1. Paleoproductivity Paleoproductivity > 1976 Regime-shift Opal (%)
Bering Sea: Skan Bay Core 10 20 30
Paleoproductivity
> 1976 Regime-shift
Bering Sea:
d13C - decrease
Opal - variable
Gulf of Alaska:
d13C - increase
Opal - increase
-22.0
-21.0
-20.0
Paleoproductivity
d13C
Opal (%)
Gulf of Alaska: GAK 4 Core
-25
-24
-23 8 10 12
d13C
GOA GAK 4
2 cores summarized for paleoproductivity indicators over the last 300 years. Map in lower right shows locations. One core from Gulf of Alaska (GAK 4 site central gulf shelf) One core from Bering Sea (Skan Bay) 2 Productivity indicators are plotted for each core, opal, which represents diatom productivity (blue) and delta 13C of organic matter (red) all organic productivity. Increases in productivity would be indicated by an increase in either indicator. So, you can see variability over last 300 years from this for each region. In text in upper right of figure I summarized inferred change since 1976 Regime shift for each core/region. Bering: C13 decrease and opal about average GoA: both increase. So, there seems to be an East-West difference, which is interesting as some other ecosystem components also have this difference (ie Stellers).
Opal (%)
Skan Bay
d13C
Opal (%)
2000
1950
1900
1850
1800
1750
1700
Finney et al.
Year AD