When the issue of marine pollution is raised, images of abundant amounts of plastic come to mind. After all, over 300 million tonnes of plastic are produced each year to supplement a plethora of applications and usage. In fact, an estimated 14 million tonnes of plastic are eventually deposited in the ocean yearly, with plastic comprising 80% of marine pollution that is embedded in water columns, deep-sea sediments, sea beds and surface waters that eventually wash up on beaches (IUCN.org, undated).
According to Sulistiawati (2020), the main sources of marine litter are land-based, and originate mainly from sources such as inadquate waste disposal, industrial activities, urban and stormwater runoff, sewer overflows, illegal dumping and beach activities. Conversely, the fishing industry, aquaculture and related nautical activities are directly responsible for ocean-based plastic pollution.
Source: Edmond (2022)
The ubiquitous presence of plastics in marine environments are a particular cause for concern as plastics release greenhouse gases as they eventually break down into tiny particles known as nanoplastics and microplastics when in contact with natural weather conditions such as UV radiation, wind and ocean currents.The size of these particles are easier for marine organisms to ingest, and can generate a host of health problems that can prove fatal (the harmful effects of plastics on marine organisms will be expounded on further in the next post!).
Moreover, Edmond (2022) suggests how even low levels micro and nanoplastics have far-reaching implications for climate change as they alter the capacity of marine microorganisms such as zooplankton in absorbing carbon dioxide and releasing molecular oxygen. Zooplankton is essential to the survival of living organisms as they primarily produce half of the Earth’s oxygen via photosynthesis, rendering the ocean a crucial carbon sink. According to a study by the Helmholtz Centre for Ocean Research Kiel, when zooplankton populations consume microplastics (Check out this youtube video of plankton ingesting microplastics) instead of their natural food unknowingly, this generates catastrophic ecological consequences as it affects nutrient cycling and leads to a growth in algal blooms.
Source: Coppock et al. (2019)
Hence, when a surplus of toxins are released, marine organisms will ultimately suffer and this will result in dire effects for the food web. While Kvale et al. (2021) assert that these findings are preliminary, they nonetheless should provide an impetus to expand the breadth of Earth system models to incorporate the effects of plastic pollution as a key agent in ocean change. Therefore, this should serve as an imperative for governments to work together with corporations in exploring and evaluating legally binding agreements that address this epidemic since marine plastic pollution directly hampers to control the rate of climate change.
References
Helmholtz Centre for Ocean Research Kiel (GEOMAR)., 2021. Microplastics affect global nutrient cycle and oxygen levels in the ocean: GEOMAR study points to possible major changes in the marine ecosystem. ScienceDaily.
Edmond, C., 2022. We know plastic pollution is bad – but how exactly is it linked to climate change?. [online] World Economic Forum. Available at: <https://www.weforum.org/agenda/2022/01/plastic-pollution-climate-change-solution/>
Kvale, K., Prowe, A.E.F., Chien, CT. et al., 2021. Zooplankton grazing of microplastic can accelerate global loss of ocean oxygen. Nat Commun 12, 2358 . https://doi.org/10.1038/s41467-021-22554-w