Larval survival and growth of Arbacia punctulata (Echinodermata: Echinoidea) fed with five micro-algae at two salinities

Fertilized eggs from an spontaneously spawn of thirty sexually mature sea urchins (Arbacia punctulata) were incubated to complete embryonic development. The echinopluteus larvae (3 ind/ml) were distributed into 50 plastic containers (25 containers at 30 psu and 25 containers at 40 psu) and fed on Tetraselmis chuii, Nannochloropsis oculata, Isochrysis galbana, Chaetoceros gracilis and C. calcitrans under a natural photoperiod. The water of the containers was partially renewed (75%) everyday. Larval anatomic development aspects, daily survival and growth were determined. The growth was determined through postoral arms and body length measurement, and body diameter of twelve larvae during metamorphosis. During the planktonic larval phase, only the I. galbana diet produced similar results for both salinities. The relative growth of larvae was isometric (I) for larvae fed on I. galbana at two salinities and positive allometric for those fed on C. gracilis and C. calcitrans at both salinities. In this study A. punctulata started metamorphosis at day 14 and was completed 30 days after fecundation. Significant differences were detected in post-settlement body growth between the two salinities (F = 23.58, p < 0.05): growth was better for larvae at 30 psu (final body diameter was 3.14 +/- 0.44 mm). The final rate of planktonic larvae was highest with I. galbana (58.33%). For juveniles the rate was 6.48% for those fed on C. gracilis (40 psu in both larvae and juveniles). We recommend the use of this diet and 40 psu for survival or 30 psu for growth.     

Development of the tropical fish Xenomelaniris brasiliensis (Pisces: Atherinidae) from embryo to larva and time to metamorphosis

Embryonic-larval development, and metamorphosis larval time, were studied in the tropical fish Xenomelaniris brasiliensis. Twenty nine sexually mature specimens were used, 16 females (10.86+/-1.01 cm and 7.63+/-2.62 g) and 13 males (10.43+/-0.57 cm and 6.54+/-1.44 g) which produced gametes through abdominal massage. Fertilized eggs were spherical (1.18 +/-0.44 mm diameter), greenish, transparent, benthonic and vitelus-rich; rugose striated chorion with numerous external filaments randomly distributed and abundant oil globules (0.11 + 0.07 mm diameter). The embryonic development was finished at 26.36+/-2.03 degrees C, 39.67+/-0.58 PSU and pH 8.30+/-0.10. Larvae (4.56+/-0.97 mm total length) hatched at 143 hours and 19 minutes. with vitteline sac vestiges and a single oil globule. The larvae were fed on Brachionus plicatilis and Isochrysis galbana. After the second week .4rtemia nauplii were added and I. galbana maintained. Flexion started 13 days after larvae hatched (6.10+/-1.54 mm total length) and was completed 32 days later (11.25+/-1.87 mm total length) with the hipural complex completely developed. In conclusion, X brasiliensis showed direct larval development and started larval metamorphosis (13.08+/-2.07 mm total length) to juvenile 40 days after hatching.     

Effects of amino-acid mixtures on food utilization and growth in Tenebrio molitor L

Ten holidic diets, varying in amino-acid concentration or composition, were fed to larvae of Tenebrio molitor for four weeks at 27 +/- 0.25 degrees C and 65 +/- 5% r.h. Effects of diet on growth, food utilization and energy utilization were recorded for individual larvae. Differences in gains in fresh weight or in dry matter among larvae fed diets containing 0% to 5% of the amino-acid mixture were not demonstrated. However, larvae fed 10% or 20% of this mixture gained more than the former, but less than larvae fed a diet of ground whole wheat and brewer's yeast (9:1, w/w). When the amino-acid mixture was supplemented with alanine, aspartic acid, and serine, or with these three and asparagine, and was fed to larvae at the 10% level, growth was slower than with the unsupplemented mixture. Supplementation of the amino-acid mixture with the first three amino acids did not reduce larval growth when fed at the 20% level. Amounts of food and of energy utilized were positively correlated with larval fresh-weight and dry-matter gains. Energy utilization was negatively correlated with dietary amino-acid level. Food and energy utilization and larval growth were influenced by dietary amino acids, either metabolically or through phagostimulation.     

