Publication Date:
2022-05-25
Description:
Author Posting. © The Author(s), 2013. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Estuaries and Coasts 36 (2013): 74-97, doi:10.1007/s12237-012-9560-5.
Description:
Biogeochemical cycles in estuaries are regulated by a diverse set of physical and
biological variables that operate over a variety of time scales. Using in situ optical sensors, we
conducted a high-frequency time-series study of several biogeochemical parameters at a mooring
in central Long Island Sound from May to August 2010. During this period, we documented
well-defined diel cycles in nitrate concentration that were correlated to dissolved oxygen, wind
stress, tidal mixing, and irradiance. By filtering the data to separate the nitrate time series into
various signal components, we estimated the amount of variation that could be ascribed to each
process. Primary production and surface wind stress explained 59% and 19%, respectively, of the
variation in nitrate concentrations. Less frequent physical forcings, including large-magnitude wind events and spring tides, served to decouple the relationship between oxygen, nitrate, and
sunlight on about one-quarter of study days. Daytime nitrate minima and dissolved oxygen
maxima occurred nearly simultaneously on the majority (〉 80%) of days during the study period;
both were strongly correlated with the daily peak in irradiance. Nighttime nitrate maxima
reflected a pattern in which surface-layer stocks were depleted each afternoon and recharged the
following night. Changes in nitrate concentrations were used to generate daily estimates of new
primary production (182 ± 37 mg C m-2 d-1) and the f-ratio (0.25), i.e., the ratio of production
based on nitrate to total production. These estimates, the first of their kind in Long Island Sound,
were compared to values of community respiration, primary productivity, and net ecosystem
metabolism, which were derived from in situ measurements of oxygen concentration. Daily
averages of the three metabolic parameters were 1660 ± 431, 2080 ± 419, and 429 ± 203 mg C
m-2 d-1, respectively. While the system remained weakly autotrophic over the duration of the
study period, we observed very large day-to-day differences in the f-ratio and in the various
metabolic parameters.
Description:
This work was supported by the Yale
Institute for Biospheric Studies, the Sounds Conservancy of the Quebec-Labrador Foundation,
and the Yale School of Forestry and Environmental Studies Carpenter-Sperry Fund.
Description:
2014-01-01
Keywords:
Long Island Sound
;
Nitrate
;
Nitrogen
;
New production
;
In situ measurements
;
Eutrophication
;
Dissolved oxygen
;
Net ecosystem metabolism
;
Wind forcing
;
Wind stress
;
f-ratio
Repository Name:
Woods Hole Open Access Server
Type:
Preprint
Format:
application/pdf
Permalink
