Characteristics of the aquatic environment as a basis for brackish water pond development in the Cilacap Regency Area

The coastal of Cilacap is a large aquaculture area for vannamei shrimp (Litopenaeus vannamei). The purpose of this study is to determine the concentration of water quality in borewell and pond as the basis for brackish water development. The research method used a descriptive method by describing the sample results compared to environmental quality standards for biota based on Government Regulation Number 22 of 2021. Sampling was carried out monthly during May-July 2022 at 3 location. Observations were made on water physico-chemical parameters (temperature, pH, salinity, dissolved oxygen, BOD, nitrite, nitrate, ammonia and phosphate). Based on the analysis, it is known that the water quality of the borewell varied, namely temperature (29.75±0.96°C), pH (7.74±0.26), salinity (15±6.42%o), DO (6.52±2.83) mg/l, BOD (2.48.±1.67) mg/l, nitrate (0.43±0.38) mg/l, nitrite (0.02±0.02) mg/l, ammonia (0.46±0.30) mg/l and phosphate (0.13±0.10) mg/l. As for the pond water quality parameters, the temperature values were (30.14±1.46°C), pH (7.94±0.22), salinity (12.22±6.02%o), DO (7.58±1.30) mg/l, BOD (26.10±24.83) mg/l, nitrate (1.86±1.30) mg/l, nitrite (0.09±0.15) mg/l, ammonia (1.07±0.30) mg/l and phosphate (0.128±0.098) mg/l. Based on Government Regulation Number 22 of 2021 it is concluded that the water conditions are still suitable for the life of aquatic biota and good enough for fishery development.


Introduction
Indonesia is an archipelagic country which has approximately 16,771 islands with a coastline as long as (± 95,181 km) [1].This makes the coastal area as a mainstay of income for the Indonesian people.One form of management of coastal areas is to use them as an aquaculture area [2].The food production sector is currently growing so rapidly and globally this production continues to increase and (89% come from Asia).In 2018, Indonesia was ranked 2 nd for capture and aquaculture production [3].Based on data from the Ministry of Maritime Affairs and Fisheries in 2018, shrimp became Indonesia's first leading export commodity in 2018 (with a total volume 146,164,096.07kg), and the economic value of shrimp contributes to foreign exchange USD 1.3 billion (36.96% of the total export value) [4].
Shrimp ponds are generally built in mangrove forest areas, and if it is not carried out with good planning it will result in a decrease in the quality of the coastal environment, including changes in 2 ecosystems, coastal typologies, characteristics and carrying capacity of land.This is feared to threaten the sustainability of the aquaculture business itself.The emergence of these concerns is based on the fact that the sustainability of pond productivity is closely related to the environmental quality of coastal areas.Currently, shrimp ponds in Indonesia have an area of not less than 600 thousand ha, and most of them (> 85%) are shrimp ponds that are managed traditionally.To reduce ecological pressure on mangrove forests, and to obtain good water quality, in the last decade, ponds have been developed in sandy areas (non-mangrove), especially in the sandy areas of the southern coast of Java.However, in general, pond construction only uses a type of plastic mulch that leaks easily.Considering that the water extraction system for pond purposes is generally carried out through drilled wells built around the coast, pond leakage results in contamination of the pumped water.There was cross-pollution between one pond and another, and this resulted in the spread of disease in the area.
Cilacap Regency is located on the south coast of Java Island, whose coast is widely used as cultivated land.This regency is geographically located at 108°57'51.66''-109°23'38.87''East and 7°37'2.77"-7°47'4.68''South with elevation 0 -9 m above sea level [5].Since 2016 the south coast of Cilacap Regency has begun to be widely used for the cultivation of vannamei (Litopenaeus vannamei) shrimp ponds.The characteristics of sandy beaches can be found almost along the coast, with slightly muddy beaches, especially around river mouth [6].
Based on the results of previous research, it is known that the area of vannamei shrimp cultivation in Cilacap district has has increased since 2017 covering an area of 65.78 ha until 2020 the area reaches 227 ha.The increase in the number of ponds resulted in an increase in shrimp production from 3,387 tons in 2017 to 4,149 tons in 2018.In 2019 it decreased to 2,941 tons and then in 2020 it increased again to 4,786 tons [7].This fluctuation is allegedly related to the intrusion of pond water into the soil layer around the coast and pumped back to irrigate other ponds, so that the spread of disease cannot be avoided.
By looking at the potential that exists on the coast of Cilacap as a vannamei shrimp aquaculture area, a study of the environmental conditions of the coastal waters of Cilacap Regency is needs as a reference in the development of sustainable shrimp ponds.The purpose of this study was to determine and analyze the condition of the waters of shrimp ponds in the southern part of Cilacap Regency, as a basis for the development of sustainable aquaculture ponds.

