80 sediment stations and 4 sediment cores
collected in the Sea of Okhotsk were used in this study in order to reveal additional
proxy for past climate reconstruction based on planktonic foraminifera.
Variation in diversity indices (Simpson, Shannon and equitability indices)
along the sea became additional criteria for 5 biogeographical provinces based
on planktonic foraminifera. All of them show different structure aspects of the
planktonic foraminifera assemblages that is very informative in cases of high
relative abundance of N. pachyderma sin. and influence of carbonate dissolution
factor. During the last 100 ky the diversity indices were changed and we can
assume the migration of biogeographical provinces borders: borders of the
Northern province were mov- ed to the central part in cold MIS 2, 4, structure
of assemblages during MIS 3, 5 was close to the modern Central province but
characterized by low total foraminiferal abundance in the sediments. The
Simpson and Shannon indices are more sensitive to changes in structure of
planktonic foraminifera assemblages when equitability index varies lightly
during the Late Pleistocene-Holocene.
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