Sediment trap time series from the North Pacific

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1 Sediment trap time series from the North Pacific Ocean David Timothy data analyses/ presentation CS Wong Program organiser Frank Whitney lab and sampling logistics Janet Barwell-Clarke John Page Linda White lab and data analyses Tim Soutar Ron Bellegay Darren Tuele trap and mooring preparation Alex Bychkov Oleg Ibadulaev Logistical support for western Pacific traps Officers and Crew of the JP Tully

2 TIME SERIES FROM: Ocean Ocean Station PAPA Alaska Alaska Gyre and North Pacific Western Gyre Line Line P with emphasis at La Perouse Bank

3 Marine sediments are composed of biogenic silica calcium carbonate organic matter and rocks!

4 OSP: overlapping deployments 37 m - 38 m total dry weight (mg m -2 d -1 ) 4 37 m 38 m July A S O N D J F M A M June total dry weight (mg m -2 d -1 ) Sept Oct Nov Dec 22

5 Sediment-trap moorings deployed by IOS 6 5 latitude yrs ~3 yrs ~1 yr OSP: 1982 to present (3 depths) La Perouse Bank: 1986 to present Alaska Gyre: 199 to longitude stations in the Western Pacific: August, 1991 to June, stations along line P: sporadically from 1995 to 1997

6 TIME SERIES FROM: Ocean Station PAPA Alaska Alaska Gyre and North Pacific Western Gyre Line Line P with emphasis at La Perouse Bank

7 2 m 1 year of fluxes from OSP 1 m 38 m

8 total dry weight (mg m -2 d -1 ) "21 years" of sediment-trap flux at OSP 1 38 m 2 m 1 m

9 characterising seasonality and filling gaps to generate a single time-series

10 POC (mg m -2 d -1 ) CaCO 3 (mg m -2 d -1 ) BSi (mg m -2 d -1 ) TDW (mg m -2 d -1 ) deployments per day 2 m fluxes at OSP sorted by Julian day years of data

11 TDW (mg m -2 d -1 ) m fluxes at OSP sorted by Julian day POC (mg m -2 d -1 ) CaCO 3 (mg m -2 d -1 ) BSi (mg m -2 d -1 ) deployments per day years of data

12 TDW (mg m -2 d -1 ) m fluxes at OSP sorted by Julian day CaCO 3 (mg m -2 d -1 ) BSi (mg m -2 d -1 ) deployments per day POC (mg m -2 d -1 ) years of data

13 TIME-LAG IN FLUX BETWEEN SHALLOW AND DEEP TRAPS For each constituent, maximum correlation between 1 m and 38 m occurred at a day shift, which is close to the average deployment period. TDW (mg m -2 d -1 ) Material took ~8 to 24 days to sink 28 m, for sinking rates of about 1 to 4 m d -1. The shift for CaCO 3 (12 days) was less than the shift for TDW, BSi and POC (16 days). Is CaCO 3 sinking faster than BSi, and is POC associated with BSi moreso than with CaCO 3? Correlations (lower fig) were determined by shifting the entire time series, not the seasonally averaged fluxes as implied by the upper figure. 5 1 m 38 m corr coefficient (r) shift (d)

14 TDW (mg m -2 d -1 ) total dry weight flux at OSP with 16 day shift between 1 m and 38 m 5 1 m 38 m 1 m TDW 38 m TDW m flux / 38 m flux 31 day smooth flux decreases with depth flux increases with depth seasonally averaged change in flux with depth

15 BSi (mg m -2 d -1 ) biogenic silica flux at OSP with 16 day shift between 1 m and 38 m 2 1 m 38 m 1 m BSi 38 m BSi 2 1 flux decreases with depth seasonally averaged change in flux with depth 1 m flux / 38 m flux 31 day smooth flux increases with depth

16 CaCO 3 (mg m -2 d -1 ) CaCO 3 flux at OSP with 12 day shift between 1 m and 38 m 2 1 m 38 m 1 m CaCO3 38 m CaCO m flux / 38 m flux 31 day smooth flux decreases with depth flux increases with depth seasonally averaged change in flux with depth

