Temporal study of coral reef health in Kepulauan Seribu Marine National Park

Coral reefs are one of ecosystems that have high biodiversity and productivity. The condition of coral reefs in Seribu Islands is currently being threatened by various marine industry development activities. This study aims to determine coral reef health in Seribu Islands, DKI Jakarta. The study was conducted at eight observation stations in Kepulauan Seribu Marine National Park area on 7-10 March 2022 (First Monitoring) and 31 May until 3 June 2022 (Second Monitoring). Coral reef data collecting were using Underwater Photo Transect (UPT) method. Reef fish data collecting were using Underwater Visual Census (UVC) method. While for macrobenthos data collecting were using the Belt Transect method. The coral reef health index was determined based on two main components, there are benthic component and reef fish component. Overall, coral reef health from eight observation stations during two monitoring sessions had high recovery potential, although some stations had low coral cover and low target fish biomass. In addition, several species of macrobenthos are bioindicators that can contribute to purifying waters.


Introduction
Kepulauan Seribu is an area with a group of small islands located between Java Sea and Jakarta Bay.Geographically, Kepulauan Seribu is located extending from North to South with small white sandy islands and coral reefs formed from natural dynamics between coral and their associations [1].Kepulauan Seribu has a fairly diverse marine ecosystem and its territory is supervised by Kepulauan Seribu Marine National Park by establishing several zones for conservation purpose [2].One of ecosystems that is preserved is the coral reef ecosystem.
Coral reefs ecosystems have high biodiversity and productivity [3][4][5].Coral reef ecosystem have an ecological function as spawning ground, feeding ground, and habitat for their associated biota [6].Relationship between coral reef and their associated biota must continue to run dynamically so that the marine environment becomes healthy and primary productivity is maintained.According to [7], coral reef health can be seen benthic component and reef fish component.In addition, other coral association

Study site and period
Observations were conducted at eight observation stations (see Figure 1) in Kepulauan Seribu Marine National Park area, DKI Jakarta.The observation stations are in Pramuka island (2 stations), Panggang Island (2 stations), Semak Daun island (2 stations), and in the patch reef of Karang Congkak (2 stations).This observation is divided into three stages.The first stage is the installation of a permanent transect as a reference for the monitoring area.The second stage is the observation of ecological data conducted on 7-10 March 2022 (Monitoring 1) and 31 May-3 June 2022 (Monitoring 2).The third stage is analysis of survey data conducted at the Indonesia Sustainable Coral Foundation, Bekasi, West Java.

2.2.2.
Reef fish observation method.Reef fish observation using Underwater Visual Census (UVC) method [13].The length of the transect used is 50 m with a visibility of 2.5 m to the right and left to form a rectangle (see Figure 3).Observation were made at 6-8 m depth.The data taken include families, species, size estimates, and number estimates.The tools used were SCUBA set, roll meter, slate, newtop paper, and pencil.

Macrobenthos observation method.
Macrobenthos observation used Belt transect method [13].This method is carried out by stretching 50 m long transect with zigzag sweeping 1 m to the right and 1 m to the left (see Figure 4).Observation were made at 6-8 m depth.The data taken in the observation are species, number, and size (for macrobenthos which has economic value).The tools used were SCUBA set, slate, pencil, sewing meter, and newtop paper.

