Monitoring of water quality and spesies composition of plankton in polyculture of tiger shrimp ( Penaeus monodon ), gesit tilapia

. The polyculture system cultivation activity is an effort to increase the production of aquaculture and optimal use of ecological space/niches. Water quality is a living medium for aquatic biota that really needs to be considered. This study aims to evaluate the water quality and species composition of plankton in a polyculture system. Water quality factors were temperature, dissolved oxygen, temperature, pH, alkalinity, salinity, ammonia, nitrite, nitrate, phosphate, and total organic matter. The variables observed during the study were water quality including dissolved oxygen, pH, temperature, alkalinity, salinity, phosphate, total organic matter, ammonia, nitrite, and nitrate. Plankton including phytoplankton and zooplankton were observed every two weeks. The results of the research on monitoring water quality parameters, the temperature range 28.4-32.4 0 C, dissolved oxygen in treatment A ranged from 2.55-4.56 mg/L, treatment B ranged from 2.58-4.57 mg/L, and treatment C ranged from 2.25-3.43 mg/L, Ammonia content in treatment A 0.0255-0.4913 mg/L, treatment B 0.0282-0.5409 mg/L, treatment C 0.0427-0.3799 mg/L. The plankton community found during the study in each treatment were 22 species, consisting of 9 types of phytoplankton and 13 types of zooplankton. The most type of phytoplankton was Oscillatoria sp 16,362 ind/L and zooplankton was Nauplii Copepod 2,659 ind/L.


Introduction
One of the indigenous shrimp species is the tiger shrimp P. monodon.that has been widely cultivated in brackish water ponds in Indonesia.Production increase black tiger shrimp besides being focused on efforts disease control also needs to be done through efforts to increase the rate of growth [1].The increase in shrimp production can be done through extensification (expansion of cultivation area), Intensification (technological improvement), and Diversification (adding types of aquaculture commodities and cultured products Efforts to improve the environmental quality of shrimp habitat caused by accumulation of organic matter can be carried out physically, chemically and biologically.However, one way to improve water quality that is economical, environmentally friendly and increases pond productivity is the application of polyculture cultivation by utilizing various organisms.The polyculture system brings together various species occupying several suitable niches, with low stocking density and low culture management in one pond.
Some of the advantages of cultivation with a polyculture system are obtaining more than one cultivation commodity for optimal use of ecological space/niches, increasing land carrying capacity, improving environmental quality which can reduce the risk of crop failure compared to monoculture cultivation systems and can increase added value for pond cultivators.That raising fish or shrimp with a polyculture system is more profitable than monoculture.Furthermore, it is said that with more animal species or plant communities in polyculture ponds will lead to more stable, and more efficient use of energy than monoculture systems [2].One of the factors that need to be considered in mixed cultivation is the opportunity to use natural food effectively so that it can support increased production [3].Furthermore, it is said that the species stocked should be from species that have different feeding habits with densities that do not cause competition.
Studies on the integrated aquaculture of Penaeid shrimp with omnivorous fish such as tilapia have shown that the water quality of organic waste from the diet provided improves, with the shrimp selectively eating on bigger and bigger unicellular algae.zooplankton that boosts the dominance of advantageous phytoplankton and boosts fish biomass's ability to retain nutrients [4].A number of fish species (including tilapia, snapper, seabass, and rabbitfish) have the ability to restrict the growth of the dangerous bacterium Vibrio harveyi in shrimp raising water, hence increasing shrimp survival [5].
Seaweed can be used to reduce and convert dissolved inorganic nutrients from waste disposal from coastal and aquaculture system [6], [7], [8].There are several advantages of using seaweed over microalgae in aquaculture systems.1) Seaweed cultivation is more stable and the factors that influence the failure of its cultivation are less than microalgae, 2) Seaweed can physically survive and develop itself more easily in the cultivation system than microalgae because thallus can survive in containers/tanks.Seaweed as often as possible absorbs nutrients from sewage or recirculation systems.
Tilapia can be grown in fresh, brackish, and marine environments in ponds and marine cages as a fish belonging to the euryhaline family [9] [10], [11].One of the advantages of tilapia is that it is very adaptive to the environment.In Indonesia, tilapia cultivation can be found in brackish waters, swift pools, flowing rivers, natural lakes, artificial reservoirs and rice fields.The advantage of tilapia farming in brackish water ponds is that fish grow faster in brackish water ponds than in freshwater ponds.Additionally, pond-grown tilapia has a savory, chewy meat flavor and doesn't smell like mud, making it a prime candidate for usage as a raw material in the processed food industry [12].
The success of shrimp farming, among others, is determined by water quality factors and the population of pathogens.Water quality, especially levels of total ammonia and organic matter that exceeds the threshold, is one of the factors causing the decline in shrimp production [13].Ammonia in ponds mainly comes from the ammonification of organic matter found in the rest of the feed and the direct excretion of ammonia by shrimp and fish.According to [14], organic matter from uneaten feed, dead plankton, fertilizer application and shrimp faeces on an ongoing basis will accumulate at the bottom of the pond.In the organic nitrogen decomposition process, the decomposition of nitrogen into ammonium, nitrite and nitrate does not cause toxic effects, but if ammonia is formed, even at low levels it will cause disturbances to aquatic organisms and even be deadly.Therefore, for successful cultivation, it is necessary to know water quality parameters and regularly monitor water quality conditions in ponds [15].
The aims of this research is to assess the water quality and plankton species composition in a system that contains seaweed, tiger shrimp, and gesit tilapia.

