2000 Volume 39 Issue 5 Pages 439-449
Diatom analysis was carried out in order to reveal Holocene paleoceanographic history in the SW part of the Sea of Okhotsk with a piston core, recovered off Shiretoko Peninsula, eastern Hokkaido. As the result, we recognized that percent abundances of Thalassionema nitzschioides and Neodenticula seminae, both of which indicate high productivity, have increased for the last 7, 300 years, whereas those of ice-related, allochthonous, and brackish species have decreased. In addition, we detected pulse-like occurrence of the warmwater species Fragilariopsis doliolus as a sensitive indicator of the Soya warm current in spite of its low frequency.
We show that the pulse-like occurrence of F. doliolus is likely to be related to the pulses of the Tsushima warm current in the Sea of Japan. These warm pulses in the Sea of Okhotsk can also be correlated with the eustatic curve based on geomorphological features and temporal and spacial distribution of warm molluscs such as Meretrix lusoria in some shell mounds around eastern Hokkaido.
