DEVELOPMENT OF SUSTAINABLE SHRIMP FARMING BASED ON LAND SUITABILITY AND COASTAL WATERS CARRYING CAPACITY

1. Doctoral Program Multidisciplinary of Postgraduate Study University of Brawijaya, Malang 65145, Indonesia. 2. Faculty of Fisheries and Marine Science, University of Brawijaya, Malang 65145, Indonesia. 3. Faculty of Biology and Natural Sciences, University of Brawijaya, Malang 65145, Indonesia. 4. Faculty of Fisheries and Marine Science, Universitas Muslim Indonesia, Makasar. ...................................................................................................................... Manuscript Info Abstract ......................... ........................................................................ Manuscript History Received: 05 October 2019 Final Accepted: 07 November 2019 Published: December 2019


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The development of farm fishery commodities must consider the economic aspects, including the potential for strong market demand and high selling prices, in both the domestic and international markets. It is expected to be produced at a reasonable cost and to provide opportunities for value added products (Anderson, 2007). B. Widigdo (2013) explains that maximizing short-term economic benefits without considering ecological support would only result in an environmental degradation and an ecological crisis.
Indonesia especially in Java has a negative experience with the development of shrimp farming, pursuing high production without paying much attention to the carrying capacity of the environment, consequently leading to rapid environmental degradation and failure of aquaculture (in 1990). Development of shrimp farming is generally conducted using an intensive farming scale. Ecological changes in the ponds will affect the carrying capacity of the entire environment which will ultimately affect the overall production. The carrying capacity of the environment for a pond farming means its natural ability to provide for a pond (Barg, 1992). According to (Nash et al., 1995;Lewis, 2005) the the impact of organic waste discharges consisting of left overs, feces and dissolved materials on an intensive scale has been proven to impact and to risk the environment.
Therefore, the development of sustainable shrimp farming should consider two important aspects, including the quantification of pond waste and the ability of coastal waters to contain pond waste or its carrying capacity (Soewardi, 2002). One method developed to measure the ability of coastal areas to contain pond waste is by calculating the carrying capacity of the environment, which is based on the capacity of available dissolved oxygen in the waters to decompose the organic wastes generated from farming activities. This estimation is done by predicting the amount of waste that can be accommodated by coastal waters based on the capacity of available dissolved oxygen in the water column depending on the tides (Boyd;Meade, 2012). In addition, the development of the farming must be set at a location that meets the parameters of the farming to obtain compatibility.
In farming activities, determining the suitable location is the initial stage. A suitable location will support the sustainability of farming and can minimize its negative impact on the surrounding environment (Radiarta et al., 2008). Suitability analysis is a complex stage in which researchers must consider several aspects including such as physical and chemical characteristics, and fertility of waters (Valavanis, 2002). Land suitability analysis may utilize the Geographic Information System (GIS). GIS and remote sensing data play an important role in the development and management of aquaculture, especially shrimp farming. The applications of GIS for aquaculture have been comprehensively documented (Kapetsky & Aguilar-Manjarrez, 2007; Aguilar- Manjarrez et al., 2010). Studies generally focus on: zoning and land suitability, the impact of farming on the aquatic environment, planning for aquaculture development with regard to other land users, and inventory and monitoring of aquaculture activities. Therefore, this research aims to determine the suitability of shrimp farming land, taking it into consideration in sustainable aquaculture management, and in assessing the carrying capacity of coastal areas for shrimp farming development based on the quality and quantity of waters.

Research Period and Site:
This research was conducted from March to December 2018. The research site was in the coastal district of Pasangkayu Regency, West Sulawesi. Pasangkayu Regency is located at the coordinates of 0˚ 40' 10" -1˚ 50' 12" of south latitude and 119˚ 25' 26" -119˚ 50' 20" of east longitude. Pasangkayu Regency consists of 12 districts, covering an area of 3,043.75 Km. The distribution of district areas is presented in Table 1.  (1) biophysical data collection in the farming area, consisting of water quality parameters and soil parameters, (2) biophysical data collection of water channels at the opening, primary and secondary channels. The replication was performed 3 times for each spot. The quality parameters of the observed water environment and the tools/methods of measurement are presented in Table 2. The analyses explored the suitability of the coastal area for farming and the carrying capacity of the pond environment. Measurement of suitability analysis based on water quality for carrying capacity of the area was based on the quantity and quality of water.
Tidal observations were conducted at a depth of 3 meters at the lowest tide using a scale stick, for approximately 15 (fifteen) days. Tidal data released by the 2016 Naval Oceanographic Hydro Office was used as a comparison. Tidal current speed was measured using the current meter. While the current pattern was observed by tracing the direction of current movement. Analysis of suitability of pond areas used geographic information systems (GIS) with the Arc View GIS Application Version 3.3.

