Beat Plastic Pollution

Setting sail on Lake Victoria to beat plastic pollution

From the sheer volume of fresh water, to its deep history enshrined in rock art and Ptolemy’s maps, and its diverse communities, Lake Victoria provokes both intrigue and reverence. The earliest mention of Africa’s largest great lake and the source of the Nile River dates back to the maps of ancient explorer Ptolemy in the second century CE.

The lake borders three countries in East Africa, Uganda, Tanzania and Kenya, and covers a massive 68,800km2. This makes it the largest tropical lake in the world and the world’s second-largest freshwater lake, second only to Lake Superior in North America.

Over the last few decades, the population living around the lake has grown at one of the fastest rates in the world. The last estimation was 40 million people, though this is projected to skyrocket to 53 million in 2020.

In one way or another, the lake supports her people. Be it income through fishing, tourism, transportation or agriculture, the Lake Victoria basin is abundant with seemingly endless opportunities.

Supporting roughy 200,000 fishermen catching 1 million tons of fish every year, Lake Victoria is recognised as the largeest freshwater fishery in the world. The income from this supports the livelihoods of 4 million people.

The lake, like so many other places around the world, faces multiple threats, including overfishing, deforestation and water pollution. But more recently, we’re beginning to realise there is another significant threat facing the lake.

In this article, we (the Flipflopi) will highlight current research on the growing presence of plastics in Lake Victoria and what this might mean for the people who survive by her shores.

THE RESULTS

While there have been many studies focused on the presence of plastics in the world’s oceans and freshwater lakes, very little has been done to investigate plastic pollution in the great lakes of Africa.

As the population around Lake Victoria balloons and more and more people are either working or spending leisure time on the lake, the presence of plastics is to be expected, in line with studies in similar bodies of water.

In 2015, Biginagwa et al tested this theory by analyzing the gut contents of Nile Perch and Nile Tilapia — resident fish populations in the lake.

Microplastics were found in 20 per cent of the fish they tested.

Microplastics are pieces of plastic smaller than 5mm at the longest edge. Most microplastics are broken down from larger pieces of plastics.

However, there were some limitations to the machinery they used to test the plastics as some particles were so small they could not be recognised. With this in mind, the researchers suspect that the actual figure may be far higher.

The most common polymers they found were: Polyethylene, most commonly used in bags, wrappers, films; Polyurethane, most commonly found as foam bedding and sponges; Polyester, found in clothing; Polyethylene/polypropylene copolymer, hard plastics like bottle tops; and Silicone rubber, often used to coat electricals.

The identified polymers led researchers to assume that most of the waste came from drainage ditches that were filled with urban waste. These ditches often overflowed into the river with heavy rains.

However, the extent of microplastic pollution in Lake Victoria cannot be proved by testing the guts of fish alone.

And that’s where Egessa and his colleagues took the research a step further.

In 2019, the researchers wanted to identify if there was plastic found along the shores and in the sediment.

They took 18 samples from six beaches of differing uses in northern Lake Victoria.

Plastics were found to be present at all but one of the samples tested.

The most common microplastics found in the sediment were in the form of fragments, filaments, foam and pellets. While the most common meso- and macroplastics were fragments, filaments and foam.

Most of the plastic debris was made from the breakdown of larger plastic products that are often used by the communities surrounding the lake.

These findings support previous research, which found the massive use of plastics worldwide has undoubtedly led to a build-up of plastic debris across the shores of other freshwater systems.

Furthermore, to investigate the presence of microplastics on surface water in Lake Victoria, the team identified three site categories to conduct their research to see how the amounts of plastic differed across the lake.

These consisted of sites: in the vicinity of fish landing and recreational beaches within the urban or semi-urban setting; in the vicinity of only fish landing beaches within a rural community setting; and in the vicinity of river inflows.

The most amount of microplastics were found in the first category and the least in the third category. These findings support previous research that there is a higher abundance of microplastics in places of greater human activity.

Now we know that microplastics exist in the waters, sediment and fish of Lake Victoria, what does this mean for the communities that live on her shores?

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