Plymouth Marine Laboratory is an independent research charity whose scientists study how microplastics move through plankton and shellfish (its 'Mussel Power' project was backed by Waitrose's Plan Plastic). Gifts fund research on climate, biodiversity and marine pollution.
It is registered charity 1091222 in England and Wales (company 4178503). There is no online donate button; the Support Us page asks you to email the fundraising team, which is normal for a research institute. Ask for your gift to be directed to microplastics work.
How to start: pml.ac.uk/support-us/