Analysis Method:-
The method was quantitative analysis of the assimilation capacity and carrying capacity of the pond environment both ecologically and physically. Carrying capacity analysis is a development planning instrument providing an overview of how land use is related to environmental capability. According to (Krom, 1986) the carrying capacity of an area for the development of ponds is the ability of the coastal environment to produce optimal fish products using certain technologies and at certain seasons. The carrying capacity analysis can provide the information needed in assessing the level of land capability in supporting all farming activities in the coastal area.

Pond Waste Assimilation Capacity of the Waters
The dilution capacity of coastal waters was determined by the quantification of the volume of water available on the coast for farming ponds. Quantification of available water volume on the coast was determined by: (1) the volume of sea water entering the beach when the tide rises and (2) the volume of discharge of river water entering the coastal waters. the bottom slope of the beach X : the distance between the coastline at the time of the average tide towards the sea to a point where at a depth of 1.5 meters it is no longer affected by basic water turbulence.
Next , to determine the volume of seawater left when the sea water recedes (V Ls ), the following formula was used: assuming h > 1 Then, remaining time : 2. River water discharge entering coastal waters (Q n ).
To find out the volume of water available in the river every month, an estimation was conducted using a method based on meteorological analysis of water balance, in the following formula: DRO : Ws -I ……………………………….………………….. (4) DRO : direct runoff I : infiltration; Ws = R -E = water surplus; R = precipitation E : evapotranspiration of catchment area The monthly volume of water entering the coastal areas through the river could be calculated using the following formula :  (6) in which : V Pt = the volume of sea water entering the coastal waters (Q)n = freshwater/river water entering the coast  n i n Q) ( = total amount of freshwater/river water entering the coast n = total number of rivers

Quantification of Waste from Farming Activities
Quantification of farm waste was determined in the following assumptions: 512 1. The outcome of organic waste load corresponds the result of the study by (Primavera, 1997)stating that 35% of the total feed given will become friendly pollutants as it is left unconsumed (15%) or as it turned into feces (20%).
2. The load of inorganic waste per 1,000 kg of shrimp production will become polluting nitrogen of 21 kg ha -1 and phospor of 3,6 kg ha -1 (Boyd) 3. Pond waste load from good quality feed with a protein content in the range of 35% -45% will be able to produce FCR of 1.5. This suggests that to produce 1 kg of shrimp, 1.5 kg of feed is needed, and the waste discharged into the water in the form of a total solid suspension (TSS) is 514 grams (Huisman et al., 2002)

Analysis of the Carrying Capacity of Pond Environment
The carrying capacity of the environment (land) for the development of farming ponds was estimated using three approaches: 1. By exploring the relationship between the quantity of water (the volume of water for farming activities) and the waste load, referring to the study by Rakocy and Allison (1981), claiming that the capacity of waters to contain waste is directly proportional to the quantity of water. To maintain the quality of the waters, the containing waters must have a volume of 60-100 times the volume of waste discharged into it. 2. The carrying capacity of the waters is based on the capacity of the available dissolved oxygen content.
Availability of dissolved oxygen in water bodies is the difference between the concentration of O 2 dissolved in inflow (O in ) and concentration of O 2 dissolved in a minimum amount for the farming system (O out ), which is 3 ppm (Boyd, 1990 (8) If the amount of organic waste/kg organism = B, the carrying capacity of the aquatic environment (per kg organism) for farming is: Carrying Capacity = ………………………… (9) = C kg organisme The carrying capacity analysis was based on the assimilation capacity of the waters, which is the ability of waters to contain waste without causing the waters to be polluted. Waste parameters used as benchmarks in determining the assimilation capacity included nitrogen and phosphorus. The feasibility of nitrogen and phosphorus as waste parameters referred to the statement in (Poernomo, 1992; B. J. J. I.-i. P. d. P. I. Widigdo). The allowed nitrogen amount for farming is 1,0 mg lt -1 , and the allowed amount of phospor is 0,5 mg lt -1 .

