EFISIENSI DAN ENERGETIKA PENETASAN KISTA ARTEMIA ( Artemia salina ) PADA SALINITAS MEDIA YANG BERBEDA EFFICIENCY AND ENERGETICS OF ARTEMIA ( Artemia salina ) CYSTS HATCHING IN DIFFERENT OSMOLARITY MEDIA

Hatching rate of Artemia salina cysts in the hatching process is variable due to many factors. Osmolarity of the medium is one of the factors determining hatching process of A. salina cysts. The purpose of this study is to assess the hatching process of A. salina cysts in a various osmotic condition on the hatching energetics efficiency and rate. The experimental design used was a 2 x 5 factorial completely randomized design. The first factor is an addition of chlorine (non-decapsulation and decapsulation) and the second factor is osmolarity of medium (640.27; 787.02; 901.76; 1080.51 and 1227.25 mOsm.LH2O). The results showed that hatching of A. salina cyst on various osmotic condition has significantly differed the hatching rate. No significant differences in the hatching energetics efficiency were obtained from each experimental groups. Media with osmolarity level of iso-osmotic to hyperosmotic (901.76-1227,25 mOsm.LH2O) provides a high hatching rate. Energetics efficiency of artemia cysts hatching is ranged from 640.27 to 1227.25 mOsm.LH2O in both hypoosmotic, isosmotic and hyperosmotic media.


Introduction
Artemia salina is one of the natural food that has high nutrient content and most widely used in shrimp aquaculture, particularly in a hatchery.As a natural food, A. salina can be used in the stadia of Nauplius and adults (Pangkey, 2011).The problem on the artemia cultivation is the limitation of the supply in the market and the low hatching rate of the cyst (60%) Low hatching rate of A. salina cysts is this is due to the high energy needed for hatching.The high energy of hatching associated with high energy needs for osmoregulation process.To overcome the problem with high energy for osmoregulation, the cyst hatching process might be performed in an isosmotic condition.
Salinity is closely linked to the osmotic pressure of ions and water.Osmolarity of media as one of the factors for optimum hatching rate and energetics efficiency of A. salina is unknown.Therefore, this experiment was conducted in order to assess the efficiency and energetics hatching artemia cysts on various media osmolarity (Lantu, 2010).

Material and Methods
Research conducted at the Institute of Seed and Brackish Water Aquaculture and Marine Unit Brackish Water Fish Seed, Sluke Rembang. A. salina cysts are hatched at a density of 150,000 cysts/L.Media water used to hatching artemia using sea water from around Satker PIAP Sluke, Rembang. A. salina hatching container using gallons of mineral water with a capacity of up to 15 liters of 5 pieces.
The method used in this study is an experimental method with a laboratory scale.The experimental design used was completely randomized design with a 2x5 factorial design.The first factor is the addition of chlorine (non-decapsulation and decapsulation) and the second-factor osmolarity media (640.27; 787.02; 901.76; 1080.51 and 1227.25 mOsm.L -1 H 2 O).The variables measured were the average level of osmotic work, hatchability cyst, hatching energetics efficiency and enzyme activity of Ca-Chorionase.This study uses ten treatment and four replications.
The rate of observed data is Osmotic Work (TKO) is calculated based on the difference in the value of artemia with the osmolarity of blood osmolarity test medium.The measurement technique and blood osmolarity media A. salina by using Automatic Micro Osmometer Roebling, while the employment rate osmotic value criterion according to (Anggoro & Nakamura, 1996): Efficiency energetics of A. salina cyst hatching is determined by calculating the magnitude of the use of energy yolk-eggs for embryonic development and cyst hatching process, using the following formula (Anggoro and Muryati, 2007): where : E = efficiency energetic of cyst hatching Ne = calorific value after the initial larval cysts hatch Te = initial calorific value : cysts in phase 2 cells Ca-chorionase enzyme activity is determined by following Johnson (2003), by taking a sample of fluid vitelline cyst A. salina 5000 gr mass at 10 hours of incubation, homogenized and consolidated with a reagent calcium phosphate, and then examined with CP -2004 spectrophotometer.The technique of taking liquids vitelline follow the way Anggoro and Nakamura (2002), with the help of Fisher microtonal-blender -3000 and CP -35 micropipettes.
Water quality parameters measured media such as temperature, pH, DO and salinity.Measured electrolyte content consisting of Na + , Cl -, Ca 2+ , Mg 2+ , and K + .

