by Grace Wong, University of Reading

This dissertation was awarded a First from the University of Reading

Abstract

Rationale

Methodology

Results

Discussion

Conclusions

Graphs

Pie Charts

Appendix

Human disruptions damaged coral community, altered the coral reef community. Two coral reefs in the Wakatobi National Marine Park were compared. A damaged reef, Sampella Buoy 2, was compared with a pristine reef, the Kaledupa Buoy 4, to access the changed in reef structure and also the decreased reef species richness as a result of human activities.

The heterogeneity in a coral reef affected the reef fish species richness. The Kaledupa reef was higher in the diversity in the substrate composition, expressed in the percentage coverage. Less substrate was exposed to the open water and more spaces were created between the coral and the substrate. The hiding spaces created were able to support a higher variety of reef fishes. The higher proportion of live corals attracted greater numbers of grazer. The depth did not have a great effect in the number of species and the abundance of the reef fish.

In the degraded site where extensive coral mining had been taking place and still happening at present days (Dioum, 2000), the species richness and the substrate coverage in the coral was reduced. Even though the Sampella reef had a lower heterogeneity in the habitat the abundance of reef fishes was high, sometimes even higher than the pristine reef, Kaledupa. The reef was less diverse in the substrate composition but more varied in the topography. The coral mining removed many corals but, as a result, created a complex structure in the reef. Many holes and crevices have been created; these are convenient hiding places where animals may go in seeking shelter to avoid predation or protection during storm events (Berkeland, 1997).

Compared to Kaledupa, Sampella is a less ideal site for coral growth. The frequent bomb fishing caused the high percentage cover of dead coral and sand. The high level of sediment load in Sampella decreased the amount of light penetration through the water column, hence limiting the coral growth rate or the damaged coral recruitment rate. Some species of coral would be killed being smothered by the sediment.

Introduction

The species diversity in the marine ecosystem in Indonesia is one of the richest in the world, but unfortunately, the coral reefs are being rapidly destroyed by pollution, sedimentation and over-fishing due to ever increasing populations (Berkeland, 1997). The oceans have long been exploited for food and are under increasing pressure. In many South-East Asian countries reef fisheries provide the main source of protein while First World countries have developed a much greater taste for exotic fish (Dioum, 2000). In the area being studied, the Buton of the South-East Sulawesi, traditional fishing methods are generally not harmful to the reef. The main reasons for many reef fisheries to decline are due to:

1. Habitat destruction by the local people from bomb fishing and cyanide fish for the aquarium and live fish restaurant trade. Possibly 73% of Indonesia’s coral reefs have either disappeared or been damaged because of the use of explosives and cyanide poison by fishermen.
2. Habitat destruction by the Bajau people from mining of building materials. The Bajau people are sea jepaes whom used to live on the sea. They became settled down half a kilometer away from Kaledupa less about a century ago. They extract coral as the bases from which their houses are built on.
3. The rapidly increasing human population.

Reef fish populations, their distribution, abundance respond or are dictated by the structure and composition of the reef habitat. They are affected directly or indirectly by the changes brought about to that habitat, either naturally induced or due to human intervention. Since reef fish species depend in some way on reef structure, reef destruction upsets the reef fish community. Identifying the relationship between the changes in the reef structure and the reef fish’s community, management plans may be designed to combat and solve the problems that have been causing the damages, hence, helping to conserve the precious marine ecosystem.

The Wallacea Region

This investigation had been based on the fringing reef around Pulau Kaledupa (pulau is ‘island’ in Indonesian) within the Wallacea Region of the Indo-Pacific region. The Pulau Kaledupa was a small island within the Wakatobi National Marine Park of the Wakatobi archipelago. The Wakatobi archipelago is part of the Tukang Besi Archipelago (‘iron craftsman’ islands is the direct translation), which is a remote island group of about 200, 000 hectares, off South-East Sulawesi of Indonesia (Dioum, 2000). Sulawesi together with surrounding smaller islands between Kalimantan, Java and Papua New Guinea collectively make up the Wallacea region.

