Kabonga Besar mangrove ecosystem health status, Donggala, Indonesia – an analysis of viability versus threats

Mangrove ecosystem functions mainly to provide habitat for thousands of marine species, prevent erosion and stabilize shore-line. Based on that, this research aims to determine the health status of the mangrove ecosystem located at Kabonga Besar, Donggala, Indonesia, by assessing its viability and threat level. This research was critically important as the mangrove ecosystem is being designated by the Government of Indonesia as a site for recreational use. The method used was qualitative research applying a series of focus group discussions involving interviews and observation. Data collection processes involved observing the ecosystem condition, interviewing key stakeholders, and studying relevant documents. The obtained data, i.e., Key Ecological Attribute covering the aspect of Landscape Context, Condition, and Size, and Threat data were analyzed using The Conservancy’s Framework for Viability and Threats. Viability and Threats were analyzed using the Software Application of CAP v6b. The results show that the viability of the mangrove ecosystem was good, but the threat level was high. To improve the ecosystem, as part of the coastal management, the health status of the site should be enhanced by increasing its viability or decreasing its threat level.


Introduction
Mangrove ecosystem health is one of the indicators of its sustainability.Two approaches are used to determine the health, first from viability and second from threats level.The more increased the viability, the healthier the ecosystem or, the more down the threats, the healthier the ecosystem.Therefore, one can improve viability or reduce threats to improve health status [1].Three main factors determine the importance to have of a well-managing mangrove ecosystem.First, mangrove forest stabilizes the coastline, preventing erosion, and providing homes for thousands of marine organisms to spawn.The success of reaching these mangrove functions lies in the efforts to maintain its health [2].
Meanwhile, the mangrove ecosystem has faced significant degradation in many places due to human activities, directly or indirectly.Mangrove ecosystem impairments appeared as a result of, for instance, land conversion, illegal logging, illegal hunting, recreational use, waste dumping and many others [3].The anthropogenic impact on the mangrove forest, such as the harvest of crabs, shrimps, prawns, and fish, not to mention timber and firewood collections, in an alarming amount due to the lack of updated management [4].Sucharitakul and Hardy [5] discussed the issue from a tourism aspect mentioning that 1253 (2023) 012113 IOP Publishing doi:10.1088/1755-1315/1253/1/012113 2 about 70% of mangroves were lost.Hazem et al. (2022) identified that on the Jazan Coast, disruption to mangroves has brought about a destructive and irreversible environmental impact [6].
Having various degradation, as mentioned earlier, different studies have developed many approaches to formulate how mangrove ecosystem health is measured.Prasetya et al [7], for instance, developed a Mangrove Health Index (HMI) based on the parameters of distribution and diversity.Parman et al [8] studied the health of the mangrove ecosystem and mapped it using the geostatistical technique in Matang Mangrove Forest Reserve (MMFR).While Hanum et al [9] developed a Mangrove Quality Index (MQI) considering the mangrove forest, contributing components of a mangrove forest, soil, surrounding marine ecosystem, hydrology, and socio-economic variables.
As mentioned earlier, this study focused on assessing the health status of the Kabonga Besar mangrove ecosystem at a site designated only for recreational use in Donggala, Indonesia.The study concentrated on determining viability and threats as they reflected the site's health.The research becomes vital as the mangrove ecosystem continually faces degradation due to human activities, particularly the growing population [10].
The need to study the health status of the site was due to the increased number of recreational visitors for the last two years, particularly after the tsunami in 2018.The Kabonga Besar mangrove ecosystem has a relatively small site (about 3 ha) operated by a village community group called The Gonenggati Farmer Group.However, the site operated with a lack of robust management applied and with a relatively small amount of annual government funding may create managerial problems in the future.The potential problems lead this research to map the health status in advance.