Temperature-dependent development and demography of Scymnus subvillosus (Coleoptera: Coccinellidae) reared on Hyalopterus pruni (Homoptera: Aphididae)

The development, survival, and fecundity of Scymnus subvillosus (Goeze) (Coleoptera: Coccinellidae) were studied at 20, 25, 30, and 35 degrees C, 60 +/- 5% RH, and a photoperiod of 16:8 (L:D) h (5,000 lux) under laboratory conditions. The total developmental time from egg hatch to adult eclosion ranged from 22.6 d at 20 degrees C to 10.6 d at 35 degrees C. The developmental rates of the egg stage, the larval stage, and total preadult stage at different temperatures increased linearly with increasing temperature. The thermal summation of the egg stage, the larval stage, and the total preadult stage was 77.5, 145.8 and 300 degree-days (DD), respectively. The developmental threshold of the egg stage, the larval stage, and the total preadult stage was 7.4, 4.1, and 7.1 degrees C, respectively. The life history raw data were analyzed using the age-stage, two-sex life table. The intrinsic rate of increase was 0.0845, 0.1138, 0.1395, and 0.0668 d(-1) at 20, 25, 30, and 35 degrees C, respectively. The net reproductive rate was highest at 25 degrees C (R0 = 78.7), and lowest at 35 degrees C (R0 = 4.7). The mean generation time was shortest at 35 degrees C (T = 23.9 d). The life table data can be used for the projection of population growth and designing mass rearing programs.     

Use of freeze-dried microalgae for rearing gilthead seabream, Sparus aurata L., larvae. II. Biochemical composition

The objectives of this study were to test whether freeze-dried microalgae are nutritionally adequate for rearing rotifers as food for gilthead seabream larvae. The elemental composition (C, N, H) and fatty acid composition were analysed in larvae of gilthead seabream, Sparus aurata L., rotifers Brachionus plicatilis and Brachionus rotundiformis and freeze-dried microalgae Nannochloropsis oculata. Four larval feeding treatments were tested: (A) larvae fed rotifers cultivated with freeze-dried microalgae and daily addition of freeze-dried microalgae to the larval tanks; (B) larvae fed rotifers cultivated with freeze-dried microalgae and daily addition of live microalgae to the larval tanks; (C) larvae fed rotifers cultivated with freeze-dried microalgae, without addition of microalgae to the larval tank and (D) larvae fed rotifers cultivated with live microalgae and daily addition of live microalgae to the larval tanks. No significant differences were observed between the biochemical composition of larvae with treatment A (with freeze-dried microalgae) and the composition of larvae in treatment D that were obtained with the acceptable methods for culture systems (with live microalgae).     

Development rates of two Xenopsylla flea species in relation to air temperature and humidity

The rate of development of immature fleas, Xenopsylla conformis Wagner and Xenopsylla ramesis Rothschild (Siphonaptera: Xenopsyllidae) was studied in the laboratory at 25 degrees C and 28 degrees C with 40, 55, 75 and 92% relative humidity (RH). These fleas are separately associated with the host jird Meriones crassus Sundevall in different microhabitats of the Ramon erosion cirque, Negev Highlands, Israel. This study of basic climatic factors in relation to flea bionomics provides the basis for ecological investigations to interpret reasons for paratopic local distributions of these two species of congeneric fleas on the same host. Both air temperature and RH were positively correlated with duration of egg and larval stages in both species. Change of humidity between egg and larval environments did not affect duration of larval development at any temperature. At each temperature and RH, the eggs and larvae of X. ramesis did not differ between males and females in the duration of their development, whereas female eggs and larvae of X. conformis usually developed significantly faster than those of males. For both species, male pupae developed slower than female pupae at the same air temperature and RH. Air temperature, but not RH, affected the duration of pupal development. At each humidity, duration of the pupal stage was significantly longer at 25 degrees C than at 28 degrees C: 15.3+/-1.7 vs. 11.7+/-1.2 days in X. conformis; 14.1+/-2.0 vs. 11.5+/-1.7 days in X. ramesis, with a significantly shorter pupal period of the latter species at 25 degrees C. These limited interspecific bionomic contrasts in relation to basic climatic factors appear insufficient to explain the differential habitat distributions of X. conformis and X. ramesis.     