Time and location
This study was conducted for 3 months, starting with observation activities in May -July 2022.The study location is in the sandy coastal aquaculture area of Cilacap District (Central Java).Sampling locations were carried out at three observation stations (locations), namely location 1 (Tegalkamuyan Village), Location 2 (Menganti Village), and location 3 (Slarang Village) (Table 1 and Figure 1).Water sample analysis were carried out at the Environmental Laboratory, Faculty of Biology, Jenderal Sudirman University, Purwokerto.

Materials and tools
The materials used in this study were HNO 3 and HCl 4 .The tools used in this study were a sample storage box (cooler box), large plastic, buckets, sample bottles, thermometer, pH meter, DO meter, refractometer, measuring pipettes, GPS and stationery.

Research procedure and analysis
Research activities consist of observations, interviews, water sampling and analysis of water samples in the laboratory.Water samples from shrimp pond water and coastal borewell water were measured insitu and ex-situ analysis.The water sample was put into a sample bottle and preserved by cooling it in a cooler box.After that samples was analyzed in the laboratory.The parameters observed in the study, the units used, the method of analysis, and the place of analysis are shown in

Physical-chemical parameters
The following are the value of water quality from field measurements and results of laboratory analysis consisting of several physical and chemical parameters.The results of the water quality of the coastal borehole waters are presented in Table 3 and pond water quality in Table 4.

a. Temperature
Based on the results of surface temperature measurements carried out directly in the field (in situ), it was found that the water temperature of drilled wells on the coast ranged 28.2 -31.6 o C (29.75 o C on average) (Table 3).Meanwhile, the pool temperature ranged 28.4 -32.1 o C (average 30.14 o C) (Table 4).
The mean temperature of the borewell water at the three locations was lower than that in the pond.This is because the well water is in the ground and is not affected by external temperature (Figure 2).Based on Government Regulation No. 22 of 2021, the temperature parameters in Cilacap waters are still in a good category because they are still within the threshold value of sea water quality standards (28-30 o C).
If based on SNI 01-7246-2006 for the quality requirements of supply water (inlet) or maintenance of vannamei shrimp in ponds with intensive technology, the temperature of the waters on the coast of Cilacap is still in a good condition to be used as supply water and the temperature of the pond as a place for biota to live.The optimal temperature for the growth of vaname shrimp ranges from 26-32 o C [8].

b. Salinity
Based on the results of observations made for 3 months, the salinity value of coastal well water varied (7-26 %o) (Table 3), while the salinity value of the pond maintenance ponds ranged 5-21 %o (Table 4).
Based on Figure 3, it is known that the lowest salinity value was in Slarang Village (Location 3), which was an average of 5%o for pond water and 7.67%o for bore well water.Based on Government Regulation Number 22 of 2021, the standard value for seawater quality is 33-34%o, so it is still said to be far lower than the seawater quality standard value.Even so, the average salinity value obtained is still said to be good for supporting the sustainability of vannamei shrimp farming in Cilacap.Vannamei shrimp can live in a wide range of salinity (euryhaline) (2-40 ppt) [9].Based on SNI 01-7246-2006 for 6 supply (inlet) water quality requirements or maintenance of vannamei shrimp in ponds with intensive technology, good salinity for supply water is 10-40 ppt while for pond maintenance it is 15-25 ppt.3).Meanwhile, the pH value of rearing water (pond) ranged from 7.6 to 8.21 (Table 4).Based on Figure 4, it is known that from the three locations the pH value obtained is in accordance with the standard value of sea water quality according to Government Regulation Number 22 of 2021 for marine biota, which is between 7 to 8.5.
Meanwhile, based on SNI 01-7246-2006 for supply water quality requirements (inlet) or vaname shrimp rearing in ponds with intensive technology, the optimal pH value is 7.5 -8.5.So from the three locations, the value of the degree of acidity (pH) of the waters is in a good category to support vanname shrimp cultivation activities.Based on the observations made, the DO values obtained varied.DO values in well water ranged from 3.2 í 12 mg/l (average 6.5 mg/L) (Table 3).Meanwhile, DO values in ponds ranged from 6 -9.8 mg/L (average 7.6 mg/L) (Table 4).Based on Government Regulation Number 22 of 2021 concerning water quality standards for biota life, a waters can be categorized as good waters if the dissolved oxygen level (DO) is > 5 ppm.Meanwhile , based on SNI 01-7246-2006 for the maintenance of vaname shrimp is good if the DO value > 3.5 ppm.So the DO value obtained is feasible to support shrimp pond cultivation activites.

