Sustainability Series Part I: Mangroves as a Case Study for Effects and Implications of Plastic Waste on Flora and Surrounding Populations in Latin America

By Luke Morales

There is growing research interest in mangrove forests, and these ecosystems are present in many different parts of the world, such as Latin American and Caribbean countries, Asia, Africa, North and Central America, and Australia (Walters et al., 2008; NASA Earth Observatory, 2010). By using mangrove populations as a case study, this article will show that plastic waste poses a significant threat to important floral populations and their surrounding environments, which may impact local communities whose livelihood depends on affected flora. This article also reveals a need for further research on the importance of mangrove systems specifically within Latin American regions, effects attributed to their deterioration, and how plastic waste in particular affects their development and survival. Due to the lack of literature regarding plastic waste in Latin America, this article will apply studies from other parts of the world to shed light on the issue. 

Mangroves are “coastal forests that inhabit saline tidal areas along sheltered bays, estuaries, and inlets in the tropics and subtropics throughout the world” (Barbier et al., 2011, p. 181). They provide multiple valuable ecosystems services including raw materials, carbon sequestration, education, and research (Barbier et al., 2011). In Brazil, the largest country in Latin America, there are 17,287 km2 of mangrove forests from the coast of Amapá to Santa Catarina, and as of 2000, these forests occupy 140,000 km2 of land (Silva de Medeiros et al., 2020). 

Mangroves act as natural barriers to protect the land on which local villages, aquatic animals, and land animals live (Barbier et al., 2011). Their root structure reduces shoreline erosion and deterioration because of their ability to stabilize and retain sediment and soil (Barbier et al., 2011). Researchers found that during a cyclone that struck Orissa, India in 1999, mangroves significantly reduced fatalities and damages to property and other assets. The researchers estimated that “there could have been 1.72 additional deaths per village within 10 km of the coast if the mangrove width along shorelines had been reduced to zero” (Barbier et al., 2011, p. 182). Mangroves also act as barriers in the other direction: they protect coral reefs, seagrass beds, and important navigation waters against siltation and pollution (Barbier et al., 2011). 

In addition to water pollution, with mangrove deterioration comes atmospheric pollution due to increased carbon emissions. In 2020, Adame et al. examined future carbon emissions from global mangrove forest loss. Mangroves specifically are blue carbon ecosystems that “can store large amounts of carbon for long periods, and their protection reduces greenhouse gas emissions and supports climate change mitigation” (Adame et al., 2020, p. 1). By using comprehensive datasets, the researchers created a predictive model of mangrove carbon emissions, and revealed that the highest emissions were predicted in six regions: the West Coral Triangle, Sunda Shelf, and the Bay of Bengal (southeast and south Asia); the Tropical Northwest Atlantic (the Caribbean); the Andaman coast (West Myanmar); and north Brazil (Adame et al., 2020). These regions were predicted to account for 90% of the total potential carbon dioxide emissions should mangrove populations deteriorate (Adame et al., 2020). 

One of mangroves’ most valuable ecosystem services includes their use by local communities for products (Barbier et al., 2011). In a 2019 study examining the contribution of mangrove forests to the livelihood of local communities in the Ayeyarwady region in Myanmar, researchers found that income from the collection of mangrove forest products was the highest income source (Aye et al., 2019). About 53% of households relied on different mangrove forest products for income (Aye et al., 2019). Mangrove products harvested by the locals include timber, fish, crab, and prawn (Aye et al., 2019). “Timbers from mangrove trees are used as poles, firewood and charcoal making for domestic purposes such as cooking, heating and ironing” (Aye et al., 2019, p. 7). Additionally, fisheries and catching prawn are dependent on intact mangrove ecosystems, as mangroves provide shelter, nursery, and breeding habitats to aquatic animals, including globally threatened species such as the hawksbill turtle, the mangrove terrapin, the great knot, the Irrawaddy dolphin, and others (Aye et al., 2019). 

This study also examined income from mangrove forest products based on income level. Researchers did this by separating households based on their total income: high (more than US$ 1700), medium (US$ 1000-1700), and low (less than US$ 1000) (Aye et al., 2019). The contribution of mangrove products to income was 32.8% for high-income households, 52.8% for middle-income households, and 79.4% for low-income households (Aye et al., 2019). According to the study, most middle-income and low-income households were dependent on mangrove forest resources for their livelihoods (Aye et al., 2019). High-income households, however, owned agricultural land and could afford to have better jobs, such as working at and owning private shops (Aye et al., 2019). 

The study’s revelation that socio-economic factors influence dependency on mangroves brings to question who would suffer most if mangrove ecosystems deteriorated. Based on Aye et al.s findings, wealthier families can better afford alternatives to mangrove resources, while lower-income families cannot. The survival of healthy mangrove forests is important to Indigenous communities who use their natural resources, because otherwise, these communities would be left with no choice but to change their ways of life, which have been in place for generations. Mangroves are an important part of many Indigenous cultures who rely on the forests: “their traditional use of mangrove resources is often intimately connected with the health and functioning of the system. These uses are often governed by customary rights, traditions, and heritage, and they are often closely tied to the culture of the local communities (Walters et al., 2008, p. 227). Additionally, “if there was no mangrove forest, people who rely on the mangroves would suffer from a lack of forest products and food security, especially in fisheries, reduced crop yield and the direct impact of natural disasters” (Aye, 2019, p. 2). 

