1.0 Coral Survey?
There is several methods used to determining and estimating coral and macroalgal cover. Manta tow is a method by which a large area of coral reefs can be examined within a short period of time. This method is widely used to observed the changes in coral reef area due to damage by coral bleaching, weather, or predator such as Crown-of-thorns starfish, Acanthaster plancii.. It does not need a special qualification and will save the time usage. Quadrat is another method that can be used to eatimate the coral cover within specific area. Compared to other method of coral survey, quadrats is relatively rapid and cheap to be used in the field. The main disadvantages of quadrat is it is difficult to be used to sample large branching corals. The coral cover that estimated by using point intercept transect is calculated by the vegetation that intercept with the line build .This coral survey aims to observed the coral reef communities and to determine the health status of coral in Bidong Island .
2.0 Methodology
Coral survey was done by using a Point Intercept Transect. A 50m transect line was laid on the top of reefs at chosen site. Observers were then snorkel along the transect line.The life form of coral reefs were identified and recorded on the slate board every 1 meter point.
3.0 Result & Discussion
Figure 1. Percentage abundance of lifeform in Safari Beach,pulau Kapas.
| R : Rubble | ACB : Acropora branching |
| DC : Dead coral | ACD : Acropora digitate |
| CM : Non-acropora massive | CE : Non- acropora branching |
| S : Sand | SP :Sponge |
Figure 2. Percentage abundance of macrobenthic cover.
CORAL INDEX (CI)
Coral index is use to indicate the coral assemblage and also degree of stress on reefs.
CI = log ₁₀ [CR / (DC + AL + OT)]
Where,
CR = percentage area cover of live coral category
DC = percentage area cover of dead coral category
AL = percentage area cover of algae category
OT = percentage area cover of other fauna category
Thus,
| · CR = 4% + 4% + 5% + 21% = 34% | · DC = 22% |
| · AL = 0 | · OT = 1% |
CI = log ₁₀ [ 34/ (22 + 0 + 1)]
CI = log ₁₀ [ 34 / 23]
CI = 0.1698 (fair)
DEVELOPMENT INDEX (DI)
Development Index is use to indicate the degree of coral reef assemblage development. From here, we can determine the condition at particular are and thus provide the natural background of the reef by simulate the almost the same original condition.
DI = log ₁₀ [ ( CR + DC + AL + OT) / AB]
Where,
CR = percentage area cover of live coral category
DC = percentage area cover of dead coral category
AL = percentage area cover of algae category
OT = percentage area cover of other fauna category
AB = percentage area cover of abiotic category (RB + S)
Thus,
| · CR = 4% + 4% + 5% + 21% = 34% | · DC = 22% |
| · AL = 0 | · OT = 1% |
| · AB = 7% + 37% = 44% | |
DI = log ₁₀ [ ( 34 + 22 + 0 + 1) / 44]
DI = log ₁₀ [ 57 / 44]
DI = 0.1125 (fair)
SUCCESSION INDEX (SI)
Succession Index is uses to indicate the level of succession occurring on the reef and also indicate the degree of coral reef.
SI = log ₁₀ [OT / (DC + AL)]
Where,
DC = percentage area cover of dead coral category
AL = percentage area cover of algae category
OT = percentage area cover of other fauna category
Thus,
| · DC = 22% | · AL = 0% |
| · OT = 1% | |
SI = log ₁₀ [1 / (22 + 0)]
SI = log ₁₀ [1 / 22]
SI = - 1.345 (very poor)
Table 2 : Coral health status by Manthachitra (2004) .
| Percentage | Quality |
| >80.01% | Very Good |
| 60.01% - 80.00% | Good |
| 40.01% - 60.00% | Fair |
| 20.01% - 40.00% | Poor |
| <20% | Very Poor |
Based on pie chart above, rubble dominates the life form of coral cover in that area with percentage abundance 37%. Dead coral is the second highest life form with percentage abundance 22% followed by Acropora digitate. While the least life form found in that coral reef area is sponge with percentage abundance 1%.
A live coral that can be found in that area comprises of four life forms which is Acropora branching, Acropora digitate, Non-acropora massive, and Non-acropora branching.
The coral assemblage and degree of stress on reefs classified as fair with coral index 0.1698. A degree of coral reef assemblage development in that area is fair with development index of 0.1125. In addition, the level of succession occurring on the reef classified as very poor with succession index of -1.345.
Referring to Figure 2 and Table 1 above, the coral health as this area was classified as poor.