Developmental times and life tables for shore flies, Scatella tenuicosta (Diptera: Ephydridae), at three temperatures

Development times and survivorship of immature shore flies and longevity and reproduction of adult shore flies, Scatella tenuicosta Collin, reared on algae-infested filter paper, were studied at three temperatures (constant 20, 26, and 28.5 degrees C) through life table analysis. The development time for each individual life stage and the total time from egg to adult decreased with increasing temperature. Duration of the third (ultimate) larval instar ranged from 3.3 +/- 0.09 d at 20 degrees C to 1.4 +/- 0.04 d at 28.5 degrees C and was 1.7-1.9 times longer than the approximately equal first and second instars. Development of male and female shore flies from egg to adult needed an average of 14.5 +/- 0.13, 8.2 +/- 0.05, and 7.0 +/- 0.04 d at 20, 26, and 28.5 degrees C, respectively, and needed an estimated 154.4 +/- 1.2 thermal units (degree days). At these respective temperatures, adult females lived 21.8 +/- 2.2, 19.9 +/- 2.4, and 15.0 +/- 1.4 d and produced 379 +/- 62, 710 +/- 119, and 477 +/- 83 eggs during oviposition periods of 14.3 +/- 2.1, 15.0 +/- 2.2, and 10.8 +/- 1.4 d; daily lifetime egg production averaged 16.3 +/- 2.3, 33.5 +/- 3.8, and 29.7 +/- 3.5. Developmental stage-specific mortality was relatively low for all life stages at all temperatures, with maximum percent mortalities of 5.7% occurring in both the egg stage and in the third instar. The highest net reproductive rate (R(o)) was obtained for insects reared at 26 degrees C and was 329.6. The intrinsic rate of natural increase (r(m)) was highest at 28.5 degrees C and was 0.430. Generation time and doubling time of the population were shortest at 28.5 degrees C and were 12.4 and 1.6 d, respectively. Results suggested that 26 degrees C was near optimum for reproduction.     

Interactive effects of diet and temperature on the scope for growth of the scallop Argopecten purpuratus during reproductive conditioning

Mature individuals of Argopecten purpuratus from suspended culture in Tongoy Bay, northern Chile were conditioned at two temperatures (16 and 20 degrees C) and three different diets (mixture of pure microalgae, microalgae supplemented with lipids and microalgae supplemented with carbohydrates). The food, equivalent to 3% daily of the animal dry weight was supplied continuously by a peristaltic pump. The rates of different physiological processes were measured on 18 scallops (three replicates per temperature/diet combination) during the third week of conditioning. Nine scallops came from the group conditioned at 16 degrees C and other nine from the group conditioned at 20 degrees C (each scallop from a different tank). As in the conditioning experiment, physiological measurements were made in controlled temperature rooms using the same experimental diets. Argopecten purpuratus did not show significant differences in clearance rate between 16 and 20 degrees C when fed with pure microalgae and microalgae+lipids, showing a well known capability of bivalves to acclimate their physiological rates within a certain range of temperature. On the other hand a clear effect of the composition of the diet on the clearance rate was observed. When microalgae were supplemented with a lipid emulsion, clearance rate was highly stimulated, showing values significantly higher in comparison with either pure microalgae, or a mixed diet of microalgae+carbohydrate. These highest feeding rates can be related with the presence of essential fatty acids in the diet, which are considered as very important compounds during the gametogenesis of invertebrates as well as during the development of ova into normal larvae. Thus A. purpuratus can actively regulate clearance rate and does not simply switch between feeding and non-feeding states. The data also suggest the presence of chemical receptors at the level of the gills and/or labial palps, which seem able to detect specific nutritive compounds present in the diet. Absorption efficiency was independent of temperature and was higher with pure microalgae and with microalgae+lipids. The lowest efficiencies were recorded with the diet supplemented with carbohydrates. The energy expended in oxygen uptake and ammonia excretion was very similar in the different experimental diets and temperatures. Scope for growth in A. purpuratus appears mainly affected by the diet and not by temperature. While the lower SFG seems to be associated with diets composed of pure microalgae and microalgae+carbohydrates, the highest values being found for a diet rich in lipids. The data were in agreement with the reproductive conditioning of A. purpuratus, where the highest percentage of ripe scallops occurred in individuals fed with a diet of microalgae supplemented with lipids at both temperatures. Similarly the highest larval survival rate was obtained from gametes released by scallops conditioned with the diet containing lipids.     

