In addition, the expansion of aquaculture is also limited due to its heavy reliance on fishmeal (Browdy et al., 2001). Microalgal antimicrobial metabolites have gained more and more interest in recent years (Cavallo et al., 2013).
Aims and objectives of the study
Algal habitats range from open oceans (occupied by planktonic microalgal species), to rocky shores (occupied by marine macroalgae or seaweeds and benthic microalgae), to freshwater habitats (often inhabited by noticeable filamentous algae), including rivers, lakes, ditches and ponds (Stengel et al., 2011). The proximate composition of microalgae is influenced by culture parameters such as light (intensity and photoperiod), temperature and pH (Khatoon et al., 2014).
Taxonomic Classification and Characterization of the Microalgae Species .1 Tetraselmis chuii
- Penaeus monodon
- Color in life
- Distribution
- Life history
- Reproduction and Sexuality
- Morphological Development .1 Embryo
- Longevity
- Feeding behavior
In addition to the ability to produce antioxidants and other economically valuable bioactive compounds, microalgae also have commercial application due to its rapid growth rate and lower amount of nutrients required during cultivation (Lee et al., 2006). Penaeus monodon is known as the tiger shrimp in Asian countries, especially in the waters of the Bay of Bengal. The carapace is carinated and almost touches the posterior edge of the carapace with the rostral carina.
The abdomen is dorsally carinated from the anterior third of the fourth to the posterior end of the sixth. According to Motoh (1985), the early juvenile stage megalopa (commonly known as postlarvae or 'fluff' for commercial purposes) is translucent with a dark brown band at the apex of the teleson on the ventral side of the antennular flagellum. Under laboratory conditions, on the sixth day of the post-larval period, the post-larvae become benthic.
Study area and Collection of microalgae species
This chapter deals with the methods followed and materials used to achieve the objectives of the study. Dried biomass of selected microalgae was kept in the refrigerator for further use during feed preparation. In the second phase, growth, survival rate and nutritional profile of marine larvae Penaeus monodon were studied by feeding with the two algal diets.
Seawater collection
Media Preparation
Culture of Microalgae
Mass Culture of Microalgae
Feed Formulation for Penaeus monodon Postlarvae
Proximate Analysis of the Formulated Feed .1 Protein Analysis
Lipid Analysis
Samples were extracted from 4.5 ml of methanol:chloroform (concentration 2:1) and centrifuged for 10 min at 10,000 rpm. After extracting the supernatant from the biomass, the sample was centrifuged again to separate the two phases with 1.5 ml of chloroform and 1.5 ml of distilled water. The carbonization process lasted 15 minutes at 200°C, then the test tubes were cooled and 3 ml of water was added to each test tube.
Carbohydrate Analysis
The tanks were thoroughly washed and soaked in 20 mg L-1 chlorine overnight to prevent any transmission of disease through the culture vessels. The tanks were then intensively rinsed with running tap water until the chlorine smell disappeared and left to dry in the sun. The tanks were not randomly assigned, as the feeding trials were conducted in a closed hatchery with evenly distributed fluorescent light.
Each tank was given constant aeration and breeding tanks were maintained under a 12 h light:12 h dark cycle. To maintain water quality, fecal matter and uneaten food residue are removed daily to less than 10% of the culture volume. Surviving shrimp from each tank were counted at the end of the feeding trials and weighed to estimate mean survival for the treatment and control groups.
Physical Analysis
Chemical Analysis
Determination of Phosphate phosphorus (PO 4 -P)
One ml of mixed reagent was added to the test tube containing 10 ml of a water sample.
Survival and Growth Analysis of Shrimp Postlarvae
Proximate composition of different microalgae
Proximate Composition of the Formulated Feed
Proximate composition of Shrimp postlarvae
28 | P a g e Figure 8: Proximate composition of Penaeus monodon fed with two different algae (a) Tetraselmis chuii (b) Chlorella sp.
Water Quality in Shrimp Culture Tanks .1 Physical Analyses of Water Quality
Chemical Analyses of Water Quality
Figure 9(a) shows the total ammonia nitrogen (TAN) in the water sample from P.monodon postlarvae (PLs) tanks fed with different experimental diets. On the other hand, the TAN of the water sample from the tank supplied with the addition of different T. Although T25 showed a significantly lower (p<0.05) TAN compared to other treatments, both T50 and T75 also manage to maintain a low TAN throughout the experiment compared with control (Figure 9a).
Based on Figure 9(b), the NO2-N of the water sample from the tank fed with the addition of different T. Figure 9(c) showed phosphate phosphorus (PO4-P) (mg L-1) of the water sample from the tank fed with the addition of various T.
Based on Figure 10(a), the TAN of the water sample from the tank fed with the addition of different percentage of C.vulgaris showed a significantly lower (p<0.05) TAN. A significant decrease (p<0.05) in the TAN towards the end of the experiment compared to control (CF) was observed. The TAN of CH25, CH50 and CH75 did not differ significantly (p>0.05) throughout the experiment and the NO2-N was maintained at a relatively low level until Day17.
On the other hand, control (CF) showed significantly higher TAN compared to other treatments and the TAN value increased significantly (p<0.05) until day 17 compared to treatments with different percentages of C.vulgaris addition (Figure 10a). Based on Figure 10(b), the NO2-N water sample from the tank supplied with the addition of different C.vulgaris percentages showed a significantly lower (p<0.05) NO2-N. A significant decrease (p<0.05) in NO2-N towards the end of the experiment compared to control (CF) diet was observed.