Materials and methods of research
The research was carried out in Maros Regency, South Sulawesi, Indonesia, at the Experimental Pond Installation of the Research Institute for Brackish water Aquaculture and Fisheries Extension (RIBAFE).
The research containers used were 500 m 2 in size, with 9 ponds and a water intake and outflow system.Before the shrimp and fish are stocked into the rearing pond, the pond preparation must first be carried out include drying ponds, removing mud, eradicating pests, and growing natural feed using inorganic fertilizers.The test animals used were tiger prawns and saline tilapia which were reared for 3-4 weeks.The tiger shrimp stocking density in the grow-out pond was 4 ind/m 2 and tilapia 1 ind/m 2 and seaweed 2,000 kg/ha or 100 kg/pond.Water quality parameters were observed in each treatment, namely treatment A = tiger shrimp, B = tiger shrimp and gesit tilapia and C = tiger shrimp, gesit tilapia and seaweed.The rearing period of the polyculture system was 98 days.
The insitu parameters of dissolved oxygen, temperature, pH, and salinity were measured for the water quality data every week in the morning.Alkalinity, ammonia, nitrite, nitrate, phosphate, TOM, TSS, and plankton composition parameters were also measured every two weeks.A sample vial was used to collect samples up to 500 mL for laboratory analysis utilizing the research analysis instruments and techniques listed in Table 1.SNI is used as the research analysis approach for parameters related to water physics and chemistry.Meanwhile, the accepted technique is used to identify plankton (APHA).Plankton was gathered and filtered from water up to 100 L using a plankton net with a mesh size of 60 m until only 100 mL remained.Following that, the plankton was preserved in a 1% Lugol solution and identified using a microscope and cell counting processes.[16], [17].The data of water quality insitu, data exsitu from the laboratory analysis and composition and the abundance of plankton were collected according to the observation schedule.Water quality parameter data and composition of plankton were analyzed descriptively and presented in tables and graphs form.