Data analysis
Calculation of coral reef health refers to [7] by looking benthic component and reef fish component.The benthic component considers two factors, there are current condition which can be calculated from live coral cover and the level of resilience which can be calculated from fleshy seaweed and rubble.The benthic component analysis from Underwater Photo-Transect (UPT) method using benthic photos.Total all of benthic photos collected from eight observation station was 400 photos (each stasion collected 50 photos).Identification all benthic photos using program called Photoquad.After identication all benthic photos, the program would automatically make benthic cover percentage calcultation as the result using the formula [14]  Source: [7] Meanwhile, the assessment of benthic resilience level components of coral reef ecosystem refers to [7] consisting the following categories: -Turf algae are algae that grow and have a smooth shape with height less than 2 cm.The thicker presence of turf algae means the lower level of resilience.-Fleshy seaweed are a group of macro algae such as Sargassum, Padina, and others.The more presence means the lower level of resilience.-Rubble caused by waves crashing or using explosives to catch fish.The more presence means the lower level of resilience.-Coral juvenile, the denser presence means the higher level of resilience Source: [7] Reef fish assessment refers to [7] which is expressed by total biomass variable of economically important fish consisting of 7 families, there are Scaridae, Serranidae, Lutjanidae, Lethrinidae, Haemulidae, Siganidae, and Acanthuridae.Reef fish biomass data collection was carried out by recording the total length of the fish by estimation.The length-weight equation was used to estimate the weight of fish based on the length of the fish, the median value was taken from the length (cm) of the fish and then converted to weight (grams) using the length-weight index obtained from fishbase.com[15].The equation that can be used in calculating the weight of fish is as follows: (3) Note: -Reef fish biomass 970 kg / ha = 33.950g/ 350 m 2 -1940 kg / ha = 67,900 g / 350 m 2 of reef fish biomass -Area per reef fish transect = 350 m 2 Determination of coral reef health index refers to [7] by combining two main components to produce a coral reef health index value which can be seen in the Table 4.