e. Biochemical Oxygen Demand (BOD)
Based on the results of laboratory analysis on BOD, the BOD values in bore well water and pond water were very different (Figure 6).The values obtained in coastal bore well water ranged from 0.06 -7.48 mg/L (average 2.48 mg/L) (Table 3).According to Government Regulation Number 22 of 2021, the standard value of sea water quality for maximum biota is 20 mg/L.The level of pollution is low if the BOD value is 0 -10 mg/L, while the level of pollution is moderate if the BOD value is 10 -20 mg/l [10].So, for coastal well water, it can be said that the value is included in the lightly polluted category.However, according to the reference of SNI 01-7246-2006 for the quality of supply water (inlet water), the resulting BOD value is less than optimal because it is less than 3 mg/L.This is because when a body of water is polluted by organic substances, bacteria can use up dissolved oxygen in the water during the oxidation process, resulting in the death of fish or other biota that live in it.In contrast, the BOD value in ponds was quite high and varied from 9.36 to 74.82 mg/L (average 26.098 mg/L) (Table 4).Based on Figure 6, it can be seen that from the three locations the BOD value content is above 20 mg/L.Based on Figure 7, the highest BOD value is in Slarang Village.f.Nitrate (NO 3 ) Based on the results of laboratory analysis, the value of nitrate)\ in bore well water obtained ranged from 0.055 to 1.1184 mg/L (average 0.433 mg/L) (Table 3).Meanwhile, the value of nitrate in pond water ranged from 0.377 to 4.39 mg/L (the average was 1.86 mg/L) (Table 4).Based on Government Regulation Number 22 of 2021 concerning water quality standards for biota life, the nitrate concentration value is not more than 0.06 mg/l.Meanwhile, based on SNI 01-7246-2006 concerning water quality requirements for vannamei shrimp rearing in ponds with intensive technology, the tolerance limit for nitrate value is 0.5 mg/L.So it can be said that the nitrate concentration in Cilacap coastal waters, both in well water and pond water at the three locations, has exceeded the quality standard limit (Figure 7).

g. Nitrite (NO 2 )
Based on the results of laboratory analysis, the concentration of nitrite values in coastal bore wells and ponds varied (Figure 8).The concentration of nitrite in coastal bore well water ranged from 0.001 to 0.075 mg/L (mean 0.018 mg/L) (Table 3).Meanwhile, the value of nitrite in pond water ranged from 0.007 to 0.444 mg/L (the average was 0.087 mg/L) (Table 4).However, according to the Canadian Council of Ministers of the Environment (2008), states that natural waters generally have a nitrite value of approximately 0.001 mg/L and should not exceed 0.06 mg/L [11].Meanwhile, based on SNI 01-7246-2006 concerning water quality requirements for vaname shrimp rearing in ponds with intensive technology, the tolerance limit for nitrite value is 0.01 mg/L.Based on Figure 8, it can be seen that the concentration of nitrite in well water at three locations is still in the good category.Meanwhile, the value of nitrite concentration in the pond has exceeded the water quality requirements for vanname shrimp rearing.h.Ammonia (NH 3 ) Based on the results of the analysis shows that the concentration of total ammonia in coastal bore well water ranged from 0.186 to 1,348 mg/L (average 0.46 mg/L) (Table 3).Meanwhile, the ammonia value in pond water ranged from 0.232 to 3,785 mg/L (average 1.068 mg/L) (Table 4).Based on Government Regulation Number 22 of 2021 concerning water quality standards for the life of the biota, the concentration of ammonia is not more than 0.3 mg/l.Based on the results of the concentration analysis in three locations, the ammonia concentration in the villages of Tegalkamulyan and Slarang has exceeded the quality standard limit.Meanwhile in Menganti village the ammonia concentration is still normal (Figure 9).

