Health Status of Coral Reef in Tunda Island, Banten Province, Indonesia

Coral reef is an important underwater ecosystem supporting people’s lives in coastal areas. One of the communities depending on the coral reef ecosystem for its food, livelihood, shoreline protection, and recreation needs is a community in Tunda Island. This research aims to analyze and determine the health status of coral reef in the island using a survey method. It was conducted in July 2018 and July 2019. Underwater photography transects were established at two depth areas of ± 3-4 m (shallow water) and ± 10-11 m (reef slope). Analysis of the results of live coral cover was divided into eight categories of groups based on CPCe output series 4.1. The values of coral reef cover at first depth (± 3-4 m) were 64.86% (east side of the island), 55.76% (north toward east side), and 32.22% (west side). The values of coral reef cover at second depth (± 10-11 m) were 36.36%, 25.00%, and 23.63% on the north toward east, east, and central north sides of the island, respectively. In shallow waters of Tunda Island, the coral reef health is classified as moderate to good, mostly those located on the east and the north toward the east sides. At reef slope, the coral reef health is classified as damaged to poor, particularly those located on the south and the south toward the west sides. The difference in the health values implies that most corals occur in shallow waters while deep corals differ from those near the surface and are not safe from impacts of the activities in the coastal area of Tunda Island.


Introduction
Tunda Island is one of the seventeen small islands in the Serang District area (BPS Serang District, 2018). It is located in Wargasara Village, Tritayara Sub-District, Banten Province, Indonesia. Based on the plan of zoning of the coastal areas and small islands in Serang District from 2013-2033, Tunda Island is included in a development program for marine tourism zone (Regional Regulation of Serang District No. 2/2013). Tunda Island is a diverse marine and coastal area. It is an attractive site for ecological research and tourism, and has an abundance and diversity of coral reef and reef fish (Zamani, 2015).
The development of marine tourism areas is a resource management strategy that would be beneficial for businesses and the community in Tunda Island in terms of sustainable management, protection, preservation and utilization of ecosystem services of marine and fishery resources. Currently, the abundant underwater property in Tunda Island has enough potential to be developed as a marine tourism area for diving, snorkeling, and fishing tour (Alam et al., 2017). Tunda Island has three important ecosystems along the beach and coastal area: coral reef, seagrass, and mangrove forest. Of which, the coral reef ecosystem is the basis for the development of marine tourism in the island.
Existing coral reef ecosystem is used as an indicator of environmental change because it is more sensitive to physical and chemical changes in the marine environment (Guzman and Jimenez, 1992;Al-Rousan et al., 2007;Jayaraju et al., 2009;Riska et al., 2015). This change is seen from the health and physiology of coral polyp (Esselemont et al., 1999;Chan et al., 2014) and physical and chemical characteristics on its skeleton (Abelson et al., 2005;Riska et al., 2015). Coral reefs are formed from massive sediments of calcium carbonate (CaCO3) produced by reef organisms, which form coral hermatypic reef) from phylum Cnidaria. Scleractinia order builds themselves a hard skeleton and lives in symbiosis with zooxanthellae, and a little addition of calcareous alga and other organisms that secrete calcium carbonate (Dhiecho et al., 2015).
The numerous and varied benefits of a coral reef ecosystem can be direct or indirect. Direct benefits include the availability of fish another biota as habitat, and marine tourism. Meanwhile, the indirect benefits are abrasion barrier and breakwaters. A coral reef is one of the important marine ecosystems providing crucial ecosystem services, such as base food source for some commercial biota/organism, marine tourism support, beautiful sand on the beach, and barrier of waves and erosion (Westmacott et al., 2000;Dhiecho et al., 2013;Nugraha et al., 2017).
At present, tourism activities in Tunda Island need a regulation especially the activities on the beach and coral reef waters. The regulation must be proper, well planned and adhere to the principles and goals of sustainable development. This research aims to analyze and determine the health status of coral reefs in Tunda Island The increasing impact of human activities is endangering the survival of this ecosystem and learning about the coral reefs will help the government, the community and other stakeholders understand what is needed to protect.

Materials and Methods
Samplings were done in July 2018 and July 2019 in Tunda Island waters, Serang District, Banten Province (see Figure 1.) by Rapid Reef Assessment. This assessment combined the methods of manta tow, Line Intercept Transect (LIT), and Underwater Photo Transect (UPT) (Jonker et al., 2008) where the length of the transect line used was 50 meters. UPT combines underwater digital camera and computer software developed by P2O-LIPI (Giyanto et al., 2014). Subsequently, the generated pictures were analyzed using CPCe (Coral Point Count with Excel extensions) Software version 4.1 to obtain quantitative data. Observation and collection of data were done in 2 depths, i.e. ±3-4 m (shallow water) and ±10-11 m (reef slope). Placement of line transects and transect quadrates was done from 0 m to 50 meters in the bottom waters (sea). The value range of ±3-4 m and ±10-11 m were used because in coral reef habitats it is difficult to get final values. Mujiyanto and Syam (2014) found that in bottom waters, producing a fixed value to place the line transects and transect quadrates was difficult.
Results of the percentage of reef colony cover were grouped into thirteen based on CPCe output (Kohler and Gill, 2006) which was developed and modified by P2O-LIPI (Giyanto et al., 2014).  Analysis to find out the similarity between stations based on the cover percentage of coral reef was done by cluster. The method used to measure the similarity of the object was Complete Linkage (Hidayatullah and Perihatini, 2016). This method an overall group distance from all stations including a cluster with all stations in another cluster. The analysis was performed using Minitab 15 software.

