Anusha Rajkaran looks for the little things in the ocean that are hard to see with the naked eye.
As principal investigator at the Laboratory for Microplastics & Coastal Research (MCR) — launched last year at the University of the Western Cape — she and her team investigate the distribution, sources and effects of plastics in the environment and on society. The cost of this pollution, according to the WWF, “is at least 10 times higher than [the] market price paid by primary plastic producers”.
Microplastics, small plastic pieces less than 5mm long and harmful to ocean and aquatic life, have been found in places as high as Mount Everest and as deep as the Mariana Trench.
Rajkaran focuses her team’s investigations on the mangroves, salt marshes and seagrasses that create blue-carbon habitats in coastal and marine ecosystems: natural refuges for fish and invertebrates.
Marine animals seek out these “to support a particular life stage or complete their life cycle”, says Rajkaran. “Blue-carbon habitats create complexity within the environment ... that can be used for protection and as a vast variety of food sources.”
As plastics move from rivers to estuaries, “larger plastics result in entanglement; smaller microplastics result in ingestion [that] will alter the way animals function physiologically,” Rajkaran says.
Her team is quantifying microplastics in estuaries. The intention is to get “an idea of where they are depositing and which animals would be most likely to interact with those microplastics.”
Rajkaran says: “[This can] take us to a place where we can ask: how do we manage this great threat? It’s not an emerging threat any more. It’s a major threat to the habitats.”
But quantifying the problem is not Rajkaran’s end goal. “We want to use our research to change [human] behaviours at multiple scales,” including households, business and government, she says.
It’s not an emerging threat any more. It’s a major threat to the habitats
— Anusha Rajkaran
The next step, after measuring the prevalence of microplastics, is to “determine the polymers that the microplastics are made up of”. Studying turtle faeces in partnership with Cape Town’s Two Oceans Aquarium has shown that there are “plastics that are bigger than 5mm, plastics we can actually see,” Rajkaran says.
To measure microplastics in smaller animals such as filter feeders, MCR became one of the few labs in South Africa last year to use a sophisticated device that collects spectral data: a Fourier transform infrared microscope, bought with the support of the department of science & innovation and the South African Institute for Aquatic Biodiversity, a facility of the National Research Foundation.
Diversity was a defining feature of Rajkaran’s upbringing and still is in her area of study. She was born in Port Shepstone and grew up in Mthatha, which at that time was the capital of the Transkei homeland. “From a social point of view, from an ecological point of view, [Mthatha was] a much more diverse environment,” she says. Her school friends came from countries such as Nepal, Ghana, Uganda, Kenya, India, the West Indies and Iran.
Rajkaran’s research has taken her to the Seychelles, to a Japanese island just west of Taiwan, and to mangrove networks of different species in the western Indian Ocean, the coastline of East Africa and the coast of Florida in the US, as well as the southern and eastern coast of South Africa.
But the place that shaped Rajkaran’s career, she says, is the Wild Coast, “with its plentiful estuaries, some with mangroves, some without”.
Her father was a keen fisherman, “sowe were always trying to spend time on the beach or in the coastal environment”.
Rajkaran grew up in a family of teachers. “My grandfather was the principal of a school. My father was a teacher in high school and then [lectured] at university. My mother taught catechism at church. My sister is a high school deputy principal in Alexandria in the Eastern Cape,” she says.
Yet she describes herself as having been “a very average student, right up until the end of my first degree”.
That was when she got into research and discovered her mission as a professor. “As [microplastics] became more and more prevalent in the literature it became obvious that more people in South Africa needed to look at it,” she says.
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