Results
The most significant factor in aquaculture is water quality, which is critical for the growth and survival of raised tiger shrimps, tilapia and seaweed in the waters.Figures 1 and 2 show the outcomes of the study's water quality observation.[14].The good temperature for optimal growth of tilapia ranges from 22-29°C [18].Ideal temperature for the growth of Gracilaria spp. was determined to be between 20 and 35 °C for the following Gracilaria species: G. incurvata, G. foliifera, G. corticata, G. edulis, G. licheniodes, G. arcuata, G. textorii, G. vermiculophylla, 26-30 °C is the ideal range for shrimp growth [19].
The percentage of dissolved oxygen in the pond is crucial for tiger prawn survival.In polyculture aquaculture ponds, treatment A had dissolved oxygen levels that ranged from 2.55 to 4.56 mg/L, treatment B from 2.58 to 4.57 mg/L, and treatment C from 2.25-3.43mg/L.Shrimp have a 3.0 mg/L maximum tolerated level of dissolved oxygen.Shrimp typically exhibit signs of abnormally sluggish motion and swim at the water's surface when oxygen levels are below 2.5 mg/L [14].During the growing of tiger shrimps, the range of the dissolved oxygen content was 2.95-6.01mg/L, with an average of 4.11 mg/L [20].Tiger shrimp culture has a dissolved oxygen limit of greater than 3.0 mg/L, and the ideal range is between 4.0-7.0mg/L [21].The nursery tiger shrimp using a happa system had dissolved oxygen measurements that varied from 3.0-4.3mg/L [22].
Salinity measurement result during the study in treatment A ranged from 11-29 ppt with an average of 19±5.43 ppt, treatment B ranged from 11-31 ppt an average of 21±6.17 ppt, and treatment C 11-31 ppt an average 21±5.91 ppt.Tilapia may be produced in both freshwater and brackish water because it is a euryhaline species that can survive a wide variety of salinities [24].The tiger shrimp's ideal salinity range for growth was 10-35 ppt [25].G. verrucosa may thrive in a wide range of salinities (5-35 ppt), but it grows best in the 15-25 ppt range [26].
The pH obtained during the observation in each treatment was 7.8-9.0an average of 8.3±0.30 in treatment A, treatment B was 8.0-9.0 an average of 8.3±0.26, and treatment C was 7.5-8.8an average of 8.1±0.35.This value can still support the life and growth of tiger shrimp, tilapia and seaweed.The pH value is an indicator of the acidity of the waters.Several factors that affect the pH of the waters include photosynthetic activity, temperature, and the presence of anions and cations.Each type of aquatic organisme will show a different response to changes in pH and the impact it causes is different.The pH range of 7.5 to 9.0 was typically regarded as an ideal range for producing shrimp [27].The best pH for shrimp growth is between 7-9 [28].The pH value Tilapia cultivation ranges from 6.5 to 8.5 [29].
Alkalinity measurement results in treatment A ranged from 105.8-173.6 mg/L with an average of 147.9±19.55mg/L, treatment B ranged from 121.6-172.2mg/L an average of 151.2±12.46mg/L, and treatment C ranged from 113.4-159.7 mg/L an average of 143.7±12.23 mg/L.Waters with an alkalinity value that is too high are not very favored by aquatic organisms, because it is usually followed by a high alkalinity value, high hardness or high salt content [30].The alkalinity range that has to be maintained during black tiger shrimp cultivation was 80-140 mg/L [31].Total pond water alkalinity is typically measured at 80 mg/L.If the alkalinity of the pond water is low, lime might be used to improve it [32].
The findings of the ammonia concentration monitoring during the trial revealed differences between the three treatments.The ammonia range in treatment A was 0.0255-0.4913mg/L with an average of 0.109±0.14mg/L, treatment B ranged from 0.0282-0.5409mg/L with Average 0.123 ± 0.15 mg/L, and treatment C ranges from 0.0427-0.3799mg/L with an average of 0122 ± 0.11 mg/L, ammonia levels of 0.65 mg/L are poisonous and deadly for fish.[33].At the end of the study the concentration of ammonia decreased in treatment C this was due to the presence of seaweed organisms that could absorb organic matter dissolved in water.Seaweed can also make the waters clear [34].The ammonia concentration of water should not exceed 1.2 mg/L [32].Ammonia is harmful to tilapia at concentrations of 2.5 mg/L and 7.1 mg/L in unionized form.Maximum ammonia concentration in conditions less than 0.05 mg/L [35].
The concentration of nitrite (NO2) in the three treatments during the study, the nitrite content ranged from 0.0048-0.0559mg/L an average of 0.016±0.02mg/L in treatment A, in treatment B it ranged from 0.0032-0.2422mg/L an average of 0.039±0.07mg/L, and in treatment C ranging from 0.0011 to 0.0450 mg/L an average of 0.018±0.02mg/L.The recommended limit of nitrite (NO2-N) level for shrimp farming was <0.25 mg/L [36].Water naturally contains 0.001 mg/L of nitrite, and it is best to keep nitrite levels at 0.05 mg/L as it may be hazardous to aquatic life [37], [30].For shrimp production, nitrite levels should be between 0.01 and 0.05 mg/L [38].Shrimp metabolism and respiration can be hampered by changes in nitrite levels in the aquatic environment, which can also lead to hypoxia in the tissues.The maximum nitrite content acceptable for shrimp cultivation is 0.1 mg/L [39].One of the crucial nutritional components in the creation of animal and plant proteins is nitrate.The ammonia concentration of water should not exceed 1.2 mg/L [32].Ammonia is harmful to tilapia at concentrations of 2.5 mg/L and 7.1 mg/L in unionized form.Maximum ammonia concentration in conditions less than 0.05 mg/L [36].Nitrate is the best nitrogen source for the growth of several types of marine algae.The red algae Thallus bleaches as a result of low nitrate levels.Nitrate levels be between 0.1 mg/L and 3 mg/L in order for algae to flourish [37].The primary nutrient for algal plant growth is nitrate.Nitrates are created by the full oxidation of nitrogen compounds in water and are very easily soluble in water and stable.When the quantity of nitrate-nitrogen in the water exceeds 0.2 mg/L, the water becomes eutrophicated (enriched), which stimulates the fast growth of algae and aquatic plants (blooming) [30].
