1. Organic Matter Metabolism in a Coastal Ocean Ecosystem Patricia Matrai Mike Sieracki Nicole Poulton Carlton Rauschenberg Bigelow Laboratory for Ocean Sciences W. Boothbay Harbor Maine NASA OCRT 4/11-13/06 Newport, RI

2. In Collaboration with: University of New Hampshire Center for Coastal Ocean Observation and Analysis Janet Campbell Joe Salisbury

3. Talk outline Project objectives Study site and measurements Some first year results Respiration models Preliminary remote sensing results Conclusions

4. Project Objectives Primary Objectives: Can microbial respiration be modeled by temperature, chlorophyll, primary production, and DOM? If so, how well can surface water respiration be estimated by satellite remote sensing? Secondary Objectives: What is the balance of planktonic microbial respiration to primary production in a river plume system? How does planktonic food web structure relate to the system metabolic balance?

5. Gulf of Maine Primary Study Area (GoMOOS C) (GoMOOS B)

6. Study Methods Monthly cruises from Kennebec River (Bath, Maine) to Portsmouth, NH 5 Stations, surface samples Respiration (24h O 2 incubations) Primary production (12h 14 C incubations) Microplankton and particle analysis FlowCAM, flow cytometry, microscopy Size spectra, 0.2 - >200 µm Chlorophyll, T, S, TOC, POC, ∆ 13 C, nutrients Bacterial single-cell respiration (CTC)

7. Temperature and Salinity Temperature pattern similar at all stations River and plume stations show spring and fall runoff peaks (low salinity)

8. Bacteria and <20µm Phytoplankton Abundances Eukaryotes Synechococcus Heterotrophic Bacteria

9. Microphytoplankton Abundance (15 - 200 µm, FlowCAM) Apr Jun OctDec

10. Chl 1° Prod Seasonal Trends in Chlorophyll, Primary Production, and Respiration Resp

11. Chl 1° Prod Resp Seasonal Trends in POC, Nutrients, and δ 13 C/ 12 C POC δ 13 C/ 12 C PO 4 NO 3 + NO 2

12. Annual Station Means Downstream: Chlorophyll declines 1° Production declines Respiration increases RiverCoast Chl Resp PP

13. Surface respiration vs. primary production (µgC L -1 d -1 ) 1:1 Overall system mean: R is 30% of P

14. Surface respiration vs. primary production (µgC L -1 d -1 ) River + plume Aug, Sept Spring bloom May, June 1:1

15. Ecosystem relationships Cole et al. 1988, White et al. 1991, del Giorgio et al. 1997 Rivkin & Legendre 2001 Method #1 BA = f(Chl) BR = f(BA, T) Method #2 BP = f(BA, T) BR = f(BP, T) Method #3 BR = f(NPP)

16. Example Gulf of Maine Respiration Images 13 May 2005 SST CHL BR1 (BA) BR2 (BP)

17. Conclusions Kennebec River plume/Gulf of Maine system is dynamic, biologically rich, and productive Primary production exceeds respiration most of the year, R was 30% of P for the whole system over 1 year. Preliminary estimates of respiration from remote sensing data using ecosystem relationships are within an order of magnitude of in-water measurements, but further analysis and validation are needed.

18. And Thanks to: Kay Kilpatrick, RSMAS, U. Miami Ben Tupper, Bigelow Laboratory Paul Pelletier, Capt. R/V Gulf Challenger Chris Hunt, Mike Novak, UNH Coastal Transect crew Carbon Cycle Science