Conservative estimates suggest that approximately 8 million tonnes of plastic waste enter our ocean ecosystems each year. While some of this waste originates offshore from ships, vessels and platforms, over 80% of it originates from land, often finding its way to the sea via rivers and beaches or from mismanaged waste along the coastline.
Estuaries are the brackish-water interface between riverine and coastal ecosystems and as such, estuarine litter, which can include anything from small pieces of plastic, like nurdles and other microplastics, to larger items such as straws, cigarette butts, bottles, packaging and even abandoned fishing gear, poses a prolific problem to the ecosystem as a whole, including a path into our oceans.
All of this litter has to come from somewhere! There are hundreds of sources that contribute to our estuary’s litter problem, and we know that plastic comes from lots of different places throughout the estuary. But we don’t know exactly which pieces come from where, making the problem difficult to solve with one simple solution!
Rivers can transport litter into the estuary from anywhere within the catchment. The windy conditions we often experience across the estuary can also mean that litter blows into the water course from a multitude of land-based sources, like open bins, landfill sites, and street litter. Mis-used drains and sewers are a significant source of sewage related debris like sanitary items, nappies and cotton bud sticks – particularly in times of heavy rainfall when sewage systems become overwhelmed. Finally, the Severn Estuary is directly connected to the global ocean via strong currents and tides which can bring in litter from all over the country, as well as from across the globe!
All these varied sources contribute to the large amounts of litter which end up in our estuary and along our coastline every year, causing problems for estuarine habitats, wildlife, water quality and humans alike.
These are the largest form of microplastics, about the size of a lentil, which are used as a raw material in the manufacturing and recycling of plastic products.
The generic term given to all pieces of plastic measuring 5mm or less in size. Microplastics can be further classified as either primary which means they begin life and enter water courses as a microplastic, for example nurdles or microbeads from cosmetics; or secondary, which means that they form as a result the breakdown of larger items of plastic which have degraded in the been left in the environment over long periods of time.
Recent estimates suggest that there are more than 1 trillion microplastic particles floating on the surface of the world’s oceans and they have been recorded in even the most remote, uninhabited places on earth including mountain tops, glaciers and the deepest ocean trenches. The size, shape and pervasive nature of microplastics (and indeed all plastics which take hundreds of years to breakdown in the natural environment) means that the presence of plastic pollution in all water courses – including estuaries – is causing significant concern. Common problems associated with plastic – and microplastic – pollution include:
- Wildlife getting entangled in and or ingesting discarded pieces of plastic where they are mistaken for food sources.
- When ingested by some creatures and a significant number of seabirds, microplastics accumulate (i.e. build up) in stomachs which causes a false feeling of fullness or even blockages in digestive systems which can be fatal. Some bird species are known to regurgitate ingested plastic to their young which can also be fatal.
Harmful environmental and industrial toxins can attach to and ‘piggyback’ on pieces of estuarine litter. When consumed by estuarine wildlife, these naturally bioaccumulating chemicals can be passed through trophic levels; poison wildlife and cause severe physiological impairment. Bioaccumulation is the gradual accumulation of a substance in bodily tissues through the natural food chain.
There are many organisations, including the Severn Estuary Partnership, trying to better understand local sources of estuarine litter, in order to stem the flow and reduce the problems estuarine litter poses. The Marine Conservation Society is a UK-wide charity working to protect our seas and coastal environments through campaigning for better awareness and protection of our marine environment. Keep Wales Tidy is another national charity aiming to promote a “clean, safe and tidy Wales”. Both organisations campaign for cleaner estuarine environments and organise many coastal and beach cleans throughout the year to reduce the litter seen around our estuaries and coastlines.
SEP’s flagship project, Litter Free Coast and Sea Somerset is a community campaign which aims to protect bathing water quality and reduce marine and beach litter in Somerset, by encouraging local communities to consider their own impacts on water quality and marine litter. Visit the website here for more information.