50
Table 3.13. Distribution of major benthic groups on near shore rocky reefs of Western Ghana by habitat type A, exposure B and wave strength C. Kruskal-Wallis K-W
2
and probability p provided.
Crustose corallines
Turf algae Fleshy algae
Blue-green algae Sand A. By habitat type
K-W
2
p K-W
2
p K-W
2
p K-W
2
p K-W
2
p
11.3 13.2
0.004 5.4
0.2 23.3
0.0001 1.9 0.6
Habitat type Mean
SEM Mean
SEM Mean
SEM Mean
SEM Mean
SEM
Bay 30.9
5 24.3
4.1 16.8
1.8 10.5
2.9 15.6
3.1 Headland
50.9 5
21.1 4.1
1.5 1.8
11.2 2.9
7.9 3.1
Island 24.7
9.1 30.9
7.4 12.7
3.4 2.1
5.4 24.9
5.7 Patch
56.3 6.8
18.5 5.5
7.3 2.5
0.4 4
11.4 4.2
B. By exposure K-W
2
p K-W
2
p K-W
2
p K-W
2
p K-W
2
p
8.1 0.02
3.21 0.2
13.41 0.001
2.65 0.27
11.14 0.004
Exposure level
Mean SEM
Mean SEM
Mean SEM
Mean SEM
Mean SEM
Exposed 44.6
5.2 25.5
4 1.9
2.0098 10.7
3 9.2
3 Semi-exposed 49.2
4.6 18
3.6 13.6
1.7976 7.2
2.7 11.1
2.7 Sheltered
23.4 6.7
28.2 5.2
12 2.5946
4.7 3.9
23.7 3.9
C. By wave strength K-W
2
p K-W
2
p K-W
2
p K-W
2
p K-W
2
p
7.8 0.02
0.2 0.9
29.7 0.0001 5.6
0.06 18.1
0.0001
Wave strength
Mean Std
Error Mean
Std Error
Mean Std
Error Mean
Std Error
Mean Std
Error
Low 30.8
5.5 22.7
4.3 13.2
1.8 3.1
3.1 24.9
2.9 Medium
51.8 4.6
22.5 3.6
1.6 1.5
9.3 2.6
8.2 2.4
High 38.5
6.5 23.4
5.1 18.7
2.1 11.8
3.7 6.6
3.4
51 Wave strength had significant effects on coralline, fleshy algal and sand distributions, with strongest effect on fleshy algae
and sand Table 3.13.C. Fleshy algae had higher cover on both low and high wave action areas, corallines in areas with medium wave action while sand associated mainly with low wave action areas. Wave action had only marginal effect on blue-
green algal distribution, areas with medium and high wave action having higher cover than those with low wave action. Wave action had no effect on turf algal distribution.
Multiple regression results showed that acanthurid biomass was the main variable influencing blue-green algal and coralline distribution Table 3.14.. Blue green algal cover increased while coralline cover decreased with acanthurid biomass. Cover of
turf algae was mainly influenced by wave action showing a negative relationship. Distribution in cover of sand was mainly explained by wave action, cover decreased as wave action increased. Fleshy algal distribution was explained by several
variables with depth, rugosity and pomacentrid biomass having negative effects whereas exposure, acanthurid, scarid and chaetodontid biomass all had positive effects.
Table 3.14. Summary of multiple regression results on the relationship between benthicsubstrate and environmental and biotic variables.
Dependent R
2
adj ANOVA F
p Main explanatory factor
Relationship Corallines
0.62 4.62
0.032 Acanthuridae
-ve
Turf algae 0.21
4.35 0.06
Wave action -ve
Fleshy algae
0.99 502.52
0.0001 Depth
-ve Exposure
+ve Rugosity
-ve Acanthuridae
+ve Chaetodontidae
+ve Pomacentridae
-ve Scaridae
+ve
Blue-greens
0.88 16.65
0.0008 Acanthuridae
+ve
Sand 0.71
8.53 0.004
Urchin abundance -ve
