Temporal effects of cockle treatment on the density of the five most dominant species per study site.

<p>Densities are shown as mean ± SE for plots without (NC) and with (C) cockles during both experimental trials, i.e. during recruitment (May–June) and post-recruitment (October–November) in the cohesive sediments (left panel) and in the non-cohesive sediments (right panel).</p

Spatio-temporal effects of cockle treatment on biological sediment properties.

<p>Species richness, diversity, evenness and total density for the total community (A–D) and the less-mobile surface deposit feeders (LDSDF, E–H); shown as mean ± SE for plots without (NC) and with (C) cockles in the two contrasting sediments during both experimental trials, i.e. during recruitment (May–June) and post-recruitment (October–November). Note that presented densities are square root transformed.</p

Spatio-temporal effects of cockle treatment on physical sediment properties.

<p>Sediment median grain size, water content, and chloroplastic photopigment equivalent (CPE) concentration, shown as mean ± SE for plots without (NC) and with (C) cockles in the two contrasting sediments during both experimental trials, i.e. during recruitment (May–June) and post-recruitment (October–November).</p

Temporal variation in suspended sediment concentration (SSC) at both study sites in 2011.

<p>Black bars indicate the two experimental periods. SSC were retrieved from the public url: <a href="http://www.waterbase.nl" target="_blank">www.waterbase.nl</a>. SSC at Paulina (black lines) was calculated as the average value from recordings at Terneuzen, Vlissingen and Hansweert, whereas SSC at Viane (grey lines) was calculated as the average value from recordings at Zijpe and Wissenkerke; see Figure S1 in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0065861#pone.0065861.s001" target="_blank">File S1</a> for indication of sampling locations. Solid lines indicate average concentrations, dashed lines the minimum and maximum concentration recorded at a sampling location.</p

Analysis of variance on difference in early life history processes of <i>Macoma balthica</i> reared in the different pH treatments, and correlation with seawater pH.

*<p>indicate results from product moment correlations of logarithmic transformed data,</p>**<p>indicate results from non-parametric Spearman-rank correlation. For more details: see text.</p

<i>Macoma balthica</i>: Ocean acidification effects on larval development.

<p>Shell length, survival and development stage of larvae between day 3 and day 19 of development reared at three seawater pH conditions: ∼pH_8.1 (circles, solid line), ∼pH_7.8 (squares, dashed line), and ∼pH_7.5 (triangles, dotted line). Regression lines in (a) and (b) indicate average larval growth rate (µm.d⁻¹) and mortality rate (d⁻¹) for each treatment.</p

<i>Macoma balthica</i>: Ocean acidification effects on fertilization and embryogenesis.

<p>(a) fertilization success, (b) hatching success, and (c) size of larvae that have developed a shell after 3 days, reared at three pH conditions: control (∼pH_8.1), ∼pH_7.8 and ∼pH_7.5. Level of replication: n = 5 for fertilization success, n = 3 for hatching success and size. Presented error bars are standard errors.</p

Sediment O₂ profiles.

<p>Mean ± sd O₂ concentration in control (▴) and acidified (•) treatments of the two sediment types (115bis: fine sandy; 330: permeable) and two seasons (February and April).</p

Sediment–water fluxes.

<p>Measured Sediment Community Oxygen Consumption (SCOC, mmol O₂ m⁻² d⁻¹), NH_x and NO_x effluxes and estimated nitrification and total N mineralization (mmol N m⁻² d⁻¹) (mean ± sd) from control and acidified treatments of the two sediment types (115bis: fine sandy; 330: permeable) and two seasons (February and April).</p

Sediment pH profiles.

<p>Mean ± sd pH in control (▴) and acidified (•) treatments of the two sediment types (115bis: fine sandy; 330: permeable) and two seasons (February and April). No data for permeable sediment in February.</p