Carbon stocks and sources in Oyster Harbor (W Australia) seagrass sediments

In March 2012 we collected 3-replicated sediment cores (9 cm diameter and 12-15 cm long) per restored site along the planting chronosequence (i.e. years 1994, 1997, 2003, 2004, 2006). Similarly, we collected 3 sediment cores in two bare sites, previously colonized by seagrasses, and in a large seagrass patch that survived the disturbances in the second half of the 20th Century that we considered a mature and thus reference meadow. We measured sediment bulk density and organic matter content and carbon stocks along all sediment cores sliced at 1 cm interval. Organic carbon content (% Corg) was estimated from loss of ignition (% LOI) at 550oC for 5 h using the empirically fitted equation for Oyster Harbour sediments,Log % Corg = -0.62 + (1.33 * Log % LOI) SEintercept = 0.01, SEslope =0.10, N = 55, R2 = 0.77, P<0.0001 We analyzed the ƌ3C of the organic carbon in the top 3 cm sediment layer (ƌ13Csediment) along the chronosequence to estimate the fraction of seagrass (X) and sestonic (1-X) deposition as ƌ13Csediment = [X . Log % Corg = -0.62 + (1.33 * Log % LOI) SEintercept = 0.01, SEslope =0.10, N = 55, R2 = 0.77, P<0.0001 We analyzed the ƌ3C of the organic carbon in the top 3 cm sediment layer (ƌ13Csediment) along the chronosequence to estimate the fraction of seagrass (X) and sestonic (1-X) deposition as ƌ13Csediment = [X . ƌ13Cseagrass] + [(1-X) . ƌ13Cseston] being ƌ13Cseagrass -9.65 ‰ and ƌ13Cseston -22 ‰ (Dauby 1989).