Model of suitability of brackish water farming land:
Analysis of suitability of land for marginal farming used geographic information system (GIS), specifically the Arc View GIS Application Version 3.3. Area mapping was done by overlaying various maps of land suitability in the current coastal area. It used the geographic information system (GIS), by querying GIS data using the principles of the area discussed earlier, so that spatial information could be obtained: (1) which areas are available for aquaculture development activities using traditional, semi-intensive, and intensive technology, (2) what activities are permitted and not permitted; (3) issues on: (a) the suitability of the area with its allotment; (b) land use for its purpose; (4) the result of the mapping of the area in accordance with its allotment being different from the use of the current area. The suitability of coastal land for aquaculture activities was based on several criteria. They were arranged based on relevant biophysical parameters. In this study, the suitability is divided into four classes: 513 1. Class S1 (Highly suitable). This land is not limited for a certain use only in a sustainable manner, or is only slightly limited and it would not significantly affect what the land produces, and will not increase the expenses for the exploitation of the land. 2. Class S2 (Suitable). This land is moderately limited for a certain sustainable use, the limitation will reduce the productivity or the benefits of the land and increase expenses for the exploitation of the land. 3. Class S3 (Conditionally Suitable). This land is highly limited, but the condition is still manageable, meaning that it can still be improved using a more sophisticated technology or with additional treatment at a reasonable cost. 4. Class N (Not Suitable). This land is seriously limited, thus it would not be possible to use it for a certain sustainable use.
The division of classes was adjusted based on the use of technology in shrimp farming, including the traditional, semi-intensive, and intensive methods. The weighting on each limiting factor was based on the dominance of these parameters on a land allotment. The weighting was indicated by a parameter for the entire evaluation of the land, slope as a parameter of farming pond suitability has a greater weight compared to soil type.
The use of land for farming was based on the criteria of suitability of farming ponds. The criteria used in determining the suitability of farming land were based on the land suitability matrix of the farm area. Based on the weighting and scoring of the parameters, the scores of land suitability classes could be determined for the area of the farm.

Model of land suitability and carrying capacity for brackish water farming based on the level of technology
Scoring was conducted based on data/information from the results of laboratory analysis and direct measurements in the field, along with the climate, tidal data and freshwater availability data. Scoring was determining a value to the unit of land based on its characteristics. Land assessment with a scoring system, according to (Kapetsky & Aguilar-Manjarrez, 2007), is carried out by combining the results of laboratory analyses of soil and water samples and their eligibility criteria to obtain parameters of land characteristics. A score of 4 is "highly suitable" (S1), score 3 is "suitable" (S2), score 2 is "conditionally suitable" (S3), and score 1 is "not suitable" (N).
The weighting of each limiting factor or variable was based on the dominant influence of the variable on the suitability of the vaname shrimp farm, which were then sorted based on how much they affected the allotment. The next step was digitizing the information system by merging thematic maps to get an overview of the coastal areas potential for the application and development of farming ponds. In the GIS process, thematic maps of each parameter of soil and water quality were scored, weighted and categorized based on land suitability, then classified using a score system. The next step was to overlay all soil quality parameters. The result of the merging process was then overlaid again by water quality through matching method to obtain potential locations for farming management. Based on the results of this GIS analysis, thematic maps of land suitability and the level of technology for farming were obtained.

Results and Discussion:-Land Suitability Analysis
The land suitability analysis was based on the land suitability criteria according to the technical guideline by the (Poernomo, 1992). These criteria were arranged based on biophysical parameters relevant to each activity.

Analysis of Suitability Parameters
Details of land and water suitability parameters are presented in Table 3.

Topography:
Land slope greatly affects the management of pond environment. In addition to its excavation and levelling for a new use being costly, it has an impact on the loss of fertile surface soil at the time of water disposal (Higgins et al., 2013). Therefore, it is very important to select a flat or level land or with a slope of around 0% -1%. In general, lands in Pasangkayu have a flat surface with a slope range of 0% -1%, thus they were suitable to be used for shrimp farming due to adequate supply of sea water with tidal energy and freshwater drainage.

