase in marine litter will have disastrous consequences on the environment and create socioeconomic development challenges that will impact biodiversity, infrastructure, tourism, and fisheries’ livelihoods (Jambeck et al., 2018). Important pressures include population growth, rapid urbanisation, projected economic growth, and increased trade combined with an already constrained public and private sector waste services and infrastructure (Godfrey et al., 2019; UNEP, 2018b) driving increased marine litter inputs.

The current land-based sources of marine litter in Africa are driven by linear product design, population growth, and lack of infrastructure and services. There is increasing dependence on commercially available single-use products which don’t consider recyclability or reuse in the design phase. With 3.5% annual growth, Africa’s population is growing faster than any other continent (UNEP, 2018b; Wilson et al., 2015). In addition to population growth, Africa has seen rapid urbanisation driven by a changing climate (Henderson et al., 2017), environmental degradation, and socioeconomic factors (Awumbila, 2017). Housing, urban planning, infrastructure for waste (including recycling services) and sanitation services have not managed to keep up with this rapid urbanisation (AfDB et al., 2020; UNEP, 2018b). Thus, this rapid development corresponds with the increase of both macro and microplastics leaking into the environment from the waste stream across Africa (Alimi et al., 2021; Jambeck et al., 2015, 2018; UNEP, 2018a, 2018b). The issues around waste management in Africa are well captured by the African Waste Management Outlook (UNEP, 2018a).

It should be noted that in the context of Africa, the Blue Economy and marine litter, the upstream aquatic environments such as rivers and lakes, and the litter that feeds into them are important. The importance of the upstream aquatic environments is not only limited to the pollution of these water sources but also to the transport of litter through the riverine systems to the sea. Figure 1.1a shows the extensive range of African rivers, many of which are transboundary in nature and pass-through landlocked countries. Inland cities in Africa are often positioned on rivers, and part of their mismanaged waste may be transported to the ocean through rivers (see Chap. 2 for more details). It is noted that this transport may be river-dependent, as comparative research monitoring litter in rivers is in its infancy (UNEP, 2020). Litter also becomes trapped on river banks and in sediments (Weideman et al., 2020). Heavy rains or flooding may see the discharge of this litter into the marine environment (Biermann et al., 2020). The extent of settlement of litter within riverine systems versus transport to the ocean is dependent on the hydrological conditions within the river catchment and is influenced by the climate and weather as well as local sources (Biermann et al., 2020; Moss et al., 2021; Ryan & Perold, 2021; Tramoy et al., 2020; Weideman et al., 2020). The importance of the landlocked African countries in tackling waste management and the resulting marine litter issue highlights the shared responsibility and the need for a regional response.

Africa is not currently managing its waste volumes in environmentally sound nor sustainable ways. The UNEP/IUCN reports highlight this, suggesting that as much as 90% of waste is mismanaged in Kenya, Tanzania, and Mozambique (IUCN et al., 2020a, 2020b, 2021). Future projections raise further concerns regarding Africa’s ability to deal with future waste and resulting marine litter, highlighting the need to develop a circular economy within Africa. The future projections which raise these red flags are outlined in the following points:

First, population growth in Africa shows no sign of abating (Wilson et al., 2015). Currently, the African continent has the fastest-growing population with an annual increase of about 2.51%. With a population of 1.34 billion in 2020, pre-COVID-19 predictions by the United Nations estimated that the African population will reach 2.83 billion in 2050, or 40% of the world population, against the current 17% by 2100 (AU-IBAR, 2019a; UNDESA, 2017, 2019). An increase in population is linked to increased waste production. For Sub-Saharan Africa, the annual generation rate of waste was 174 million tonnes in 2016; with it projected to either triple or quadruple by 2050 (Kaza et al., 2018; World Bank, 2018). Whilst, North Africa is expected to double its annual waste generation rates by 2050 (Hoornweg & Bhada-Tata, 2012; Kaza et al., 2018).

Second, economic drivers of urbanisation and migration in Africa are sensitive to climate change impacts (Niang et al., 2014). Rapid urbanisation is projected to continue, with most cities in coastal zones or near river systems (Jambeck et al., 2018). Rapid urbanisation in Africa is such that the number of people living in urban environments are projected to rise from 11.3% in 2010 to 20.2% by 2050 when comparing the percentage of African urban areas to total global urban areas (Awumbila, 2017). Increased urbanisation leads to more waste generation in the urban areas, creating more strain on already underdelivering waste systems. Additionally, rapid urbanisation causes a rise in the cost of land in the cities and housing and an increase in informal settlements. This leads to several “practical solutions,” such as in Freetown, Sierra Leone, where solid waste, including plastics, is increasingly being used to reclaim coastal land for the construction of informal settlements and residential houses (Sankoh, 2021, personal communication).

