The reflection of the present distribution of the primary production in the bottom sediments of the Sea of Okhotsk

Regionalized primary paleoproduction variability in the sea of Okhotsk during late Pleistocene and Holocene

“…The decanted extracts were measured by spectrophotometers Shimadzu UV-1650PC and UV-3600 or spectrofluorometer Hitachi MPF-4 with proven technique (Bosin et al, 2010;Harris and Maxwell, 1995;Zakharkov et al, 2007). The accuracy and precision for chlorin analysis, determined from hundreds of replicate samples, usually are better than 5%.…”

“…These derivatives of chlorophyll-a is remaining in sediment at least up to 1 million years (Nürnberg and Tiedemann, 2004). Reliability of this proxy for reconstructions of the OS environmental changes was demonstrated in number of studies (Bosin et al, 2010;Gorbarenko et al, 2007a;Nürnberg and Tiedemann, 2004). Therefore the chlorin content allows to estimate changes in the total primary production of all types of producers in the photic zone, while each micropaleontological proxy allow to trace the production of a single phytoplankton segment and most of geochemical proxies affected by water chemistry and water depth.…”

“…All these factors make the OS susceptible to as regional as global climate changes and suitable for high-resolution paleooceanography studies. Recently great efforts were focused on study of the OS productivity due to its important role in understanding of the modern and past environment evolution (Bosin et al, 2010;Gorbarenko and Goldberg, 2005;Gorbarenko et al, 2010bGorbarenko et al, , 2007bLapshina, 1996;Mordasova, 1997;Nürnberg and Tiedemann, 2004;Seki et al, 2004Seki et al, , 2009Shuntov, 2001;Sorokin and Sorokin, 1999;Zakharkov et al, 2007).…”

“…Also changes of the chlorin concentration reproduce varieties of the primary production in the past despite of bioturbation and diagenetic processes in surface sediment; however linearity of this relation is not certain. On average about 1% of the total produced organic matter buried in sediment, but this amount can varied from 3% in area with high productivity and high sedimentation rate to 0.2% in pelagic realm (Bosin et al, 2010). Comparison of the chlorin content with other paleoproductivity proxies allow to bind peaks of productivity with the dominant phytoplankton groups and trace the succession of primary producers.…”

“…It was established that the OS productivity was maximal during the warm marine isotope stages (MIS) and minimal during the cold ones due to severe climate conditions (Bosin et al, 2010;Gorbarenko and Goldberg, 2005;Nürnberg and Tiedemann, 2004;Seki et al, 2004). High silica phytoplankton production (diatom) started at 4-6 kyr ago in the Holocene (Gorbarenko et al, 2002a;Seki et al, 2004) in contrary to the NW Pacific region (Gorbarenko, 1996;Keigwin, 1998;Sancetta, 1992).…”