By Luke Morales
The world ocean is the largest ecosystem on earth (Das et al., 2006). It acts as a carbon sink, produces over half of the world’s oxygen, regulates climate and weather patterns, provides us with medicinal products, and supplies a variety of foods and ingredients to world populations (National Oceanic and Atmospheric Administration, 2021). However, over the past few decades, humanity’s extensive production of plastic waste has been piling into the world’s oceans (Susanti et al., 2021). This article will discuss how marine litter—specifically plastics—affects faunal populations and other environmental factors while also proposing potential routes for remediation. The research presented also emphasizes the need for further research on microplastics and the marine environment globally and also in Latin America and the Caribbean specifically.
Marine litter is defined as “any solid waste of anthropogenic origin that ends up in the sea, whether deliberately or unintentionally” (Todd et al., 2010). About 75% of all marine litter is plastic, and “this debris has been reported to be accumulating on beaches, on shorelines of even the most remote islands, at the sea surface, in the deep sea, and in arctic sea ice” (Napper & Thompson, 2020, p. 1). The issue of marine litter has only recently entered mainstream conversation, and the lack of coordination of world governments has been found to contribute to the prevalence of waste in the ocean (Napper & Thompson, 2020).
The European Union Marine Strategy Framework Directive (MSFD), an expert group on marine litter, recently stated that plastics are a serious threat to the welfare of aquatic life (Napper & Thompson, 2020). The number of organisms interacting with plastic waste increased from 265 species in 1997 to 557 species in 2015 (Naidoo & Sershen, 2020). Now, over 700 species of marine organisms interact with plastic debris, which can cause physical harm or death, or effects on behavior and ecological interactions, for example migration patterns (Napper & Thompson, 2020). In addition to ingested plastics accumulating in the stomachs of fauna and having consequences for reproduction and growth, plastics may also transfer contaminants absorbed from the water (Napper & Thompson, 2020). Two examples of contaminants are endocrine disruptors and persistent organic pollutants. Endocrine disruptors interfere with the body’s hormones and “are linked with developmental, reproductive, brain, immune, and other problems” (National Institute of Environmental Health Sciences, 2021). Persistent organic pollutants (POPs) are “chemicals that can stay in the environment for a long time and travel vast distances in water or the atmosphere,” and they are toxic to living organisms, including humans (Australian Department of Agriculture, Water and the Environment, 2021).
Plastics can be categorized into two main types: “end-user products such as plastic bottles, bags, packaging, etc., and small resin (e.g., polypropylene and polyethylene) granules or pellets that are used as the raw material by industries making plastic goods” (Todd et al., 2010, p. 1073). We can further categorize these plastics into macro- (>5 mm long) and microplastics (<5 mm long) (Todd et al., 2010). According to the World Health Organization (WHO), microplastics enter freshwater environments primarily from surface run-off and wastewater, as well as from “combined sewer overflows, industrial effluent, degraded plastic waste and atmospheric deposition” (WHO, 2019, p. vii). In a 2019 study examining microplastics in drinking water, the WHO claimed that, although there is insufficient data to firmly conclude the toxicity of microplastics, no reliable information identifies it as a concern (WHO, 2019.) Additionally, no current data addresses microplastics as causing overt health concerns through drinking water (WHO, 2019). The language the WHO uses in its conclusions on the health effects of microplastics in drinking water are revelatory of the need for further research on microplastics and how they affect human populations specifically.
According to researchers, “laboratory- and field-based control experiments have provided insight into understanding the possible impacts of microplastics on observed vertebrates and invertebrates” (Palmer & Herat, 2021, p. 4). Using biomarkers to observe organisms, scientists have been able to better understand biological impacts of these plastics in marine organisms (Palmer & Herat, 2021). Biomarkers are defined as medical signs which can be measured accurately, and which reflect an interaction between a biological system and a potential hazard: for example, pulse and blood pressure (Strimbu & Tavel, 2010). Ecotoxicologist Heather Leslie of VU University Amsterdam said that, even without absorbed contaminants, “plastic particles can induce immunotoxicological responses, alter gene expression, and cause cell death, among other adverse effects” (Seltenrich, 2015, p. 39). Other researchers, using marine species to monitor effects of plastic pollution, found that ingested plastic blocked food intake and compromised proper digestion, and increased morbidity and mortality among these species (Alimba & Faggio, 2019).
In addition to the consumption of microplastics, the entanglement of marine species may have detrimental effects on their populations. “Entanglement of invertebrates, sharks, turtles, birds, and marine mammals is mainly caused by microplastics, and leads to reduced mobility, ineffective foraging and subsequent mortality” (Naidoo & Sershen, 2020, p. 43). Conducting their experiments in South Africa, these researchers noted that “most entanglement occurs with improperly discarded or accidentally lost fishing gear such as nets, lines ropes, and straps from bait boxes” (Naidoo & Sershen, p. 44). However, though this article focuses on a number of marine species, at the time of their review there was no published research on the impacts of entanglement and ingestion of plastics at the population level (Naidoo & Sershen, 2020). In other words, despite scientists finding evidence of the entanglement of faunae, no comprehensive research exists discussing its effects on the entirety of their respective populations. Without further research into how microplastics can affect species as a whole and on national levels, as seen in this research in South Africa, it will be impossible to comprehensively analyze long-term, big-picture effects on surrounding environments in other parts of the world.