i. Phospat (PO 4 )
Based on the results of the analysis carried out for 3 months, the value of the phosphate concentration varied.Phosphate concentrations in coastal bore well water ranged from 0.026 to 0.302 mg/L (mean 0.128 mg/L) (Table 3).Meanwhile, the phosphate content in pond water ranged from 0.032 to 0.461 mg/L (average 0.245 mg/L) (Table 4).Based on Government Regulation Number 22 of 2021 concerning water quality standards for the life of biota, the concentration of phosphate is not more than 0.015 mg/l.It can be seen from Figure 10

Discussion
Cilacap Coast is currently widely used as vannamei aquaculture land.Improved cultivation technology makes a positive contribution to the economy of the cultivating community but also has a negative impact or problem on the ecosystem and socio-economic community.Water quality management considers the concentration of nitrogen compounds in water consisting of nitrate, nitrite, and ammonia.Base on the measurement of water quality parameters, The quality of sea water used for marine biota and other activities should ideally meet standards, both physically, chemically, and biologically.The value of water quality is compared to sea water quality standards based on Government Regulation Number 22 of 2021 concerning the Implementation of Environmental Protection and Management ratified by the President of the Republic of Indonesia.The value of the quality of marine waters that exceeds the maximum threshold for its designation will be classified as polluted waters.
The water temperature of the ponds or borewell at the three locations is categorized as good.Temperature has a very important role in controlling the condition of an aquatic ecosystem.Temperature can affect all processes that occur in waters both from the physical, chemical and biological aspects of water bodies.The light factor is important for aquatic organisms.In shrimp culture systems, light intensity affects the performance and biomass of shrimp and their microbial community [12].Temperature also affects salinity and dissolved oxygen.If the temperature increases, the salinity will also increase while the dissolved oxygen decreases [13].
Salinity in water affects the balance of osmoregulation of the body with energetic processes which in turn affect growth.Under certain conditions, pond water sources can become hypersaline/high salt content (above 40 ppt), this often occurs in the dry season [8].At salinity > 45 ppt the biota is very difficult to adapt.Types of biota that have a wide range of salinity such as white shrimp (Litopenaeus vannamei) [14].The salinity value belongs to the good category in the villages of Tegalkamulyan and Menganti.Meanwhile, Slarang village has a lower salinity value compared to the other two locations.This is because it is located right at the mouth of the Serayu river.The difference in salinity values in the Cilacap coastal waters at the three locations is due to high rainfall at the time of sampling, and the many influences from the mainland.The existence of sedimentation in the Menganti area caused abrasion around the Tegalkamulyan and Slarang coasts which caused the location of the drilled well to eventually move to become increasingly indented towards the mainland.In addition, differences in evaporation and precipitation can also result in variations in the value of water salinity.The low salinity value in Slarang village is one of the reasons why the level of shrimp production in Slarang village is not optimal so that many ponds have been converted into fish ponds and land function specialists into housing.Although vannamei shrimp are euryhaline, young shrimp aged 1-2 months require a salt content of 15-25 ppt for optimal growth.After more than 2 months of age, shrimp growth is relatively good at salinities between 15-30 ppt [8].
Variations in the pH value of the waters greatly affect the biota in a waters.In an aquatic ecosystem, living things have different abilities to tolerate water acidity (pH) [15].The concentration of pH affects the level of fertility of the waters because it affects the life of micro-organisms.Acidic waters tend to cause death in biota as well as at pH values that are too alkaline An increase in pH can result in an increase in ammonia concentration, whereas if the pH is low, there will be an increase in H2S concentration.However, water conditions with extreme pH can also make shrimp stressed, carapace softening, and shrimp survival is low.The optimal water pH for shrimp culture is 6.5 to 9 [16].From the three locations, the value of the degree of acidity (pH) of the waters is in a good category to support vanname shrimp cultivation activities.Factors that affect the pH of different waters are due to the presence of organic matter from shrimp pond waste.The pH value obtained from pond ponds is higher than the pH in borewell water because in pond ponds feeding is carried out which causes the level of eutrophication in the pond ecosystem, which is followed by an increase in phytoplankton biomass which in turn can affect fluctuations in pond water pH.In addition, another factor that can affect the pH is the time of sampling.The pH value of water is influenced by the concentration of CO2 during the day or at night.During the day there is a process of photosynthesis which causes the concentration of CO 2 to decrease so that the pH of the water increases.On the other hand, at night all organisms in the water release CO 2 as a result of respiration so that the pH of the water decreases.
