UNEXPECTED RESPONSE TO VITAMIN B 12 OF DOMINANT CENTRIC DIATOMS FROM THE SPRING BLOOM IN THE GULF OF MAINE (NORTHEAST ATLANTIC OCEAN) 1 , 2

• Published in: Journal of Phycology
• Main Authors: Swift, Dorothy G., Guillard, Robert R. L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1978
• Subjects: Northeast Atlantic
• Online Access: http://dx.doi.org/10.1111/j.1529-8817.1978.tb02456.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1111%2Fj.1529-8817.1978.tb02456.x; https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1529-8817.1978.tb02456.x

ABSTRACT Twelve clones (seven species) representative of centric diatoms dominant in the spring phytoplankton bloom in the Gulf of Maine were isolated and rendered axenic. Genera included were Thalassiosira, Porosira and Chaetoceros. Unlike most centric diatoms studied previously, none of these has an absolute requirement for vitamin B 12. However, B 12 (5 ng.l ‐1 ) stimulated growth of most clones by eliminating or reducing the lag phase and increasing the growth rate. Bloom population densities developed 4–54 days earlier with B 12 present. Several clones grown with B 12 removed more than 80% of the vitamin from the medium. When grown in vitamin‐free medium the cells put 0.01–0.7 ng.l ‐1 B 12 into the medium. We conclude that vitamin B 12 is of ecological significance even though the requirement for it is not absolute .