Relationships between coral habitat attributes and associated
species richness
Three physical attributes of finger coral habitat structure: coral
status (live/dead) (p<0.0001), overhead surface area
(p=0.0025) and maximum coral branch length (p=0.0005), predicted the
number of species associated with the corals (Table 2). Ordinary Least
Squares (OLS) regression analysis indicated that total species richness
was positively and linearly related to the top surface area of the
colonies, although the significance and strength of these relationships
varied between live and dead corals and across time points (Figure 6).
Species-area relationships were significant for live corals across all
time points (Figure 6, bottom panel), whereas they were only significant
for dead corals for the two latter time points (Figure 6, top panel).
Surface area also explained a greater proportion of total variation in
species richness for live versus dead corals (r2 =
0.26 to r2 = 0.62 versus r2 =
0.15, respectively, Figure 6). The richness of coral-associated
macrofauna increased by 14-22 species per a projected 1.0
m2 increase in live coral surface area across time
points, and by 18 species per a projected 1.0 m2increase in dead coral surface area (Figure 6). Tighter species-area
relationships on live corals were driven by fishes (r2= 0.47 to r2 = 0.58) relative to invertebrates
(r2 = 0.19 to r2 = 0.29). For dead
corals, richness of associated species was poorly predicted by coral
surface area for both fishes (r2 = 0.08 to
r2 = 0.14) and invertebrates (r2 =
0.06 to r2 = 0.14) (Figure S4A-B).
Species richness of the associated community was also predicted by the
length of live finger coral branches (Figure S5). The richness of
coral-associated macrofauna increased in live corals by 8-25 species per
a projected 1.0 m increase in coral branch length at three of four time
points (r2 = 0.29 to r2 = 0.43). On
the other hand, branch length of dead finger corals showed either a weak
positive (r2 = 0.21, July 2009) or weak negative
(r2 = 0.17, February 2010) relationship with species
richness of the associated community (Figure S5 top panel).