Estuaries and Coasts

, Volume 39, Issue 6, pp 1827–1844

Comparing Measures of Estuarine Ecosystem Production in a Temperate New England Estuary

  • Autumn Oczkowski
  • Christopher W. Hunt
  • Kenneth Miller
  • Candace Oviatt
  • Scott Nixon
  • Leslie Smith

DOI: 10.1007/s12237-016-0113-1

Cite this article as:
Oczkowski, A., Hunt, C.W., Miller, K. et al. Estuaries and Coasts (2016) 39: 1827. doi:10.1007/s12237-016-0113-1


Anthropogenic nutrient enrichments and concerted efforts at nutrient reductions, compounded with the influences of climate change, are likely changing the net ecosystem production (NEP) of our coastal systems. To quantify these changes, scientists monitor a range of physical, chemical, and biological parameters sampled at various frequencies. Water column chlorophyll concentrations are arguably the most commonly used indicator of net phytoplankton production, as well as a coarse indicator of NEP. We compared parameters that estimate production, including chlorophyll, across an experimental nutrient gradient and in situ in both well-mixed and stratified estuarine environments. Data from an experiment conducted in the early 1980s in mesocosms designed to replicate a well-mixed mid-Narragansett Bay (Rhode Island) water column were used to correlate changes in chlorophyll concentrations, pH, dissolved oxygen (O2), dissolved inorganic nitrogen, phosphate, and silicate concentrations, cell counts, and 14C carbon uptake measurements across a range of nutrient enrichments. The pH, O2, nutrient, and cell count measurements reflected seasonal cycles of spring blooms followed by late summer/early fall respiration periods across nutrient enrichments. Chlorophyll concentrations were more variable and rates of 14C productivity were inconsistent with observed trends in nutrient concentrations, pH, and O2 concentrations. Similar comparisons were made using data from a well-mixed lower Narragansett Bay station and a more stratified upper Narragansett Bay station in 2007 and 2008. Trends among pH, O2, and nutrient concentration parameters were similar to those observed in the mesocosm dataset, suggesting that continuous free water measurements of pH and O2 seem to reliably reflect ecosystem metabolism and, while not perfect measures, may be underused indicators of NEP.


pH Dissolved oxygen Production Estuary Eutrophication Nutrients Ecosystem 

Supplementary material

12237_2016_113_MOESM1_ESM.doc (2.2 mb)
Table S1Results of a correlation analysis for the MERL mesocosm dataset. For each comparison, the top correlation value indicates the strength of the correlation, where positive values (0 < r ≤ 1) indicate a positive correlation and negative values (0 > r ≥ −1) indicate a negative correlation. The closer to |1|, the stronger the correlation. p values <0.05 indicate a statistically significant relationship. The “no. pairs” means the number of data pairs uses for each correlation analysis. Results are presented for the Control, 1×, 2×, and 4× mesocosms (DOC 2268 kb)
12237_2016_113_MOESM2_ESM.doc (2.2 mb)
Table S2Results of the correlation analysis for the Narragansett Bay data collected near the GSO dock. Analytical results are set up in the same manner described in Table 2 where, briefly, correlation indicates the strength of the correlation and p value gives significance. The number of pairs analyzed is listed in the heading (n). Fluor. is an abbreviation for fluorescence and refers to the chlorophyll estimates made from the in situ fluorescence data. As there were fewer samples available, discrete chlorophyll samples and 14C measurements were analyzed in monthly bins and the results of these analyses are presented in Table S1 (DOC 2269 kb)
12237_2016_113_MOESM3_ESM.doc (2.2 mb)
Table S3Results of a correlation analysis for the 2007–2008 lower Narragansett Bay dataset, where data were analyzed in monthly bins (DOC 2267 kb)
12237_2016_113_MOESM4_ESM.doc (2.2 mb)
Table S4Results of a correlation analysis of data from the Bullock Reach station in Rhode Island. Monthly bins were used (DOC 2267 kb)
12237_2016_113_MOESM5_ESM.doc (2.2 mb)
Table S5Results of regression models comparing chlorophyll concentrations in the MERL mesocosms, and weekly mean fluorescence data at the GSO station, to nutrient concentrations and pH and O2 concentrations. The number of records used in the analysis, as well as the R-squared values resultant from the model, are presented (DOC 2266 kb)

Copyright information

© Coastal and Estuarine Research Federation (outside the USA) 2016

Authors and Affiliations

  • Autumn Oczkowski
    • 1
  • Christopher W. Hunt
    • 2
  • Kenneth Miller
    • 3
  • Candace Oviatt
    • 4
  • Scott Nixon
    • 4
  • Leslie Smith
    • 5
  1. 1.Atlantic Ecology DivisionUS Environmental Protection AgencyNarragansettUSA
  2. 2.Ocean Process Analysis LaboratoryUniversity of New HampshireDurhamUSA
  3. 3.CSCAlexandriaUSA
  4. 4.Graduate School of OceanographyUniversity of Rhode IslandNarragansettUSA
  5. 5.Your Ocean Consulting, LLCKnoxvilleUSA

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