The NCMA maintains the largest and most diverse collection of publically available marine algal strains in the world. The algal strains in the collection have been obtained from all over the world, from polar to tropical waters, marine, freshwater, brackish, and hyper-saline environments. New strains (50 - 100 per year) are added largely through the accession of strains deposited by scientists in the community. A stringent accession policy is required to help populate the collection with a diverse range of strains.