The Wallacea region is named after Alfred Russel Wallace, the British explorer naturalist who, together with Darwin, was the first to suggest the theory of evolution by natural selection (Dioum 2000, Tomascik, Nonthi & Moosa, 1997). Wallace spent much of his life travelling in the Far East and noticed that the animals of Sulawesi, Halmahera, Lesser Sundas and others were different from those of Borneo, Bali and Papua New Guinea despite being geographically close. The unique groups of animals found within the Wallacea region were created by the plate isolation during the Ice Ages. During the Ice Ages, much of the planet’s water had been locked up in ice and causing the sea level to be 100m lower than recent time. As the continent shifted over time, islands like Java, Sumatra and Borneo, which are surrounded by shallow seas, were joined to the Asian shelf, whilst Papua New Guinea and others were joined to Australia. The Wallacea region was located in such a way that it joined neither of the shelves but being isolated by deep ocean trenches. As evolution goes on within the region being isolated to surrounding plates unique groups of animals were created in the Wallacea region.

Site Description

The two sites being investigated were located on the North of Kaledupa, which was one of the four major islands in the Wakatobi archipelago off South-East Sulawesi. The Global Positioning Satellite (GPS) reading for Kaledupa Buoy 4 was S05° 282.70’, E123° 43.468’ and Sampella Buoy 2 was S0529.013’, E12344.968’. The two sites were approximately 1.5 km apart.

Sampella Buoy 2 was a relatively shallow reef, sloping gently reaching a depth of about 12m. It was located within a close vicinity to a Bajau village and mangrove. The combination of frequent bombing and coral mining by the local fishermen together with the sediment run-off from the mangroves caused Sampella Buoy 2 to be classed as a degraded reef.

Kaledupa Buoy 4 was located on a fringing reef where there was a patch of sand flat at the depth of 5m the reef slope dropped fairly sharply to the bottom of the reef at a depth 25 m. Being a fair distance away form the Bajau village, this reef had been relatively free from coral mining; it had been much better preserved.

About Operation Wallacea

This investigation has been conducted as part of the environmental preservation expedition of the Operation Wallacea. The Operation Wallacea is an environmental conservation group established in summer 1995, it concerns in the natural habitat conservation in the Buton region of Indonesia (Dioum 2000). The survey data collected by volunteer divers and naturalist who have joined the Operation Wallacea are used by the Indonesian government to support the establishment of wildlife and marine reserves and to develop management plans.

Rationale

Marine environment is a complex ecosystem; different factors are constantly interacting with one another, both physical and the geographical structure of the environment (Birkeland, 1997, Dahl, & Salvat, 1998). In addition to their natural features, the marine ecosystem is often disrupted by external factors, which could be caused by the nature itself or the humans.

The aim of this project was to focus on the damages caused to a coral reef as a result of human destruction. The effect would be accessed by the change in the reef structure in terms of the heterogeneity between two reefs of different qualities, accessing the heterogeneity in both substrate composition and in the coral species diversity. Kaledupa Buoy 4 was a pristine reef where it had been relatively unaffected by human impact. The second site, Sampella Buoy 2, was a degraded and damaged site. The structure in the reef substratum determined the array of reef-building or non reef-building coral species that might grow there. The combination of the abundance and diversity in coral species affected the amount of space created, and in turn affected the diversity of fish species the reef would able to accommodate. Therefore, a changed in the reef fish community was expected, the species richness and their abundance were recorded.

Methodology

Data collection was carried out between the 9^th August and 6^th September 2000.

Transect lines had been set up at each Buoy at three depths; at the reef flat (5m), the reef crest (7m) and the reef slope (10m). At each transect line, various data were collected; the percentage cover, line intercept and the topography of the coral reef. For the ease of data collection, the transect lines were marked at every 5m. Within each 5m sections, the data was collected region 2.5m either side of the transect line. At the beginning of each data collection, a measuring tape was first laid down.

