Microplastic pollution in Lake Victoria

Interview with Mr. Bahati Mayoma, Tanzanian researcher specializing in Aquatic Ecology and Pollution Management. During the Flipflopi Lake Victoria Expedition in March 2021, Mr. Bahati was investigating the extent of micro plastic pollution in the lake.

Bahati Mayoma holding a Van Dorn microplastic water sampler in Lake Victoria, March 2021

How widespread is micro plastic pollution?

Microplastic pollution is spread in all environmental compartments which include water, sediment, air and land.

Is micro plastic pollution a public health concern, and should we be worried?

Yes microplastics pollution (MPs) is a public health concern which has to be addressed with all efforts.

MPs are tiny particles (<5mm) which have potential to associate with both natural and human induced toxic compounds as well as pathogens thereby serving as vector for health related diseases. Due to their sizes, MPs are readily available to wide range of species some of which are consumed by human being. Depending on their sizes, some MPs can be found suspended in the air and could be inhaled. While there is no substantial evidence of direct side effects of human-MPs interactions due to limited researches, the concerns is increasingly growing in species which human consume therefore without taking initiatives to address MPs there is a potential that human will also be impacted.

Samples collected in Lake Victoria will be analyzed at the University of Dar es salaam Tanzania and Northumbria University in UK. photo/James Wakibia

You have previously investigated micro plastic pollution in fish from Lake Victoria, what were the findings?

The investigation found that about 20% of fish species namely Perch and tilapia had ingested microplastic in their stomach (Gastrointestinal tract)

Do you think there are enough studies that governments can rely on to address micro plastic pollution especially in our water bodies?

The available studies are just a snap shot of what could be found in our water bodies. Our water bodies lags behind other global waters of similar size in terms of research and yet the water bodies are surrounded by cities and towns which have not invested fully in sustainable waste disposal mechanisms.

Like climate deniers, do you feel some people will deny the threat micro plastic is posing?

The community awareness has recently grown and more people now understand the adverse effects which could be posed by microplastics as compared to 5 years back when microplastics research began in Lake Victoria. However, without research data there will be hesitation from people who would like to understand the extent pollution for them to take action.

Generally plastics are lightweight and tend to float on water, but then there are reports of micro plastics deep below, how do they end up in the lower areas of the ocean or lakes?

There are two ways plastic can be found deep below, first it’s through inherent properties i.e plastic being manufactured with higher density than water for example nylon which makes them sink, secondly light plastic could interact with biological organisms such as algae, bacteria , fungi etc which make them attain extra weight and therefore sink at the bottom of the water bodies.

When we met during FlipFlopi Lake Victoria expedition in March this year you were conducting micro plastic water sampling, which techniques were you using?

Two methods were used namely surface sampling which was conducted using equipment called manta trawl and Vertical water sampling which was conducted using Van Dorn sampler. The manta trawl was towed for 30minutes and filtrate retained by the manta net was fixed for laboratory analysis. The vertical water sampling was done after a fixed interval from surface to the bottom. Samples were filtered to through 300micron and 50micron to capture microplastics in that range.

Manta Trawl, a microplastic surface water sampler. Photo/James Wakibia

How effective are these techniques in investigating the extent of pollution?

The techniques are globally practiced and accepted among standard methods for microplastics assessment in water compartments.

When should we expect to see the findings?

Samples will be analyzed at the University of Dar es salaam Tanzania and Northumbria University in UK. Results will be available by the end of the year 2021.

There has been increased uproar against rising tide of plastic pollution, could this be the reason for the growing research studies on micro plastic pollution?

Yes to some extent the society want to know how safe are their ecosystems including the environments which interact or obtain resources such as water, fish etc. In line with this, researchers have core function to ensuring that information is not only available but also accessible to the society in non technical/user friendly language.

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