Dissolved oxygen (DO) is a very important water quality variable in shrimp farming.All aquatic organisms need dissolved oxygen for metabolism, either fish, bacteria, and phytoplankton.Oxygen enters the water through several processes.Oxygen can be diffused directly from the atmosphere after contact between the surface water and air containing oxygen.Other sources of oxygen in aquaculture ponds are aerators or waterwheels and water changes [14].In shrimp farming to keep salinity and dissolved oxygen within acceptable values, the aerator wheel must be turned on to maintain optimum temperature levels.This causes the DO value in the pond to be higher than that of the well water, as shown in Figure 5.At the three locations, the DO value of the pond water was higher than that of the DO in well water.DO will decrease if BOD and organic matter increase [9].The average DO value of drilled well water on the coast of Cilacap is high because the substrate of the well location is a sandy area that has high porosity, thus allowing the entry of pond waste water that is dumped directly onto the beach into the soil causing high DO.However, it can be said that the DO parameter value is still appropriate to support the development of vannamei shrimp culture in Cilacap.
Biochemical Oxygen Demand (BOD) is a characteristic that indicates the amount of dissolved oxygen required by microorganisms to decompose or decompose organic matter under aerobic conditions.BOD is an index number for pollutant benchmarks from waste in a waters.The greater the concentration of BOD in waters, the higher the concentration of organic matter in the water [10].The high content of BOD at several points and times indicates the possibility of contamination, both from the way the pond water quality is maintained, the age of the shrimp in the pond, and must also be considered from other parameters.So if the pond waste water is directly discharged to the beach, it can cause high water pollution.Although the presence of pond water into the soil, it does not really affect the BOD value.This is because the sand can filter the particles contained in the pond wastewater so that the BOD concentration decreases.The highest BOD value is in Slarang Village due to its location near the mouth of the Serayu river and electric steam power plant (PLTU) Cilacap.The high content of BOD comes from domestic waste generated by human and industrial activities that dump waste into river bodies or directly into waters.Community and industrial activities that like to dispose of waste into river bodies contribute to the burden of organic matter pollution in rivers [17].
The high value of nitrate concentration in well water and ponds on the coast of Cilacap is due to the high concentration of ammonia which is influenced by the input of organic matter from several activities on land such as aquaculture waste from feed and probiotics, or input from household, agricultural and even industrial waste.Ammonia is then oxidized through the nitrification process to produce nitrate.The high concentration of nitrate is also caused by the inhibition of the denitrification process, which is the process of reducing nitrate to nitrogen gas (N2) with the help of heterotroph bacteria such as Bacillus [14].The high value of nitrate concentrations causes eutrophication (enrichment) of waters and stimulates the rapid growth of algae and aquatic plants (blooming) if supported by the availability of nutrients along with feeding with high protein.The presence of blooming algae can eventually cause the death of the shrimp.Nitrification is the process of oxidation of ammonia into nitrites and nitrates.This process is important in the nitrogen cycle and takes place under aerobic conditions.Nitrate content is an important form of nitrogen in waters for aquaculture, because it can be utilized by plankton.The oxidation of ammonia to nitrite is assisted by the bacteria Nitrosomonas sp. while the change of nitrite to nitrate by Nitrobacter sp.[10].
Nitrite is the only partially oxidized form of nitrogen.Nitrite does not last long and is a temporary state of the oxidation process between ammonia and nitrate.Nitrite is not fixed and can turn into ammonia or oxidized to nitrate [18].The concentration of nitrite in natural waters is generally very low due to its unstable nature due to the presence of oxygen [19].Because nitrite is a transitional form from ammonia to nitrate, there is no specific reference for quality standards for the concentration of nitrite in waters.The high concentration of nitrite is caused by the disruption of the nitrification process in waters which is influenced by light, temperature, salinity, dissolved oxygen, pH, ammonia levels and the bacteria that play a role in it.Excess nitrite can cause a decrease in shrimp immunity so that it is susceptible to disease.Toxic nitrite binds to hemoglobin (in shrimp it is called hemocyanin), so it cannot bind oxygen, causing IOP Publishing doi:10.1088/1755-1315/1260/1/01202712 the shrimp body to lack oxygen and nutrients [20].The concentration of nitrite also increases by the length of time of cultivation.Ammonia (NH 3 ) is one of the chemicals commonly contained in waste.Ammonia levels in seawater are highly variable and can change rapidly.Ammonia can be toxic to biota if its levels exceed the maximum threshold for ammonia sources in the waters [10].The main source of ammonia in ponds is excretion from shrimp or