Third, Africa has seen increased economic activity and resulting in increased GDP since the 1980s (continental average), with a pre-COVID-19 growth of 3.7% per year (International Monetary Fund, 2021). As solid waste generation is strongly correlated with gross national income per capita (Hoornweg et al., 2013; Wilson et al., 2015), such projected increases in GDP are likely to be associated with increased waste.

Fourth, Africa’s economic development is associated with a growing middle class (Ncube & Lufumpa, 2014; Scharrer et al., 2018), which will likely result in a further increase in spending and associated solid waste generation.

Fifth, increased economic activity and increased trade internationally have seen, and is predicted to see, an increase in shipping and transport. With 3% of the world’s volumes, African shipping has a relatively small impact on international trade. However, in the 5 years preceding COVID-19, traffic in African container ports grew 3% faster than global levels (AU-IBAR, 2019b). This means that shipping in African waters increased, and ports were expected to process more waste from ships. Ryan (2020) and Ryan et al. (2021) show, using plastic bottles as an indicator, that despite the existence of MARPOL Annex V, plastic waste is still being dumped from ships. Thus, until adequate enforcement of MARPOL occurs globally, increased shipping is likely to be associated with increased marine litter from ships. However, for MARPOL Annex V to be adequately enforced, there needs to be proper port reception facilities, downstream waste management infrastructure, and port enforcement. Concerningly, a study of the port reception facilities in South Africa shows this is not the case (APWC, 2020). As South Africa has one of the largest economies in Africa and assuming enforcement is linked with economic development, similar lapses in infrastructure can be expected across Africa. Linking in with increased trade, an increase in the extensive packaging used in the shipping of shipped goods and the shipped goods themselves can be observed. Used goods (everything from used electronics, cars, clothes etc.) are imported into Africa as second-hand goods and/or charitable donations (Maes & Preston-Whyte, 2022; UNDESA, 2020). The working order, usability, life span, and quality of these goods is raising increasing concern as an additional waste stream for Africa to deal with (Maes & Preston-Whyte, 2022).

Sixth, in January 2018, China closed its borders to certain imported recyclable materials, including most plastic. Until then, China had been the world’s leading importer of plastic waste. This resulted in global turmoil concerning plastic recycling (Wang et al., 2020), forcing other economies to increase their waste treatment capacity. It was not possible for other large economies to immediately replace the role of China (Huang et al., 2020). This has led to two impacts on Africa. First, the price of used PET bottles fell without an end-market, impacting existing recyclers. Second, high-income countries, along with implementing some wastes reduction strategies (Wang et al., 2020), have shifted their exports to other or low or medium-income countries, which are often ill-equipped to deal with the influx of waste (Brooks et al., 2018). This raises concerns regarding plastic waste imports into Africa. In 2019, to control exports and imports of most plastic scrap and waste, Parties to the Basel Convention adopted plastic scrap and waste amendments. These amendments apply to countries party to the convention (see Chap. 4 for contracting countries) and require prior notice and consent from importing and transit countries before transboundary movement can occur. These amendments took effect on January 1, 2021, and should lead to benefits for African markets with adequate enforcement.

Whether the bulk of plastic used is a domestic product or imported is country-dependent. However, considering imports of polymers and plastics for Africa as a whole, Babayemi et al. (2019) estimated that roughly 172 MT were imported into Africa between 1990 and 2017 (excluding cars, electronics, and sports equipment). Most (51%) were imported into Egypt, Nigeria, South Africa, Algeria, Morocco, and Tunisia (in decreasing order). A further calculation on the end-of-life estimated that between 1990 and 2017, 82.4 MT of plastic waste was produced (in the 33 countries with data, which formed 117.6 MT of the 172 MT). Without policy change, plastic import volumes are forecasted (pre-COVID-19) to double by 2030 (Babayemi et al., 2019; Jambeck et al., 2018). Without a proper waste management plan and strategy, there will be a build-up of billions of tonnes of plastics within both terrestrial and aquatic environments in the near future (Geyer et al., 2017).

