# Presentation: 222538

## 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

## In Collaboration with: University of New Hampshire Center for Coastal Ocean Observation and Analysis

*Janet Campbell*
*Joe Salisbury*

## Talk outline

*Project objectives*
*Study site and measurements*
*Some first year results*
*Respiration models*
*Preliminary remote sensing results*
*Conclusions*

## 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?*

## Gulf of Maine Primary Study Area

**(GoMOOS C)**

**(GoMOOS B)**

## 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)*

## Temperature and Salinity

*Temperature pattern similar at all stations*

*River and plume stations show spring and fall runoff peaks (low salinity)*

## Bacteria and <20μm Phytoplankton Abundances

*Eukaryotes*

*Synechococcus*

*Heterotrophic*
*Bacteria*

## Microphytoplankton Abundance(15 - 200 μm, FlowCAM)

## Resp

**Chl**

**1° Prod**

*Seasonal Trends in Chlorophyll, *
*Primary Production, and Respiration*

**Resp**

## Resp

**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**

## Annual Station MeansDownstream:Chlorophyll declines1° Production declinesRespiration increases

**Chl**

**Resp**

**PP**

## Surface respiration vs. primary production (μgC L-1 d-1)

- 1:1

- Overall system mean:
**R is 30% of P**

## Surface respiration vs. primary production (μgC L-1 d-1)

- River + plume
- Aug, Sept

- Spring bloom
- May, June

- 1:1

## 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)

## Example Gulf of Maine Respiration Images13 May 2005

**SST**

**CHL**

**BR1 (BA)**

**BR2 (BP)**

## 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.*

## 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