The Adaptive Capacity of Corals Based on the Health Level to Estimate the Carrying Capacity of the Marine Ecotourism in Enggano Island

Enggano Island is one of the outermost islands of Indonesia. Among the recoverable resources that exist in Enggano Island are coral reef ecosystems. A coral reef ecosystem is also one of the ecosystems with a high level of biodiversity productivity having a major role as habitats, feeding places, and the coastal protection from the crashing of waves and strong currents. Currently, coral reefs are being destroyed either by nature or humans. The ability of an ecosystem to adapt to a disturbance or potential damage is called adaptive capacity. The aim of the study was to assess the adaptive capacity of corals in terms of their health levels to estimate the carrying capacity of marine ecotourism. The observation method used was survey method. Adaptive capacity measurements were carried out by analyzing six parameters: hard coral cover (%), distances from human settlements (km), dominance of lifeform, types of lifeform, reef fish species, and coral reef depth (m). The results of this study showed that Enggano Island corals had the adaptive capacity that fell into three (3) categories: not adaptive, moderate and adaptive.


Introduction
Enggano Island is one of the outermost inhabited islands that are located in North Bengkulu Regency, Bengkulu Province.Geographically, Enggano Island is located between 5017' South Lalitude-5031' South Lalitude and 102005' East Longitude-102025' East Longitude.The Enggano Island region includes several small islands, namely Dua Island, Merbau Island, and Satu Island.The distance from Bengkulu City is 156 km (90 nautical miles), and the closest distance to the mainland of Sumatra is Manna City, South Bengkulu Regency, about 96 km (60 miles).The sea transportation service of Enggano Island is using a ferry or pioneer ship with a travel time of about 14 hours and the air transportation service of Enggano Island is using a pioneer aircraft with a travel time of about 45-50 minutes.Both the transportation modes operate 2 times a week.
The main potential of the coastal ecosystems of Enggano Island are coral reef ecosystems.The ecosystems are typical of tropical regions with high levels of biodiversity productivity.In addition, the coral reefs also serve as habitats and feeding places, as well as the coastal protection from strong waves and currents.Currently, coral reef ecosystems are being destroyed either by nature or humans.According to Subur (2012), the adaptive capacity of coastal ecosystems such as coral reef ecosystem play an important role in the face of changes as well as external pressures.The ability of a system to adapt to a disturbance or potential damage is called adaptive capacity (Gallopin, 2006).
Adaptive capacity is also one dimension that causes vulnerability (Fussel and Kelin, 2006;Turner et al., 2003).It plays an essential role in reducing vulnerability, from high vulnerability to low vulnerability with high adaptive capacity or otherwise (Luers, 2005) The parameter which encompasses the adaptive capacity of corals is biophysical parameter.Considering the importance of the adaptive capacity of corals, it is necessary to carry out this research as the first step to assessing coral reef ecosystems in Enggano Island for specific purposes such as marine ecotourism.After the adaptive capacity of the coral ecosystems in Enggano Island was obtained, it would be decided whether it was categorized as not adaptive, moderately adaptive (medium) and adaptive.This also supports the efforts of Bengkulu Provincial Government which has established Enggano Island as the center of fishing and tourism industry for the Years 2013 to 2025.