It has already been recognised that not all international and high-income country solutions to waste management and marine litter are relevant to an African context (The African Development Bank, 2002). Rather there is a need to focus on and support innovative African-based solutions (UNEP, 2018b), and circular economy initiatives. Taking this into account, the African continent has great opportunities to leapfrog across ineffective systems and approaches which have been applied and now engrained elsewhere. Global emergencies, such as COVID-19, and the inward response of countries and regions, further highlight this need.

Box 1.2: Impact and Uncertainty Driven by COVID-19

COVID-19 has had a profound effect on waste production. This includes increases in personal protective equipment (masks, gloves etc.-both used in health care and privately) (Fadare & Okoffo, 2020; Prata et al., 2020; Zambrano-Monserrate et al., 2020), and an unconfirmed, speculated increase in other single-use items (as people become nervous of reuse in a public pandemic environment), and packaging from increased home delivery (Vanapalli et al., 2020). Africa is particularly susceptible to the increase in personal protective equipment in hospitals as solid medical waste management in most African countries is sub-standard (Udofia et al., 2015). The impact of the COVID-19 pandemic on the existing plastic pollution problem in Africa is highlighted by Benson et al. (2021), who estimate that over 12 billion medical and fabric face masks (105,000 tonnes) are discarded monthly in Africa, with 15 countries considered significant contributors: Nigeria (15%), Ethiopia (9%), Egypt (8%), DR Congo (7%), Tanzania (5%), and South Africa (4%).

COVID-19 has the potential to have long-term social and economic impacts on Africa.

The negative economic impact of COVID-19 may divert vital resources from waste management infrastructure projects and solutions to the rising plastic waste problem and marine litter—both through international investments and regional and local funds. Before the start of the COVID-19 pandemic, Africa was the second fastest-growing region globally, with annual economic growth of 3.4–3.7% (International Monetary Fund, 2021; United Nations, 2020). For the first time in a decade, investment expenditure rather than consumption accounted for more than half the GDP growth (United Nations, 2020). Pre-COVID-19 projections forecast Africa’s economy to grow, despite external shocks, including a commodities shock caused by a decrease in demand from China and a resulting recession in commodities impacting African economies between 2018 and 2020 (The Economist, 2021). The economic hardship and recession caused by COVID-19 and the diversion of funds to tackle the pandemic could lead to African governments placing less budget on waste management issues, and hence an increased fraction of wastes could enter the ocean as marine litter.

The pandemic, associated lockdowns, and the downturn in global trade led to an observed decrease of −2.1% real GDP (African Development Bank Group, 2021). Lone and Ahmad (2020) provide a review, summarising the economic damage caused by COVID-19 in Africa—what it has generated so far, and what is still expected to come. Recovery is expected to vary across the region (The Economist, 2021), and contrasting predictions occur. Growth on the continent was forecast to rebound to 5% in 2021, if supported by effective response measures and global economic recovery (United Nations, 2020). However, compared globally, Africa is showing and is predicted to have, a slower recovery from the economic and social effects of COVID-19 compared to more developed regions (The Economist, 2021; United Nations, 2022). Vaccine inequality has contributed (United Nations, 2022) to a slow vaccination rollout in Africa, dragging out the pandemic on the continent (The Economist Intelligence Unit, 2021). An extended pandemic through slow vaccine rollout will have drastic social and economic effects on Africa. Economic output in Africa is projected to rise at a lower and slower rate than pre-pandemic projections. For example, 2023 projections for Africa show a gap of 5.5% compared to pre-pandemic economic growth projection (United Nations, 2022).

There is a danger that the COVID-19 pandemic could push 27 million Africans into extreme poverty, exacerbate existing income inequalities, especially in health and education, and ignite the first recession in Africa in 25 years with a GDP loss of $62.8 billion (United Nations, 2020; Zeufack et al., 2020). Before the pandemic, there was a need for investment in education and infrastructure for good returns in long-term GDP (United Nations, 2020). Socially, in addition to widespread school closures affecting education and household income loss, Africa is likely to see a reduction in female education specifically (The Economist, 2021). Female education is directly linked to proactive family planning, and reduced family size (Subbarao & Raney, 1995), reducing population growth. Any adverse effect on female education through economic and social stresses can further increase population growth in Africa.