The success of coral Acropora sp. transplantation with various methods in Raja Ampat Regency, Indonesia

Climate change and anthropogenic pressures have caused massive damage and degradation of coral reef ecosystem services in almost all countries in the Indian Ocean. The status of coral reefs at 1,067 sites in Indonesia is included in the poor category with 386 sites (36.18%) and the reefs in the moderate category with 366 sites (34.3%). The condition, area, and function of this coral reef ecosystem can be restored through rehabilitation activities using the transplant method. This study aimed to determine the success of coral Acropora sp transplantation in two different methods in Raja Ampat Regency, i.e., Yensawai Village. The research was conducted from September to December 2021 using PVC and iron racks. The increase in length of coral fragments was measured using a caliper and survival was calculated for the number of coral fragments at the end of the study. The results showed that coral fragments with PVC racks had a growth rate of 0.67±0.54 mm/day and a survival rate of 81.25%, while those on iron racks had a growth rate of 0.64±0,66 mm/day and a survival rate of 90%. Both methods showed a high coral survival rate (>80%). T-test statistical analysis revealed no apparent variance between the two approaches (p= 0.85). Our findings suggest that both methods are suitable for use in Yensawai Village.


Introduction
A large variety of marine flora and fauna is found on coral reef as the one of the world's most intricate ecosystems [1].Through coastal protection, fisheries, tourism, and recreational opportunities, coral reef ecosystems support the livelihoods of millions of people while also helping to sequester significant amounts of carbon.Massive bleaching due to global climate change has led to the degradation of corals throughout the world.Anthropogenic influence also destroyed reefs greatly such as illegal fishing, anchoring activities, and coral mining [2].According to satellite imagery, there are 2.5 million ha of coral reefs in Indonesia [3] and the bad condition category is 36,18% followed by 34,3% for moderates, 22,96% for good or 6,56% for very good.[4].The average percentage of live coral (HC) cover in the shallow water of Raja Ampat is 32.24% [5].
Increased damage of corals is not supported by the ability of corals to produce, so corals need a long time to recover.The recovery period for damaged reefs varies widely, and is highly reliant on the nature of the disturbance and the restoration efforts undertaken [6].The restoration of coral reefs is predicted to increase the population of highly valuable fish and foster the growth of marine tourism enterprises, both of which are good for Yensawai's sustainable coastal communities.In addition to climate action and measures for conservation and protection, it is also necessary to preserve and renovate reef ecosystems [7].This study's aim is to figure out the success of coral transplantation Acropora sp in terms of survival and growth rate of coral seedlings with two different methods (PVC and iron rack) in Yensawai Village, Raja Ampat Regency.

Date and study area
The study was conducted from September to December 2021 in Yensawai Village, Raja Ampat Regency (Figure 1).Coral transplantation is carried out in an easily accessible location to be monitored by the community independently.Transplanted corals were monitored every two weeks.

Data collection
2.2.1.Monitoring of transplanted coral.Donors (coral fragment) were taken from healthy coral colonies that are accessible close to the restoration site.The transplantation used two methods (PVC and iron racks) (Figure 2).The coral species monitored for this study was Acropora sp.The number of samples marked was 30 from a total of 800 coral fragments from each method.The study site has sand and rubble substrate with a water depth of 5 meters and the distance from the shoreline is about 60 meters.The increase in length and width of coral fragments was measured using a caliper and the number of live corals in all transplanted seedlings was calculated as survival rate.

Water quality
Water quality measurements are carried out directly in the field.Parameter measured are temperature, salinity, pH, water transparency and water current.The temperature ( 0 C) was measured by dipping a thermometer in the water, and all values were recorded.Samples for salinity ( 0 /00) were measured with a hand refractometer.Degree of acidity (pH) was measured using pH meter.Whereas to measure water transparency is done by using Secchi disk.

Data analysis 2.4.1. Survival rate and growth rate analysis.
The transplanted coral fragments were calculated for growth rate and survival rate.The coral survival rate can be calculated by comparing the number of corals present at the research's end with the total of transplanted corals.The survival rate of coral fragments is calculated based on the formula:

‫ܰ‬
Where: SR = survival rate (%); Nt = Total of coral fragments at the end of research; N0 = Total of coral fragments at the beginning of the study.Whereas the growth rate of transplanted coral fragments is calculated based on the formula: Where: P = growth rate of transplanted coral fragments (mm/day); Lt = length/width of coral fragments after the t-observation (mm); Lo = length/width of coral fragment at the beginning of the study (mm); ‫ݐ∆‬ = Measurement time interval.

Statistical analysis
Microsoft Excel has been used for statistical analysis.The t-test was performed to compare the differences in coral growth rates between PVC and iron racks methods.