fish as well as accumulation of organic matter from feed residues and dead plankton.Shrimp that use protein as an energy source produce ammonia in metabolism.Protein content in feed strongly supports the accumulation of organic-N in ponds and then becomes ammonia after undergoing the ammonification process [21].The ammonia value of well water is high due to the entry of pond water waste that is discharged directly to the beach and into the ground, indicating an indication of a leak at the bottom of the pond.Ammonia is one of the parameters of organic pollution in waters, so if the concentration of ammonia in waters is too high, it can be assumed that pollution has occurred in these waters [10].Apart from being sourced from shrimp farming activities on the coast of Cilacap, high levels of ammonia are due to organic matter pollution from other activities on the coast, such as those found in locations 1 (Tegalkamulyan Village) and 3 (Slarang Village), the location of the shrimp ponds are quite close to people's houses, rice fields, hospitals and power plants.While at location 2 (Menganti Village) the location is closer to residential areas, PLTU and also the mouth of the Serayu River.As is the case with excessive concentrations of nitrite in water, ammonia concentrations are toxic.In the intensive cultivation of vannamei shrimp in Cilacap, the cultivation is carried out with a high stocking density, causing limited space for shrimp to move.The high residue of feed and feces which is also getting higher causes high organic matter.If there is a decrease in oxygen, the process of disassembling organic matter will be hampered and cause high levels of Nitrite (NO2) and ammonia (NH 3 ) to increase which makes shrimp susceptible to disease and death in shrimp.So it is often done early harvest to reduce losses and crop failure.
Phosphate is one of the most important nutrient compounds in the sea.Phosphate is a nutrient needed for the growth process and metabolism of phytoplankton and other marine organisms in determining water fertility.The distribution of phosphate from the offshore area to the coastal area shows a higher concentration towards the coast [10].Phosphorus is a very important limiting factor in productive and unproductive waters, phosphorus plays an important role in determining the amount of phytoplankton [22].In Cilacap waters, both borewell water and pond water in all three locations have exceeded the quality standard.This condition can be dangerous for marine biota that live in it and can cause eutrophication.Sources of phosphate in the coastal waters of Cilacap are thought to come from human activities, such as domestic waste, aquaculture, industry, and agriculture that have been going on for a long time.
The values of temperature, salinity, pH, DO, and BOD parameters are still in the good category because they are in accordance with the quality standards.Meanwhile, the nitrogen content (nitrate, nitrite, ammonia) and phosphate in aquaculture waters has exceeded the quality standard threshold.The dynamics of nitrogen concentration in ponds is highly dependent on the integrated nitrogen cycle process.The high content of these parameters is a source of pollutants in the water which eventually causes polluted waters.
The quality of sea water used for marine biota and other activities should ideally meet standards, both physically, chemically, and biologically.
Vannamei shrimp cultivation activities that are carried out intensively require a variety of aquaculture inputs such as feed, fertilizer, lime, shrimp seeds, probiotics and new water changes will affect the organic matter content in the pond and surrounding waters to be higher.Based on the results of monitoring that has been carried out on intensive ponds, it is stated that 15% of the feed given will dissolve in water, while 85% of what is eaten is mostly returned to the environment in the form of waste.Only 17% of the amount of feed given is converted into shrimp meat, 48% is wasted in the form of excretion (metabolism, excess nutrients), ecdysis (moulting) and maintenance (energy), 20% of the feed given is returned to the environment in the form of solid waste in the form of feces.This condition has the potential for an oxygen deficit which in turn can lead to anaerobic conditions in the cultivation system [23].Intensive shrimp farming can cause eutrophication, namely an increase in the concentration of nutrients and organic matter in an aquatic ecosystem.In addition, shrimp pond waste triggers the emergence of reduced compounds, one of which is ammonia (NH 3 ) which is toxic (poison) so that it can kill all living things in coastal areas.The influx of pond waste into the surrounding waters is also caused by the construction of a pond on the coast of Cilacap which was not built according to regulations without a wastewater treatment plant (WWTP).
