The Relationship Between Water Quality and Phytoplankton Abundance at The Eastern Part of Segara Anakan Cilacap, Central Java

Received : 27/08/2019 Accepted : 30/10/2019 Abstract Phytoplankton is the primary producer whose existence depends not only on the nutrient. The eastern part of Segara Anakan waters experienced changes where the decline in quality which received input from organic and inorganic wastes. The area was also get the residu from residential, industrial and factory wastes of Holcim and Pertamina factories. The purpose of this research is to study the water quality and to study the relationship between water quality and abundance of phytoplankton at the eastern part of Segara Anakan. The result showed that Water quality in Segara Anakan waters in the east part of Cilacap consists of several parameters that beyond the quality standards according to the Keputusan Menteri Lingkungan Hidup No. 51 of 2004 such as pH, Nitrate, Ammonia, Phosphate, and TSS. Water temperature is a physical factor which has a strong negative correlation with the abundance of phytoplankton, followed by TSS as a physical factor which has a positive correlation. The chemical factor which has a positive correlation with abundance is TDS, Nitrite and pH, followed by Phosphate, Salinity, Ammonia, and Nitrate which has a negative correlation with the abundance of phytoplankton.


INTRODUCTION
The eastern part of Segara Anakan waters received the organic and inorganic waste from the domestic activities, factory, and industry, such as cement factory (Holcim) and oil industry (Pertamina). Several industrial event on the eastern of Segara Anakan which contains oil and the cement industry are predicted as producing wastes to the rivers, tend to cause environmental defilement and low quality in the aquatic area (Sulistiono, 2017).
The existence of phytoplankton can depict the rate of its productivity (Sachlan, 1980). If the abundance of phytoplankton in the water is at a high level, the water tends to have a high productivity level (Raymont, 1980). Phytoplankton has several functions, such as primary oxygen supplier for the aquatic organisms, synthesizing organic matters, as food sources of zooplankton and poisonous substances absorbance (NH3 and H2S). Phytoplankton also could be an indicator of of environmental defilement, for example, Skeletonema sp. will be abundant in the water with high level of nutrient (Arinardi, 1997).
According to Djumanto et al.(2009), abundance and distribution of plankton influenced by physical conditions of waters such as light penetration, temperature, salinity and surface currents. The plankton abundance is fluctuating according to the season where the east/dry season (July) produces less phytoplankton compared to western seasons/rainy season (November). The rainy season increase the water mass and upwelling bottom layer with higher salinity and rich nutrient content due to high rainfall. On the research of (Pratiwi, 2018), Donan River has reported that there are three classes of phytoplankton inhabit in the eastern of Segara Anakan. Bacillariophyceae, Chlorophyceae, and Dinophyceae have a significant correlation with the environmental and affected by some factors (light penetration, temperature, salinity, surface current, and content of nutrient). The lack of information about the spatial and temporal variation of phytoplankton in Segara Anakan, Cilacap, Central Java causes the need for doing research.
Based on the data above, the purpose of this research as follows as , 1) To study the water quality of the eastern part of Segara Anakan waters of Cilacap spatially and temporally; 2) To analyze the relationship between physical and chemical factors that affect the diversity and abundance of phytoplankton.

MATERIAL AND METHOD Material
The object was the abundance and diversity of phytoplankton species. The tools were thermometer, depth sounder, Secchi disk, refractometer, pH meter, vacuum pump, Erlenmeyer, plankton net no. 25, sample bottles, dropper pipettes, buckets, GPS (Global Position System), Oven, Burette &Statif, Inverted Microscope, Sedgewick Rafter, Label paper, Stationery, and Boat.

Method
The research has been conducted by a survey method with purposive sampling technique in 7 locations ( Figure 1) during the dry and rainy seasons. The sampling has been done in April, May, August, and September 2018.
The dependent variables were water quality in the eastern part of Segara Anakan, Cilacap. The independent variables were abundance and diversity of phytoplankton. The planktons were identified with identification book of Planktononogi by Sachlan (1982), The Marine and Freshwater Plankton by Davis (1955).
The plankton samples at each Station were observed with 1 ml with a Sedgewick rafter. Each individual seen was recorded, then calculated by the formula: Diversity Shannon-Wiener (Odum, 1993). The study of the relationship between water quality and abundance of phytoplankton spatially and temporally and the factors which influence the diversity and abundance the most were analyzed by using Bio-ENV with PRIMER software 5. According to Sugiyono (2010), the correlation coefficient is divided into several category, such as values between 0-0,19 categorized as very weak, 0,20-0,39 categorized as weak, 0,40-0,59 categorized as moderate, 0,60-0,79 categorized as strong and values between 0,80-1 categorized as very strong.