Shrimp Survival and Specific Growth Rate
Figure 11(b) represents the survival rate of PL fed with different types of formulated feeds containing different percentages of T. Microalgae are used as live food during all developmental stages of bivalve molluscs (e.g. oysters, scallops, clams and mussels), from early larval/juvenile stages of molluscs, crustaceans and some fish species, as well as for zooplankton used in aquaculture and commercial aquaculture. Microalgae act as the primary producer for the entire aquatic food chain, which makes it a very important nutrient source in aquaculture, especially during the culture of shrimp, fish and shellfish (Muller-Feuga, 2000).
Researchers suggested several cost-effective protein sources for feed preparation to achieve optimal growth of fish (Tacon &. Metian, 2008). Microalgae species are used in this study because of their importance as food for both the larval and growth stages of bivalves, shrimp and certain fish species in aquaculture (Guedes and Malcata, 2012). In this study, PL of Peneaus monodon were fed with different formulated diets, replacing 25%, 50% and 75% of the fishmeal with two native marine microalgae species, Tetraselmis chuii and Chlorella vulgaris as protein sources.
Proximate Composition of Microalgae and Formulated Feed
In the present study, the protein content of the custom-made feed was found to be higher than the treatment feeds with T. However, the protein content of the treatment feed is still within the recommended limits for shrimp growth and survival. According to Biedenbach et al. 1989), higher dietary protein is required for postlarvae during the nursery stage than later stages.
A study showed that 40 to 50 percent protein with 20 percent carbohydrate and (5 – 10)% lipid gave Penaeus monodon juveniles the best growth and survival (Bautista, 1986). According to Sick and Andrews (1973), an improvement in the growth of Penaeus duorarum fed a diet containing 10% lipid. The results of this study were consistent with the results of Piña et al. 2006), which showed that Tetraselmis sp.
Proximate Composition of Shrimp Postlarvae
In the case of Chlorella sp. the carbohydrate content turned out to be 23 percent. in PL feed could therefore provide a sufficient amount of proteins and lipids, as well as the required carbohydrates, as well as a source of antioxidants for PLs. 25% replacement of fishmeal which strongly correlates with the result of Jamali et al. 2015) where diet supplemented with Tetraselmis sp. In the case of Chlorella vulgaris, PL also showed higher protein content when fishmeal was replaced 50% by Chlorella sp.
In the present study, a slight reduction in protein levels in Penaeus monodon postlarvae was observed as Chlorella inclusion was increased. Similarly, slightly lower protein levels were reported in whiteleg shrimp (Litopenaeus vannamei Boone) as higher inclusions of the marine alga Tetraselmis were incorporated into their diet (Kiron et al., 2012). Similar findings were also reported when different species of microalgae in the diets of P.
Water Quality of the Culture Tanks
According to Chuntap et al. 2003) the use of phytoplankton (green water technique) in large species of aquaculture species has been shown to result in better growth and survival compared to pure water culture. In addition to maintaining lower TAN, NO2-N and PO4-P throughout the culture, the medium of PL fed T25, T50 and T75 also showed a decrease in TAN, NO2-N and PO4-P towards the end of the culture. . This result was in agreement with Chen et al. 2012) who found that T. chuii showed the highest TAN uptake compared to the other three species studied, resulting in lower nutrient values towards the end of cultivation.
According to Thompson et al. minimal water exchange in PL fed with T chuii inclusion can be considered. 2002) and this is advantageous because of the cost and labor usually required to maintain good water quality for regular water exchange in aquaculture. In the case of chlorella-treated tanks, PL fed with CH25, CH50 and CH75, NO2-N and PO4-P gradually increased in smaller amounts from day 4 of the experiment, but TAN did not increase. These findings were in agreement with Mujtaba et al. 2015) who reported that the highest TAN uptake was shown by Chlorella vulgaris, which contributed to lower nutrients at the end of cultivation relative to NO2-N and PO4-P.
Specific Growth and Survival Rate of Penaeus monodon Postlarvae
The findings of this study use a type of microalgae as a fishmeal substitute that can be used and has a potential role in increasing growth and survival. Future studies should also be conducted on the effect of the combination of microalgae Tetraselmis chuii and Chlorella sp. Effect of biofloc dietary supplement on growth and digestive enzyme activities in Penaeus monodon.
49 | P a g e Presence of Penaeus monodon on the continental shelf of Para state, northern Brazil (Crustacea, Decapoda, Penaeidae). Studies on the fishery biology of the giant tiger prawn, Penaeus monodon in the Philippines. Proceedings of the First International Conference on Penaeid Shrimp / Prawn Culture, Iloilo City, Philippines, December 4-7, 1984.
Survival, development and growth of larval Pacific white shrimp Litopenaeus vannamei protozoea fed monoalgal and mixed diets. Effect of probiotics on the growth and activity of digestive enzymes of the shrimp Penaeus vannamei.
Mass culture of Tetraselmis chuii
Centrifuging to collect biomass of microalgae
Dry biomass of microalgae
Experimental setup for feeding experiment
66 | P a g e Appendix 12: One-way analysis of variance examining protein, lipid and carbohydrate contents of Penaeus monodon treatment tanks following microalgae used as diet. 69 | P a g e Appendix 10: One-way analysis of variance examining the SGR and survival rate of treatment tanks of Penaeus monodon following the microalgae used as diet.
