Live feeds play an important role in aquaculture operation. Presently,

the groups of live feeds employed in the culture systems are

limited to afew species ofphyto and zooplankters. Dunaliella salina,

(greenmicroalga), a member of Chlorophyceae, is an unconventional

live feed. The culture of this species is presently limited to laboratory

experimental stage only. In view of the paucity of studies

on the culture and utilization of Dunaliella salina, the present investigation

was undertaken to explore and estimate the potential use of this

species. The results of rearing of Juvenile clams with Dunaliella as live

feeds are presented and discussed

Bindhu, K B

Gireesh, R

Gopinathan, C P

Smitha, K S

CMFRI Digital Repository

PERSPECTIVES IN MARICULTURE Editors N. G. Menon and P. P. Pillai Central Marine Fisheries Research Institute, Cochin The Imveitigator The Marine Biological Association of India Post Box No. 1604, Tatapuram P.O., Cochin - 682014 2001 Dunaliella salina - an unconventional live feed R. Gireesh, K.S. Smitha, K.B. Bindu and C.P. Gopinathan Central Marine Fisheries Research Institute, Cochin-682 014 ABSTRACT Live feeds play an important role in aquaculture operation. Pres-ently, the groups of live feeds em-ployed in the culture systems are limited to afew species ofphyto and zooplankters. Dunaliel la sal ina, (greenmicroalga), a member of Chlorophyceae, is an unconven-tional live feed. The culture of this species is presently limited to labo-ratory experimental stage only. In view of the paucity of stud-ies on the culture and utilization of Dunaliella salina, the present inves-tigation was undertaken to explore and estimate the potential use of this species. The results of rearing of Ju-venile clams with Dunaliella as live feeds are presented and discussed. • s & -« » • -# » # » *l\ • • ^ - * ^ • W • • * • ^ - • • • • . • ^ • • % . ! ' 1 • ^ * « * • ib •?! - • • ' . : • • • . ' : Perspectives in Maricultwe Introduction In aquaculture systems, several live feeds are used presently such as Chaetoceros, Isochrysis, Skeletonema, etc. The hatchery rearing of prawn/ mollusc larvae is dependent on these live feeds. There are innu-merable species of phytoplankton in our waters; but only very few of them are used as live feeds in aquaculture. In view of this, the present study was undertaken to evaluate the culture possibilities of Dunaliella salina and to study its effect on the growth, survival rate and performance in Juvenile clams. Dunaliella scdinais a member of Chlorophyceae; a green halotolerant (ie., thrives in media with a very board range of salt concentrations) microalga. The dominant pigment - chlorophyll, is masked by the pres-ence of a pigment - haematochrome. It accumulates large amounts of commercially valuable chemicals - glycerol b and - carotene. Dunaliella is cultured in coastal ocean areas in large outdoor ponds In regions of high solar radiation and moderate temperatures. An attempt has been made in this brief work to evaluate the performance of Dunaliella salina in laboratory / hatchery conditions. Materials and methods Four live feeds viz, Dunaliella, Chaetoceros, Tetraselmis and Nanochloropsis were cultured in laboratory conditions using Walne's me-dium in sterilized seawater at 30 ± 2ppt salinity. Juvenile clam of Villorita cyprinoides (7.52g average initial weight) were brought from a local farm off Cochin and reared in 8-10 ppt salinity under labouratory conditions. The clams were acclimatized for rearing in 8-10 ppt salinity under laboratory conditions. The clams were accli-matized to the rearing conditions for over a period of one week. Prior to starting of the experiment, the clams were starved for 48 hrs . The clams were then grouped into four goups; each group containing 10 animals (Table 1). Each group was fed on separate feeds to study the comparative efficiency of Dunaliella with respect to the other conventional live feeds. — 236 — Dunaliella salina Table 1. Groups, feeds and feeding rate used in the experiment Groups Group I Group 11 Group 111 Group IV Feeds Dunaliella Chaetoceros Tetraselmis Nanochloeopsis Feeding rate 500-700 cells/ml -do--do--do-The animals were maintanined in separate tubs with 3 1 of filtered seawater. The feed ration was divided into two and given at intervals of 8hrs. 100% water exchange was done every day. The feeding rate (inges-tion rate) was determinded as : Feeding rate or ingestion rate = CI - C2 x V x 60 nt where, CI - initial cell concentration (cells/ml) C2 - final cell concentration (cells/ml) V _ Volume of water (1) t _ duration of the experiment n _ no. of animals. The animals were reared with the respective feeds for a period of 15 days. At the end of the experiment, the animals were sacrificed and their biochemical composition estimated. Growth and survival rate was also studied. Biochemical assays were carried out to estimate the protein, carbohydrate and lipid contents. Protein was estimated following the procedure of Lowry etal. (1951). The values were obtained by comparing with standard graph. Carbohydrate was estimated using Glucose as standard. Fat (lipid) was determined using gravimetric method. Simultaneously a group of 10 clams were maintained as control for the same length of period as that of the experimental only. All conditions were the same for this group also, except that they were not fed any feed. — 237 — Perspectives in Maricidtwe Culture of Dunaliella ; The cand ida t e species , Dunaliella salina, w a s cul-t u r e d In th ree different m e d i a for a period of 15 days a t 3 0 p p t sal ini ty a n d 240c . Medium I - Walne ' s m e d i u m Medium II - Mlquel 's m e d i u m Medium III - Enr i ched seawa te r m e d i u m (modified 'F' med ium) . 