Percentage of live coral cover in shallow water
The percentage of live coral cover observed at ±3-4 meters on 8 stations showed a high level of healthy corals. Station 5 (East Tunda Island Side) had the highest coral cover at 64.86%. The level results from the calculation of category groups included Live Coral (LC) at 55.10%, Gorgonians (G) at 0%, Sponges (S) at 0%, Zoanthids (Z) at 0%, Other Live (OL) at 9.76%, and Coralline Algae (CA) at 0%. The range of percentages of coral health at 3-4 meters on 8 stations was 11.82% -42.12%. In addition, the highest value was found on the North Side of the island while the value for the North toward the East Side was 55.76%. The result of the analysis with a focus on the LC category was benthic life composition life coral from Acropora and non-Acropora type. Coral reef conditions can be based on the percentage of coral cover life from hard coral type (Acropora and non-Acropora) (Adriman et al., 2014).
The health of the reef in shallow waters in all stations can be classified as moderate to good. These are located on East Side (Station 5) and North toward East Side (Station 6.). Meanwhile, reef health on other sides are classified as damaged to poor, including those on the Central North Side (Station 7.) and North toward West Side (Station 8.) ( Table 1).
The percentage value of healthy coral cover on the East Side and on the North toward the East Side has been dominated by massive and branching live corals. Other types have also been found, such as a mixture of Other Live (OT) and Coralline Algae at 9.76% on the Central North Side and 8.18% on the North toward the East Side). The percentage of reef health on the North and East sides can be classified as good because of the fewer fishing activities in the area. The East Side also has high waves and currents (Prameswara and Suryawan, 2019). Meanwhile, the Central North Side and the Central South Side have damaged to poor coral cover because the locations are being used as snorkeling area, for fishing with a spear gun, and for other activities performed by Tunda people and tourists. The poor condition in these locations is caused by destructive fishing activities, including the use of fishing gears that damage coral reef, and by coral mining that takes out live corals for use as building materials (Hermansyah et al., 2017).
The percentage of live coral cover were also used in the identification of the type of damage based on the following category groups: Dead Coral (DC), Fleshy Seaweed (FC), Dead Coral with Algae (DCA) and Sand (S), Rubble (R) and Rock (RK). At ±3-4 m depth at 8 sampling stations, the highest level of coral reef damage observed was located on the South Side Station near Kampung Barat Port and on the North Side of Centre Part (Station 2.). The percentage values on the South Side close to Kampung Barat Port and the North Side (Station 7.) were 7.58% and 9.09 %, respectively.
Fishing is the main source of livelihood for the people in Tunda Island. Tunda Island people work as traditional fishermen and their major fishing location is the coral reef ecosystem (Nugraha et al., 2017). High dependence on the fish resource is due to the direct benefit of the coral reef ecosystem in coastal areas. In terms of occupation, around 80% of Tunda people are fishermen while the rest are workers (10%) or with other jobs (10%) (insert source). Based on the level of economic prosperity, most of the 200 families belong to the underprivileged and prosperous group 1. Considering the link between their livelihood and economic welfare conditions, it is reasonable to assume that the livelihood of people as fishermen in the region has not been able to provide adequate welfare for their families. Coral reef ecosystem is one part of the coastal ecosystem that is very important as food resource, habitat for some fish and other commercial organism, marine tourism support, sand provider for the beach, and breakwater and barrier of beach erosion (Westmacott et al., 2000;Dhiecho et al., 2013;Nugraha et al., 2017).