Naupliar development times and survival of the copepods Calanus helgolandicus and Calanus finmarchicus in relation to food and temperature

We measured egg hatching times and stage specific naupliar developmenttimes of the key calanoid copepods Calanus helgolandicus andC. finmarchicus in response to temperature, food quantity andfood type. Calanus helgolandicus development times decreasedwith increasing temperature and when fed Isochrysis galbana(4.4 µm ESD) rather than Prorocentrum micans (29.5 µmESD). Nauplii needed higher food carbon concentration to developpast the first feeding stage (N3) when fed I. galbana comparedwith P. micans. At low food carbon concentrations nauplii developedmore slowly past N3 than at more saturated levels. The survivalof nauplii fed P. micans increased with temperature, but starvednauplii survival decreased at higher temperatures. We parameterizeda temperature-dependent model of development for both specieswhich fitted the observed stage durations under non-limitingfood extremely well and demonstrated that C. finmarchicus developsfaster than C. helgolandicus. Further data are needed to clarifythe effect of food-temperature interactions on development rates.     

Eclosion rate, development and survivorship of Aedes albopictus (Skuse)(Diptera: Culicidae) under different water temperatures

In tropical areas, where vector insects populations are particularly numerous, temperature usually range between 25 degrees C and 35 degrees C. Considering the importance of such temperature variation in determining mosquitoes population dynamics, in this work the developmental, eclosion and survival rates of the immature stages of Aedes albopictus (Skuse) were compared under constant 25, 30 and 35 degrees C (using acclimatized chambers) and environmental (25 degrees C to 29 degrees C) temperatures. The hatching rate was considered as total number of larvae recovered after 24h. The development period as well as larval and pupal survival rate were evaluated daily. Eclosion rate was significantly higher under environmental temperature than under the studied constant temperatures, suggesting that temperature variation may be an eclosion-stimulating factor. The mean eclosion time increased with the temperature, ranging from 2.8h (25 degrees C) to 5.2h (35 degrees C). The larval period was greatly variable inside each group, although it did not differ significantly amongst groups (11.0 +/- 4.19 days), with individuals showing longer larval stages in water at 35 degrees C (12.0 +/- 4.95 days) and environmental temperature (13.6 +/- 5.98 days). Oppositely, survival was strongly affected by the higher temperature, where only one individual lived through to adult phase. The results suggest that population of Ae. albopictus from Recife may be adapting to increasing of environmental temperatures and that the limiting temperature to larval development is around 35 degrees C.     

Application of a growth-promoting bacteria for stable mass culture of three marine microalgae

The practical mass culture of marine microalgae, facesoccasionally unexpected problems or collapse. The effect of amarine bacterium, Flavobacterium sp., which was found topromote growth of a marine diatom Chaetoceros gracilisin the axenic culture condition, was examined on the masscultures of three marine microalgae.Three marine microalgae (C. gracilis, Isochrysisgalbana, and Pavlova lutheri) were mass cultured in 3 lflatbottom flasks (2.5 l capacity of culture medium), in anindoor culture room at a commercial pearl oyster hatchery. Themicroalgal cells and the bacterium were inoculated at the sametime, in the culture media. The specific growth rate andmaximal cell density were determined in treated cultures (withadded bacterial strain) and in controls (without addedbacterial strain). The specific growth rate of C.gracilis in treated cultures was significantly higher thanthat of control cultures, and the stationary growth phase inthe treated cultures lasted longer till the end of the cultureperiod. However, the bacterium had no apparent effect on theexponential growth phase of two phytoflagellates, I.galbana and P. lutheri, but kept longer the high celldensity in the stationary growth phases. The added bacterialstrain (Flavobacterium sp.) was the dominant species(more than 45%) among the bacterial flora during the cultureperiod.     

Early Developmental Stages of the Green Tiger Prawn, Penaeus semisulcatus de Haan (Crustacea, Decapoda, Penaeidae)

Gravid females of Penaeus semisulcatus were spawned in the laboratory by natural means. The embryos were documented and the larvae were reared from hatching to postlarval stage at 28.2–30.0 °C and 33.5–34.5 g kg⁻¹ salinity for about 10 days (223 h 55 min). Six naupliar stages, three protozoea stages, three mysis stages and the first postlarval stage were described and illustrated. The larvae were fed only with microalgae Tetraselmis tetrathele and Chaetoceros gracilis from first protozoea until the second mysis, with about 90% survival rate; from the third mysis until the first postlarva they were fed with similar microalgae coupled with rotifer Brachionus plicatilis and Artemia nauplii. The embryonic and larval stages of P. semisulcatus are generally similar to those of other closely related species in the family Penaeidae, such as Melicertus canaliculatus, Fenneropenaeus merguiensis, and Marsupenaeus japonicus, except for the size and structure of diagnostic characters, setation of appendages and duration of metamorphoses. The change in the feeding habit during ontogeny was related to morphological transformation of the feeding apparatus of larvae and postlarvae. This paper is the first comprehensive and complete account of the early developmental stages of P. semisulcatus.     