17 POC (mg m -2 d -1 ) POC flux at OSP with 16 day shift between 1 m and 38 m Shoaling of seasonal thermocline in Aug high primary production (D Crawford, pers. comm.) 2 1 m 38 m similar double peak but different remineralisation dynamics than presented yesterday at HOTS 1 m POC 38 m POC flux decreases with depth seasonally averaged change in flux with depth 1 m flux / 38 m flux 31 day smooth

18 6 4 2 average m fluxes at OSP with merged 38 m fluxes TDW mg m -2 d m (measured) 38 m (translated to 1 m) deployments per day years

19 Southern Oscillation Index 2-2 Pacific Decadal Oscillation 2-2 BSi flux anomaly CaCO 3 flux anomaly POC flux anomaly

20 Southern Oscillation Index 2-2 La Niña El Niño 2 BSi/CaCO 3 flux 1 anomaly CONCERNS and ONGOING WORK 1. Large anomalies in general. Need to average fluxes over longer periods? How long? 2. Large anomalies in winter. Longer averaging? is a period when 38 m fluxes were translated to 1 m. Need to assure 1988 anomaly exists relative to the 38 m time-series.

21 2 m fluxes at OSP 3 16 TDW (mg m -2 d -1 ) TDW CaCO 3 (mg m -2 d -1 ) CaCO 3 1 m 38 m 2 m 5 1 m 38 m 2 m BSi (mg m -2 d -1 ) BSi 1 m 38 m 2 m POC (mg m -2 d -1 ) m 38 m 2 m POC

22 OSP conclusions The seasonal cycle of flux at OSP occurs with spring and summer peaks in the fluxes of BSi and POC, but only a spring peak in the flux of CaCO 3. Particles sink at rates of 1-4 m d -1 below 1 m, with the possibility CaCO 3 sinks faster than BSi and POC. POC follows BSi more closely than it follows CaCO 3. The time series from OSP is long enough for correlations with SOI and PDO. Preliminary analysis shows a greater predominance of diatoms during La Niña a and coccolithophorids during El Niño, consistent with Wong and Crawford (22).

23 TIME SERIES FROM: Ocean Ocean Station PAPA Alaska Gyre and North Pacific Western Gyre Line Line P with emphasis at La Perouse Bank

24 Alaska Gyre: 199 to latitude yrs ~3 yrs ~1 yr longitude

25 POC (mg m -2 d -1 ) CaCO 3 (mg m -2 d -1 ) BSi (mg m -2 d -1 ) TDW (mg m -2 d -1 ) 3 Alaska Gyre mg m -2 d N 145 W trap depth = 37 m bottom depth = 39 m TDW BSi CaCO 3 POC x 1

26 3 stations in the Western Pacific August, 1991 to June, WP-D latitude yrs ~3 yrs ~1 yr WP-A WP-B longitude stations WP aka GEMS

27 North Pacific Western Gyre sediment-trap fluxes WP D WP A WP B N E 43 m bottom depth = 52 m N 165 E 53 m bottom depth = 586 m 45 5 N W 52 m bottom depth = 5755 m BSi (mg m -2 d -1 ) TDW (mg m -2 d -1 ) CaCO 3 (mg m -2 d -1 ) POC (mg m -2 d -1 )

28 sediment composition at deep traps %BSi W Pacific 43 m 53 m OSP 38 m Alaska Gyre 37 m %CaCO %POC 4 2

29 TIME SERIES FROM: Ocean Ocean Station PAPA Alaska Alaska Gyre and North Pacific Western Gyre Line P with emphasis at La Perouse Bank

30 54 53 OSP P2 P16 P12 P4 British Columbia Latitude (N) Longitude (W)

31 La Perouse Bank N W prior to 1991: 5 m after 1991: 7 m bottom depth = 13 m deployments per day TDW mg m -2 d yrs of data

32 Resuspended fluxes at La Perouse Bank

33 no signal of primary production in the bulk flux at La Perouse Bank, and up to 75% of the sediment was lithogenic. lithogenic sediment = total - biogenic TDW mg m -2 d -1 lithogenic mg m -2 d -1 biogenic sediment = BSi + CaCO (POC) 1 5 biogenic mg m -2 d -1