Phosphate content during the study in treatment A 0.0135-0.1465mg/L, treatment B 0.0103-0.0797mg/L and treatment C 0.0133-0.0712mg/L.The highest phosphate content was observed in the fourth observation in treatment A. The range of phosphate levels (PO4) that were appropriate for shrimp farming operations was between 0.05 and 0.5 mg/L [40].Because of the high amounts of dissolved inorganic phosphate (1.0-0.0 mg/L) present during the culture period, the length of the growth and shrimp harvest periods may be reduced [32].A pond's fertility rate can be classified into three categories based on the amount of phosphate present in the water: low fertility rate (phosphate content of 0.000-0.02mg/L), medium fertility rate (phosphate content of 0.021-0.05mg/L), and high fertility rate (phosphate content of 0.051-0.2mg/L).During the seaweed, G verrucosa culture in the pond, the phosphate concentration in the water was around 0.002-0.445mg/L [30] The results of observations of the total organic matter content obtained in treatment A ranged from 59.28-75.56mg/L, treatment B 54.51-74.56mg/L, and treatment C ranged from 57.02-69.26mg/L.Minimum TOM in water is usually 15 mg/L and optimal for shrimp culture < 50 mg/L [14].TSS values during the study in treatment A ranged from 24-41 mg/L average 32±12 mg/L, treatment B ranged from 27-52 mg/L with average 39±17 mg/L, and treatment C ranged from 20-51 mg/L with average 36±22 mg/L [14] Total suspended solids were 30 mg/L during shrimp stocking, 20 mg/L in reservoir/reservoir plot water, 40 mg/L during mid and late shrimp rearing, and 30 mg/L in waste water [40].
The results of observations of biological parameters (composition of phytoplankton and zooplankton species) in polyculture ponds of tiger shrimp, gesit tilapia and seaweed is presented in Table 2 and Table 3. Types of phytoplankton found were Coscinodiscus sp, Arthospira sp, Chaetoceros sp, Ginosigma sp., Naviculla sp, Nitzshia sp, Oscillatoria sp, Pleurosigma sp, and Ryzoselania sp.The most abundant type of phytoplankton found was Oscillatoria sp and the least phytoplankton type found was Ryzoselania sp only found in treatment C. While the zooplankton types were Acartia sp, Apocyclops sp, Brachionus sp, Euplotes sp, Favella sp, Lecane sp, Mesodinium sp, Nauplii copepods sp, Oithona sp, Tintinopsis sp, Tortanus sp and Vorticella sp.
The most abundant type of phytoplankton found was Oscillatoria sp.The dominance of Oscillatoria sp. is owing to its euryhaline nature, which enables it to grow at salinities ranging from 0 to 35 parts per trillion, and its ability to survive and flourish in environments deficient in nitrogen due to its ability to bind N-free from the air.Oscillatoria is a good indicator of contaminated waters since it has a high capacity for utilizing organic carbon [41].Naupli copepod sp. was the most common form of zooplankton found.Copepods are a type of zooplankton that contributes significantly to the food chain in an aquatic habitat.Copepod naupli are suitable as fish larvae feed because, in addition to having a high nutritional content, they fluctuate in body size and so match the developmental stage of fish larvae.The large number of zooplankton species of Naupli copepods was found due to the high value of phosphate quality which can support the growth of plankton in ponds.Copepods are critical to aquatic life as primary feeders and as a connection between phytoplankton and higher trophic levels.Copepods provide the primary food supply for all pelagic fish species.Its quantity and distribution are influenced by the physical characteristics of the waters, such as temperature, salinity, and feed availability, and so fluctuate seasonally and geographically.It is frequently related to water fertility [42].The largest abundance of individual phytoplankton was seen in treatment B, which varied between 10-7,452 ind/L, followed by treatment A, which ranged between 124-6,854 ind/L, and treatment C ranged between 19-2,059 ind/L (Tabel 2).While treatment B had the highest concentration of zooplankton individuals (10-1062 ind/L), treatment A had a concentration of 11-893 ind/L, and treatment C had a concentration of 10-702 ind/L (Tabel 3).The number of plankton genera in waters varies by season; some genera are plentiful during the dry season, while others are abundant during the rainy season.Numerous factors contribute to these changes, including temperature, pH, nutrient concentration, light, weather, and disease: fish and zooplankton predation, species competition, and algal toxins [14].The abundance of phytoplankton is determined by the seasonal and tide-related changes in the environmental parameters of pond waters [43].Integrated cultivation of tiger shrimp (P.monodon), gesit tilapia (O niloticus) and seaweed (Gracilaria sp.) can provide more than one commodity, increase added value for pond cultivators, land carrying capacity, and improve environmental quality.Each commodity's growth can be supported by the water quality during the study.13 species of zooplankton and 9 species of phytoplankton were discovered throughout the study.Oscillatoria sp. from the Cyanophyceae class dominates the phytoplankton types, while Copepoda sp. from the Crustaceae class dominates the zooplankton types.

