South Africa is a major culprit when it comes to waste plastic entering the sea. A 2015 study found that South Africa is the 11th worst country worldwide when it comes to plastic pollution in the ocean, due to the combination of a high per capita use of plastic and the low proportion of rubbish that ends up being recycled or disposed of appropriately.
To date, efforts to clean up marine debris in South Africa have mainly targeted beach litter. Some volunteer efforts have removed seabed litter from harbours and other high-risk areas, but there has been little focus on intertidal debris, especially on rocky shores. Thus when a group of longboarders of the LadySliders Union led by Charmaine Adams and Aaniyah Omardien wanted to start an environmental project in Muizenberg, I suggested that we focus on the rocky intertidal at Surfers’ Corner.
Written by Prof. Peter Ryan, Director at Percy FitzPatrick Institute of African Ornithology, UCT
Worldwide, at least 5 million tonnes of plastic is estimated to enter the sea every year, with approximately 250,000 tonnes thought to be floating on the sea’s surface. Most of this either washes up on beaches, or ends up on the seabed. Marine debris – litter and other solid waste that ends up in the sea – has become a major environmental concern in recent years. Two issues have driven this concern. First, the discovery that floating debris, mainly plastic, is accumulating in subtropical gyres, forming so-called ‘garbage patches’ in the mid-ocean basins. And second, the impact of microplastics on marine foodwebs. Microplastics – tiny pieces of plastic ranging from a few microns to a few millimeters across – form either when larger plastics are broken down by UV light, or are made deliberately for use in cosmetics or other cleaning applications. They carry a cocktail of potentially toxic compounds that are released when consumed by marine organisms, affecting marine predators, including humans.
Although you might not think so if you visit in the afternoon, when beach-goers and the tide have dumped a fresh load of rubbish, Muizenberg beach is cleaned every morning by municipal workers. To get an idea of what the beach would look like without their efforts, walk east past Sunrise Beach towards Strandfontein, where cleaning is much more sporadic. Here, the upper beach is festooned with litter. In 2015 we found an average of 38 litter items per metre of beach, including 11 plastic bags, 13 food wrappers, 2 straws, 1 bottle and 3 bottle caps, and all manner of other debris. Most of this litter is either blown or washed into False Bay from Cape Town’s suburbs.
Despite not being cleaned regularly, there doesn’t seem to be too much rubbish in the rocky intertidal at Surfers’ Corner. But appearances can be deceptive. The first clean up in March 2015 collected 758 litter items that filled 12 large refuse bags from the first 130m of rocky shore. Monthly cleanups have yielded since then with an average of 360 items weighing about 5kg after being washed and dried. The amount and type of litter varies greatly from month to month. Litter loads spike after the first winter rains flush the Cape Flats wetlands, and when wave action strips away much of the sand in the area, exposing buried litter.
Because most plastics float, we expected plastic items to be less common in the intertidal than on the adjacent sandy beach, where they comprise 97% of litter items. However, almost 80% of all intertidal debris is made of plastic. Some items are snagged in seaweeds or among mussels, a few are used as sunshades by sea urchins, and others are eaten by sea anemones. Perhaps the most surprising finding is how plastic bags become filled with sand, even through the smallest of holes, forming solid, brick like structures that are soon colonized by a wide range of marine organisms.
Beach cleanups are not without their rewards. Apart from feeling good to be making a difference, we have found interesting treasures ranging from surfboard skegs and toy dinosaurs to false teeth! Intertidal cleanups also offer a rich diversity of marine life, from nudibranchs to octopus. We challenge others to adopt a stretch of rocky shore for regular cleaning.
If you would like to get involved in regular beach clean-ups at Surfers’ Corner, Muizenberg, contact Aaniyah Omardien (Surfers In Action Founder and Project Co-ordinator) at email@example.com for more info. Lead Image: Surfers’ Corner Beach Cleanup, Muizenberg © Aaniyah Omardien