Research methods
The research method used was qualitative as seen in Table 1.The research framework applied to guide the data analysis was taken partly from TNC (2007) [11], focusing on Viability and Threats Variables.The focus group discussion (FGD) of 17 members consists of three scientists (two fishery expert, two forestry experts, and one psychologist), five individuals from the local people, two site visitors, and three individuals from the local government.(A series of) meetings and observations were conducted from June to August 2022.For sustainability analysis, the Multi-dimensional Scaling (MDS) Method algorithm was used to determine the sustainability of Kabonga Besar Mangrove Ecosystem management assessed based on two reference points, i.e., "good" and "bad" points.A "good" point with a score of 100% indicates that an attribute reflects conditions that support sustainability, and a "bad" point with a score of 0% indicates that an attribute reflects conditions that do not support it.The ordination technique (distance determination) in MDS is based on the Euclidian distance in an n-dimensional space.The ordination technique (distance determination) in MDS based on the Euclidian distance in an n-dimensional space can be written as follows.
The configuration or ordination of an object or Point in MDS was then approximated by regressing the Euclidian distance () from Point i to Point j with the origin  as in the following equation.
In assessing the sustainability index of the site, each category consisting of several attributes was given a score.Scores were generally ranked between 0 and 4. The score results were entered into a matrix table with i as the row that represents the fisheries resource utilization category and j as the column that presents the attribute score.The ALSCAL method optimizes the square distance (ij) to the origin (Oijk), which in five dimensions (i, j, k) is written in the following S-Stress formula.
Where the square distance is the weighted Euclidian distance or what is written as: Using the computer software application of RAPFISH, five dimensions of sustainability are involved, i.e., ecological, economic, infrastructure, institutional and moral.However, only the ecological dimension was used to determine the site's health status.The mangrove forest canopy was determined using the formula: Basal Area = Composition is determined as the proportions (%) of various plant species in relation to the total on a given area.
Lastly, the overall number of trees within the surveyed area determined the population size of the mangrove forest.

Viability
In determining viability, key ecological attributes selected within the category of size, condition, and landscape context corresponding to related indicators.Indicators are the measurable entities used to assess the status of key ecological attributes.They are described based on the criteria that objectively define an indicator into 1 to 4, i.e., 1 for Poor, 2 for Fair, 3 for Good, and 4 for Very Good.Guides to find different indicator ratings centered on the acceptable ranges of variability concept.The table 3 below summarizes the viability assessment process:

Threats
The research proposed two underlying questions.Firstly, what threats are affecting our targets?Secondly, what factors are causing the stresses?The questgions assess threat agents (source of stress) and the impacts of the threatening process on KEA.Threats are classified based on the assessment that defines the likelihood and their ecological consequence on the KEA [12].To avoid bias, assumption that there is no ongoing mitigation activity should prevail.Finally, threats are ranked as low, fair, strong, or very strong.Below is the summary of how the threats analyzed (Table 4).

Viability
Despite three out of seven indicators showing an excellent rank, i.e., rated as very good, the site's overall health was only good.Following is the summary of the results (Table 5).Seven underlying aspects contributed to the viability of the site.Those (ranked from poor to very good) are forest canopy, species composition, population size, ecologic sustainability, seedling availability, density, and mangrove zonation, respectively.

Mangrove canopy
We calculated the tree canopy using a 20 x 20 dot grid basal area.The percentage coverage of the canopy was 83%, indicating the ability of the tree forest to reproduce, maintain, and propagate trees.Tinambunan et al [13] developed criteria for canopy coverage as summarized in the Table 6.The higher the canopy, the more intact the forest.The percentage canopy is an indicator for evaluating mangrove forests' health and growth.Tree canopy, even, determines precipitation, temperature, and cyclone frequency locally and globally [14].Table 6.Criteria for mangrove damage.

Ecologic sustainability
The sustainability of the mangrove ecosystem can happen due to the dynamic relationships between the social and ecological systems.However, unsustainable problems often occur due to social factors and economic development.The Government of Indonesia has appointed the Kabonga Besar mangrove ecosystem as a tourist site, making it a broader possibility to interact with human activity [15].This appointment is the basis for including Sustainability Index as a viability indicator.Also, as the site is located just outside the Capital of Donggala District, the Sustainability Index can be used to evaluate whether or not there is any unfavorable influence of urban activity on the site.We calculated the Sustainability Index for the Kabonga Besar Mangrove Ecosystem as 69.83%, as seen in the following figure.
Ecologic Sustainability is viable with such an index, considering that the site is very close to an urban settlement and open to tourists.Ecologic sustainability refers to the ability of an ecosystem to maintain or support biodiversity processes over time.

