520
Fig. 5 S<strong>and</strong> shedding efficiency <str<strong>on</strong>g>of</str<strong>on</strong>g> the experimental species within a IOOO-min period. Values are proporti<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> applied <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g> cleared by the <strong>corals</strong>. Lobophytum depressum, Sinularia dura, <strong>and</strong> S. leptoclados were <strong>on</strong>ly tested with <strong>on</strong>e single grain size <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>. Data from species indicated with asterisk are from <strong>on</strong>e specimen <strong>on</strong>ly S<strong>and</strong> clearing efficiency " & ~ "Q) "- '" " ., 13 1) ~ 0: Q is ~ ~ e Co ~ -J ~ v; ~ " g ~ .,; ~ g ~ ..; ~" "5 (j u Q ~ ~ ~ ~ (j .. ~ $I. "0 ~ ~ 521 .coorse s<strong>on</strong>d ~ fine s<strong>on</strong>d 0 very fine s<strong>on</strong>d Table 1 Characterizati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <strong>corals</strong> tested in experiments. Data from species indicated with asterisk are from <strong>on</strong>e specimen <strong>on</strong>ly, in all other species n = 8. (na not applicable; L large, >8 mm; M medium, 4 to 8 mm; S small, 0.05 with fine <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>; t=-0.03, p>0.05 with coarse <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>) <strong>and</strong> no correlati<strong>on</strong> existed between sphericity <strong>and</strong> either clearing rate or efficiency (r= 0.53, p>0.05 with very fine <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>; r=0.30, p>0.05 with fine <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>; r= 0.37, p > 0.05 with coarse <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>; Table 1) indicating the importance <str<strong>on</strong>g>of</str<strong>on</strong>g> other morphological <strong>and</strong> behavioural factors. All scleractinia cleared away over 50% <str<strong>on</strong>g>of</str<strong>on</strong>g> the <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g> within 1000 min. Alcy<strong>on</strong>acea showed much less activity <strong>and</strong> success in rejecting <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g> than the scleractinia. Passive run<str<strong>on</strong>g>of</str<strong>on</strong>g>f rates were low due to flat growth forms, except in small specimens <str<strong>on</strong>g>of</str<strong>on</strong>g> Sarcophyt<strong>on</strong> glaucurn (around 5 cm in length), which were distorted under the weight <str<strong>on</strong>g>of</str<strong>on</strong>g> the <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>. This was not the case in large specimens (around 20 cm length) <strong>on</strong> which <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g> remained. Run<str<strong>on</strong>g>of</str<strong>on</strong>g>f <strong>and</strong> c<strong>on</strong>centrati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g> in certain areas was enhanced by the radially arranged ridges in Lobophyturn venusturn <strong>and</strong> Sinularia dura <strong>and</strong> the finger-like projec- L M M M S S M S S L 6- 8 22- 24 29- 35 7- 10 110-120 60- 70 17 170 83 4 0.04:1:0.02 0.04:1:0.01 0.05 :1:0.02 0.06:1:0.02 0.02:1:0.01 0.02:1:0.01 0.02:1:0.01 0.03 :to.Ol 0.02:t0.Ol 0.05 :to.03 0.05 :to.Ol 0.03 :to.Ol 0.05 :to.Ol 0.05 :to.Ol 0.02:t0.Ol 0.02:t0.Ol 0.03 :to.Ol 0.02 :to.Ol 0.03 :to.02 O.O7:t :0.03:0.01 O.O7:t O.O8:t :0.02 O.O6:t:0.02:0.01:0.01: O.O3:t O.Ol:t O.O2:t O.O2:t O.O5:t:0.02:0.02 O.O6:t ti<strong>on</strong>s in S. leptoclados. N<strong>on</strong>e <str<strong>on</strong>g>of</str<strong>on</strong>g> the alcy<strong>on</strong>acea showed any polyp-activity, but inflati<strong>on</strong> <str<strong>on</strong>g>of</str<strong>on</strong>g> the col<strong>on</strong>ies by as much as 30% <str<strong>on</strong>g>of</str<strong>on</strong>g> their resting volume was observed. The importance <str<strong>on</strong>g>of</str<strong>on</strong>g> calyx size <strong>and</strong> the degree <str<strong>on</strong>g>of</str<strong>on</strong>g> me<strong>and</strong>rizati<strong>on</strong> in scleractinia was unclear. A linear relati<strong>on</strong>ship between calyx size <strong>and</strong> clearing rate was obtained in plocoid <strong>corals</strong> (Galaxea fascicularis, Cyphastrea chalcidicum, Favia favus, Favites pentag<strong>on</strong>a, G<strong>on</strong>iopora djiboutensis, Hydnophora microc<strong>on</strong>os) <strong>on</strong>ly with very fine <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g> or when the reacti<strong>on</strong>s to all <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g> sizes were averaged (Fig. 6). The situati<strong>on</strong> was similar with degree <str<strong>on</strong>g>of</str<strong>on</strong>g> me<strong>and</strong>rizati<strong>on</strong>, which <strong>on</strong>ly correlated with clearing rate when fine <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g> was used or the clearing rates were averaged between the <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g> size classes (Fig. 7). No correlati<strong>on</strong> was found between number <str<strong>on</strong>g>of</str<strong>on</strong>g> calices per surface area unit <strong>and</strong> clearing rate (r=-0.44, p>0.05 with very fine <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>, r=-0.54, p>0.05 with fine <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>; r=-0.49, p>0.05 with coarse <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>). There were no differences in clearing rates between plocoid <strong>and</strong> me<strong>and</strong>roid species (Favia favus, Favites pentag<strong>on</strong>a, Favites abdita, Cyphastrea chalcidicum versus Platygyra daedalea, Gyrosmilia interrupta: t=-2.2, p>0.05 with very fine <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>; t=-1.91, p>0.05 with fine <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>; t=-1.89, p>0.05 with coarse <str<strong>on</strong>g>s<strong>and</strong></str<strong>on</strong>g>).