Methodology from\u00a0Smyth, A. R., Piehler, M. F. and Grabowski, J. H. (2015), Habitat context influences nitrogen removal by restored oyster reefs. J Appl Ecol, 52: 716\u2013725. doi:10.1111/1365-2664.12435
\nSediment cores (contained in 6\u00b74-cm-diameter by 17-cm-long polycarbonate tubes, 10\u00a0cm depth) were collected adjacent to each reef habitat (n\u00a0=\u00a03) and control habitat (without reefs,\u00a0n\u00a0=\u00a03) in each context at low tide on 28 June 2010. Cores collected from oyster reefs did not contain live oysters. Additionally, ~100\u00a0L of water was collected for use in the laboratory incubations. Following collection, sediment cores and water were transported to an environmental chamber (Bally, Inc., Morehead City, NC, USA) at The University of North Carolina Institute of Marine Sciences in Morehead City, NC. Surface water measurements of dissolved O2, salinity and water temperature (YSI 600 Series Sonde and Model 650 data logger; Yellow Springs Instruments, Yellow Springs, OH, USA) were also collected. Oyster density in the reef was determined by placing a 0\u00b725-m2\u00a0quadrat\u00a0on each reef (one\u00a0quadrat\u00a0per reef) and counting all the oysters present with a shell length >25\u00a0mm (Powers\u00a0et\u00a0al.\u00a02009).
Oyster reef data from several landscapes in coastal North Carolina.
Methodology from\u00a0Smyth, A. R., Piehler, M. F. and Grabowski, J. H. (2015), Habitat context influences nitrogen removal by restored oyster reefs. J Appl Ecol, 52: 716\u2013725. doi:10.1111/1365-2664.12435
\nStatistical analyses were performed using\u00a0r\u00a02.13.1 (R Foundation for Statistical Computing\u00a02011). Linear mixed-effects models (lme\u00a0in\u00a0R nlme\u00a0package), 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\u00a0( [math formula] \u00a0+\u00a0 [math formula] )\u00a0 [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\u00a0\u00d7\u00a0habitat 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\u00b705. Interactions were assessed using Tukey's HSD (lsmeans\u00a0in\u00a0R lsmeans\u00a0package). 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.
\nBCO-DMO Processing Notes:
\n- column names reformatted to comply with BCO-DMO naming standards.
\n- lat and lon\u00a0columns added to correspond with locations.