Result and discussion
The assessment of benthic component consisted of live coral cover and resilience levels.The observation results of benthic cover from eight observation stations during two times of monitoring can be seen in Figure 6.Each observation station has a different percentage of cover especially during two monitoring seassions (see Figure 5).Semak Daun 1, Karang Congkak  However, in determining coral reef health is good, it cannot only be seen from the coral cover.This is because the condition of the waters always changes that can affect to the coral cover itself.Benthic cover is a manifestation of an ecosystem that is facing complex changes.So that, there are other factors that need to be observed to assess coral reef health itself, namely the ability of resilience.Resilience is the capacity possessed by an ecosystem to maintain its structure and function when facing disturbances and changes that will occur [16].According to [7], in coral reef health conditions, there will be no signs of serious damage affecting their recovery, such as not much rubble or abundant fleshy seaweed.In this observation, rubble which should be included in the abiotic category is made separately so that it can be seen the amount of rubble cover at the station being observed.
The results of resilience levels from eight observation stations in Kepulauan Seribu Marine National Park area showed that Pramuka 1 station was dominated by rubble cover both in monitoring 1 and monitoring 2 with percentage are 47.07%and 61.13%.Other stations that have the same condition are Pramuka 2 station 49.53% (monitoring 2) and Panggang 1 station 35.07%(monitoring 2).The number of rubble found from observation station is thought to be due to the density of physical activities around the location such as fishing, tourism, transportation and even reclamation activities [17].On the other hand, rubble can be a living and developing media for coral larvae [2], but if there are too many, it indicates that the waters are under pressure.
Mostly, the fleshy seaweed cover from all stations did not show cover percentage value less than 3% based on [7].However, there are several stations that have a percentage of fleshy seaweed cover above 3% including Pramuka 2 station which is 3.47% in monitoring 1.In monitoring 2, there is Pramuka 1 station (5.00%), Semak Daun 1 (3.93%), and Semak Daun 2 (5.53%).The high cover of fleshy seaweed can cause competition between corals and algae [18].In addition, macroalgae groups can also indirectly cause increased coral mortality by attacking microbes associated with corals through the transfer of microbes or hydrophilic compounds through water-mediated mechanisms [19].From Figure 6, apart from coral reefs, there are other fauna that coexist with coral reef, namely macrobenthos.Macrobenthos are organisms that live on the seabed either crawling, sticking, and digging holes in the substrate [20].These organisms live side by side with coral reef as associated biota, so their presence might affect coral reef health.The observation results of macrobenthos from eight observation stations in Kepulauan Seribu National Park area were carried out for two times monitoring to determine its composition and abundance.Macrobenthos observed were organisms belonging to eight phyla including Chordata (Subphylum Tunikata), Platyhelminthes, Cnidaria, Echinoderms, Porifera, Annelida, Molluscs, and Arthropods (see Figure 7).composition value in the Chordata phylum (66.94%).In monitoring 2, the observation stations Karang Congkak 2, Panggang 1, Pramuka 1, and Semak Daun 2 have the highest composition of phylum Porifera, each with a percentage of 37.50%, 47.23%, 57.39%, and 29 ,28%.Phylum Chordata has the highest compositional value at Karang Congkak 1 (32.58%),Panggang 2 (47.06%), and Pramuka 2 (66.84%).Meanwhile, the phylum with the highest composition at the Semak Daun 1 observation station was the phylum Echinoderms with percentage 29.67%.Overall, phylum Porifera, phylum Chordata, and phylum Echinoderms were the most common phyla from the eight observation stations in both monitoring 1 and monitoring 2. From that three phyla, two of them (phylum Chordata and Echinoderms) include organisms that live in colonies and in one colony there are many.This can affect the abundance of macrobenthos species found in Kepulauan Seribu Marine National Park (see Figure 8).
The highest abundance of macrobenthos in monitoring 1 was found at Semak Daun 2 station with 36 macrobenthic species, while the lowest abundance was found at the Pramuka 2 station with 17 macrobenthos species.Furthermore, in second monitoring, the highest abundance of macrobenthos was found at the Panggang 1 station with 29 macrobenthos species, while the lowest abundance was found at Semak Daun 1 station with 17 species.
The involvement of macrobenthos as an associated biota of coral reef ecosystem has an important role not only as part of the food chain but also in determining the quality of waters (bioindicator) [21].These organisms contribute to purifying the waters so that they can help marine organisms that need sunlight to carry out photosynthesis so that the primary productivity of the waters can running well and the waters become healthy.Although macrobenthos have low mobility, these organisms are able to accumulate pollutants or organic material into their bodies based on their functional feeding guilds (FFG) [22] or which can be categorized as filter feeders.Some groups of macrobenthos that can be categorized as filter feeders are sponges (Porifera), bivalve (Molluscs), tunicates (Chordata), several types of sea cucumbers (Echinoderms), and others.Xestospongia muta is one of example of filter feeder organism that found at several observation stations (see Figure 9  Another component used for the assessment of coral reef health is reef fish component.Reef fish are fish that live part or all of their lives in coral reef ecosystem.The composition of reef fish found is influenced by the condition of coral reefs, chemical, physical, and biological conditions of the waters [23].The results of observing the composition of reef fish from eight observation stations in the Kepulauan Seribu Marine National Park area during two monitoring sessions (see Figure 10) showed that in the first monitoring, there were 18 families of reef fish, 34 genera, 62 species, and 3139 individuals.While in the second monitoring, there were 15 families of reef fish, 32 genera, 53 species, and 3742 individuals.During these observations, it was shown that the most common reef fish families were the Pomacentridae, Labridae and Apogonidae families.These three families have a high number of species and are widely distributed in coral reef ecosystems [24].