Quality of Waters:
Pond water conditions are affected by the water sources (sea and river). Not only does the distance from water sources affect the quantity of water but also the quality of water. Water quality in the farming area of Pasangkayu Regency is presented in Table 3. The effect of the distance from the water source on the pond water conditions is also determined by the slope, elevation, and tidal differences (Lucas et al., 2019) As a tropical country, the climate in Indonesia also affects the condition of water quality at the farming site. However, differences in water quality conditions will not be extreme despite the change of seasons (McQuillan, 2004). The result of water quality measurements is presented in Table 4.  (Subasinghe et al., 2009). Water temperature is highly influential on the physical, chemical, and biological characteristics of ponds, which consequently affects the physiological life of aquaculture organisms. Generally, the rate of shrimp growth will increase as the temperature rises to certain limits (Ponce & Bour, 1997). Specifically, the temperatures of pond waters in Pasangkayu Regency were still appropriate for shrimp farming. The result of temperature measurements is presented be seen in Table 4.

Salinity (mg/l)
The water for irrigating shrimp ponds can be obtained directly from the sea with a salinity of 30 Table 4.  Table 4.

Phospat/PO4 (mg/l)
Phosphate found in waters originates from domestic waste in the form of detergents, agricultural residues (fertilizer), industrial waste, crushed organic matter and phosphate minerals (Lin et al., 2002). Generally, the phosphate content in natural waters is very small and never exceeds 0.1 mg/l, except when there are additions from external sources including fish food waste and agricultural waste. The result of water quality analysis showed phosphate level in the waters of Pasangkayu Regency ranging from 0.04-2.19 mg/l, with an average value of 1.1 mg/l. The result of PO4 measurements is presented in Table 4.

Nitrate NO2 (mg/l)
The result of measurements of nitrate level in Pasangkayu waters indicates a range of 0.03-1.63mg/l, with an average value of 0.83 mg/l. Generally, the nitrate content of Pasangkayu waters was above the water quality standard, which requires the nitrate content for raw water to be a maximum of 10 mg/l. Thus, it can be concluded that the waters of Pasangkayu were polluted by nitrate compounds. The content of nitrate and phosphate in traditional farming pond water is indispensable to stimulate the growth of kelekap, plankton, and moss as the main natural food for fish and shrimp. Sea water nitrate content appropriate for marine life is 0,008 mg/L (Brown et al., 2013). Phosphate content in natural waters ranges from 0.005 to 0.020 mg/L, whereas it is usually around 0.02 mg/L in ground water (Effendi, 2003) (Effendi, 2003). Result of nitrate measurements is presented in Table 4.

Ammonia / NH3 (mg/l)
Ammonia can be present in a molecular form (NH3) or an NH4 ion form, with NH3 being more toxic than NH4 (Mook et al., 2012). NH3 can penetrate parts of the cell membrane faster than NH4. NH3 content of 0.05-0.20 mg/L shall inhibit the growth of aquatic organisms in general. The NH3 content in pond waters in Pasangkayu Regency was detected in the range of 4.03 mg/L with an average of 2.22 mg/L (Table 3, Figure 9). (Chanratchakool et al., 1995) states that the ammonia content permitted for shrimp farming is less than 0.1 mg/L. Ammonia calculation result is presented in Table 4.

Acidity (pH)
The tolerance limit of aquatic organisms for pH varies and is affected by many factors, including temperature, dissolved oxygen, alkalinity, and the type and stage of the organism. A good pH range for shrimp is at 7.5-8.5 with an optimum of 8.0-8.5 (Harahap et al., 2015). In situ measurement of the pond water pH level in Pasangkayu Regency showed a neutral level thus allowing farming development in Pasangkayu Regency area. The result of pH measurements is presented in Table 4.

Suitability Level
Determination of the land suitability class for the area of the farming pond using the parameters is presented in Table 5. The suitability level of the farm in the area was categorized into 4 classes including highly suitable (S1), suitable (S2), conditionally suitable (S3) and not suitable (N).
516   Table 5 and the data collected, the result of the suitability analysis shows the area of farming in each district as presented in Table 6:  Table 6, it shows that overall farming pond in Pasangkayu Regency has an area of 3,965.76 ha, with 732.95 Ha of highly suitable land, 2,984.98 Ha of suitble land, and 247.83 Ha of conditionally suitable land. The level of land suitability based on GIS analysis is illustrated in Figure 1.

Figure 1:-Map of land suitability of ponds in Pasangkayu Regency
Map of the level of suitability of ponds in each district is in Figure 2 for Sarjo Sub-district, Figure 3 for Bambaira Sub-district, Figure 4 for Bambalamotu Sub-district, Figure 5 for Pasangkayu Regency, Figure 6 for Pegongga Subdistrict, Figure 7 for Dapurang Sub-district, Figure 8 for Tikke Raya Sub-district, Figure 9 for Lariang Sub-district, Figure 10 for Baras Sub-district, and Figure 11 for Sarudu Sub-district.

