1. Daphnia sp / Daphnia magna
Daphnia is an Arthropod phylum that lives in general in fresh water. Species of the Daphniagenus are found from tropical to arctic with various habitat sizes ranging from small ponds to large lakes. Of the fifty species of this genus worldwide, only six species are normally found in the tropics. One of them is the Daphnia magna species (Delbaere & Dhert, 1996)
Daphnia sp. is one of the animals poikiloterm so that the rise and fall of environmental temperature can affect the heart rate or work. The metabolism of the poiciloterm animals is influenced by the environment, as well as the heart rate. The body wall of Daphnia sp.transparent so that its internal organs will be visible under the light microscope and its heart work can be seen clearly (Susanto, 1989)
Daphnia is a small crustacean that lives in fresh water, often also called a water flea. So called because of the unique way of moving from this organism in the water. There are many species (more or less 400 species) of Daphniidae and their distribution is extensive. Of all the species available, Daphnia and Moina are best known, and often used as feed for fish larvae (Pangkey, 2009).
Interesting Facts About Daphnia sp
- Daphnia is very susceptible to alcohol. According to Watterman, (1960) toxic compounds cause the entire body tissue system in Daphnia to be disturbed and alcohol is a toxic compound for Daphnia . Alcohol will cause the entire network system in the body of Daphnia to experience vulnerability to adapt to changing environments. Alcohol will stimulate the sympathetic nerves so that the work of the heart becomes stimulated and becomes faster.
- Daphnia is often used in heart rate observations. According to Soegiri, (1988) the higher the temperature of the living environment Daphnia sp the faster the heartbeat.
- Daphnia can also function toxicity / toxicity bioindicator contained in a waters. Daphnia sp.can be used as a toxicity test against pollutants because these organisms are very sensitive to environmental changes including the presence of pollution caused by chemicals such as herbicides with methyl metsulfuron active compounds. Daphnia sp.potentially as a pollutant bioindicator due to the presence of toxic substances in a waters including the active ingredient methyl metsulfuron by looking at the ratio of male sex of Daphnia sp. (Muarif, 2014).
- At a temperature of 22-31 degrees Celsius and a pH of about 6.5 to 7.4 daphnia can grow into an adult within 4 days
- Daphnia lay eggs as much as 1-2 days with the amount of about 29 grains with the ability to spawn an average of 7 times
- The egg size in normal reproduction is greater than that of parthenogenesis because the volume of egg yolk in normal reproduction is greater
Classification Daphnia magna
According to Pennak (1989), the classification of Daphnia magna is as follows:
Phylum: Arthropods
Subfilum: Crustacea
Class: Branchiopoda
Subclass: Diplostraca
Order: Cladocera
Subordo: Eucladocera
Family: Daphnidae
Subfamily: Daphnoidea
Genus: Daphnia
Species: Daphnia magna
Morphology of Daphnia magna
The division of Daphnia’s body segment is almost invisible. The head is fused, with the shape bent toward the lower body clearly visible through a clear indentation. In some species most of the limbs are covered by carapace , with six pairs of pseudo feet in the abdominal cavity. The most visible parts of the body are the eyes, the antenna and a pair of seta. In some types of Daphnia, the portion of the carapace is translucent and clearly visible through the inner microscope of the body.
Some Daphnia feed on crustaceans and small rotifers, but most are filter feeders , eat unicellular algae and a variety of organic detritus including protists and bacteria. Daphnia also eats some types of yeast, but only in controlled environments such as laboratories. Growth can be controlled easily with yeast. The filtered food particles are then formed into boluses that will descend through the digestive cavity to the fullest and through the anus are placed at the end of the digestive cavity. The first and second legs are used to form a small current when removing food particles that can not be absorbed. Daphnia organs for swimming are supported by a larger antenna. This antenna movement is very influential for the movement against the current (Waterman, 1960).
