Sediment properties as important predictors of carbon storage in zostera marina meadows: a comparison of four European areas

Seagrass ecosystems are important natural carbon sinks but their efficiency varies greatly depending on species composition and environmental conditions. What causes this variation is not fully known and could have important implications for management and protection of the seagrass habitat to continue to act as a natural carbon sink. Here, we assessed sedimentary organic carbon in Zostera marina meadows (and adjacent unvegetated sediment) in four distinct areas of Europe (Gullmar Fjord on the Swedish Skagerrak coast, Asko in the Baltic Sea, Sozopol in the Black Sea and Ria Formosa in southern Portugal) down to similar to 35 cm depth. We also tested how sedimentary organic carbon in Z. marina meadows relates to different sediment characteristics, a range of seagrass-associated variables and water depth. The seagrass carbon storage varied greatly among areas, with an average organic carbon content ranging from 2.79 +/- 0.50% in the Gullmar Fjord to 0.17 +/- 0.02% in the area of Sozopol. We found that a high proportion of fine grain size, high porosity and low density of the sediment is strongly related to high carbon content in Z. marina sediment. We suggest that sediment properties should be included as an important factor when evaluating high priority areas in management of Z. marina generated carbon sinks

Synthesis and evaluation of 2-(1H-indol-3-yl)-4-phenylquinolines as inhibitors of cholesterol esterase

A series of 2-(substituted) phenyl and 2-indolyl quinoline derivatives (10a–l) was synthesized by an efficient microwave-assisted, trifluoroacetic acid-catalyzed, solvent-free method. Evaluation of the inhibitory activity led to the identification of two quinoline inhibitors of cholesterol esterase. 2-(1H-Indol-3-yl)-6-nitro-4-phenylquinoline (10l; IC50 = 1.98 μM) was characterized as a mixed-type inhibitor with a pronounced competitive binding mode.Fil: Muscia, Gisela Celeste. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Hautmann, Stephanie. Universitaet Bonn; AlemaniaFil: Buldain, Graciela Yolanda. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Asís, Silvia Elizabeth. Universidad de Buenos Aires. Facultad de Farmacia y Bioquímica. Departamento de Química Orgánica; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gütschow, Michael. Universitaet Bonn; Alemani

Semi-log plots (log₁₀[x+1]) showing the relationship between sedimentary % C_org and grain size.

<p>The % C_org is presented with a log scale as it gave the best fit of the models. Grain size is shown as mean grain size (ɸ) and sediment particles < 0.074 mm (%) for <i>Z</i>. <i>marina</i> meadows (a and b) and unvegetated areas (c and d). The % C_org was positively linked to both sediment particles < 0.074 mm (%) (R² = 0.91, <i>P</i> < 0.001) and mean grain size (ɸ) (R² = 0.74, <i>P</i> < 0.001) for <i>Z</i>. <i>marina</i> meadows but for unvegetated areas only sediment particles < 0.074 mm (%) showed such relationship with % C_org (R² = 0.42, <i>P</i> < 0.001).</p

Sedimentary organic carbon content in <i>Z</i>. <i>marina</i> meadows and unvegetated areas.

<p>Mean (±SE) percent organic carbon (% C_org) (a) and g C_org cm^-2 (b) in sediment (for 0–25 cm sediment depth). The % C_org is presented as a mean of the content for the top 25 cm sediment, while carbon per unit area (g C_org cm^-2) is the total (accumulated) amount of carbon in the top 25 cm of sediment. For full names of the sites see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0167493#pone.0167493.t001" target="_blank">Table 1</a>.</p

Seagrass sediment data.

<p>Values are presented as mean (± SD for all variables except carbon content, which is presented with ± SE) for the depth profiles (0–25 cm) in the different areas. Mean grain size is presented with phi (ɸ) units.</p

Organic carbon depth profiles.

<p>Mean sedimentary carbon (% C_org ± SD) depth profiles grouped for the different areas showed as mean slice depth. Note that the scale on the x-axes vary among the different depth profiles due to large variation in carbon content among areas.</p

Seagrass meadow variables (mean ± SD) for the different areas.

<p>Seagrass meadow variables (mean ± SD) for the different areas.</p

Partial least square (PLS) regression model coefficient plot.

<p>The model assesses the relative influence of different predictors on % C_org in sediment (using a mean for the top 25 cm sediment). The predictor variables are ranked in level of importance (left to right) where the four variables left of the striped bar having a VIP-value > 1 (i.e. FineGrain, SedPoros, SedDens and GrainSize) and hence significantly influencing % C_org. Brown bars = sediment characteristics, green bars = seagrass-associated variables and blue bars = water depth. Variables included in the model were FineGrain (sediment particles < 0.074 mm, %), SedPoros (sediment porosity, %), SedDens (sediment density, g DW mL^-1), GrainSize (mean grain size, ɸ), Bg and Ag DW (belowground [roots and rhizomes] and aboveground [shoots] biomass dry weight, g m^-2), Depth (water depth, m), ShootDens (shoot density, shoots m^-2), Ag and Bg biomass C and N (biomass carbon and nitrogen content, %), Canopy (shoot height, cm) and SeagrCov (seagrass cover, %).</p

Summary of literature data on organic carbon (% C_org) and organic matter (% OM) content in <i>Z</i>. <i>marina</i> sediment.

<p>In studies were only % OM was presented a conversion factor of 0.43 was used to convert % OM to % C_org as calculated by Fourqurean et al. [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0167493#pone.0167493.ref005" target="_blank">5</a>] for seagrass sediment with > 0.2% OM. All studies have determined % OM and % C_org by LOI (Loss on ignition) or using an organic elemental analyzer except <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0167493#t005fn001" target="_blank">^a</a> where dichromate titration was used [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0167493#pone.0167493.ref090" target="_blank">90</a>].</p