Assimilation Capacity and Carrying Capacity of Aquatic Environment:
The estimated carrying capacity of the environment for farming ponds was based on several aspects, including: (1) the volume of waste water recipient is 60 -100 times the volume of waste discharged to the beach; (2) the capacity of the available dissolved oxygen in the waters to decompose organic waste materials.

Based on the Volume of Water on the Beach and the Volume of Waste:
The result of the calculation of the volume of sea water available on the coast for farming ponds per day for the entire study area in accordance with formulas (1 and 2) is presented in Table 7. The result of the the calculation in Table 7 was used as a basis for determining the area of farming pond based on the assumption of shrimp production capability for each technology used, including the 4 tons ha -1 MT -1 (Intensive Pond) of shrimp production; 2 tons ha -1 MT -1 (semi-intensive pond) of shrimp production; 300 kg ha -1 MT -1 (traditional ponds) of shrimp production. The potential carrying capacity of water to support intensive, semiintensive and traditional farming ponds is presented in Table 8. 523

Based on the Availability of Dissolved Oxygen
Water carrying capacity based on dissolved oxygen content in water bodies was calculated based on the modification of the formula proposed by (Meade, 2012;Boyd) The results of the study of (B. J. J. I.-i. P. d. P. I. Widigdo), (Wedemeyer, 1996)  Complete result of the calculation of oxygen capacity and carrying capacity of the environment in assimilating waste throughout the coastal area Pasangkayu Regency, using the formulas 3-8, is presented in Table 9.

Analysis of Integration of Suitability and Carrying Capacity of Farming Land
The level of suitability of the farming land resulted from the analysis was categorized into 3 classes, including "highly suitable" (S1), "suitable" (S2), and "conditionallt suitable" (S3). The result of the suitability analysis were then integrated with the level of farming technology applied by the community. Local people have been running shrimp farming in coastal areas using traditional technology, with low investment, without windmills and water pumps. The land in the highly suitable category (S1) was the area for traditional farming, in the suitable category (S2) was the area for semi-intensive farming, and in the conditionally suitable category (S3) was an area for intensive farming. Area of ponds in each district is presented in Table 10. Therefore, an area of 732.95 Ha of highly suitable land is prioritized for the use and management of traditional farming or by using traditional-plus technology. Whereas 2,984.98 ha of just suitable land and 247.83 ha of conditionally suitable land are allocated for investment development. With the pattern and direction of the use of farming land, the creation of sustainable resources and the sustainability of shrimp and milkfish farming businesses are expected to increase income, welfare, and standard of living of coastal communities and ultimately can increase regional economic growth.
Maximum utilization of farming land is expected to not exceed the carrying capacity of the aquatic environment based on the capacity to assimilate farming pond waste in the coastal districts of Pasangkayu Regency, as presented in Table 11. Based on the analysis result, the amount of waste discharged into the waters of the 10 coastal districts of Pasangkayu Regency per unit area (ha) of ponds during one planting season on average was 176.98 kg TSS ha -1 for intensive farming activities, and 50.79 kg TSS ha -1, for semi-intensive cultivation technology on average. While it was 1.34 kg TSS ha -1 for the average traditional farming. Based on this, caution is needed in shrimp farming activities for the waste becomes a burden on the aquatic environment, which can reduce the quality of the waters.

Conclusion:-
Based on land suitability calculation in terms of water quality using 7 parameters including Temperature, Salinity, DO, PO4, NO2, NH3, and pH levels, Pasangkayu area was in accordance with the water quality standard set for shrimp farming. Shrimp farming land in Pasangkayu Regency had an area of 3,965.76 ha, comprising respectively 526 of 732.95 Ha of a highly suitable land, 2984.98 Ha of a suitable land, and 247.83 Ha of a conditionally suitable land. Based on the carrying capacity of the aquatic environment to accommodate organic waste, to ensure the development of shrimp farming sustainable, the area for intensive farming was much smaller than semi-intensive and traditional farming. Development of shrimp farming with high investment or intensive technology is directed at f lands with a level of suitability S2 and S3. For the land in level S1 (highly suitable), traditional or traditional-plus farming is designed.

Funding:
This research did not receive external funding, (Independent research).

Conflicts of Interest:
The authors declare no conflicts of interest.