Covers of bryozoans on kelps on pilings after experimental addition of urchins.

<p>Mean (± S.E.; <i>n</i> = 5) percentage cover of bryozoans on kelps 1 month after urchins were transplanted to pilings in 2006 and 2007. Treatments are: Undisturbed pilings (P), Transplanted (i.e. kelps with sea-urchins; TP) and Undisturbed reefs (U). Site 1, white bars; Site 2, grey bars.</p

Covers of bryozoans on kelps on reefs after experimental exclusion of urchins and shading.

<p>Mean (± S.E.; <i>n</i> = 8) percentage cover of bryozoans on kelps 1 month after experimental exclusion of urchins and shading. Treatments are: Shade Undisturbed (SU), Shade Disturbed (SD), Shade Excluded (SE), Control Undisturbed (CU), Control Disturbed (CD), Control Excluded (CE), Undisturbed reefs (U), Disturbed (D), Excluded (E) and Undisturbed Pilings (P).</p

Analysis of mean percentage covers of bryozoans on <i>E. radiata</i> for each individual 1 month after the shade and urchin exclusion experiment in 2009.^†

<p>†Shade was a fixed factor with 3 levels; Urchin was fixed and orthogonal with 3 levels; Patch was a random factor nested in Shade×Urchin with 4 levels and Kelp was random and nested with 2 levels. The replicates were the quadrats (<i>n</i> = 5). Cochran's test was significant (<i>C</i> = 0.14 **). Transformation of data failed to make variances homogenous, so data were not transformed. **, <i>P</i><0.01; ns, <i>P</i>>0.05.</p

Locations sampled.

<p>Locations sampled in Sydney Harbour for oyster-beds (black circles), mussel-beds (squares) and coralline turfs (white circles).</p

Summary of the effects of macroalgae (Ma) and competition (Co) on small (S, 15 mm) and large (L, 30 mm) limpets.^*

*<p>TL, total length. **, <i>P</i><0.01; *, <i>P</i><0.05; ns, <i>P</i>>0.05.</p

Changes in shell-weight of small limpets.

<p>Mean changes in shell-weight (± SE; <i>n</i> = 4) of small <i>P. vulgata</i> for each treatment at the end of the experiment. S, small limpets; L, large limpets. Black bars, without macroalgae; white bars, with macroalgae.</p

Changes in size of small limpets.

<p>Mean (± SE) changes in size of small <i>P. vulgata</i> in absence (black bars) or presence (white bars) of macroalgae (<i>n</i> = 12; a), for each treatment (<i>n</i> = 8; b) or for both (<i>n</i> = 4; c) at the end of the experiment. S, small limpets; L, large limpets.</p

Analyses of changes in size, shell-weight and body-weight of small limpets.^*

*<p>Macroalgae (Ma) was fixed with 2 levels (+/−); Treatment (Tr) was fixed and orthogonal with 3 levels; Plots (Pl) was nested in Ma x Tr with 2 levels. The replicates were the limpets (<i>n</i> = 2). Cochran's test (C) was used to test assumptions of homogeneity. Non-significant interactions (^x) were pooled when ns with <i>P</i><0.25. *, <i>P</i><0.05; ns, <i>P</i>>0.05.</p

Relationships between <i>C. harfordi</i> and organic matter and thickness of the habitat.

<p>Densities of <i>Cirolana harfordi</i> and (A) concentration of organic matter smaller than 64 µm (triangles) and 64–500 µm (circles) and (B) thickness of the oyster-bed at Greenwich (white) and Berrys Bay (black)</p

Analysis of mean densities of chlorophyll-<i>a</i> for caged and uncaged treatments with limpets at natural densities (10S +3L) at the end of the experiment.^*

*<p>Treatment (Tr) was a fixed factor with 2 levels (caged <i>vs</i> uncaged); Macroalgae (Ma) was fixed and orthogonal with 2 levels (+/−); Plots (Pl) was nested in Tr x Ma with 3 levels (<i>n</i> = 10). Cochran's test (C) was used to test assumptions of homogeneity. **, <i>P</i><0.01; ns, <i>P</i>>0.05.</p