<div><p><span style="font-family:inherit; font-size:14px">Methodology from </span><strong><span style="font-family:open sans,arial,helvetica,lucida sans unicode,sans-serif; font-size:inherit">Smyth, A. R., Piehler, M. F. and Grabowski, J. H. (2015), Habitat context influences nitrogen removal by restored oyster reefs. J Appl Ecol, 52: 716–725. doi:<a href="http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12435/abstract" style="color: rgb(0, 102, 153); margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; text-decoration-line: none;" target="_blank">10.1111/1365-2664.12435</a></span></strong></p>
<p>Within 4 h of collection, sediment cores were set up in a continuous flow core incubation system to measure steady-state nutrient and dissolved gas fluxes, described in Piehler & Smyth (2011). Briefly, cores were sealed with gas-tight lids, which had an inflow and outflow port. Water from a reservoir was pulled over the cores at a flow rate of 1 mL min−1. Triplicate dissolved gases and duplicate dissolved inorganic nitrogen samples were collected from the outflow and inflow periodically over the next 24 h. To examine how sediments from different habitat contexts responded to nitrate pulses, nitrate concentration in the reservoir water was elevated with NaNO3 (~800 μm) after 48 h of sampling. Dissolved gas and inorganic nitrogen samples were then collected for an additional 48 h. Incubations were conducted in the dark and at ambient temperature (30 °C).</p>
<p>Water samples from laboratory experiments were analysed immediately upon collection for dissolved gasses (N2, O2 and Ar) with membrane inlet mass spectrometry (MIMS). Concentrations of dissolved N2 and O2 were determined using the ratio with Ar (Kana et al. 1994). Coefficients of variation for N2/Ar were 0·05% and 0·04% for O2/Ar. Water samples from laboratory experiments for dissolved nutrient determination were filtered through Whatman GF/F glass fibre filters (25 mm diameter, 0·7 μm nominal pore size) and frozen until analysis. Dissolved inorganic nutrients were analysed with a Lachat Quick-Chem 8000 automated ion analyser for [math formula] + [math formula] (reported as NOx) and [math formula] concentrations using standard protocols (Lachat Instruments, Milwaukee, WI, USA: [math formula] / [math formula] method 31-107-04-1-A, [math formula] method 31-107-06-1-A; detection limits: 0·04 μm NOx, 0·18 μm [math formula] ; CV(%): 0·9% NOx and 2·6% [math formula] ).</p>
<p>Upon completion of the incubations, the upper 2 cm of sediment in each core was sampled for organic matter content by mass difference from dried sediments before ignition (105 °C for 6 h) and after ignition (525 °C for 3 h).</p>
<p><strong>Water Quality Data:</strong></p>
<p><img alt="" src="https://datadocs.bco-dmo.org/d3/data_docs/OysterReef_N2O_Emission/WaterQualityData.png" style="height:283px; width:500px" /></p>
<p> </p></div>
Change in denitrification (N2 Flux) due to the oyster reef.
<div><p>Nutrient flux data from several landscapes in coastal North Carolina.</p></div>
Change in denitrification - N2 flux
<div><p><span style="font-family:inherit; font-size:14px">Methodology from </span><strong><span style="font-family:open sans,arial,helvetica,lucida sans unicode,sans-serif; font-size:inherit">Smyth, A. R., Piehler, M. F. and Grabowski, J. H. (2015), Habitat context influences nitrogen removal by restored oyster reefs. J Appl Ecol, 52: 716–725. doi:<a href="http://onlinelibrary.wiley.com/doi/10.1111/1365-2664.12435/abstract" style="margin: 0px; padding: 0px; border: 0px; font-style: inherit; font-variant: inherit; font-weight: inherit; font-stretch: inherit; font-size: inherit; line-height: inherit; font-family: inherit; vertical-align: baseline; text-decoration-line: none; color: rgb(0, 102, 153);" target="_blank">10.1111/1365-2664.12435</a></span></strong></p>
<p><span style="font-family:inherit; font-size:14px"><span style="font-family:open sans,arial,helvetica,lucida sans unicode,sans-serif; font-size:inherit">Fluxes across the sediment–water interface were calculated as (Co−Ci) × f/a, where Co is the outflow concentration (μmol L−1), Ci is the inflow concentration, f is the flow rate (0·06 L h−1), and a is the sediment surface area (0·0032 m2). Successive measurements from each core (triplicates for dissolved gas and duplicates for dissolved inorganic nutrients) were averaged to give core-specific values. This results in a net N2flux (gross denitrification – gross nitrogen fixation) and does not distinguish between the sources of N2. Consequently, denitrification refers to net N2 production. Oxygen fluxes were calculated using the concentrations of O2 obtained from the MIMS, presented as sediment oxygen demand (SOD), and serve as an indicator of organic matter quality, such that more labile organic matter is associated with higher SOD (Ferguson, Eyre & Gay 2003). To determine the influence of oyster reefs on sediment N2 fluxes, the change in denitrification between the control and reef habitat pair in each zone was calculated (Kellogg et al. 2014). Denitrification efficiency was computed as the percentage of the dissolved inorganic nitrogen efflux that was N2 (Piehler & Smyth 2011).</span></span></p>
<p><span style="font-family:inherit; font-size:14px"><span style="font-family:open sans,arial,helvetica,lucida sans unicode,sans-serif; font-size:inherit">Statistical analyses were performed using r 2.13.1 (R Foundation for Statistical Computing 2011). Linear mixed-effects models (lme in R nlme package), where habitat nested in sampling location was included as a random effect for the intercept, were used to investigate the effects of oyster reef presence, habitat context, nitrate concentration (ambient vs. elevated) and the interaction between these factors on response variables. Fluxes of N2, NOx ( [math formula] + [math formula] ) [math formula] , denitrification efficiency and SOD were analysed using all three fixed effects. For sediment organic matter, only habitat context and reef presence were included as fixed effects. The effects of ambient vs. elevated nitrate concentration and habitat context on oyster reef-mediated changes in denitrification were also analysed with a mixed-effects model (fixed effects: nitrate concentration × habitat context; random effects: habitat nested in location). Relationships between oyster density and habitat context were made using a mixed-effects model (fixed effects: habitat context; random effects: habitat nested in location). Comparisons were conducted using linear contrasts and judged against an alpha level of 0·05. Interactions were assessed using Tukey's HSD (lsmeans in R lsmeans package). Assumptions of homogeneity were tested using Levene's tests. Regression analyses were used to investigate the effect of oyster density on denitrification. Models with the lowest Akaike's information criterion corrected for small sample sizes (AICc) were chosen.</span></span></p>
<p><span style="font-family:inherit; font-size:14px"><strong>BCO-DMO Processing Notes:</strong></span></p>
<p><span style="font-family:inherit; font-size:14px">- column names reformatted to comply with BCO-DMO naming standards.<br />
- lat and lon columns added to correspond with locations.</span></p></div>
704359
Change in denitrification - N2 flux
2017-06-06T20:02:55-04:00
2017-06-06T20:02:55-04:00
2023-07-07T16:10:26-04:00
urn:bcodmo:dataset:704359
Change in denitrification due to oyster reefs from the coast of North Carolina in 2010
Change in denitrification due to oyster reefs from the coast of North Carolina in 2010
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Piehler, M., Brush, M., Song, B., Tobias, C. (2017) Change in denitrification due to oyster reefs from the coast of North Carolina in 2010. Biological and Chemical Oceanography Data Management Office (BCO-DMO). (Version 1) Version Date 2017-06-06 [if applicable, indicate subset used]. doi:10.1575/1912/bco-dmo.704359.1 [access date]
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