Not only shrimp ponds, the existence of industrial, household, or agricultural activities on the coast will also provide ecological changes that will affect the carrying capacity of the environment.The location of the ponds in the Penyu Bay area of Cilacap, and among two estuaries also makes the characteristics of the waters more complex.The high influence from the mainland such as the entry of organic material from the mainland carried from the Serayu River or from the estuary of the East Segara Anakan canal.Estuary areas are generally a place of deposition of waste materials/waste so that they receive great pressure on the impact of these waste materials [24].The number of rivers that empties into Segara Anakan and several activities in Sleko Harbor and the tides have caused this area to become a nutrient trap area as well as a pollutant trap area.The existence of these industrial activities has the potential to cause environmental pollution in the form of the entry of toxic materials to the waters so that it can reduce water quality [25].The existence of industrial activities, domestic activities such as industrial shipping activities, public transportation, and fishing vessels is very possible to produce organic waste or heavy metals.Based on previous research, it is known that the average heavy metal content of Pb, Hg, Cd, and Cu in Sillaginid fish (whitung) meat caught around the Donan River estuary every month has mostly exceeded the threshold value that has been set, but there are also which is still below the quality standard [26].In addition, full-blooded mussel meat from the eastern part of the Segara Anakan waters and the western part of the Donan River is quite dangerous if consumed in large quantities [24].
The occurrence of changes in the coastline on the coast of Cilacap will of course also affect the value of the quality of the waters.The construction activity of the Cilacap steam power plant (PLTU) such as dredging has made major changes to the hydrodynamics of its waters.In addition, after the dock was built for landing coal ships, it also caused sedimentation and abrasion in several locations.Menganti Village is a village that affected by sedimentation in other areas, due to its location close to the jetty.This affects the occurrence of water quality such as the occurrence of salinity values.On the other hand, there are about 4 coastal locations in South Cilacap and North Cilacap that have been affected by abrasion, namely Menganti Kisik, Lengkong, Kemiren, and Tegal Kamulyan beaches.The process of beach abrasion in coastal areas due to sand dredging activities which causes the formation of puddles that trigger beach sand to puddle areas, causing coastal erosion.As a result of abrasion and sedimentation associated with the presence of sediment transport which can make water quality decline.Abrasion that occurred in the four villages caused the number of ponds to disappear and their number to decrease.The problem of abrasion also occurs in Slarang village.Its location at the estuary of the Serayu River makes a lot of community activities that carry out sand dredging both in the estuary and along the banks of the Serayu River.Apart from abrasion, the reduced number of ponds operating in this village is also due to frequent failures in cultivation.In dealing with abrasion at the estuary of the Serayu River, the steam power plant (PLTU) has built a breakwater that has succeeded in reducing the impact of abrasion and also offers the affected communities around the power plant if they want to sell their land.
However, the water quality in coastal borewells and ponds on the coast of Cilacap is still categorized as lightly polluted and is still adequate and good enough to support the life of the aquatic biota.The results of measurements of temperature, salinity, acidity, DO, and BOD parameters are still in a good category to support the activities and development of intensive shrimp farming on the coast of Cilacap.Previous research conducted in Segara Anakan (eastern part) also stated that the waters of the Donan River estuary were in the light polluted category according to the Decree of the State Minister of the Environment No. 51 of 2004 (1.0 < Pij 5.0) [25].When compared with the value of water quality in Banten Bay, which is also an active area with industrial activities including power plants, the water quality is not much different from Penyu Bay, Cilacap.Based on the results of research that has been carried out, the results of water quality parameters in situ temperature, salinity, dissolved oxygen (DO), and pH of the IOP Publishing doi:10.1088/1755-1315/1260/1/01202714 waters, the overall value is still in a good category, but this still needs to be managed so that the impact of pollution originating from activities in land is minimized [27].In measuring water quality, the value obtained is influenced by various factors such as time of collection, season, and climatological conditions at the time of sampling.At the time of sampling pond water, the age of the shrimp does not really affect the quality of the waters, but on the water exchange system.
The management of shrimp ponds that are not optimal and sustainable has a bad impact not only on the environment but also on the socio-economic aspects of the community.Decreasing water quality can lead to decreasing of the level of productivity and profits.Therefore, in carrying out intensive vannamei shrimp farming, it is necessary to pay attention to the entire system from pre-production, production and post-production.Pre-production is a series of preparatory activities in producing vaname shrimp such as site selection, water sources, containers, seeds, equipment, chemicals and feed.Production includes fry, water conservancy management, and sewage treatment.While post-production includes harvesting and post-harvest.By paying attention to all of these things, the balance of the ecosystem, the economic welfare of the community can be maintained, and the sustainability of vannamei shrimp aquaculture on the coast of Cilacap can be achieved.