不同饵料对魁蚶稚贝生长和存活的影响

在温度23.5～24.0 ℃和盐度29.5～30.0条件下,研究了球等鞭金藻、小球藻、牟氏角毛藻和新月菱形藻4种单细胞藻类单独及组合投喂24 d后对魁蚶稚贝生长与存活的影响.结果表明: 不同饵料投喂条件下,稚贝存活率均在95%以上,不同处理组间差异不显著.单一饵料投喂组中,球等鞭金藻组的稚贝生长最快,小球藻组的稚贝生长最慢.组合投喂组中,球等鞭金藻与其他3种单胞藻混合(1∶1)投喂组稚贝壳长及特定生长率均优于其他组,其中与小球藻混合投喂的效果最好,稚贝壳长和壳高的特定生长率分别为5.6%·d^-1和6.4 %·d^-1.研究结果可为魁蚶人工苗种培育技术的优化提供参考依据.
     

Effect of temperature and humidity on development, survival and oviposition in laboratory populations of Eriworm, Philosamia ricini (Boisduval) (Lepidoptera Saturniidae)

Experiments were conducted on laboratory populations of Eriworm, Philosamia ricini Boisduval to study the effect of temperature and humidity on development, growth, survival and oviposition. Experiments were performed at four different temperatures (22 +/- 2 degrees C, 26 +/- 2 degrees C, 28 +/- 2 degrees C and 34 +/- 1 degrees C) each with three different humidities (50%, 70% and 90% relative humidity). Shortest developmental period (42 days) was observed in 28 +/- 2 degrees C and 70% RH. Longest developmental period was (63.6 days) observed in 22 +/- 2 degrees C at 50% RH. Highest larval weight (9.1 g) was found in 28 +/- 2 degrees C at 70% RH. Best pupal weight was observed in 26 +/- 2 degrees C at 70% RH. Weight of silk material was found to be maximum in 26 +/- 2 degrees C at 70% RH. Survival was best in 28 +/- 2 degrees C and 26 +/- 2 degrees C at 70% RH. Oviposition was found to be highest in 28 +/- 2 degrees C at 70% RH.     

Mild winter temperatures reduce survival and potential fecundity of the goldenrod gall fly, Eurosta solidaginis (Diptera: Tephritidae)

We tested the hypothesis that mild winter temperatures are detrimental to the survival and reproductive potential of insects. We measured survival, body size, and potential fecundity of a freeze tolerant insect, the goldenrod gall fly (Eurosta solidaginis), after overwintering in the laboratory for ~3 mo. frozen at -22 degrees C, unfrozen at 0 degrees C, or unfrozen at 12 degrees C. Larvae held at 12 degrees C suffered high mortality (70%) and relatively low potential fecundity as adults (mean+/-SEM=199+/-11 eggs/female), while those held at 0 degrees C had both low mortality (11%) and high potential fecundity (256+/-15 eggs/female). Freezing (-22 degrees C) increased mortality (30% overall) but did not significantly reduce fecundity (245+/-13 eggs/female). Egg length and width were constant regardless of treatment group or female body size. Analysis of covariance indicated that reduced fecundity in the 12 degrees C group was related to reduced larval body weight following treatment. Patterns of larval weight loss in the experimental treatments were generally correlated with previous reports of latitudinal trends in weight loss through the winter. We conclude that mild winter temperatures may be detrimental to some overwintering insects, particularly species that do not feed following winter diapause. Low temperature and even freezing are beneficial, allowing conservation of energy reserves to maintain high survival and potential fecundity.     

Embrionary and larval development of Lytechinus variegatus (Echinoidea: Toxopneustidae) in laboratory conditions at Isla de Margarita-Venezuela

The sea urchin Lytechinus variegatus is a promissory species for aquaculture activities in tropical countries. In Venezuela, this species has some economical importance but their embryonic and larval development had not been studied. We collected specimens from seagrass beds in Margarita Island (Venezuela) and kept them in the laboratory, where they spawned naturally. With filtered sea water (temperature 28 degrees C, salinity 37 psu) and moderate aeration, the eggs and sperm were mixed (relation 1:100) and reached a 90% fertilization rate. The fertilization envelope was observed after two minutes, the first cellular division after 45 minutes and the prism larval stage after 13 hours. The echinopluteus larval stage was reached after 17 hours and metamorphosis after 18 days of planktonic life, when the larvae start their benthic phase.     