Percentage cover was the estimation on the substrate composition. The measurement were carried out having based on various parameters; hard coral, soft coral, dead coral, sand, rubble, invertebrates and algae. At the same time, any human impacts that might have elicited damage to the reef were also noted. The impact could be blasting or anchor damage. Blasting would be identified as a wide area filled with short pieces of broken dead coral, whereas the broken coral found in an area being damaged by an anchor would be larger and the coverage of the area would be much smaller.

The measurements on the topography of the coral reef were taken every 0.5m. The data was taken as the length between the transect line and the substrate, which would be either positive or negative. If the transect line was positioned above the substrate, which could be sand, rubble or coral, the value would be recorded as a negative value. Where the transect line was lined alongside the coral or the rubble the measurement would have been taken between the transect line and the top of the substrate. Where transect lines had been set up on a slope, horizontal values would be taken as well as the vertical values. Line intercept was the measurement of the size of the substrate composition that was directly underneath of the transect line. In areas covered by rubble or sand, the size would have been measured. Any corals laid directly underneath the transect line, in addition to the size the growth form and the species would be identified.

The fish survey was carried out by diving and swimming along the transect line slowly, stopping at the beginning of each 5m section for 3 minutes and swimming slowly for 5 minutes until reaching the next section. The fishes that were found within or swam pass the water column 2.5m either side of the transect line either horizontally or vertically were recorded. The fish species were recorded to species level.

Results

Reef Topography – Reef Complexity

The Topography Graph 1 to Topography Graph10 showed the profile of each transect line at the two sites. The topography graphs had been drawn on similar scales that the overall profile might be visualized and compared easily. Table 5 showed the range and the standard deviation of the topography of each transect. Comparing the transect lines of the same depth between the two reefs, the 1-sample t-test shown strong evidence that there was a significant difference on the standard deviation (p-value of 0.0006) but no significant difference on the range (p-value of 0.1579).

Line Intercept – Coral Diversity

Table 1 and Table 2 showed the coral species present at the two sites. At the Kaledupa reef, there were 64 coral species, of which 53 of them were Scleractinians and 11 of them were non-scleractinians. In the Sampella reef 25 species of corals were found, including 17 scleractinians and 8 non-scleractinians.

Pie Chart 1 to Pie Chart 6 showed the percentage of the growth forms in the coral species at each site, and the average coverage taken up by each growth form is summarized in Table 3. In Kaledupa, the most abundant scleractinian growth forms were massive and branching, taking up 16.3% and 15.6% respectively, and 17.7%of Mushroom Leather Coral and 15% of Digitating Leather Coral for the non-scleractinian.

Percentage Cover – Reef Complexity

Pie Chart 7 and Pie Chart 8 showed the average percentage of the three transect lines in the different composition of the reef substratum between the two reefs. The substratum of pristine Kaledupa reef contained a high proportion of live corals, which include hard coral and soft coral; they make up over 75% of the substratum. On the other hand, dead coral, sand and rubble dominated the Sampella reef. The hard coral and soft coral were similar in proportion in the Kaledupa reef, taking up 37% and 40%. The Sampella reef showed different proportions, a higher proportion of hard coral compared to soft coral, 12% and 6% respectively.

Reef Ecosystem Disruption

It had been observed that the dead coral and rubble made up of over half the Sampella reef (Pie Chart 8), whereas the proportion in the Kaledupa reef was much lower, 12% together. It was also noted that the Sampella reef had been impacted by bombing and sedimentation. The Kaledupa reef had not been affected by human activities.

Fish Survey

It was observed that there were a wider variety of reef fishes in the Kaledupa reef, but the observation was not supported by the data collected. The data collected did not show significant difference between the species richness and the abundance in the reef fishes between the two sites (Table 4). P-values of 0.201 and 0.117 were obtained on the species richness and the abundance respectively.