Mangrove habitat
In general, mangrove habitat has three zones, i.e., landward (freshwater influence), intermediate (brackish water influence), and fringing zone (seawater influence).We identified that the mangrove at the Kabonga Besar only existed at the intermediate zone, forming alongside the coastline of about three kilometers in length and about 50 -100 m in width (Figure 2).Hence, we ranked this viability indicator as fair.7 3.5.Vegetation density, species composition, and population size Aksarina [15] identified that about two third of the mangrove forest density was from 0 -0.06, which is known as poor, as seen in Figure 3 below.However, our field observation found it to be 1.57, which was why we ranked this indicator as fair.
In terms of species composition, considering that the site has only one zone, i.e., the intermediate zone, we found three species.Those species were Bruguiera gymnorrhiza, Rhizophora apiculate, Rhizophora mucronata.Having three species living on the site with only one zone can be considered very good.We counted the mangrove population at the site using a 20 x 20 m transect and found about 30,000 mangrove stands.

Seedling availability
As part of our sustainability analysis, one aspect that significantly contributed to strengthening its index was the availability of seedlings.Interview results processed through a Multi-Dimensional Scale and Leverage Analysis showed that the respondents position seedling availability as the second highest contributor to the ecologic sustainability of the site.This finding became the reason to rank this indicator as good.
Although the recreational use of an ecosystem is a part of an ecosystem service, it could also contribute to a jaundiced impact if managed unsustainably.One of the environmental issues was waste and litter to run-offs and leachate, heavily polluting mangrove seabed waters and affecting organisms' life on the mangroves [5].Similarly, plastic litter and other domestic waste are distributed densely over the site's seabed.We ranked this threat as high, considering that the site's mangrove formation is only spreading along the coastline with a relatively small width.
Another related issue was road development.However, the main road was outside the site but located next to each other.The main road was the Trans Sulawesi Road connecting Central and South Sulawesi.The economic prospect of the current road brings about the temptation of establishing commercial activities alongside it, creating an irreversible influence.Also, we observed about seven vehicles passing by per minute on average, creating noise that potentially disturbed wildlife species, such as water birds, on the site.

Fishing, killing and poisoning activities
Although most people residing at Kabonga Besar were fishers, illegal fishing, for the last ten years, such as collecting crabs and fish poisoning, was observed as rarely happening.We observed that fishers moored their boats on one or two occasions inside the site.Having those issues altogether ranked the threats as low.

Conclusion
The health status of the Kabonga Besar mangrove ecosystem was good despite the high threat level.When viability and threat were analyzed separately, this finding was somewhat controversial.In general, if viability is high, the threat should be low or the other way around.Nonetheless, if we want to emphasize that the site is healthy, we should mention its high viability.To better managed the recreational use of the mangrove ecosystem as part of the coastal management the health status of the site should be enhanced by increasing its viability or decreasing its threat level.
diameter Mangrove forest density was determined using the formula: Density = (Number of Tree)/(Surveyed Area)

Table 1 .
Summary of the Research Methods.The obtained data, i.e., 1) Key Ecological Attribute (KEA) covering the aspect of Landscape Context, Condition, and Size, and 2) Threat data were analyzed using The Conservancy's Framework for Viability and Threats.Viability and Threat data were analyzed using the Software Application of CAP v6b.To begin with, following is the term for some used variables (table 2): 3

Table 2 .
Variables Terminology.Aspects of a target's biology or ecology that, if missing or altered, would lead to the loss of that target over time.More technically, the most critical components of biological composition, structure, interactions and processes, environmental regimes, and landscape configuration that sustain a target's viability or ecological integrity over space and time.ViabilityThe status or "health" of a population of a specific plant or animal species.More generally, viability indicates the ability of a target to withstand or recover from most natural or anthropogenic disturbances.IndicatorMeasurable entities related to a specific information need.It should meet the criteria of being: measurable, precise, consistent, and sensitive.The proximate activities or processes that directly have caused, are causing, or may cause stresses and thus the destruction, degradation, and/or impairment of focal conservation targets.