34 Resuspended sediment at La Perouse Bank The composition of resuspended sediment was modelled after the samples where fluxes were more than 65% lithogenic and the total flux was > 9 mg m -2 d the mean composition of these samples was: 73% lithogenic 13% biogenic silica 8.3% CaCO 3 3.5% POC %lithogenic These were all in the winter when the downward flux would have been minimal TDW (mg m -2 d -1 )

35 The downward flux (total resuspended) at La Perouse Bank BSi (mg m -2 d -1 ) "downward" TDW (mg m -2 d -1 ) "downward" TDW (mg m -2 d -1 ) BSi (mg m -2 d -1 ) CaCO 3 (mg m -2 d -1 ) CaCO 3 (mg m -2 d -1 ) POC (mg m -2 d -1 ) POC (mg m -2 d -1 ) 2 1

36 compilation from Line P OSP trap: 345 m bottom: 389 m P2 trap: 31 m bottom: 355 m P16 trap: 27 m bottom: 33 m P12 P4 British Columbia Latitude (N) Longitude (W)

37 fluxes were recorded sporadically along line P between 1995 and station P 12 TDW mg m -2 d -1 station P 16 TDW mg m -2 d -1 station P 2 TDW mg m -2 d clogs!!!

38 but sorted by Julian day P 12 TDW mg m -2 d P 12 fall peaks occurred on different years and were mostly biogenic 4 3 P 16 2 P P 2 2 P

39 Summary of fluxes in the North Pacific: mean fluxes measured at deepest traps at each station distance from Vancouver Island maximum coccolithophorid biomass along Line P periodically occurs at P12 (M Lipsen, pers. comm.). POC (mg m -2 d -1 ) CaCO BSi (mg m -2 d -1 ) TDW (mg m -2 d -1 3 (mg m -2 d -1 ) ) GD GA GB AG P2 OSP P16 P12 P4 total flux at La Perouse Bank downward flux

40 distance from Vancouver Island highest BSi contributions occur In the Western Pacific %BSi %CaCO 3 BSi/CaCO GD GA GB AG P2 P12 OSP P16 P4 highest carbonate contribution occurs from P12 into the Alaska Gyre Foram? continuous plankton Recorder might help %POC 9 6 3

41 conclusions Fluxes in the Alaska Gyre at 55 o N were similar in magnitude and composition to fluxes at OSP. Fluxes at 3 stations west of the dateline were composed almost entirely of BSi. Total fluxes were very low near the dateline but in the NW, ~3x higher than in the eastern North Pacific. Fluxes along Line P decreased with distance from the coast. The downward flux at La Perouse Bank shows sping and summer peaks similar to those at OSP. Highest carbonate fluxes throughout the North Pacific were measured at P12 and P16.

42 light at OSP: MJ m -2 d

43 This slide will contain Four figures (one for each constituent), exactly like upper right of the previous four slides, but with 2 m fluxes along with 1 m and 38 m. Point will be that the same signal exists at 2 m. A lot less attenuation than expected for the 2 m 1 m depth interval. There are some analytical issues we re dealing with, so we haven t yet pushed the 2 m time series through the calculations.

44 distance from Vancouver Island BSi/CaCO litho (mg m -2 d -1 3 ) GD GA GB AG P2 P12 OSP P16 P4 CaCO 3 /POC BSi/POC 9 6 3

45 La Perouse Bank: 1986 to present 6 5 latitude yrs ~3 yrs ~1 yr longitude

46 Southern Oscillation Index 2-2 Pacific Decadal Oscillation 2-2 BSi/CaCO 3 flux anomaly POC/CaCO 3 flux anomaly BSi/POC flux anomaly BSi/CaCO 3 POC/CaCO 3 BSi/POC

Tracking El Niño using optical indices of phytoplankton dynamics in the equatorial Pacific

Abstract Tracking El Niño using optical indices of phytoplankton dynamics in the equatorial Pacific Joel Craig 1, Pete Strutton 2, Wiley Evans 2 1. College of Earth and Atmospheric Science, Georgia Institute