Step-changes in the physical, chemical and biological characteristics of the Gulf of Maine, as documented by the GNATS time series

Marine Ecology Progress Series
By: , and 

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Abstract

We identify step-changes in the physical, chemical and biological characteristics of the Gulf of Maine (GoM) using the Gulf of Maine North Atlantic Time Series (GNATS), a series of oceanographic measurements obtained between September 1998 and December 2010 along a transect in the GoM running from Portland, ME, to Yarmouth, NS. GNATS sampled a period of extremes in precipitation and river discharge (4 of the 8 wettest years of the last century occurred between 2005 and 2010). Coincident with increased precipitation, we observed the following shifts: (1) decreased salinity and density within the surface waters of the western GoM; (2) both reduced temperature and vertical temperature gradients in the upper 50 m; (3) increased colored dissolved organic matter (CDOM) concentrations and particle scattering in the western GoM; (4) increased concentrations of nitrate and phosphate across all but the eastern GoM; (5) increased silicate, particularly in the western GoM, with a sharp increase in the ratio of silicate to dissolved inorganic nitrogen; (6) sharply decreased carbon fixation by phytoplankton; (7) moderately decreased chlorophyll, particulate organic carbon (POC) and particulate inorganic carbon (PIC) in the central GoM and (8) decreased POC- and PIC-specific growth rates. Gulf-wide anomaly analyses suggest that (1) the surface density changes were predominantly driven by temperature, (2) dissolved nutrients, as well as POC/PON, varied in Redfield ratios and (3) anomalies for salinity, density, CDOM, particle backscattering and silicate were significantly correlated with river discharge. Precipitation and river discharge appear to be playing a critical role in controlling the long-term productivity of the Gulf of Maine by supplying CDOM and detrital material, which ultimately competes with phytoplankton for light absorption.

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Additional publication details

Publication type Article
Publication Subtype Journal Article
Title Step-changes in the physical, chemical and biological characteristics of the Gulf of Maine, as documented by the GNATS time series
Series title Marine Ecology Progress Series
DOI 10.3354/meps09555
Volume 450
Year Published 2012
Language English
Publisher Inter-Research
Contributing office(s) Maine Water Science Center
Description 25 p.
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Marine Ecology Progress Series
First page 11
Last page 35
Country United States
State Maine
Other Geospatial Gulf Of Maine
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