Investigating plastics in Galapagos – introduction and microplastics
Analysing fish guts will provide vital information on the presence of microplastics in marine species in Galapagos.
Nick and Mollie, volunteers from the Galapagos Science Centre, are working closely with GCT by laying the ground work for our plastics programme. Having both recently graduated with a Masters of Research from Imperial College London’s Silwood Park, they are spending two months in Galapagos. Nick loves to dive and is a shark enthusiast as well as an avid photographer of nudibranchs. He has a keen interest in the role and effectiveness of marine protected areas. Mollie is an aspiring conservation biologist, loves reptiles and wants to find ways to preserve the world’s incredible biodiversity whilst ensuring that peoples’ livelihoods prosper.
The idea of a plastic-free Galapagos is a wonderful one. If possible, not only would it make the Islands even more attractive, but would also mean that the fish, reptiles and mammals that rely on the ocean would be some of the healthiest in the world. We are spending two months working at the Galapagos Science Centre (GSC) to gather preliminary information on plastics throughout the Archipelago. Our research will be used to create plans that will hopefully help achieve the ultimate goal: a plastic-free Galapagos.
We’ve now been at GSC, located in Puerto Baquerizo Moreno, San Cristobal, for just over three weeks and we’ve already started to gather some useful data. We’ve been primarily involved with two projects; a fish gut analysis for microplastics and a beach survey project looking for macro-plastics. This week I will focus on telling you about our work surveying fish for microplastics.
Microplastics, defined as plastic fragments smaller than 5mm, have been found in fish all over the world, from the Mediterranean to the South China Sea. In order to see if this is the case in Galapagos, we are surveying for microplastics in fish that were recently caught on research expeditions throughout the Islands. Species caught range from predators such as yellowfin tuna, barracuda and swordfish, to coastal reef species such as the ocean whitefish.
We have spent the last few weeks determining which methods will be best to use for our research. This has involved trawling through past studies and identifying interesting bits of information. We are limited in what we can import to Galapagos, so whilst there are some methods that involve lots of expensive equipment, we are sticking with the simpler approaches that have been used successfully in the past. We have chosen to start by scraping out the contents of the gastro-intestinal tract of each fish, which involves cutting the stomach and intestines open in order to access the contents.
Once we have the stomach and intestinal contents of the fish, we break down the organic matter by digesting it in a strong solution of sodium hydroxide. This does a lot of the hard work for us, but can take anything between two days and a week to get from undigested gunk to something that we can work with (see images below).
Once we have a sample ready to go, we run it through a filtration system to remove the excess liquid. We then search for plastics under a microscope for a set period of time, stopping to take photos if we find anything of interest. This way, each sample is treated with the same examination methods and so our results will be comparable when we begin to analyse what we find.
Although this can be quite a smelly job, it will really help us to understand whether the fish in Galapagos are ingesting plastics and how common an occurrence this is. We then aim to determine key areas within the Archipelago where fish are more likely to have eaten plastic, which in turn will help us identify priority areas for conservation efforts. We are also trying to determine how much microplastic is in the water surrounding the Islands, but more on this in a future blog!