Appendix A. Tables showing the sectors and activities considered, the pressure types generated by each sector, and the ecological characteristics of the ecosystem that are impacted by each pressure type, as well as short descriptions of sectors, activities, and pressure types.

Tables showing the sectors and activities considered, the pressure types generated by each sector, and the ecological characteristics of the ecosystem that are impacted by each pressure type, as well as short descriptions of sectors, activities, and pressure types

Recruit abundances of <i>Austrominius modestus</i> over time.

<p>(a) Mean recruit abundance (± SE) in 25 cm² control and cumulative plots every 2 wk (<i>n</i> = 10), (b) mean recruit abundance (± SE) in plots of difference area (cm²) (<i>n</i> = 10), and (c) mean recruit density per cm² in cumulative plots in plots of different sizes (<i>n</i> = 40). Letters over bars (a–d) indicate post-hoc comparison outcomes with the same letter indicating no significant difference between recruit abundance/density. All plots irrespective of initial clearance size are pooled in (b). The period when all cumulative plots were 100% colonised is shown (dotted line).</p

Comparative recruit density in cumulative and control plots.

<p>Change in recruit abundance in 25 cm² control and cumulative plots. Recruitment was estimated every 2 wk using non-destructive photographic sampling and image analysis. Control plots were disturbed (cleared) every 2 wk and estimates are compared to its paired cumulative plot on the same statue. Cumulative plots were undisturbed following the initial clearance. Significant regression is shown (solid line; <i>R</i>² = 0.89) and dashed lines indicate 95% confidence intervals. 45^o line indicates the point where recruitment is the same in control and cumulative plots.</p

Distribution of seabird breeding sites on Alderney.

<p>(a) large gulls, (b) shags, (c) other seabirds nesting on Alderney in 2013.</p

Illustration of hypotheses.

<p>The predicted effects that increasing the densities of <i>Corophium voluator</i> and <i>Hediste diversicolor</i> will have on organic matter consumption and benthic-pelagic nutrient flux, from 0 (no effect) toward an increasingly positive effect. The solid black lines represent predictions based on the biological traits of <i>C</i>. <i>volutator</i> and <i>H</i>. <i>diversicolor</i>. For <i>C</i>. <i>volutator</i>, the dotted line represents how an interaction with <i>H</i>. <i>diversicolor</i> may enhance its effect on nutrient flux. For <i>H</i>. <i>diversicolor</i>, the dashed lines represent how an interaction with <i>C</i>. <i>volutator</i> may enhance its effect on organic matter consumption and reduce its effect on nutrient flux; whereas the grey lines represent how a different interaction with <i>C</i>. <i>volutator</i> may reduce its effect on organic matter consumption and enhance its effect on nutrient flux.</p

Seabirds breeding on Alderney and its surrounding islands.

<p>Seabirds breeding on Alderney and its surrounding islands.</p

Linear model summary for the microcosm experiment analysis.

<p>Linear model summary for the microcosm experiment analysis.</p

Transplants successfully raised the density of <i>H</i>. <i>diversicolor</i> beyond the ambient density.

<p>Variation in the sampled biomass (12 days after experiment initiation) of <i>Hediste diversicolor</i> (black; linear regression, R² = 0.59) and <i>Corophium volutator</i> (grey; linear regression, R² = 0.09) in relation to the addition biomass of <i>H</i>. <i>diversicolor</i> in field plots. The dashed line marks the maximum density of <i>H</i>. <i>diversicolor</i> recorded in plots with no experimental additions.</p

Model scores from a ROC curve.

<p>Model scores from a ROC curve.</p

Ecological function provision vs. species densities in microcosm and field experiments.

<p>Variation in organic matter consumption and nutrient flux in relation to the densities of <i>Corophium volutator</i> and <i>Hediste diversicolor</i> in laboratory microcosms (A & B, respectively; DIN = dissolved inorganic nitrogen) and field plots (C & D, respectively). The 3D surfaces are based on the predicted values from the relevant linear models, with block set to ‘block 1’ (i.e. the first experimental run), other significant terms set to their means, and other non-significant terms excluded. The points represent the actual observations and the lines connecting the points to the 3D surface represent the size of the residuals. The interaction between <i>C</i>. <i>volutator</i> and <i>H</i>. <i>diversicolor</i> is included in plots A and B, as this term was significant (<i>p <</i> 0.05) in both of these models. The interaction was not included in plots C and D, as this term was not significant in these models (<i>p</i> > 0.05). The surface for D was plotted with respect to the densities of <i>C</i>. <i>volutator</i> and <i>H</i>. <i>diversicolor</i> to show the trend of the data; however, neither term was significant. Both terms plotted in C were significant.</p