Materials and Methods
This research was conducted for 6 months in Enggano Island, North Bengkulu Regency, Bengkulu Province (Figure 1).
The materials and tools used in the research were a motor boat, Global Positioning System (GPS), Self-Contained Underwater Buoyancy Apparatus (SCUBA), slate / pencil, Underwater Camera, 50 m roller, digitized basemap, and other tools that supported data collection in the field.
The data collection was directly conducted in the field (in-situ) that covered six (6) research sites in Enggano Island, namely Satu Island, Danau Padipo, Merbau Island, Dua Island, Tanjung Gosongseng and Kaana (Figure 1).The data collected consisted of primary data and scondary data.The collection method was as follows: The data collection of hard coral cover used Line Intercept Transect (LIT) method by determining the coral lifeform and coral cover percentage (English et al., 1994).List of the classification of basic components of the coral reef ecosystem based on coral reef lifeform and its code can bee seen in Table 1.The data collection was done by spreading a 50-metertransect line at each station point.Measurements of the lifeform of corals, coral species, and other benthic categories below the transect line were recorded with accuracy approaching centimeter, further identified in reference to Suharsono (2008) and Veron (2000).
The data collection of lifeform dominance was similar to the data collection of hard coral cover.Any lifeform passed by the transect line was recorded and calculated to find out the most common type of lifeform compared to other lifeform types (English et al., 1994).The collection of the number of lifeform types was done by spreading the 50 m transect line at each station point.The measurement of this form of coral growth (lifeform) refers to English et al., (1994).
The data collection on the number of reef fish species in this study used Underwater Visual Census (UVC) method with the purpose of identifying reef fish through the observation of reef fish encountered around the points of the research locations.The identification referred to Allen and Steene (1996) and Kuiter and Tonozuka (2001).Collecting the data on the distance between the coral reef ecosystem and the settlement or community activity was done by using GPS.The analysis of the conditions of coral reef ecosystem health based on hard coral cover refers to Gomez and Yap (1988).The coral health categories based on the hard coral cover can be seen in Table 2.

Analysis of coral capacity adaptive
The assessment of the coral adaptive capacity analysis consisted of 6 parameters and 3 categories.There are 6 parameters of Anggano Island coral adaptive capacity (See Table 3) The value of the coral adaptive capacity was in the range of 0.0-1.0, with three categories consisting of "not adaptive (0.0≤KAK≤0.33)".

Results and Discussion
Hard coral cover values in six study sites were between 16.08-64.4%.The highest hard coral cover was found at Tanjung Gosongseng at 64.4%, followed by Satu Island (46.03%),Merbau Island (39.41%),Kaana (35.9%),Danau Padipo (27.95%) and Dua Island (16.08%) as can be seen in Figure 2. Some hard corals found in Enggano Island can bee seen in Figure 3.The research results showed that the coral health value of Tanjung Gosongseng based on Gomez and Yap (1988) formulation was in the criteria of good (50.00-74.90%).Based on the coral health criteria, Dua Island was categorized as damaged.Meanwhile, Kaana, Danau Padipo, Satu Island and Merbau Island were categorized as medium.Subur (2012) states that the high value of hard coral cover indicates a good health level, and this in turn will ensure the survival and existence of coral reef ecosystems.The coral cover value which is likely to be low will create favorable conditions for macroalgae growth which in turn kills corals.When disturbances occur, many corals die.The corals will soon be covered by algae because macroalgae grow very fast.Hughes et al., (2006) said that macroalgae inhibited coral colony passing (Lirman, 2001).
In general, lifeform is dominated by Coral Encrusting (CE) and branched coral lifeform (ACB) which could be seen in Satu Island, Tanjung Gosongseng and Danau Padipo (See Figure 4).The shape of b ranched coral growth is relatively fragile and can not stand the waves nor the waves that pass through it, especially in the shallow waters.This is in contrast with massive corals, which are more resistant to disturbances (Brown and Suharsono, 1990;Marshall and Baird, 2000;Ninio and Meekan, 2002).

