Environmental Engineering Reference
In-Depth Information
Table 6.6
ANOVA results showing variations in shell carbon of gastropods between species and sectors
Source of variation
SS
d
f
MS
F
P
-Value
F
crit
Between species
2.86
3
0.95
12.56
0.005
4.76
Between sectors
1.21
2
0.61
8.01
0.020
5.14
Table 6.7
ANOVA results showing variations in tissue carbon of gastropods between species and sectors
Source of variation
SS
d
f
MS
F
P
-Value
F
crit
Between species
12.99
3
4.33
13.06
0.005
4.76
Between sectors
8.72
2
4.36
13.16
0.006
5.14
within the next 10
20 years and a further 20 %
are seriously threatened with loss predicted
within 20
Corals are very slowly growing organisms;
some species grow less than 1 cm in a year, while
others add up to 5 cm each year. The same coral
may be found in different shapes and sizes,
depending on the depth and wave action of the
area. Within the tissues of the coral polyps, single-
cell dino
-
40 years.
The Great Barrier Reef, the largest coral reef
of the planet Earth, stretches more than 2,000 km
from New Guinea southwards along the east
coast of Australia. The reefs are constructed and
promoted by corals, which are colonial animals
and whose individual members are called polyps
(Fig.
6.19
).
A coral polyp is very similar to a tiny sea
anemone possessing stinging tentacles, but
unlike the anemone, a coral polyp extracts cal-
cium carbonate from the water and builds within
its tissues a skeletal cup of calcareous material.
Large numbers of polyps grow together in col-
onies of delicately branched forms or rounded
masses (Figs.
6.19
and
6.20
).
-
agellate algae called zooxanthellae are
present. Polyps and zooxanthellae have symbiotic
relationship in which the coral provides the algal
cells with a protected environment, carbon diox-
ide and nutrients (like nitrate and phosphate) and
the algal cells by the process of photosynthesis
return oxygen, remove wastes and produce carbon
compounds, which help to nourish the coral. Some
coral species receive as much as 60 % of their
nutrition from the algae. Zooxanthellae also cause
the coral to produce more calcium carbonate and
increase the growth of their calcareous skeleton.
fl
Fig. 6.19
View of coral
polyp