RESULT AND DISCUSSION Water Quality
The water quality in the eastern part of Segara Anakan represented by water temperature, pH, salinity, nitrite, nitrate, ammonia, phosphate, TSS and TDS. The parameter beyond the BMA (Water Quality Standard) was pH, Nitrate, Ammonia, Phosphate, and TSS. The result of the measurement was presented in (Table 2). Legend: Sampling Station The range of pH measurement in 7 observation sites were 6.6 -6.8 and this was below the BMA, that the range should be 7.0 -8.5. This condition might be influenced by residential and industrial activities surrounding. According to Susana (2009), one of the anthropogenic activities in the form of the use of many chemicals for the household and industrial purposes is the use of detergent, which causes a decrease in pH value and oxygen concentration in the river flow, so that the end result empties into the surrounding waters. The nitrate measurement was at the range of 3.3 -5.3 mg.l -1 . This range was beyond the BMA/ water quality standard. It should be below 0.008 mg.l -1 . According to Utami et al.(2016), that the flow of rivers around the upstream area can affect tidal waters where at low tide the flow of currents tends towards the sea and brings nitrates sourced from the river to the waters of the sea. It is proven in the Babakan area that it has the highest nitrogen concentration up to 5.3 mg.l -1 which is an upstream part of the Sapuregel River and is still influenced by tide and recede conditions and surrounded by dense mangrove vegetation.
The ammonia measurement resulted tended to be below which ranged 0,02-0,03 mg.l -1 or not exceed the limits of Sea Water Quality Standards (0,3 mg.l -1 ). According to Yulius et al. (2018) that ammonia levels exist in relatively small amounts if the oxygen content is high in the water. In conditions of high dissolved oxygen content, the ammonia present in relatively small amounts will increase with increasing depth.
Based on all sampling sites showed that the phosphate concentration was beyond the BMA, it should be below 0,015 mg.l -1 . The high concentration resulted from the location is an industrial area, settlement, and transportation of ships which are also downstream or estuary areas that have the highest depth. Putri et al. (2019) states that primary source of high phosphate originates from land, through weathering of rocks (allotons) that enter the waters through river transportation, and detergent as organic waste disposal.
The measurement of Total Suspended Solids (TSS) has beyond the specified Sea Water Quality Standard, which is equal to 80 mg.l -1 . TSS concentrations obtained ranged from 77.4 -148.0 mg.l -1 . The high TSS concentration in Teritih Kulon is caused by the proximity of the location to agricultural areas, residential areas, and industries. The substrate which dominates in this area is mud. In accordance with Yulius et al.(2018), higher TSS concentrations occur due to the influence of more dominant land which consists of mud and microorganisms originating from soil erosion (soil erosion) which is carried from the land to water bodies.