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Omni-Akuatika Vol.Wilsom et al., (2007), the structural inheritance of coral reefs is coral reef lifeform which can survive from any disturbance, and this is the complexity of coral habitats and subtrates.Complex habitats can preserve the diversity of fish and improve coral recruitment, which is essential in the recovery of coral ecosystems.
The coral reef depth is one of the parameters to measure the adaptive capacity of corals The depth of coral reef ecosystems in Enggano Island ranges from 3 to 10 m; that is why, the area will be utilized as marine ecotourism.In a certain area, the depth of the waters could reach 25 m, and the penetration level of the sunlight depends on the intensity of the light.Siringoringo et al., (2014) stated that the condition of basic substrates greatly influence the success of coral polyps to grow and develop into adult corals.Babcock and Smith (2000); Torres and Morelock (2002) stated that sedimentation and suspended materials in the water column affect coral growth by covering the polyp surface causing death.This can reduce the water brightness and ultimately disturb the coral physiological process, especially photosynthesis.As a result, there is a decrease in the percentage of coral cover.According to Thamrin (2006), species diversity and best growth were found at depths between 3-10 m.
The distances of coral reef ecosystems from the residential areas should be carefully considered.According to Algar et al., (2002), the closer the resources to human activities, the more vulnerable the resources, while the more isolated or further away from human activities, certainly the more preserved they would be.Based on the study results, in Tanjung Gosongseng, Satu Island, and Danau Padipo, the distances between coral reefs and settlements are > 5 km, but in Dua Island the distance is close to the residential area.Furthermore, the coral reef destruction was thought to be caused by the increased intensity of human activity (Wahidin et al., 2014), such as searching for shells during the lowest tide, standing and stepping on corals when snorkeling or swimming (Luthfi, 2016).

Analysis of the adaptive capacity of enggano island coral
Based on the analysis results of the six parameters, the adaptive capacity of coral reefs was distributed in three categories that were not adaptive, moderate and adaptive.The value of the adaptive capacity of Danau Padipo (0.78) was in the adaptive, while the value of the adaptive capacity of Satu Island (0.44-0.68),Tanjung Gosongseng (0.40-0.70),Merbau Island (0.42-0.56) and and Dua Island (0.36)   The value of adaptive capacities of corals in Enggano Island ranged from 0.28-0.78.The value of the adaptive capacity of Dua Island corals was 0.28, the lowest value that belonged to the medium category due to the low hard coral cover in the waters.This was allegedly due to the activity of the port near Dua Island and the many fishing vessels from outside Enggano Island which dropped their anchors which damaged the coral reef ecosystem.Based on the monitoring results, there were at least 5 fishing vessels that dropped their anchors in every full moon, when fishermen stopped their fishing activities.The many broken corals or rubbles found were the evidence that the damage to coral reefs was due to the anchors of ships.This is supported by Burke et al., (2002), saying that other factors causing coral reef death include the dropping of ship's anchor which is not environmentally friendly.
According to Subur (2012), the levels of adaptive capacity values were determined by the parameters studied.Meanwhile, according to Alger et al., (2002), the closer the resources to human settlements or human activities, the more vulnerable the resources.Therefore, it is necessary for Dua Island to be well managed so that the destruction of the coral reefs can be minimized.

Conclusion
The adaptive capacity value of Enggano Island was classified into three (3) categories: not adaptive, moderate and adaptive.The coral whose adaptive capacity value was categorized as adaptive was found in Danau Padipo, and as moderate Satu Island, Tanjung Gosongseng, Merbau Island and Kaana, and as adaptive Dua Island.

Figure 1 .
Figure 1.Site Map of Enggano Island Research The analysis of hard coral cover was conducted based on the following equation: Note: N = Percentage of coral cover li = Total length of lifeform -I L = Transect length is 50 m

:
Number of coral hard cover (%), Dominance of lifeform, Number of lifeform species, Number of reef fish species, Coral reef depth, and Distance of the coral reef ecosystems from the community settlements .Analysis of the coral adaptive capacity (KAK) is the continuation of the adaptive capacity assessment matrix.The formula used to calculate the coral adaptive capacity refers to Fertile et al. (2011).Note: KAK: Value of Coral Adaptive Capacity Ni: Total parameter value of the measurement result Nmax: Maximum value of the parameter

Figure 2 .Figure 3 .
Figure 2. The percentage value of hard coral cover at the study sites

Table 1 :
List of the classification of basic components of the coral reef ecosystem based on coral reef lifeform and its code

Table 2 .
Coral reef condition categories based on the percentage of hard coral cover

et al., 2018, The Adaptive Capacity of Corals Based on the Health Level 24Table 4 .
was in the moderate category.See Table4.Distribution of the Catagories of the Coral Adaptive Capacity at each study site