2 0 ml of Dunaliella s a l ina w a s Inoculated Into 500 ml of filtered a n d ster i l ised s eawa te r con ta in ing the respect ive m e d i u m . The cu l t u r e w a s car r ied o u t In t r ip l ica tes . (1 ml of Inocu lum con t a in s approx imate ly 500 ce l l s /ml) . R e s s u l t s Feeding experiment: The per formance of each g roup of c l ams w a s moni -tored. The efficiency of t he feed w a s de te rmined In t e r m s of growth, su r -vival a n d b iochemica l c h a n g e s of t h e c l a m s . A s u m m a r y of t h e r e s u l t s ob ta ined is s h o w n In Table 2. No morta l i ty w a s repor ted wi th a n y of the feeds. However, t h e r e s u l t s were d i scourag ing wi th r e spec t to Dunaliella fed c l ams . C l ams fed on Dunaliella showed compara t ive ly l ess p ro te in a n d ca rbohyd ra t e c o n t e n t s . However, they showed be t t e r lipid profiles, a s expla ined e l sewhere . The growth r a t e w a s more wi th Dunaliella fed c lams a s s een in Table 2; b u t b iochemica l es t imat ion gives compara t ive ly lower va lue s for Dunaliella fed c l ams . Table 2. Growth and biochemical composition of the differet groups of clams Group Feed Av. initial Av. final % growth Protein Carbohy-fed weighty welght(g) (/g) drate(/g) Upld* I II III IV Dunaliella Chaetoceros Tetraselmls Nanochlor 8.69 11.42 9.73 12.28 8.86 11.45 9.79 12.30 1.96 21/ig 0.55Mg 0.249 0.263 30/tg 1 ng 0.249 0.617 28|ig 0.8/ig 0.109 0.163 10/ig 0.4/ig 0.135 * Expres sed a s mg l ip id / gm t i s sue . Culture of Dunaliella : The per formance of e a c h m e d i a w a s de t e rmined t ak ing into cons ide ra t ion t he following facts: 238 — Dundliella salina Incubation period, ie, the time taken for the culture to start growth. -exponential period - the duration for which the bloom lasts. final maximum no. of cells/ml at the time of harvest. Accordingly, the medium with the least incubation period and high-est exponential period along with better biochemical results is recom-mended as the ideal one. The results of culturing Dunaliella with the different media is given in Table 3. Table 3. Results of Dunaliella culture with different media Blochem. compostion Media Initial no. Final no. of Incubation Exponential Carbo-of cells/ml cells/ml period period Protein hydrate. lipid (days) (days) /ig/g /ig/g mg/g Walne's 500 Mlquel's -do-Modifled F -do-13x103 3 to 4 one month * two weeks one week 17.5 14 0.773 * not determined as culture did not develop. In the case of Walne medium blooming started within three to four days after inoculation. With Mlquel's medium, blooming took ten to eleven days and declined in about two days time. With modified 'F' medium, there was no blooming at all. Since, the amount of sample that could be obtained from these two media ('F' and Miquel media) were very less, no biochemical estimation of these could be carried out. However, biochemical studies were carried out with Dunaliella cultured in Walne medium. Discussion Clams fed with Dunaliella showed a higher percentage of growth (1.96%) compared to the other groups. Also, Dunaliella fed clams showed an increased lipid content (0.2488 mg/g) compared to other groups. This is attributed to the high levels of glycerol accumulated by Dunaliella in culture conditions (Delia etal. 1995). Studies on feeding Artemia with DunolieUa have given large scale mortality. Similarly, with shrimps also mortality and collapse qf culture has been recorded (C.P. Gopinathan, unpublished). The results indicate that Dunaliella is not a substitute for the al-— 239 Perspectives in Mariculture ready widely used live feeds such as Chaetoceros and Tetraselmis. But, it can be incorporated as a supplementary live feed in moUuscan culture. The study also indicates that Dunaliella is not toxic to juvenile and adult calms. The effect of rearing larval molluscs with Dunaliella remains to be studied. As regards the lower biochemical values obtained with Dunaliella, it can be men t ioned t h a t Dunaliella u s e s a lot of i t s energy on photoconversion - where the dominant green pigmet is converted into Xanthophyll. Also the higher lipid values explains the lower protein and carbohydrate values. The results indicate that Walne medium is the ideal one for cultur-ing Dunaliella. With this medium a good bloom of the culture and excel-lent exponential growth is obtained. References Delia Croce, N; S. Connell; R. Abel (Eds.) 1995 In: Coastal Ocean Space Utiliza-tion:3; pp. 433-436. Lowry, C.H., N.J., Rosebrough, A.L. Farr and R.J. Randall, 1951. Protein mea-surement with foUn phenol reagent. J.Biol. Chem... 193: 265-275. 240 — 

Dunaliella salina – an unconventional live feed

http://eprints.cmfri.org.in/2381/1/Article_20.pdf

Dunaliella salina – an unconventional live feed

Abstract

Similar works

Full text

Available Versions

CMFRI Digital Repository