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Biogeochemical and Bacterial Aspects of AEROSE

Biogeochemical and Bacterial Aspects of AEROSE. By Ernesto Otero Department of Marine Sciences University of Puerto Rico. Data was contributed by:. Jorge Corredor Julio Morell Milton Muñoz Ana Lozada Marla Méndez. Outline. Working Hypothesis Samples collected and methodology

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Biogeochemical and Bacterial Aspects of AEROSE

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  1. Biogeochemical and Bacterial Aspects of AEROSE By Ernesto Otero Department of Marine Sciences University of Puerto Rico

  2. Data was contributed by: Jorge Corredor Julio Morell Milton Muñoz Ana Lozada Marla Méndez

  3. Outline • Working Hypothesis • Samples collected and methodology • Results of biogeochemical features and heterotrophic fluxes at 5 oceanographic stations

  4. Working Hypothesis • There are several biogeochemical provinces along the “Tropical” North Atlantic • These provinces are the result of the interaction of oceano-atmospheric dynamics • Ocean and atmospheric transport • These provinces can be detected and characterized through analysis of biogeochemical and microbiological variables

  5. 5 4 1 3 2 Trajectories of all of the NOAA AOML Drifting Buoy Data Assembly (DAC) Center's archived near-surface buoys, from 1978 to June, 2003 oceancurrents.rsmas.miami.edu/atlantic/north-equatorial_2.html

  6. Atmospheric Deposition

  7. -CHN analysis -OBS-CTD -Spectrophotometry -CTD Electrode-Winkler -Epifluorescence-DAPI -Leu Inc-Prot Prod -Reduction of Tetrazolium Measurements • Biogeochemical variables: • POC • PON • Turbidity • cDOM (a440) • O2 • Microbial Variables: • Bacterial Counts • Bacterial Secondary Production • Respiration (ETS) • Specific Yield • Growth Efficiency • Bacterial Isolation/Identification

  8. Some Important Characteristics of Bacterial Communities in Oceanography • Heterotrophic bacteria represent 22-33 percent of the total biomass (Gasol et al, 1997) • Recycle inanimate organic matter into bacterial biomass initiating a microbial loop, thus, generating important but seldom considered trophic dynamics (Pomeroy, 1974); • Modulate the accessibility of inorganic nutrients to primary producers (phytoplankton) by being the main mineralizers and competing for the released nutrients, specially under oligotrophic oceanic conditions; • Conducive to aggregation/flocculation of organic matter into particles (Muschenheim et al, 1989; Alber and Valiela, 1994), therefore being important agents for carbon sequestration below the ocean mixed layer; • Contribute quantitatively to the total biotic flux of carbon and nutrients in marine systems since their demand for organic substrates may be a large proportion of the total phytoplankton production.

  9. Importance of planktonic ETS derived respiration rates • An oceanic ETS survey provides the fastest, simplest and least expensive way to assess mesoscale variations in plankton respiration • Strong theoretical link between the function of the ETS and the physiological rate of oxygen consumption • Help establish constraints of carbon and nutrient fluxes/dynamics

  10. Collection of Samples and Data Oceanographic Rosette 24 X 15 L Niskin Bottles On Board CTD, Fluorometer and Turbidimeter, O2 electrode Preparing bottles for Calibration of O2 electrode Bacterial Cells/DAPI Bacterial Isolates

  11. Results: Biogeochemistry; POC (µM C) with overlay of Turbidity

  12. Results: Biogeochemistry; PON (µM N) with overlay of Turbidity

  13. Regression results of POC and PON vs turbidity for all 5 oceanographic stations

  14. 5 4 1 3 2 Results: Biogeochemistry; a440(CDOM) with Chla Overlay

  15. Results Biogeochemistry: SBE 43 sensor corrected by DO Winkler measurements

  16. Results: Microbial Processes- Bacterial Abundance and Production

  17. Results: Microbial Processes- Bacterial Yield

  18. ETS samples collected during AEROSE cruise • BBD to GC: ETS Samples every 8 hours and 13 depths in each rosette station • GC to PR: ETS Samples every 12 hours • Dark community respiration: 4 samplings

  19. Results: Microbial Processes- Longitudinal distribution of ETS (Respiration; uL O2.L-1.h-1) ETS Respiration rates are higher between 25 and 20 longitude degrees due to the African upwelling enrichment, reaching 1.67 μL O2.L-1.h-1. Dots represents sample depths and its value in five intervals. The higher ETS rates are for St. 4 and 5 with 0.44 and 1.1 uLO2. hese values are lower but of the same order of magnitude reported by Robinson et al. 2002

  20. Correlation between Bacterial production (background) and ETS rates (lines contour) w/o surface and 25 m at upwelling station umolC/L/d Bacterial production and ETS correlation y = 2.8482x + 0.1886 R2 = 0.5203

  21. Results: Microbial Processes- Respiration vs Bacterial Yield at the five Oceanographic Stations

  22. Conclusions Longitudinal biogeochemical and microbiological gradients cDOM eastern Atl and upwelling POC and PON showed increased levels towards stations 3 and 4 Bacterial yield distinguishes among different stations/provinces ETS and bacterial production show similar trends Mixed layer Microbial growth efficiency increased from <0.1 to 0.25 at upwelling station. Provinces similar to bacterial yield Regressions of ETS vs. bacterial yield clearly separate station 1 and 2 from 3, 4, and 5.

  23. Potential Directions Increased number of oceanographic stations Microbial rates enhancement / Sahara dust amendment assays

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