In Latin America and the Caribbean specifically, it wasn’t until 2015 that research was conducted for the first time on “the presence of microplastics on an urban Caribbean beach in Cartagena, Colombia” (Acosta-Coley & Olivero-Verbel, 2015, p. 1). The study classified the city as the most important tourist destination in Colombia (Acosta-Coley & Olivero-Verbel, 2015), making it a prime example for demonstrating the seriousness of plastic waste in sea waters. Researchers collected samples from a 2.2 km stretch of beach in the city over the course of five months, and a total of 45,520 microplastic pellets were collected and analyzed (Acosta-Coley & Olivero-Verbel, 2015). The researchers concluded that there is an urgent need for local authorities to halt the release of microplastics into the marine environment to maintain healthy aquatic ecosystems (Acosta-Coley & Olivero-Verbel, 2015).
A literature search for microplastics found that the number of studies conducted in the Latin American and Caribbean region has been increasing since 2009 (Brooks et al., 2020). It also found that the majority of research is being conducted in Brazil, followed by Chile and Mexico, and there are few freshwater studies that have been done in Latin America and the Caribbean outside of Brazil (Brooks et al., 2020). Additionally, “most studies originated with upper-middle income countries. No studies published were associated with low income or lower middle-income countries, indicating an important knowledge gap as these nations may have less resources for managing, monitoring, and reducing plastic litter” (Brooks et al., 2020, p. 32).
There are many gaps in understanding the prevalence and implications of marine plastic debris in general (Naidoo & Sershen, 2020; Palmer & Herat, 2021; Todd et al., 2010; WHO, 2019). “The widespread bioavailability of microplastics to marine organisms, their potential to act as vectors for both chemicals and microflora, and the resultant impacts on humans and other biota that consume them also represent many unknowns… This lack of data has hindered the design and implementation of appropriate mitigation strategies” (Naidoo & Sershen, 2020, p. 1). Potential strategies to reduce the amount of plastic waste released into the environment involve intervention on three levels: industry, government, and the public.
Most plastics are recyclable. However, many single-use items are not widely compatible with recycling (Napper & Thompson, 2020). Considering the disposal of a product from the design stage would contribute to sustainable production and consumption patterns (Napper & Thompson, 2020), resulting in decreased rates of plastic waste being improperly discarded. “Long-term sustainable solutions require moving from a linear economy toward a more circular economy” (Napper & Thompson, 2020, p. 5), and without this consideration, even creating products from previously-recycled material runs the risk of re-releasing the same plastic into the environment.
Government intervention on both local and international scales can play a major role in lessening the impact of marine litter on aquatic environments. “Policy can create the essential legislative framework to stimulate mitigation actions that contribute to a reduction in plastic waste at source, as well as encouraging the clean-up of plastic pollution on coastlines” (Napper & Thompson, 2020, p. 5). One example of an international policy is the United Nations Convention on the Law of the Sea (UNCLOS). It works to establish a general obligation on governments to protect marine ecosystems, and though the convention does not specifically refer to marine litter regulation, it remains applicable in this context (Chen, 2015). Policies implemented at the local level include the requirement in Mexico City for retailers to charge a fee for plastic bags, and for those bags to be biodegradable (Brooks et al., 2020). Another is the levy in Rio de Janeiro, Brazil, which “requires markets to both provide alternatives to plastic bags and take back bags for proper disposal,” and asks the public to bring their own bags through incentives such as shopping discounts (Brooks et al., 2020).
Public awareness and intervention can also promote sustainability practices (Napper & Thompson, 2020). “This is because improving public awareness of the problems produced by plastic debris is an important step toward changing people’s behavior with regard to plastic consumption” (Napper & Thompson, 2020, p. 5). One successful practice was the introduction in 2012 of “Responsible Snack Bars” in Spain (Veiga et al., 2016). Launched by the Biodiversity Foundation of the Ministry of Agriculture, Food, and Environment, the voluntary program’s goal was to encourage sustainable practices by beach snack bars (Veiga et al., 2016). During its first edition, 526 snack bars from 7 regions in Spain participated in the initiative, and during the second, the number doubled (Veiga et al., 2016). We must be cautious, however, that in the process of moving away from our reliance on plastics, we don’t encourage other unsustainable practices. For example, as much of our clothing is made from plastic, discouraging plastic use may make cotton clothing more popular (Napper & Thompson, 2020). Cotton is more expensive than synthetic plastic clothing, and it “requires a substantial amount of water for its growth, depleting it from areas that might require it for other purposes” (Napper & Thompson, 2020, p. 6). Thus, in conjunction with relying less on plastics, policies must take into consideration potential long-term effects of what gets substituted for these plastics to avoid equivalent environmental damage.
As established in this article, microplastics and other forms of plastic waste are damaging to aquatic populations. There is a contradiction in recognizing the world’s ocean as one of the most important ecosystems on the planet, but then proceeding to cause irreversible damage to its habitat. Though research on the effects of plastic waste has been increasing over the last few decades, the current literature available highlights the many unknowns we still have yet to discover. Additionally, as seen in the literature presented, there is a large lack of understanding in Latin America and the Caribbean, which contribute greatly to the issue of marine litter. The city of São Paulo in Brazil, for example, has one of the world’s fastest-growing metropolitan populations (Schneider, 2020). Increasing research into the implications of plastic waste will give way for cleaner oceanic waters and healthier marine fauna, and will also encourage better sustainability practices on local and global scales.
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