Investigating the risks of plastic to Galapagos wildlife.
When we think of plastic impacting wildlife, we think of large items such as discarded fishing gear, but there are also major risks to species in Galapagos from microplastic pollution.
So, do you think we will see any wildlife-plastic interactions whilst we are filming?” asked one of the two-person news crew that accompanied our Galapagos plastics field survey in May 2018. “Very unlikely…” we replied – we would certainly find plastic pollution on the beaches that they could film, but witnessing direct interactions between wildlife and plastic litter is very rare.
We were on San Cristobal island in the south-east of the Galapagos Archipelago. Evidence suggests that this island has some of the highest plastic pollution accumulations, partly due to the influence of the ocean currents bringing plastic litter from the South American continent and from maritime industries operating outside the Galapagos Marine Reserve. Our survey team was made up of researchers from the University of Exeter (UK), the Universidad San Francisco de Quito (Ecuador) and a Galapagos National Park ranger, all part of the Plastic Pollution Free Galapagos Network. We were there to address several key questions to understand more about the ‘plastic pollution profile’ of the Galapagos Marine Reserve – how much is here, what are the most common types, and most importantly for reducing the threat, where is it coming from?
“That sea lion is playing with a plastic bottle!” As if on cue, almost as soon as we arrived at the survey beach, a pair of sea lions were playing in the shallows. They were indeed chewing on a plastic bottle, throwing it and catching it again, like a pair of puppies playing with a tennis ball. We couldn’t believe it – but, as always, Galapagos loves to surprise.
So the news team got the shot that they wanted – a wildlife-plastic interaction live on camera. But what impact is this novel pollutant really having on the marine species in Galapagos? It is certain that plastics are changing the marine habitats of oceanic islands all around the world. But how worried should we be about it given the multitude of other threats such as invasive species and climate change? Working together with researchers from the University of the Sunshine Coast (Australia) and the Charles Darwin Foundation our project aims to investigate these risks. There are several to consider. Larger plastic items such as discarded fishing gear (known as ghost gear) pose an entanglement risk to animals such as sea turtles, sharks and marine mammals.
Smaller items like cable ties and plastic packaging also pose a risk, particularly for animals such as sea lions that are inquisitive and playful. Items like plastic bags and films may be confused for prey and can cause blockage of the digestive tracts as demonstrated in autopsies of whales and turtles.
But the problem doesn’t stop with fishing gear and bags. Microplastics are formed when larger plastics break down and fragment as well as being used in the plastics production process and in beauty products. The major risk here is that these plastic particles are in the same size range as other food sources for filter feeders such as oysters and barnacles or small fish and may be ingested. In addition to possible effects on the individual, there is a risk of bioaccumulation as the plastic is passed up the food chain, perhaps even to humans. But we don’t yet know how much harm this is likely to cause. Determining the biological impacts of plastic pollution is made even more complex by the fact that there are so many different types that behave differently – both chemically and physically. These properties may make some plastics more toxic than others, affecting what other pollutants may bind to the particles. Plastics also present a novel vehicle for rafting species such as algae and barnacles that may be an invasive species risk, not to mention microbes that may pose a risk of disease.
A Plastics Risk Map for San Cristobal island
Using San Cristobal island as a case study site, we are investigating the plastic pollution profile across a variety of different important habitats. We are measuring microplastic particles floating at the ocean’s surface and collecting seabed sediment samples to look at microplastics that have sunk through the water column. We are also investigating the beach environment and have developed a methodology where the top 5cm of sand is sieved over several quadrats on each survey beach.
As part of GCT’s Connecting with Nature programme, we aim to connect local young people with their natural environment whilst providing valuable citizen science opportunities. Working with the Galapagos Science Center and local tour operator Galapagos Sharksky Travel & Conservation, we have started a monthly survey at one of our key study sites, Punta Pitt in the north of the island. Each month, a group of local students born on San Cristobal undertake the beach survey, generating a unique time series of microplastics data for this important habitat that is home to the rarest sub-species of marine iguana Amblyrhynchus cristatus godzilla (yes, its real Latin name!) among other vulnerable species.
This information from the environmental surveys will be combined with ecological information to produce a risk map for San Cristobal island. This will support the Galapagos National Park Directorate to centre conservation efforts in high-risk areas. This can then be applied to other islands.
Over the coming months, we are also planning to focus on at-risk vertebrate species such as marine iguanas, waved albatross, green sea turtles and the Galapagos sea lion. How often are these species encountering plastics? Is there any evidence of plastics getting into the marine food web? How can we work together to reduce the plastics risk to Galapagos wildlife?
This work has been made possible thanks to GCT members, The Woodspring Trust, the Royal Geographical Society, Galapagos SharkSky Travel & Conservation and the British Embassy Quito. If you are interested in finding out more about our study or sponsoring our Playas Sin Plasticos project with local students, please contact [email protected].
This blog has been adapted from an article in our 2019 Autumn Winter biannual members’ magazine, Galapagos Matters.
Find out more about our Plastic Programme and our bid to make Galapagos Plastic Pollution Free once again here.