Evaluating whether velar lobe size indicates food limitation among larvae of the marine gastropod Crepidula fornicata

Disproportionately large feeding structures have been used to infer food limitation in some marine invertebrate larvae, but few studies have investigated whether other factors alter larval morphology in similar ways. In this study, larvae of Crepidula fornicata were reared either at five different food concentrations of Isochrysis galbana (clone T-ISO) at a single temperature (22 degrees C) (Experiments I and II); or on three different phytoplankton species (Isochrysis galbana, Dunaliella tertiolecta, and Pavlova lutheri) at both high and low concentrations at a single temperature (22 degrees C) (Experiment III); or at high and low concentrations of Isochrysis galbana at four different temperatures between 16 and 25 degrees C (Experiment IV). Shell lengths and velar lobe dimensions were determined for individual larvae at intervals to monitor relative rates of velar and shell growth. In addition (Experiment V), fast growing and slow growing larvae in Experiment I were examined separately to determine whether velar lobes developed at similar rates (relative to shell growth) for fast and slow growing larvae within individual cultures. In general, velar lobes grew significantly larger, relative to shell length, when larvae were reared at low food concentrations (P<0.0001); for larvae of similar shell length, the velar lobes of those fed 1x10(4) cells ml(-1) were on average 17.7% larger than those of larvae fed 18x10(4) cells ml(-1) of T-ISO. In contrast, larvae fed different phytoplankton species at equivalently high food concentrations did not differ in relative velum size (P=0.2666), even though shell growth rates differed significantly for larvae raised on the different diets, indicating substantial variation in food quality. We also found that relative rates of velum and shell growth differed among fast and slow growing individuals within treatments. Temperature had no significant effect on relative rates of velar and shell growth within the 16-25 degrees C range tested (P=0.121), but may have altered the relationship between food concentration and relative velar growth. These results indicate that dramatically reduced food concentration induces disproportionate growth in the velar lobes of C. fornicata, but that interpretation of data from field-collected individuals of this species will be made difficult by the potentially confounding effects of temperature, food quality, and differences in individual growth potential. Assessments of food limitation using morphological measurements for field-collected larvae will need to be supplemented with other indicators before convincing conclusions about the extent of food limitation in C. fornicata can be drawn.     

Reproductive activity of Coelomera lanio (Coleoptera: Chrysomelidae)

The Cecropia spp. (Cecropiaceae) trees are attacked by several insects; among them, Coelomera lanio (Dalman) (Coleoptera: Chrysomelidae). The reproductive behavior of C. lanio was studied under laboratory conditions (12 hour photoperiod, 24.1 +/- 0.1 degrees C and mean relative humidity 67.7 +/- 0.6%), in Vi?osa, Minas Gerais, Brazil. The insects were reared in cages and in Petri dishes and fed leaves of Cecropia pachystachya Trec. Reproductive activity began 5.8 +/- 0.2 days after adult emergence and mean copulation time was 2.5 +/- 0.1 min. The female began oviposition only after 25.7 +/- 0.7 days. Each female laid a mean of 4.7 +/- 0.4 times (range 1-9). The mean number of eggs per oviposition and female was 129.2 +/- 2.4 and 587.4 +/- 92.1 respectively, and the time between egg-layings averaged 16.3 +/- 0.8 days.     

Rearing of Fabrea salina Henneguy (Ciliophora, Heterotrichida) with three unicellular feeds

The growth rate of the ciliate Fabrea salina was studied in batch cultures in the presence of three feeds, tested separately from each other: the Prymnesiophyceae, Isochrysis galbana obtained from pure culture, the Chlorophyceae Dunaliella salina, and the commercially available yeast Saccharomyces cerevisiae. F. salina, and D. salina were harvested below the surface from the first evaporation pond and the crystallizer pond, respectively in multi-pond salterns (Sfax, Tunisia). The highest density of Fabrea was recorded with I. galbana (26 ind ml(-1)). However, the greatest length (243 microm) was recorded with Fabrea fed with D. salina. The lowest density, length and biovolume values were recorded with Fabrea fed with S. cerevisiae. The ANOVA test showed that density (F=18, d.f.=57), length (F=33, d.f.=57), and biovolume (F=19, d.f.=57) of Fabrea fed with yeast were significantly different (p<0.001) from those when Fabrea was fed with D. salina and I. galbana. The ciliate Fabrea encountered in the Sfax saltern (Tunisia) might be a valuable food source for Tunisian marine fish hatcheries.