Reproduction of Daphnia magna
The reproductive mechanism of Daphnia is by parthenogenesis. One or more young individuals are treated by sticking to the parent body. The newly hatched daphnia must do the moltingseveral times before growing up about a week after hatching. The life cycle of Daphnia sp. ie eggs, children, adolescents and adults. The size increases occur shortly after the eggs hatch inside the incubator. Daphnia sp. adult size of 2.5 mm, the first child of 0.8 mm produced by parthenogenesis. Daphnia sp. started producing the first child at 4-6 days. The age that can reach 12 days. Every one or two days, Daphnia sp. will give birth to 29 tails, the newly hatched individual is the same anatomically with the adult individual. This reproductive process will continue if its environmental conditions support growth. If the condition is not ideal new males will be produced for male sexual reproduction occurs (Waterman, 1960).
Daphnia has both sexual and asexual phases. In most waters of the population Daphnia is more dominated by female Daphnia that reproduce asexually. Under optimum conditions, female Daphnia can produce 100 eggs, and can spawn again every three days. Female Daphnia can spawn up to 25 times in her life, but on average female Daphnia can only lay six eggs in her life.Female Daphnia will start laying eggs after four days of age with 4 to 22 eggs. In bad conditions the males can produce, so sexual reproduction occurs. The eggs produced are dormant eggs ( resting eggs ). Factors that can cause this are food shortages, low oxygen content, high population density and low temperatures (Pangkey, 2009).
Male Daphnia is smaller in size than that of a female. In male individuals there is an additional organ in the abdominal section to hug the female from behind and open the female carapacae , then spermateka enter and fertilize the egg. The fertilized eggs will then be protected by a layer called ephipium to prevent from environmental threats to ideal conditions for hatching (Mokoginta, 2003).
Habitat Daphnia sp
Daphnia sp is a type of zooplankton that lives in fresh water, inhabits a pond or lake. Daphnia spcan grow optimum at 18-24 ° C. This temperature hose is the optimal temperature hose for growth and development of Daphnia sp .
Beyond that interval, Daphnia sp will tend to dormant. Daphnia sp requires a slightly alkaline pH between 6.7 and 9.2. Just like other aquatic creatures high pH and high ammonia content can be deadly for Daphnia sp , therefore the level of ammonia needs to be well preserved in a system of their cultivation. All species of Daphnia sp are known to be very sensitive to metal ions, such as Mn, Zn, and CU, and other soluble toxic substances such as pesticides, bleach, and detergents. Daphnia sp is a filter feeder , meaning they “filter” the water to get the feed in the form of single-celled creatures such as algae , and other types of protozoa and organic detritus .In addition, they also need vitamins and minerals from the water. Mineral must be present in water is Calcium, this element is needed in the formation of “shell” it.
Daphnia sp is known to be tolerant with low dissolved oxygen content. In conditions with low dissolved oxygen levels, they will form hemoglobin to aid in the distribution of oxygen in their bodies. This hemoglobin hemorrhage often causes red Daphnia sp . This will not happen if the dissolved oxygen levels are sufficient. (The color of Daphnia sp is often determined by the type of food consumed, for example if they consume algae , then their body will tend to be green).Oxygen supply can be given to culture to ensure adequate oxygen levels.
Factors Affecting the Frequency of Daphnia Heart Rate
Barnes, (1963) concluded that the factors that affect the frequency of Daphnia’s heart rate are as follows:
- Heart rate faster during the day.
- Increased metabolic rate stimulates the heart to work faster.
- Age and size tend to have a slow heart rate.
- Heart rate tends to increase with increasing temperature in a normal environment.
- The dark conditions will make the heart rate decrease.
- The addition of chemicals such as alcohol causes the pulse to increase.
- The female animal carrying the egg / child in an incubation bag will cause the heart rate to accelerate.
- At the time of the first sexual rhythm the heart rate will accelerate.
The heartbeat of the fish in the hot climates may be determined by factors such as temperature, rainfall, water levels, oxygen availability, electrical conductivity, pH water, alkaline levels, nutrient availability and food. These factors can accelerate or slow down the reproductive process and may affect egg incubation, larval development, growth and survival.The breeding of some tropical animal species depends on the climatic patterns in the environment that can ensure good conditions for eggs and larval survival (Baumgartner, 2008).
