International Journal of Marine Science, 2016, Vol.6, No.21, 1-20
8
Acer 24 reef (offshore) and Birthday reef (inshore) along 30 m transects is presented in Figure 5. Scleractinian
coral cover was significantly greater at Birthday Reef (ANOVA: p < 3.83e-07), while the benthic community at
Acer 24 contained significantly greater gorgonian coral cover (ANOVA: p < 2.01e-08), supporting our
observations from the inshore vs. offshore analyses. Gorgonian cover also displayed seasonality at Acer 24 reef,
with a greater percent cover observed during winter sampling (ANOVA: p < 0.003). This pattern was not evident
at Birthday reef. Macro algal and turf algal cover was not significantly different between the Birthday reef and
Acer 24, and accounted for greater than 30% of all reef cover. Increased macro algal cover was observed during
winter months, but this difference was not significant compared to summer.
Figure 4. Principal coordinate analysis of species occurrence from 1996-2011. The scores for each site (A) and loadings for each
species (B) following principal coordinate analysis are presented. The first two coordinates accounting for 64.5% of variation in the
data are plotted. Error bars (A) indicate 95% confidence intervals across the 15-year period. Species present in a particular quadrant
of the loadings plot are more likely to be associated with a site in the same quadrant of the score plot.
Coral community composition (Figure 3), species’ abundance (Figure 6), and colony size (Figure 7) were
important components of the dissimilarity between the two sites. Rényi diversity profiles support the dissimilarity
in scleractinian coral community composition (Figure 3). Specifically, species richness was greater at Birthday
reef as indicated by an increased diversity value at alpha = 0. Fourteen scleractinian coral species were present at
Birthday reef while only ten of these species were observed at Acer 24 reef. Additionally, both sites were
characterized by low species evenness indicated by diversity values > 1 for alpha = Infinity. The most frequently
observed colonies inhabiting Acer 24 reef were
S. siderea
,
M. cavernosa
,
P. astreoides
, and
Stephananocoenia
michelinii
(Figure 6). In addition to these four species,
Orbicella annularis
was frequently observed at Birthday
reef. Larger colonies were more frequently observed at Birthday Reef, as indicated by the greater positive skew of
total coral frequency distributions (Figure 7). Frequency distributions were dependent upon zone for the three
most common species,
P. astreoides
,
S. siderea
, and
M. cavernosa
.