The Pomacentridae family is a group of territorial fish and always lives close to their food sources and this family lives in areas with coral reefs and rubble substrates [25].Each observation location has a substrate condition that contains coral reef and rubble which is the habitat of the fish family Pomacentridae.Fish family Labridae is a group of omnivorous fish that eat small invertebrates and algae [26].This makes fish of Labridae family often found because the food sources of these fish are abundant in the coral reef ecosystem.The Apogonidae family is a nocturnal fish species that has the nature of living in groups and found in high abundance [24].The characteristics of Apogonidae family make this fish commonly found when observing coral reef ecosystem.Furthermore, the abundance of reef fish was calculated from eight observation stations in the Kepulauan Seribu Marine National Park area for two times of monitoring (see Figure 11).The abundance of fish is influenced by fishing activities and changes in living conditions.Overall, each observation station showed a different abundance of fish.Karang Congkak 2, Panggang 1, Panggang 2, Semak Daun 1, Semak Daun 2 stations showed an increase in abundance value of reef fish from monitoring 1 to monitoring 2. Karang Congkak 1, Pramuka 1, and Pramuka 2 stations have a decrease value in reef fish abundance from monitoring 1 to monitoring 2.
Pramuka 1 station had the least hardcoral cover than the other observation stations.Low percentage hardcoral cover value might ultimately lead to shift in ecosystem structure and function, such as reef fish [27].This is indicated by the abundance value of reef fish in monitoring 1 and monitoring 2 at Pramuka 1 station which has the least abundance of fish compared to other observation stasions.The high and low abundance of reef fish species is influenced by the habitat variation of the coral reef ecosystem [26].Habitat variation is not only seen from the diversity of coral reef genera, but can also be seen from other substrate conditions such as sand, rubble, and algae.Assessment of coral reef health for reef fish components used is a family of fish belonging to the target fish or economically important.The composition of the target fish obtained from the two monitoring sessions is relatively small.The small amount also affects the abundance value and biomass of the target fish itself.The highest biomass value in monitoring 1 was Semak Daun 2 station (24.87 kg/ha) and the lowest was Karang Congkak 1 (2.18 kg/ha).In monitoring 2, the highest biomass value was found at Panggang 1 station (184.94kg/ha) and the lowest was at Pramuka 1 (3.27 kg/ha).The biomass value from all observation stations is included in the low category because the value is less than 970 kg/ha [7].The low biomass value is thought to be due to overfishing of economically important fish species.According to [28], currently the use of fish resources in several parts of Indonesia is faced with the scarcity of fishery resources due to overfishing.The presence of low target fish in coral reef ecosystem can cause food chain instability in these waters.
After knowing the value of benthic component and reef fish component, then all component adjusted to the value of the coral reef health index which refers to [7] (see Table 5).The calculation results show that the eight observation stations, index values 5 and 6 are the values that appear most often.There are several observation stations that have a low index value.Pramuka 1 from second monitoring has an index value of 1 because low percentage of live coral cover, low resilience, and low fish biomass value.This shows that Pramuka 1 station is difficult to improve again.Index value 2 is found at Pramuka 2 (Monitoring 1) and Semak Daun 2 (Monitoring 2) stations because of the moderate percentage of live coral cover, low resilience, and low fish biomass value.This indicates that the station has sufficient coral cover but at risk of decline.The index value of 3 was found at Pramuka 1 (Monitoring 1), Pramuka 2 (Monitoring 2), Semak Daun 2 (Monitoring 1) stations because of the moderate percentage of live coral cover, moderate resilience, and low fish biomass values.This shows that although the station has low coral cover, it has the potential to improve again.Panggang 1, Panggang 2, and Karang Congkak 1 stations have stable index values.The condition of the corals at the station is healthy and can recover if faced with disturbances.While Karang Congkak 2 and Semak Daun 1 have an index value of 6 in monitoring 1 but decreased to 5 in monitoring 2. This condition can be said that the corals have adequate conditions and are currently in the process of recovering from disturbances.The assessment of coral reef health index is carried out to determine the condition of coral reef ecosystem which can later be used as a reference for various matters, especially monitoring activities that utilize marine space around the Kepulauan Seribu Marine National Park area.Based the Decree of the Director General of Forest Protection and Nature Conservation Number SK.05/IV-KK/2004 concerning the Zone Division of Kepulauan Seribu Marine National Park, all observation stations are included in the Utilization Zone II which is intended for the use of environmental services and nature tourism.Pramuka Island as an administrative center, settlement as well as tourism.Same with the Semak Daun island which is used as tourism.While Panggang Island is used as a residential area for local residents.The low value of the coral reef health index is suspected because the station is the impact of marine space utilization activities such as anthropogenic activities [29], tourism activities that are not environmentally friendly [30], anchorage decline and ship traffic.Although several observation stations show good coral reef health index values, if not properly monitored, it will run into degradation.The efforts of Kepulauan Seribu Marine National Park in determining zoning will be more effective if followed by activities that pay attention to the surrounding ecosystem, especially for utilization zones that will continue to be affected by human activities, either directly or indirectly.In Utilization Zone II, the management that can be carried out in this area includes supervision, inventory and monitoring of ecosystems, coaching, research and development, education, cultivation, tourism potential development, development of facilities and infrastructure, restoration of ecosystems, and others.Effectiveness in environmental management requires a good understanding in solving problems between social, economic and ecological factors [31], especially in conservation areas.The involvement of various elements such as the government, stakeholders, and the community are needed so that coastal management is integrated and sustainable.