Result and discussion
Restoration is the process of recovering a degraded ecosystem.Based on the Minister of the Environment Decree Number 4 of 2001 [8], the status of the coral reef ecosystem shows that the condition of the coral reef ecosystem in Yensawai is in the moderate category with the status of a damaged area.Damage to the coral reefs in Yensawai was caused by the entry of heavy equipment for constructing the jetty and as a place for ships to dock.These activities are essential for natural recovery.Hein et al. [9] said that the growth rate of coral fragments and their survival as important indicators of the success of the restoration.The results of monitoring the transplanted coral fragments showed a good survival rate during the three months of observation (Figure 3).According to Harriot and Fisk [10] one of the key success factors of transplantation can be calculated if the number of living corals at the end of the study of the total transplanted is greater than 50%.In this study, the survival rate of coral for PVC rack was 81.25% and for the iron rack was 90%, so this research is said to be successful because the average survival rate in both methods is above the standard (Figure 3).The survival rate of the Acropora used in this study was similar to the 90% and 89% survival rates of other Acropora transplants made to Pandawa Beach on Bali Island and Kondang Merak Beach in Malang Regency [11,12].
In this study, coral fragments of Acropora sp were still dying three months after planting.The corals that died in this observation were not only defined as biologically dead but also as the loss of corals from the media.This observation found that the survival rate of coral fragments in the iron rack was higher when compared to the PVC rack.A lot of coral in the PVC was missing from the media because of the release of coral fragments from the rack on the PVC that had not been properly tied.
The development of transplanted coral fragments is also an important factor in determining coral transplantation success [10].The growth rate of Acropora sp transplanted by both methods is shown in Figure 4.The length of transplanted coral on the Yensawai showed growth over time.The length growth rate of Acropora sp transplanted corals for two months in Yensawai showed good conditions.In the PVC racks method, the average growth rate of coral fragments is 0,64 mm/day or 4,66 mm/week.While the iron rack method, the average growth rate of coral fragments is 0,67 mm/day or 4,46 mm/week.The growth rate of coral fragments in the two transplants media was not significantly different, which was further proven by the t-test analysis in Table 2.
The results obtained in this study were slightly higher than those of Muhlis [13], which showed the skeletal growth rate of Acropora sp in Senggigi waters, Lombok to be 0,148 mm/day.Other research results by Hairunizar et al. [14] stated that the growth rate of corals of Acropora sp at a depth of 4 meters was 1.89 mm/week.Acropora is a coral genus with a high survival rate and growth rate [3].Weil et al. [15] said that Acroporids are regarded as the most rapidly growing corals, with some species having a linear expansion of more than 20 cm every year.According to Rani et al. [16], it was demonstrated that transplanted corals do not need a lot of energy to adapt to their new environment due to the ecological conditions of transplant areas, which are quite similar to donor areas.The water quality at the study site is shown in Table 1.Water temperature range of Yensawai, Raja Ampat is 28.5-29.1 o C. According to Giyanto et al. [17] coral reefs can live in a temperature range 23-30 o C, so the study site (Yensawai Waters) was suitable for coral growth.The range of salinity at the research site is 33-34 o /oo.According to Richmond [18], good salinity for coral larvae attachment ranges from 32-40 o /oo.Nybakken [19] also mentioned that good salinity for coral reefs ranges between 30-35 o /oo.
The water transparency will determine the level of photosynthesis of marine plants in the waters [20].Yensawai Waters have water transparency > 5 meter.Measurements are carried out when there is minimal current and wind so that light penetration into the waters is maximized.Water visibility is greatly influenced by the intensity of sunlight, the absorption process and the content of the suspension material.The range surface current velocity at the research site is 0.16-0.17m/s.Current velocity will affect coral transplantation, including inhibition of the supply of food and oxygen.According to Tanamal et al. [21], the current velocity suitable for coral transplantation is about 0.1-0.4m/s, so the current velocity at the study site is still suitable for transplanted coral growth.The statistical analysis (Table 2) revealed no statistically significant difference between the two methods' effects on the growth of Acropora sp.It did not have a significant difference in the growth of Acropora sp. from both methods.The use of both media in transplantation activities can be assumed to be equally effective.Referring to the observation of survival rate and growth rate which are in good condition, it also supports that both methods can be applied in Yensawai.The method using iron racks is suitable for rubble areas where coral has died, and wavy areas such as at the study site, but the cost required for making this media is relatively large [22].While the PVC media method requires a lower cost, the slippery surface of the PVC reduces the potential for algae attachment [23].
PVC racks can be a method that can be applied in the long term to community-based rehabilitation.It is because transplantation using PVC racks does not require special skills, so the community is able to replicate it independently.Meanwhile, the iron rack media needs to be welded to the welder, so it requires more effort.PVC racks are also considered more study because they are filled with cement on the inside, thus reducing the shock caused by waves.
The ability of coral fragments to survive and grow depends on a number of variables, including the method's suitability, how the fragments are treated, biological aspects like the transplanted coral's physiology, and how the coral reacts to its environment [24].Routine maintenance and self-monitoring by the community are no less important factors to maintain and ensure the transplanted fragments survive and grow.

Conclusion
The results of monitoring the transplanted coral fragments showed a good survival rate during the three months of observation, with the survival rate of coral for PVC rack was 81.25% and for the iron rack was 90%.Because both methods have an average survival rate of more than 80%, it is said to be successful, whereas PVC racks and iron racks has growth rate 0,67±0.54mm/day and 0,64±06.66mm/day, respectively.The growth rate of transplanted corals (Acropora sp.) in Yensawai also demonstrated favorable conditions.The growth rate of coral fragments in the two transplants media was not significantly different, proven by the t-test analysis (P = 0,85).Referring to the observation of survival rate and length growth rate which are in good condition, it also supports that both methods can be applied in Yensawai.

Figure 1 .
Figure 1.Location maps of the study area.

Figure 3 .
Figure 3.Comparison of the survival rates of the two methods after 3 months monitoring.

Figure 4 .
Figure 4. Comparison of the length growth rate of the two methods after 3 months monitoring.
of the coral fragmnts (mm/day)

Table 1 .
Result of the measurement of water quality.Length growth rate of transplanted coral Acropora sp.

Table 2 .
T-test analysis for the differences in coral length growth rates between PVC and iron racks method.