Percentage of live coral cover at reef slope
The results showed that the level of coral reef health at all stations has a range of 1.82 to 33.36%, with Station 6 having the highest percentage at 33.36 %. The dominant value of reef health at the depth of ±10-11 meters has a range of 1.82 to 22.00%. The lowest percentages of coral cover were found at  Soedharma et al. (2017) in Tunda Island using the LIT method at 7-8 m depth showed that the live reef percentage on the South Side was 25,5%, which is categorized as moderate. Comparing the North and South sides from 2012 until 2017, the coral reef ecosystem has decreased with the poor condition of live coral cover (Hermansyah et al., 2017).
Based on the coral reef composition of the group of categories as the output of CPCe software, the dominance of composition habitat on the South Side was Dead Coral with Algae (DCA) and Sand (S), Rubble (R), and Rock (RK). The value was taken from the highest category group of the DCA category. It is located on the North Side of Tunda Island, precisely at Station 6 (40.30%), Station 7 (50.03 %), and Station 8 (37.33%). Coral reef composition found on the Central South Side of Tunda Island was categorized into Sand (S), Rubble (R) and Rock (RK) with the values of 78.48%, 56.97%, and 72.73% at stations 2, 3, and 4, respectively. The values of coral cover by category and by research station are presented in Table 2.
Central South Side in Tunda Island waters is classified as water condition with very low transparency level and high turbidity. On the Central South side, it was observed that the water is susceptible to people's activities. The settlement of people in Tunda Island will have impact to surface and underwater ecosystems around, especially the coral reef ecosystem. According to Burke et al. (2002), environmental pressures due to land activities can reduce biodiversity in coral reef areas by 30-60%. Increasing activities of the people also can relate directly to the coral reef ecosystem. It has a significant contribution to the occurrence of sedimentation and physical damage to the coral reef. Due to the high levels of sedimentation, the shape of colonies in sequence will tend to be massive, branchy and foliose (Rahmitha et al., 2015). De Meesters et al. (2002) stated that Porites can adapt in a water environment with high turbidity to carry out active metabolism. Therefore, turbid water with low salinity is likely to have Porites as the dominant coral. The condition of coral reef at ±10-11 meters' depth is a manifestation of the impact of fishing activities in the past few years. In the past few years, fishing activities used compressors and anchor ship. They are still rife in Tunda Island because of the absence of regulation. The complexity of coral reef provides protection, which is important for reef fishes (Alvarez et al., 2011). Besides, coral reefs are threatened by local community activities like fishing that is not environmentally friendly and pollution (Sandin et al., 2008). Meanwhile, Tunda Island is a small island with a lot of human activities and has a coral reef ecosystem around coastal waters (Zamani, 2015). Riegl et al. (2012) explained that the coral reef ecosystem located near the community settlement will be the more accessible to people and tend to be most at risk of degradation. Several local threats come from the boats, anchors, destructive fishing, and tourism activities on the coral reef ecosystem in Tunda Island (Zamani, 2015;Fahlevi et al., 2017).

The similarity between the percentage of coral reef among stations
The results of the analysis of the similarity level of coral health among stations in shallow water (± 3-4 meters depth) show that four groups had the closest similarity level in terms of coral health. These are: a) Station 5 and 6, b) Station 7 and 8, c) Station 1 and 4, and d) Station 2 and 4. All four groups had the same distance at a value of similarity >75 %. The research stations at a depth of ±3-4 meters with proximity values >90% were stations 5 and 6, as well as stations 7 and 8 (See Figure 3.).
These groups have same health value tendency due to the fact that the four stations are all located on the North Side of Tunda Island. This side of the island has little activities because people's activities are still concentrated on the South Side of Tunda Island. Gladfelter et al. (1980) stated that the similarity of coral reef habitat is possibly due to the position of the reefs, especially concerning the degree of exposure to ocean current, water depth, and proximity to the main reef barrier that play a role in determining the composition of fish as reflected in the similarity fauna.
Grouping of similarity values between the percentages of coral cover and stations at the reef slope (±10-11 m depth) shows on highly similar group, composed of stations 2 and 4. Meanwhile, the similarity values >75% were found at stations 1 and 5, stations 6 and 7, and stations 2, 4 and 3 (See The water conditions were the same as the conditions at a depth of 3-4 meters. The level of similarity can be explained by the fact that the area is being used as a fishing location dominated by the use of destructive fishing equipment. The fishing method involves the use of some fishing gear that are not environmentally friendly (Mulyani et al., 2017). Therefore, coral reefs experienced some level of damage as Station 4 becomes the location of the development of fishing boat docks. Fachry and Pertamasari (2011) identified five main human activities that threaten the preservation of coral reef, including fishing with poisonous materials, fishing with explosives, rock extraction, sedimentation, and pollution.
The condition of coral reefs in Tunda Island is not secure because of excessive coral reef exploration and mining of materials for the construction of settlement foundations (Dedi et al., 2017). The community also dispose household waste to the water, which will cause damage to the  Figure 4. Dendrogram/hierarchical clustering for reef slope using Complete Linkage Method surrounding environment. Riska et al. (2015) reported that heavy metals accumulation in Tunda Island waters is increasing as seen from an annual band of Porites lutea corals. Zamani (2015) also explained that the decrease in the percentage of coral reefs in Tunda Island is caused by boat activities, such as boat anchoring and perching or grounding of local tourism boats. The dead coral has been overgrown with algae as a result of pressure from human activities and long-standing environmental factors.

Conclusion
In shallow waters in Tunda Island, the health of the corals on the East Side and North toward the East Side is classified as moderate to good. Those located on the Central North Side and North toward West Side is categorized as poor to moderate. Meanwhile, the coral reef health at reef slope in Tunda Island waters is classified as damaged to poor. The moderate category is located on the North toward East Side, while the damaged to poor one is on Central South and South toward West Side.