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

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

Results of the oxygen turnover model.

<p>Oxygen concentration in ambient pore water and body wall as a function of nematode body radius in suboxic conditions (A), nematode critical thickness (µm) as a function of sediment depth (B) and oxygen residence time in nematode body as a function of [O₂] in ambient pore water from oxic to anoxic conditions (C).</p

Measured and modeled meiofauna respiration.

<p>Observed (grey +) and modeled (line) oxygen consumption of the Nematode <i>Enoploides longispiculosus</i>, the Foraminifer <i>Ammonia beccarii</i>, the juvenile Gastropod <i>Hydrobia ulvae</i> and the undefined Ostracod species (A–D) and corresponding modeled respiration rates as a function of the available oxygen from oxic to anoxic conditions (E–H). Replicate numbers are indicated. The Ostracod model is composed of a Monod and a linear fit. The dashed line in (H) indicates the transition from Monod to linear fit (i.e. stress reaction).</p

Stable isotope biplot for the bay of the Mont Saint-Michel (BMSM).

<p>Biplot of δ¹³C and δ¹⁵N isotope values (‰) of the primary food sources (mean ± SD) and of individuals of consumer taxa of the soft bottom intertidal area of the bay of the Mont Saint-Michel for different combinations of sampling area (<i>L</i>. <i>conchilega</i> aggregation <i>vs</i>. control) and period (spring <i>vs</i>. autumn). (A) = <i>L</i>. <i>conchilega</i> aggregation—spring; (B) = control—spring; (C) = <i>L</i>. <i>conchilega</i> aggregation—autumn; (D) = control—autumn. The trophic position (TP) of the consumer taxa, based on the isopod <i>Lekanesphaera levii</i> as a baseline, are displayed on the right of the biplot. Symbols/shading represent the 8 different functional groups (fish, predator, omnivore/predator/scavenger, omnivore, deposit/facultative suspension feeder, suspension feeder, deposit feeder, herbivore). Dashed ellipses represent the trophic groups delineated based on agglomerative hierarchical cluster analyses and similarity profile (SIMPROF) permutation tests. The mean δ¹³C and δ¹⁵N values (±SD) of the clusters, as well as their taxonomic composition are listed in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0140857#pone.0140857.s001" target="_blank">S1 Appendix</a>.</p

Number of individuals incubated in each respiration measurement with their average dimensions and biomass organic carbon (average of two replicate sets for each taxon, with standard errors in brackets), nd = no data, from [30].

<p>Number of individuals incubated in each respiration measurement with their average dimensions and biomass organic carbon (average of two replicate sets for each taxon, with standard errors in brackets), nd = no data, from <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0059289#pone.0059289-Moodley2" target="_blank">[30]</a>.</p

Bayesian Layman metrics.

<p>Density plot showing the uncertainty of the Bayesian Layman metrics (NR = δ¹⁵N range, CR = δ¹³C range, CD = mean distance to centroid, MNND = mean nearest neighbour distance, SDNND = standard deviation of the nearest neighbour distance) for different combinations of location (BMSM <i>vs</i>. Boulogne), sampling area (<i>L</i>. <i>conchilega</i> aggregation <i>vs</i>. control) and period (spring <i>vs</i>. autumn). Black dots represent the modes, while the shaded boxes represent the 50% (dark grey), 75% (light grey) and 95% (white) credible intervals. Note the different scales of distance (‰) for NR and CR <i>vs</i>. CD, MNND and SDNND. SL = spring-<i>L</i>. <i>conchilega</i> aggregation; SC = spring-control; AL = autumn-<i>L</i>. <i>conchilega</i> aggregation; AC = autumn-control.</p

Conceptual model.

<p>Schematic representation of the expected impact of the ecosystem engineer <i>Lanice conchilega</i> on the structure of a soft-bottom intertidal food web. The engineer (hexagon), which is trophically coupled to the food web, affects the physical and biogeochemical characteristics of the environment (dotted arrow) and hence the base (primary producers) and higher trophic levels (macrofauna) of the food web. Consequently, the changes in the environment are expected to impact the overall structure of the food web (greyscale gradient). Nodes represent the primary producers and macrofaunal food web compartments, while arrows represent the trophic interactions, before (black) and after (grey) alteration by the engineer [based on 4].</p