Phytoplankton Abundance
Based on the results of identification of phytoplankton species spatially from seven observation stations in April, May, August, September 2018, was found that there were 43 species with a total abundance of 13460 species. Phytoplankton species found included 30 genera from 6 divisions namely: Bacillariophyceae, Chlorophyceae, Charophyceae, Cyanophyceae, Euglenophyceae, and Dinophyceae. Bacillariophyceae Division has 29 phytoplankton species identified, Chlorophyceae Division has five species, Charophyceae Division has three species, Cyanophyceae Division has four species, Euglenophyceae Division has one species and Dinophyceae Division has one species (Table 3).
The abundance of phytoplankton species spatially found ranged between 604-2931 ind.l -1 . The value of this abundance was in the medium level abundance group. According to Soegianto (1994), plankton grouping based on abundance is divided into three categories, namely abundance with a range of values <1,000 ind.l -1 including low, abundance between 1,000-40,000 ind.l -1 including moderate, and abundance> 40,000 ind.l -1 including height.
The total abundance of each Station produced was 604 ind.l -1 at Kutawaru Station (Station 6), 1143 ind.l -1 at Karangtalun Station (Station2) then Explanation Sign ( The most abundant phytoplankton was the Oscillatoria limosa species from the Cyanophyceae Division of 2531 ind.l -1 which is almost found in all Stations. The Cyanobacteria /Cyanophyceae division was a division which commonly found in the lowest salinity, Ocsillatoria is a cosmopolitan genus which can be found almost every waters condition such as freshwater, brackish and marine (Hoffman, 1996).
The abundance of this species is mostly found in the Teritih Kulon Station as many as 2781 ind.1 -1 , this was because this area is the waters of the Donan River which has the influence of waste disposal from PT Holcim's settlements and industries. In accordance Akrimi & Gatot (2002), the genus Oscillatoria was a genus of plankton which was commonly used as an indicator of water pollution because it has asexual reproduction in the form of spores and it has a high tolerance for polluted waters. While the lowest phytoplankton species with the lowest abundance were Phacus pleuronectes from the Euglenophyceae Division as much as 15 ind.l -1 and Grammatophora angulosa as many as 15 ind.l -1 in Karangtalun (Station 2) from the Bacillariophyceae division. Based on Weik (1967), Phacus was an euplanktonic (free-floating organism or open water plankton) found together with the genera Euglenophyta, Phacus was not a common species that live in a stagnant environment because these areas often do not have the right organic composition.
To find out more about the comparison of proximity between stations, cluster analysis was used to observe equations in species composition in the form of dendrograms through Figure 2.
Karangtalun and Sapuregel River Mouth which is the area that meets the Kembang Kuning River with the same waters surrounded by dense mangrove vegetation which causes this species to have the smallest abundance. According to Siregar & Telaumbanua (2010), the weak currents in the area caused by mangrove vegetation which can reduce the speed of currents where the velocity of the plankton has a large influence and abundance, due to plankton is a microscopic organism that lives floating in water with very weak swimming ability, the movement is strongly influenced by the movement of water.
Dermaga Holcim Quarry (station 4) and Sapuregel River Estuary (station 5) have the largest or closest level of group similarity which indicates the same phytoplankton abundance level which is equal to 58.02% which dominated by the same species of Melosira italica (Bacillariophyceae) with species abundance as much as 204 ind.l -1 at both stations also dominated with the same species of Coscinodiscusmarginatus(Bacillariophyceae) with species abundance as much as 22 ind.l -1 , followed by the Donan River Mouth (station 3) and Babakan (station 7) which has a similarity of 45.77% which dominated by the same species of Chlorella variegata(Chlorophyceae) with species abundance as much as 15 ind.l -1 at both stations.

Relationship Between Water Quality and Abundance of Phytoplankton
Analysis of the correlation of phytoplankton abundance with nine physical-number of variables environmental factors has been done with Bio-env analysis. The analysis has been done in sofware Primer 5 (appendix 5). The result of the analysis showed through Table 3. Based on analysis of Bioenv with Primer 5 applications resulted that water temperature as the physical factor which had -0,639 and categorized as strong, this correlation coefficient had opposite (negative) correlation, which means if the water temperature were high it would be affected by the lowest abundant of phytoplankton. According to Sugiyono (2010), the correlation coefficient is divided into several category, such as values between 0-0,19 categorized as very weak, 0,20-0,39 categorized as weak, 0,40-0,59 categorized as moderate, 0,60-0,79 categorized as strong and values between 0,80-1 categorized as very strong(negative). The other environmental factor followed with negative correlation is phosphate, salinity, ammonia, and nitrate (chemical factor). Meanwhile, TSS is the environmental factor which had a positive correlation on phytoplankton abundance and diversity with a correlation value of 0.184, which categorized as weak. This evidence is also supported by the abundance of 1854 ind.l -1 species of Oscillatoria limosa at the Teritih Kulon (station 1). According to Effendi (2003), TSS is a suspended material that causes turbidity of water consisting of mud, fine sand and microorganisms/biota in the form of plankton carried by water bodies. The other environmental factor followed with the positive correlation is TDS (physical factor), Nitrite and pH (chemical factor) which has low categorized.

CONCLUSIONS
Based on the results obtained, it can be concluded that water quality at the eastern part of Segara Anakan Cilacap consists of several parameters that beyond the quality standards according to the Keputusan Menteri Lingkungan Hidup No. 51 of 2004 such as pH, Nitrate, Ammonia, Phosphate, and TSS. Water temperature is a physical factor categorized as a strong negative correlation with the abundance of phytoplankton, followed by phosphate, salinity, ammonia, and nitrate (chemical factor) that has weak categorized. TSS is the physical factor categorized as weak which has a positive correlation with the abundance of phytoplankton, followed by TDS (physical factor), Nitrite and pH (chemical factor).