Benthic Cover in Fagatele Bay
Approximately 9 species of algae in 7 genera were recorded from the 14 transects (Table 6). The assemblage is very similar to that recorded from the 1995 survey, though algal diversity has decreased since then. Macroalgae were generally encrusting (e.g. CCA, Peysonnelia spp. or Lobophora spp.), with few turf or fleshy species other than Halimeda occurring on the transects and this was the same for both 2004 and 2007 survey years. Approximately 5 species of CCA (Appendix 2) were identified and these species are similar to those identified by Wilkins in 1995 (Birkeland et al, 2003).
Surveys showed that corals and macroalgae form the bulk of the fish habitat at all depths and transects, which was the case in the 2004 study (Tables 6, 7). Coral cover ranged from 14.6% to 55.3%, while macroalgae cover ranged from 17.8 - 83.3 %. Macroinvertebrate cover ranged from 0.0 – 27.1% and non-living surfaces ranged from 0.0 – 4.4%.
A number of general trends were noted between the survey years. Coral cover varied, with some transects showing an increase from 2004, while others showed a decrease. Changes in percent cover of coral are roughly inversely correlated with changes in percent cover of macroalgae (Fig. 5). Macroalgal cover generally increased, as did invertebrate cover (Table 7). Overall, there was a marked decrease in the percent cover of non-living surfaces (Table 7). In a 1985 survey conducts by Birkeland et al (1987), a weak trend was seen with macroalgae and particularly CCA, decreasing in percent cover with depth (Figs. 7, 8). This trend is not evident in the subsequent surveys in 1995, 2004 and 2007. However, Figures 7 and 8 show that the abundance of algae has generally decreased over time, since 1985, when Fagatele was still recovering from the major crown-of thorns outbreak in 1978 (Birkeland 1982).
Table 6. Benthic cover in Fagatele Bay
Percent Cover of Functional forms at Fagatele Bay
|
|
|
2
|
3
|
4
|
5
|
|
|
3
|
6
|
9
|
12
|
6
|
9
|
12
|
3
|
6
|
9
|
12
|
6
|
9
|
12
|
Corals
|
branching
|
14.6%
|
16.7%
|
6.3%
|
6.3%
|
8.9%
|
10.4%
|
4.2%
|
0.0%
|
6.3%
|
6.4%
|
0.0%
|
6.3%
|
10.4%
|
6.3%
|
|
digitate
|
12.5%
|
8.3%
|
4.2%
|
4.2%
|
0.0%
|
0.0%
|
2.1%
|
4.2%
|
0.0%
|
19.1%
|
0.0%
|
0.0%
|
2.1%
|
6.3%
|
|
encrusting
|
16.7%
|
6.3%
|
10.4%
|
25.0%
|
20.0%
|
4.2%
|
6.3%
|
33.3%
|
16.7%
|
14.9%
|
25.0%
|
10.4%
|
6.3%
|
8.3%
|
|
foliose
|
2.1%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
10.4%
|
4.2%
|
4.3%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
massive
|
2.1%
|
0.0%
|
0.0%
|
2.1%
|
13.3%
|
0.0%
|
0.0%
|
2.1%
|
6.3%
|
0.0%
|
4.2%
|
4.2%
|
0.0%
|
0.0%
|
|
mushroom
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
|
plate
|
0.0%
|
4.2%
|
2.1%
|
10.4%
|
8.9%
|
4.2%
|
2.1%
|
2.1%
|
0.0%
|
10.6%
|
0.0%
|
4.2%
|
12.5%
|
29.2%
|
Macroalgae
|
encrusting - brown
|
0.0%
|
2.1%
|
2.1%
|
6.3%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
encrusting - red
|
8.3%
|
10.4%
|
4.2%
|
10.4%
|
6.7%
|
16.7%
|
16.7%
|
4.2%
|
16.7%
|
8.5%
|
14.6%
|
12.5%
|
12.5%
|
8.3%
|
|
blue-greens
|
0.0%
|
0.0%
|
2.1%
|
0.0%
|
0.0%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
4.2%
|
0.0%
|
0.0%
|
0.0%
|
|
Halimeda spp.
|
0.0%
|
0.0%
|
2.1%
|
2.1%
|
0.0%
|
0.0%
|
4.2%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
8.3%
|
|
macroalgae
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
turf
|
2.1%
|
4.2%
|
0.0%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
4.2%
|
6.3%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
geniculate CCA
|
0.0%
|
2.1%
|
6.3%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
crustose coralline algae
|
35.4%
|
33.3%
|
60.4%
|
27.1%
|
11.1%
|
60.4%
|
60.4%
|
12.5%
|
37.5%
|
34.0%
|
45.8%
|
54.2%
|
54.2%
|
33.3%
|
Invertebrates
|
ascidian
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
11.1%
|
0.0%
|
0.0%
|
8.3%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
clam
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
hydrozoan
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
soft coral
|
4.2%
|
4.2%
|
0.0%
|
0.0%
|
2.2%
|
0.0%
|
2.1%
|
0.0%
|
2.1%
|
0.0%
|
2.1%
|
0.0%
|
2.1%
|
0.0%
|
|
sponge
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
13.3%
|
0.0%
|
0.0%
|
18.8%
|
4.2%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
urchin
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
zooanthid
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
8.3%
|
0.0%
|
0.0%
|
|
other
|
2.1%
|
4.2%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
Non-Living
|
crevice/hole
|
0.0%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
reef matrix
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
4.4%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
|
rubble
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
|
sand
|
0.0%
|
0.0%
|
0.0%
|
2.1%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
|
0.0%
| |
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