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2008
Smith, KL, Ruhl HA, Kaufmann RS, Kahru M.  2008.  Tracing abyssal food supply back to upper-ocean processes over a 17-year time series in the northeast Pacific. Limnology and Oceanography. 53:2655-2667.   10.4319/lo.2008.53.6.2655   AbstractWebsite

Detrital aggregates episodically deposited on the seafloor represent an underestimated food source to deep-sea communities. A 17-yr time-series study was conducted from 1990 to 2006 in the abyssal northeast Pacific (Sta. M, 4100 m in depth) to evaluate the importance of this food source and its temporal relationship to water column and surface ocean processes. Detrital aggregates appeared on the seafloor from June through December, with the highest peaks in 1990, 1994, 2001, and 2002 reaching a maximum density of 23 m(-2) in fall 2001. A total of 15,816 aggregates were measured, most less than 20 cm(2) in area and with a mode of 9 cm(2). Density of detrital aggregates was highly correlated with particulate organic carbon (POC) flux at 600 and 50 m above the bottom (p < 0.001) with no time lag. Export flux of organic carbon from the euphotic zone was significantly correlated with aggregate density, lagged earlier by 1-4 months (p <= 0.001). Zooplankton displacement volume was significantly correlated with POC flux (p =0.023) and with detrital aggregate density (p =0.028) on the seafloor when lagged earlier by <= 1 month. The Bakun upwelling index computed for the region around Sta. M was significantly correlated with detrital aggregate density when lagged earlier by 2-5 months (p < 0.001). A strong correlation exists between surface ocean processes and abyssal food supply, including POC flux and detrital aggregates. This direct coupling through the entire water column must be considered in resolving the marine carbon cycle.

2006
Smith, KL, Baldwin RJ, Ruhl HA, Kahru M, Mitchell BG, Kaufmann RS.  2006.  Climate effect on food supply to depths greater than 4,000 meters in the northeast Pacific. Limnology and Oceanography. 51:166-176. AbstractWebsite

A long time-series Study was conducted over 15 yr (1989-2004) to measure particulate organic carbon (POC) flux as an estimate of food supply reaching > 4,000-m depth in the northeast Pacific. Sequencing sediment traps were moored at 3,500-and 4,050-m depth, 600 and 50 in above the seafloor, respectively, to collect sinking particulate matter with 10-d resolution. POC fluxes were compared with three climate indices in the Pacific: the basin-scale multivariate El Nino Southern Oscillation index (MEI) and northern Oscillation index (NOI) and the regional-scale Bakun upwelling index (BUI). The NOI and MEI correlated significantly with POC flux, lagged earlier by 6-10 months, respectively. The BUI also correlated with POC flux. lagged by 2-3 months, suggesting a direct relationship between upwelling intensity and rates Of POC Supply to abyssal depths. Satellite ocean color data for the surface above the study site were used to estimate chlorophyll a concentrations and, combined with sea surface temperature and photosynthetically available radiation, to estimate net primary production and export flux (EF) from the euphotic zone. EF was significantly correlated with POC flux. lagged earlier by 0-3 months. An empirical model to estimate POC flux, with the use of NOI, BUI, and EF yielded Significant agreement with measured fluxes. Modeling of deep-sea processes on broad spatial and temporal scales with climate indices and satellite sensing now appears feasible.