The species of reef fishes varied between the two sites. In Kaledupa, the grazing groups were more abundant, while the Damselfishes were more abundant in Sampella.

Discussion

The destruction of coral reef on effects of fish communities had been profound, a change in the community structure was observed. There were significant declines in coral cover, diversity, and associated fish assemblages.

Reef Destruction and Percentage Cover

Coral mining exerted devastating impact on the Sampella reef; the coral community was disrupted. With the 64 species of coral (Table 1) present in the pristine Kaledupa reef compared to the 25 in Sampella (Table 2). Favored corals as building material include the slow-growing massive species such as Porites, Goniastrea, Favia, Favites and the branching coral. The percentage of area coverage below the transect line on the massive growth form had been recorded as the highest in Sampella, which had differed from expected. This might be due to the fact that massive form of seleractinian were more tolerant to sedimentation, while the plate form would be easily smothered by the high sediment load. Although the percentage of massive form of scleractinian was high (Table 3) but the overall percentage coverage (Pie Chart 8) was relatively low, 12%.

For the reason that Kaledupa reef was located further away from the Bajau village, the reef had been much better preserved. The percentage coverage of life coral, which included hard coral and soft coral, made up over 75% of the reef substratum.

As a consequence in the removal of corals, the substratum became had became crumbly, unstable and more vulnerable to wave action and storm. During storms, the silty substrate would often get stirred up. The sediment might remain suspended in the water for days, which would decrease the light penetration through the water column. With increased wave effects on the reef and sedimentation posing difficult conditions for larval recruitment. The combination of high sediment load and the poor light penetration reduce the growth rate of corals and the recruitment rate of damaged coral. This could be the explanation for the high percentage coverage in the dead coral, rubble and sand at the Sampella Reef (Table 3).

Reef Complexity – Line intercept and Topography

Line intercept together with topography would help the analysis on the reef complexity. The original undestructed Sampella would probably have a similar range of coral species as in the Kaledupa reef. In terms of substratum composition, the Kaledupa reef had a greater complexity. The more variation there was in the composition of the substratum, the greater the complexity in the reef.

On the other hand, the structure Sampella reef was more complex in terms of its topography. The ranges in the topography between the two sites were similar but the Sampella reef had a greater variation (Graph 1 to Graph 10).

Fish Surveys – The diversity and the abundance of reef fishes

As the substratum of the Kaledupa reef had a greater coral coverage, more spaces were created between the coral and the substrate. As more spaces are created, more reef animals might utilize the space for resting, escaping predation and also as a shelter during storm events.

Since Sampella was a degraded reef, compared to the pristine site a general expectation on Sampella would be less diverse and also less abundant in reef fishes. An interesting observation was the fish diversity in Sampella was lower as expected but the abundance was often higher. Although the substratum was more exposed compared to Kaledupa reef due to the coral mining, but at the same time, the destructive event created a complex habitat. Many holes and crevices were created, which could be the explanation to the high fish abundance.

Different species of reef fishes were more abundant at the two sites. At the Sampella reef, the territorial damselfish were very abundant. Territorial damselfish colonized dead reef surfaces and enlarge their territories by invading dead coral patches (Glynn L&D of C.Reef Ch.4). In Sampella where dead corals were very common, was a suitable site for the territorial damselfishes. Compared to Sampella, the grazing groups Surgeonfishes (Acanthuridae) and parrotfishes (Scaridae) were more abundant in Kaledupa. Since Kaledupa reef was more abundant in live corals, these grazers that fed on live coral tissues and extract invertebrates from coral colonies were more abundant.

Conclusion

The structure of a coral reef community much to do with its arrangement with space. The organisms of the reef system are closely linked through highly evolved types of interaction. This system is stable within certain limits, but fragile if pushed beyond the limits. Human impacts, such as the overuse of the reef resource, destabilize of modify the substrate, mobile populations, species composition, and underlying materials. The stresses that lead to a disturbance need to be evaluated and recovery is only possible if the cause of the disturbance is removed.

