Study area and collection

As part of the “idhelper” project we collected 224 samples across seven institutions (Aquarium de Paris (France), Chester’s Zoo (UK), Haus des Meeres-Vienna (Austria), Horniman Museum and Gardens (UK), Royal Burgers’ Zoo (Netherlands), Tierpark Hagenbeck Aquarium (Germany), ZSL London Zoo (UK)). Branch tip fragments of 2 cm were collected and stored in single ethanol (+ 95%) vials labelled with a unique identifier. During the sample collection the colonies were tagged and photographed with collection dates and tank locations were recorded. The photographs and tags were also recorded in the “idhelper” database [database—idhelper.net (2020)]. After collection samples were stored at − 20 °C until extraction, with an initial change of ethanol after 1–2 days aimed at reducing degradation. We analysed 127 Acropora samples from these collections before COVID-19 restrictions stopped further progress on this project.