Thanks.
We would like to thank all of the technicians and analysts that assisted with sample preparation and analysis (Abdul Gappar, Haryani, Aswar Rudi, St Suleha, St Rohani, Debora Ayu, and La Ode Muh Hafizh Akbar).Contributor statement: The main contributors are A. Sahrijanna and H S Suwoyo.

Fig. 1 .
Fig. 1.Fluctuations of water quality variable's values (A) temperature, (B) oxygen, (C) salinity, (D) pH and (E) alkalinity measured during 98 days rearing period Temperature is a physical parameter that can affect the life of organisms that are in cultivation in ponds.Temperature is extremely essential in controlling ecological conditions.Temperature in polyculture ponds during the study in each treatment was A ranging from 28.4-32.4o C an average of 30.2±1.06 o C, treatment B ranged from 28.9-32.1 o C an average of

Table 1 .
Water quality parameters and measurement methods 3±1.02 o C and treatment C 28.9-32.2o C an average of 30.3±0.98 o C. At the beginning of the study the increase in temperature in each treatment ranged from 32.4 o C and decreased to 28.4 o C. Changes in temperature in the waters can be influenced by the intensity or amount of sunlight entering the pond waters.The polyculture system did not affect the temperature change significantly.Optimal temperature for growth shrimp and fish is 25-32 o C

Table 2 .
Spesies composition and abundance (ind/L) of phytoplankton in each treatment

Table 3 .
Spesies composition and abundance (ind/L) of zooplankton each treatment