Content of Daphnia Sp
The nutritional content of Daphnia varies with age and depends on the food eaten. Protein content is usually about 50% of dry weight. Adult Daphnia contains higher fat than juvenile which is about 20 -27%; and 4 – 6% in juveniles. In some species found to contain up to 70% protein. Daphnia also contains a number of digestive enzymes such as proteinase, peptidase, amylase, lipase and cellulase (acts as an eco-enzyme in the digestion of fish larvae) (Pangkey, 2009).
Bacillus subtilis
Bacillus subtilis
This bacterium is a common type of bacteria found in soil, water, air and decomposed plant matter. Including groups of gram-positive bacteria, aerobics, capable of forming endospores. B. subtilis has the ability to produce antibiotics in the form of lipopeptides, one of which is iturin.Iturin helps B. subtilis compete with other microorganisms by killing other microorganisms or lowering their growth rate. Iturin also has fungicid activity against pathogens (Buchanan, 1975).
Here is the classification of B. subtilis : (Madigan, 2005)
Kingdom: Bacteria
Phylum: Firmicutes
Class: Bacilli
Order: Bacillales
Family: Bacillaceae
Genus: Bacillus
Species: B. subtilis
In some studies it was found that the addition of B.subtilis waters can improve water quality by reducing the concentration of CO 2 waters. The use of B. subtilis in shrimp farms shows that B. subtilis can increase the survival of tiger shrimp larvae and prevent vibriosis disease due to Vibrio harveyi. In addition B. subtilis naturally bersimbiosis on the digestive tract of tiger shrimp (P.Kungvankij, 1985).
B. subtilis requires optimum conditions to grow. The following are the optimum chemical physics conditions for this bacteria (Graumann, 2007):
- DO: this bacteria is obligate aerobic type, the higher the DO then the better for optimum growth. The minimum is in the range of 2 mg / L
- Temperature: the optimal temperature to grow for B. subtilis is between 25 – 35 0 C
- pH: optimal pH between 7 – 8.
Ammonium also has an effect on B. subtilis that can minimize cannibalism among bacteria B. subtilis (Nandy & Venkatesh, 2008).
3. Nitrifying bacteria
According to Ward (1996), nitrifying bacteria is a group of chemoautotrophs that grow by utilizing inorganic nitrogen compounds. Many of these bacterial species have internal membrane systems where there is a key enzyme in the nitrification process. Such enzymes include ammonia monooksigenase (oxidizing ammonia to hydroxylamine) and nitric oxireductase (oxidizing nitrite to nitrate). Here is the classification of nitrifying bacteria: (Holt et.al, 1994)
Kingdom: Prokaryotes
Division: Bacteria
Family: Nitrobacteraceae
Genus: Nitrosomonas and Nitrobacter
4. Common Zooplankton Culture System Performed
4.1 Zooplankton culture system
In general, there are four types of zooplankton culture systems for the purposes of live feed in aquaculture process namely:
i). Static system
Static or batch systems are the most commonly used culture systems. In a static system, after inoculation of culture will be developed for a certain period, then harvesting on culture as a whole. This static system is extensive and requires a lot of space in the process. However, this system has advantages that are easy to do (Snell, 1991).
ii). Semi-continuous system ( Semi-continuous system )
In this semi-continuous system, the zooplankton density is kept constant by harvesting periodically. In semi-continuous system part of culture volume is harvested every day, then culture plus new medium with the same volume. This method is also called the thinning method(Snell, 1991).
iii). Continuous system
Continuous system is an intensive culture system. The purpose of this system is similar to that of semi-continuous systems, but this continuous system is more consistent in maintaining water quality through the high frequency of water culture change and the use of kemostat (Suantika, 2001; Snell, 1991). A new culture medium is always added in this system, so no special treatment is needed to maintain the pH and reduce the accumulation of ammonia. In this system, constant high-quality culture density can be achieved. The productivity of culture with continuous system is higher when compared with static and semi-continuous culture system (James & Abu Rezeq, 1997).
Continuous culture system has a deficiency that is only applied in experimental or experimental scale, and has not been applied in the hatchery . This system has a high risk of technical failure because it is complicated, has many variables to be controlled, and requires high costs (Suantika, 2001).
iv). High density culture system ( Ultra-high density culture system )
High density culture systems are an effective way to culturize zooplankton without extending the culture area. This system has advantages that the number of workers needed a little, has a high productivity and consistent throughout the year (Suantika, 2001).