Management Plans of the Operation Wallacea

Current ongoing reef recovery projects include the use of. Artificial reefs are put down at degraded reefs to increase the settlement of coral and also to increase catch rates of fish on areas of damaged corals. Rompongs (offshore fish attraction devices – FADs) and seaweed farming have been introduced as alternative income from reef fishing by destructive techniques. Educational courses have been prepared for local school children to promote awareness of the importance of reef conservation, which is to begin at the end of this survey season. Programs on the development of sustainable income sources are also to be educated to the residents of the Wakatobi National Marine Park

Limitation

It was observed that the fish species were more abundant in the pristine site, Kaledupa, but the evidence had not been shown in the data collected. This could be due to the identification skill on the data collector. The reef fishes identification skill had been relatively poor in the beginning but gradually improved as the project progressed.

Acknowledgements:

The six weeks expedition on the conservation of coral reef in the Wakatobi Marine Reserve Park was organized by the Operation Wallacea. The project was lead by Dr. Debbie Lloyd and data was collected together with the help of Laura Freeman from the University of Birmingham.

References:

1. Birkeland, C. (1997) Life and death of coral reefs. Chapman & Hall. New York
2. Dahl, L., and Salvat, B., (1998) Proceedings of the Sixth International Coral Reef Symposium, Townsville, Australia, 8th-12th August 1988. Symposium Executive Committee. Townsville
3. Dioum, B. (2000) Operation Wallacea, Marine Survey Information Pack 2000 (2^nd edition). Operation Wallacea.
4. Gosliner, T., Behrens, D., & Williams, G. (1996) Coral Reef Animals of the Indo-Pacific. Sea Challengers Inc., USA.
5. Kuiter, R. (1992) Tropical Reef-fishes of the Western Pacific, Indonesia and Adjacent Waters. Gramedia Pustaka Utama, Hakarta.
6. Lieske, E., & Myers, R. (1994) Collins Coral Reef Fishes. Harper Collins
7. Mather, P., & Bennett, I. (1978) A Coral Reef Handbook Australian Coral Reef Society (3^rd ed.). Surrey, Beatty & Sons Pty. Ltd., Australia
8. Rupert, E:E: & Barnes, R:D: (1991) Invertebrate Zoology. Saunders College Publishing
9. Tomascik, T.A., Nonthi, A., & Moosa, M., (1997) The Ecology of the Indonesian Seas – Part One, Vol. VII. Periplus Editions (HK) Ltd.
10. Tomascik, T.A., Nonthi, A., & Moosa, M., (1997) The Ecology of the Indonesian Seas – Part Two, Vol. VIII. Periplus Editions (HK) Ltd.
11. Wallace, C.C. (1997) Proceedings of the 8th International Coral Reef Symposium Panama, 24-29 June 1996, Smithsonian Tropical Research Institute. Balboa

Graphs

Scleractian Non-scleractian

Acropora sp. (Br) Sinularia sp. (DLC)

The coral species were identified with reference to Mather and Bennett 1978.

Categories on the growth form of scleractinian

Br - Branching

En - Encrusting

Fol - Foliose

M - Massive

Sm - Sub-massive

Pl - Plate

Tb - Tabulate

Categories on the growth form of soft non-scleractinian

DLC - Digitating Leather Coral

FC - Flower Coral

Mu - Mushroom

MLC - Mushroom Leather Coral

RLC - Ridged Leather Coral

WC - Wire Coral

Other categories

DCA - Dead Coral with Algae

SC - Soft Coral

Scleractian species

Non-scleractian species

* "–" not present

* Values have been corrected to 1 decimal place.

* Values have been corrected to 4 significant figures.

* The reef fishes have been identified with reference to Kuiter, 1992, Kuiter & Develius, 1997 and Lieske & Myers, 1994