Conclusion
The condition of the coastal waters of Cilacap is still suitable for the life of aquatic biota and is still good for the development of fishery activities.However, in the use of the coast, it is still necessary to pay attention so as not to provide excessive risk and or change the ecosystem in the surrounding coastal area.

Figure 2 .
Figure 2. Results of Water Temperature measurements in aquaculture pond of coastal area in Cilacap.

Figure 3 .
Figure 3. Salinity measurement results in aquaculture pond of coastal area in Cilacap

Figure 4 .
Figure 4. Results of pH measurements in in aquaculture pond of coastal area in Cilacap.

Figure 5 .
Figure 5. DO Measurement results in aquaculture pond of coastal area in Cilacap.

Figure 6 .
Figure 6.Concentration of BOD in aquaculture pond of coastal area in Cilacap.

Figure 7 .
Figure 7. Concentration of Nitrate in in aquaculture pond of coastal area in Cilacap.

Figure 8 .
Figure 8. Concentration of Nitrite in in aquaculture pond of coastal area in Cilacap.

Figure 9 .
Figure 9. Ammonia Concentration in in aquaculture pond of coastal area in Cilacap.
that from the three locations, the well water phosphate concentration values have all passed the quality standard values.Meanwhile, based on SNI 01-7246-2006 regarding water quality for vaname shrimp rearing in ponds with intensive technology, the value of phosphate concentration in pond water in three locations has also exceeded 0.1 mg/L.

Figure 10 .
Figure 10.Water Phosphate Concentration in in aquaculture pond of coastal area in Cilacap.

Table 2
. Data analysis was carried out descriptively by comparing laboratory test results with Government Regulation Number 22 of 2021 concerning Seawater Quality Standards which is specifically for marine life.

Table 2 .
Parameters observed, unit, method of analysis, and place of analysis parameter unit.

Table 2 .
Parameters observed, unit, method of analysis, and place of analysis parameter unit (cont.).

Table 3 .
Results of measurement and analysis of water quality of Cilacap coastal borewell.

Table 4 .
Results of measurement and analysis of water quality of pond.