This culture system was developed by Japanese researchers. Using a B. plicatilis culture capable of achieving a density of 10,000 individuals / mL in a 1 m 2 tank (Yoshimura et al. 1995, 1995 in Suantika, 2001).
4.2 Daphnia sp. Culture system .
According to FAO (1996), the mass culture system Daphnia sp. known two special systems:
i) Detrital System
This system is a system made from a mixture of soil medium, manure, and water. Manure functions as a natural fertilizer to initiate an increase in the amount of algae that is feed Daphnia sp. The mixture of manure is proportional to 1kg: 200 gr part diluted in one liter of water. This system has the advantage of being easy to treat and Daphnia is not susceptible to nutritional deficiencies, due to the varied algae in abundance. This system has a weakness because it does not adequately support the condition of standard requirement (uncontrolled) Daphnia , so that can occur condition of lack of oxygen that cause high level of death of Daphniaand low of egg production.
ii) Autotrof System
The autotroph system is another way of adding cultured algae into Daphnia cultures. Green water cultures (10 5 to 10 6 sel.ml -1 ) were added from monoculture cultured algae or from fish ponds that have diverse algae species. Cultural control will be easier if the algae used are monocultures, such as Chlorella , Chlamydomonas or Scenedesmus , or a mixture of the two algae cultures. The disadvantage of this system is not being able to sustain Daphnia culture for continuing generation without vitamin supplementation into Daphnia cultures. These vitamins include B complex vitamins, calcium pantothenate, biotin and thiamin.
5 Water Quality Parameters
5.1 Temperature
Temperature is an important environmental factor for all aquatic organisms. The tolerance limit of each organism to temperature varies, depending on the physiology of the organism. In temperature waters affect the solubility of oxygen, which is important for the survival of the majority of aquatic organisms. In this experiment the temperature was maintained at the optimum temperature of Daphnia sp. ie 25 0 C. A stable optimal temperature will keep pH and DO stable (Mokoginta, 2003).
5.2 The pH value
The pH or potential hydrogen value is an indicator of the hydrogen ion concentration that describes the acid concentration. This value is inversely proportional to temperature, the higher the temperature causes the lower the pH.
According to Pennak (1989), a good pH for growth of Daphnia sp. Ranges from 6.5 to 8.5. In general, a neutral and relatively alkaline water environment in the pH range of 7.1-8.0 is better for growth of Daphnia sp. (Mokoginta, 2003)
5.3 Dissolved Oxygen (DO)
According to Cole (1994), the solubility of a gas (including oxygen) in the liquid medium is characteristic of the gas itself, and is affected by pressure, altitude, temperature and salinity.The solubility of gases in the liquid medium decreases with increasing temperature and the amount of dissolved minerals in the medium (Salmin, 2005)
Dissolved oxygen has an important role in the life of Daphnia sp. In general, Daphnia sp. can live at a high enough dissolved oxygen concentration of about 4.2 to 5.1 ppm and can not live at dissolved oxygen concentrations less than 1 ppm (Mokoginta, 2003), whereas according to Delbaere & Dhert (1996), minimum dissolved oxygen levels which required the culture of Daphnia sp. is about 3.5 ppm.
5.4 Ammonia
Aquatic animals commonly excrete ammonia as a result of metabolic processes. There is unionized ammonia (NH 3 ) and ionized ammonia or ammonium ion (NH 4 + ). Ammonia is toxic to larvae or aquatic organisms such as Daphnia sp. because it can pass through the membrane of internal organs, while the ammonium ion can not pass through the membrane (P.Kungvankij et.al, 1985). According to Cole (1994), every day a Daphnia pulex releases 0.2 μg of nitrogen.
Ammonia levels in the water will increase with increasing temperature and pH. High levels of ammonia can decrease the reproductive rate of Daphnia sp. Safe ammonia levels for culture Daphnia sp. is below 0.2 mg / L (Delbaere & Dhert, 1996).
source: Lecture Notes