TKO
Hatching rate cyst of A. salina of each treatment can be seen in Figure 1 .This results proves that the energy meeds for osmoregulation in isosmotic condition is relatively small compared to the hyperosmotic and hypoosmotic conditions.Treatment A in the present study show that osmolarity value of A. salina cyst is higher than the osmolarity of the medium.This suggests that the environmental conditions is hypotonic.
In a hypotonic environment, body fluid of aquatic animal is hyperosmotic to the environment.In a hypertonic environment, aquatic animal body fluids is hypoosmotic to the medium, therefore water from the body fluids tends to move to the outside by osmosis (Hamka et al., 2013).

Hatching Rate (HR)
The average value A. salina cyst hatching during the study can be seen in Figure 2. When the osmolarity level of the medium is too high, hatching proccess of the artemia cysts will be disturbed.In the very high osmotic condition, artemia cysts could not have a chance to obtain enough water for the metabolism proccess and vice versa (Jubaedah et al., 2006).According to Drinkwater and Crowe (1991), hatching of artemia cysts occurs when there is a differences in osmotic pressure between outside and inside the cysts.

Energetic efficiency hatching artemia cysts
The average value of energetic efficiency of A. salina cysts hatching in the present study can be seen in figure 3.
Based on the Figure 3, energetic efficiency of nondecapsulated artemia cysts hatching at the medium osmolarity of 1227.25;901.76; 787.02; 1080.51 and 640.27 mOsm.L-1H 2 O is 89.54; 87.76; 86.58; 86.00 and 79.24 cal/g, while the average value.Analysis of variance showed that the presence of chlorine and osmolarity of medium give no significant effect on the energetic efficiency of A. salina cysts hatching (p>0.05).
Highest value was obtained on the TKO of treatment A. The high value of TKO require energy to make ballance to the environment which further lowering the hatching rate efficiency.

Ca-Chorionase enzyme activity
Ca-Chorionase enzyme activity is demonstrated at Table 1.Non-Decapsulation; Decapsulation activity.This results is consistent with the result demonstrated by Anggoro and Muryati (2007), which indicated that the environment with too high or too low salinity will thwared hatching process of artemia cysts and weakening the Ca-chorionase enzyme activity, therefore the embrio have a difficulty in breaking the eggshell (chorion).
The mechanism of hatching occurs for two reason.
First is due to the embrionic activity and movement, and second is due to the Ca-chorionase enzyme activity.Ca-chorionase enzyme activity plays a role in the process of embrittlement and softening of the eggshell layer to assist the embrio to release from the chorion in the right time (Isriansyah, 2011).

Conclusion
Media with osmolarity level of isoosmotic to hyperosmotic (901.76-1227.25 mOsm.L -1 H 2 O) are able to provide high osmotic rate with low energy for A. salina cysts hatching proccess.The energetic efficiency of A. salina cysts hatching is the same in the range of 640.27-1227.25 mOsm.L-1H2O in the media with osmolarity of hypoosmotic, isoosmotic and hyperosmotic.
Osmotic (mOsm.L -1 H 2 O) P osm blood = blood osmotic pressure (mOsm.L -1 H 2 O) P osm media = osmotic pressure of the media treatment (mOsm.L -1 H 2 O) Hatching rate artemia cysts is done by calculating the A. salina.Based on the number of cysts A. salina hatched by the number of Nauplius generated.The method can be used to determine the degree of hatching according to Khumaidi (2012), where : HR = hatching rate N = number of cysts hatched C = the total number of cysts were hatched Based on the Figure1, highest values of osmotic rate of non-decapsulated A. salina first instar were existed on the media with osmolatiry of640.27;1080.51;787.02; 901.76 and 1227.25, with the value of 154.71;  47.54; 12.99; 10.76 and 7.28  mOsm.L -1 H 2 O. On the other hand, the decapsulated artemia instar obtained highest osmotic rate at the media with the osmolarity of640.27;1227.25;1080.51;787.02 and 901.76 with  the value of 158.64; 91.29; 48.44; 24.93 and 10.82   mOsm.L -1 H 2 O, consequtively.The analysis of variances indicated that the osmotic rate of the artemia cysts was significantly different with the addition of chlorine and various osmotic condition (p<0.05).

Figure 2 .
Figure 2. Average value of hatching rate of A. salina cyst Remarks : Non-Decapsulation; Decapsulation

Table 1 .
Ca-Chorionase enzyme activity on A. salina cyst hatching Results of the experiment demonstrated that Ca-chorionase enzyme activity is decreased in hypoosmotic environment.the lower osmotic condition inhibit the hatching process due to the low enzyme