As we have seen thus far, mangroves serve as vital natural resources for environmental functioning. Plastic waste, however, has been negatively affecting these mangrove ecosystems, which could prove detrimental to the habitats and human populations whose survival relies on mangrove forests (van Bijsterveldt et al., 2021). “Worldwide, regions with high mangrove cover often also have serious plastic management issues” due to inadequate waste collection and disposal services (van Bijsterveldt et al., 2021). Two factors contributing to the mismanagement of waste in regions with high mangrove cover may include (1) the dense human population of these areas, such as in Java, Indonesia, or (2) the fact that most rural places lack garbage collection services (van Bijsterveldt et al., 2021). Being that the majority of mangrove species have aerial roots, the presence of plastics can induce tree suffocation, which may lead to serious implications for mangrove populations (van Bijsterveldt et al., 2021). 

Van. Bijsterveldt et al. examined the effects of plastic waste on mangroves in Java, Indonesia. First, they investigated how much of the forest floor was covered by plastic in the field, and if plastic was also buried in the upper layers of the sediment (van Bijsterveldt et al., 2021). Then, based on a range of plastic cover percentages (0%, 50%, and 100%), they investigated the effects of plastic “on root growth, stress response of the tree and tree survival over a period of six weeks” (van Bijsterveldt et al., 2020, p. 1). The data revealed that plastic was often buried in the sediment, potentially creating anoxic (without oxygen) conditions (van Bijsterveldt et al., 2021). It also revealed that prolonged suffocation by plastic could cause leaf loss: though trees in the 50%-plastic cover treatment were resilient and able to maintain their canopy, trees in the 100%-plastic cover treatment had a significantly decreased leaf area index and survival rates (van Bijsterveldt et al., 2020). Prior to this study, and to the researchers’ best knowledge, no manipulative studies had yet been conducted to support the hypothesis that certain mangrove species could be at risk of suffocation due to the burial of plastic (van Bijsterveldt et al., 2020). 

The deterioration of such flora can have devastating environmental consequences, as described in this essay. The studies on mangrove ecosystems in this research are lacking in Latin American context, and being that the region is home to some of the world’s most diverse and important ecosystems, ignoring the significance of its wellbeing runs the risk of also ignoring detrimental effects on the environment and local populations, which, as presented in this essay, has been shown to threaten worldwide populations alike. Perhaps increasing research efforts in the region may prompt local and federal governments to prioritize mitigating the accumulation of plastic waste in the environment. The findings in this paper reveal the importance of attention not only to how plastic waste may affect the habitats in this region but also to how mangrove deterioration can compound with other factors—such as Amazon deforestation—and future implications for the environment and its inhabitants.  

 


 

References 

Adame, M. F., Connolly, R. M., Turschwell, M. P., Lovelock, C. E., Fatoyinbo, T., Lagomasino, D., Goldberg, L. A., Holdorf, J., Friess, D. A., Sasmito, S. D., Sanderman, J., Sievers, M., Buelow, C., Kauffman, J. B., Bryan, B. D., & Brown, C. J. (2021). Future carbon emissions from global mangrove forest loss. Global Change Biology, 27(12), 2856–2866. https://doi-org.pitt.idm.oclc.org/10.1111/gcb.15571 

Aye, W. N., Wen, Y., Marin, K., Thapa, S., & Tun, A. W. (2019). Contribution of Mangrove Forest to the Livelihood of Local Communities in Ayeyarwaddy Region, Myanmar. Forests, 10(5). 

Barbier, E. B., Hacker, S. D., Kennedy, C., Koch, E. W., Stier, A. C., & Silliman, B. R. (2011). The value of estuarine and coastal ecosystem services. Ecological Monographs, 81(2), pp. 169–193. https://doi-org.pitt.idm.oclc.org/10.1890/10-1510.1 

Silva de Medeiros, A., Gomes da Costa, J., Dantas Araújo, K., Rodrigues Calheiros, A., Cabral de Sant’Anna, S. A., Francisco da Silva, J. A., Andrade Souza, M., & Xavier Nascimento, V. (2020). Anthropic interference in mangrove areas of the Mundaú-Manguaba estuarine lagoon complex (CELMM), Alagoas (Brazil) as a case study. Ciência Rural, 50(10), 1–10. https://doi-org.pitt.idm.oclc.org/10.1590/0103-8478cr20200356 

van Bijsterveldt, C. E. J., van Wesenbeeck, B. K., Ramadhani, S., Raven, O. V., van Gool, F. E., Pribadi, R., Bouma, T. J. (2021). Does plastic waste kill mangroves? A field experiment to assess the impact of macro plastics on mangrove growth, stress response and survival. Science of the Total Environment, 756. https://doi-org.pitt.idm.oclc.org/10.1016/j.scitotenv.2020.143826 

Walters, B. B., Rönnbäck, P., Kovacs, J. M., Crona, B., Hussain, S. A., Badola, R., Primavera, J. H., Barbier, E., & Dahdouh-Guebas, F. (2008). Ethnobiology, socio-economics and management of mangrove forests: A review. Aquatic Botany, 89(2), pp. 220–236. 

 

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