Conclusion
Coral reef health index from eight observation stations during two monitoring sessions have various value.Panggang 1, Panggang 2, and Karang Congkak 1 have same high value both in first and second monitoring.Karang Congkak 2 and Semak Daun 1 have change in value from each monitoring but still in good condition.Pramuka 1, Pramuka 2, and Semak Daun 2 have low index value from each monitoring.Overall, average had a high recovery potential even though some stations had low coral cover and low target fish biomass.In addition, several species of macrobenthic bioindicators were found that could contribute to purifying the waters.For future study, it is necessary to observe water quality and socio-economic status of the community so that these observations are not only seen from the environment but also from various aspects such as the socio-economic aspects of coastal communities in order to achieve integrated and sustainable coastal management.

Figure 1 .
Figure 1.Map of observation stations for coral reef health monitoring in Kepulauan Seribu Marine National Park, DKI Jakarta.

Figure 2 .
Figure 2. Illustration of coral reef observation using Underwater Photo Transect (UPT) method.

Figure 3 .
Figure 3. Illustration of reef fish observation using Underwater Visual Census (UVC) method.

5 𝑊
per species (cm) a and b = Species specific index Fish stock in units of biomass (B) is the individual weight of the target fish (W) per area of observation.The formula for individual weight of economically important fish (W) per m 2 area of observation. =  (  ℎ ) 350 2 1 and Karang Congkak 2 station had the highest percentage of live coral cover compared to other observation stations during two monitoring periods.Semak Daun 1 Station has a coral cover percentage of 39.67% (Monitoring 1) and 28.93% (Monitoring 2).Karang Congkak 1 station, the percentage were 49.66% (Monitoring 1) and 43.53% (Monitoring 2).While at Karang Congkak 2 station, the percentage is 58.66% (Monitoring 1) and 33.80% (Monitoring 2).In addition, there are other observation stations that also have the highest live coral cover but have different results from the two monitoring such as Panggang 1 station (31.47%) in monitoring 1.The observation also show that Semak Daun 2 and Panggang 2 station is dominated by Dead Coral with Algae cover both in monitoring 1 and 2.

Figure 6 .
Figure 6.The percentage of benthic cover from eight observation stations in Kepulauan Seribu Marine National Park area during two monitoring sessions.

Figure 7 .
Figure 7.The composition of macrobenthos phylum from eight observation stations in Kepulauan Seribu National Park area during two monitoring sessions.

Figure 8 .
Figure 8.The abundance of macrobenthos species found from eight observation stations in the Kepulauan Seribu Marine National Park area during two monitoring sessions.

Figure 9 .
Figure 9. Xestospongia muta is a macrobenthos species from phylum Porifera which is included in filter feeder organism.

Figure 10 .
Figure 10.The composition of reef fish from eight observation stations in Kepulauan Seribu Marine National Park area for two times monitoring

Figure 11 .
Figure 11.Abundance of reef fish found from eight observation stations in Kepulauan Seribu Marine National Park during two monitoring

Figure 12 .
Figure 12.Map of coral reef health index from eight observation stations in Kepulauan Seribu Marine National Park area during two monitoring.

Table 1 .
and exported data program was CSV.format that can be open using program Microsoft Excel.Live coral cover categories.

Table 2 .
Category of coral reef resilience levels.

Table 4 .
Coral reef health index.

Table 5 .
Coral reef health index from eight observation stations in Kepulauan Seribu Marine National Park area during two monitoring.