MarLIN has undertaken Key Information reviews on 848 species. The species key information research focused on species listed under the UK Biodiversity Action Plan, the EC Habitats Directive, and the Wildlife & Countryside Act (click here for information) or species that are nationally rare or scarce. Reviews are also undertaken for species that are important to the ecosystem structure and functioning of marine habitats. For instance 'key structural' species, also known as 'ecosystem engineers', provide habitats for others species and include kelps, mussels, seagrass etc, whilst 'key functional' species influence the community through activities such as predation and grazing.).

MarLIN has undertaken Key Information reviews on 129 biotopes. Biotope key information targets biotopes identified within the interest features marine Special Areas for Conservation (SACs) in English and Scottish waters. The key information reviews are augmented by basic information pages on many more keystone, characteristic, 'important', or common species.