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Sufficient high‐quality microalgae are required for indoor nursery of juvenile Ruditapes philippinarum. However, culturing numerous microalgae to support clam feeding is a heavy burden on many hatcheries. The effects of detritus from the macroalgae Ulva pertusa, Chondrus ocellatus and Undaria pinnatifida on the growth, amino acid content and fatty acid profile of R. philippinarum were assessed as potential substitute diets. The green microalga Tetraselmis cordiformis served as comparative diet. Results revealed that the clams ingesting distinct diets presented no significant differences in growth of soft tissues, but the nutritional component of these clams differed dramatically. The clams fed with Undaria + Tetraselmis had the highest content of essential amino acids and proteins. In addition, the clams fed with single macroalgal diets and mixed macroalgal detritus and Tetraselmis showed significantly higher or statistically equal levels in n‐3/n‐6 ratio and docosahexaenoic acid (DHA)/eicosapentaenoic acid (EPA) ratio with respect to Tetraselmis diets. The relative percentages of EPA and DHA in clams fed with Undaria were 28% and 63% higher than those fed with Tetraselmis, and the arachidonic acid abundances in clams ingesting Undaria + Tetraselmis and Tetraselmis were significantly higher than those in clams ingesting other diets. Together, the diets containing single Undaria or mixed Undaria + Tetraselmis produced Manila clams with nutritional advantages in terms of essential amino acids and polyunsaturated fatty acids. Thus, the detritus of macroalgae, especially Undaria, is an appropriate substitute diet, at least partially, for culture of nutrition‐improved R. philippinarum.

Feeding copepods during early larval culture stages of marine fish has proven to be advantageous for growth and survival of marine finfish larvae. However, commercial availability of most copepods is limited; thus, there is an impetus to evaluate promising copepod species to meet the diverse dietary demands of various marine fish. The marine cyclopoid copepod, Oithona colcarva, was isolated out of zooplankton samples taken from waters within Tampa Bay, Florida. Once isolated, trials were conducted to determine the appropriate culture parameters for producing nauplii to feed marine fish larvae. The effects of temperature (22°C, 26°C and 30°C), salinity (15, 20, 25, 30 and 35 g L−1), stocking density (0.5, 1.0, 2.0, 4.0 and 8.0 individuals mL−1) and diet (Nanno 3600 microalgae paste, Colurella adriatica, Rhodomonas lens, Tisochrysis lutea, Chaetoceros gracilis and/or Tetraselmis chuii) on nauplii production during a single life cycle of reproducing individuals were examined. Results of those trials indicated that a culture temperature of 30°C and a salinity of 30 g L−1 were advantageous for maximum nauplii production. Furthermore, a diet containing a 1:1:1 mixture of T. lutea, C. gracilis and T. chuii and a stocking density of at least 8 individuals mL−1 were identified as beneficial. The results of these trials, the potential for large-scale culture and observations on the performance of marine fish larvae fed Oithona colcarva nauplii are discussed.

We report the results of survival and growth in size and dry mass of spat of the Caribbean pearl oyster Pinctada imbricata cultivated under outdoor (field culture) and indoor (Laboratory) conditions. Field group fed on environmental seston. Laboratory groups were fed with mono, binary and ternary mixtures of three cultivated algae: Isochrysis galbana (Ig), Tetraselmis chuii (Ig) and the Chaetoceros sp. (Ch-A, isolated from north-eastern Venezuela). After 30 days of trial, fatty acid profiles of spat were determined along with growth in length and height shell, adductor muscle and soft tissue dry mass. During the field grow-out phase (field culture), samplings were performed at days 1, 15 and 30 to measure environmental variables of phytoplankton biomass (chlorophyll a), dissolved oxygen, seston, temperature and salinity. A significant increase in size and soft tissue mass occurred in spat fed the diets including the tropical diatom (Chaetoceros sp.). In contrast, monoalgal diets of Tc and Ig yielded no significant differences in size and mass of spat, compared with the field culture. These results suggest that nutritional requirements of cultivated spat for specific fatty acids of physiological importance for marine bivalves, such as: 16:0, 16:1n-7, 18:2n-6, 20:4n-6, 18:3n-3 and 20:5n-3, were satisfied from microalgal diets with Ch-A, alone or in combination, compared with spat fed from the field culture.

The residual water from intensive aquaculture production systems can be utilized in integrated multitrophic cultivations. In this work, Artemia franciscana received daily feedings of 10 mg L−1 of Tetraselmis chuii, Nannochloropsis oculata and Chaetoceros muelleri, which were grown using residual water from an intensive biofloc Litopenaeus vannamei cultivation system. The goal of this study was to verify which species provide the best zootechnical performance and best crustacean biomass production efficiency. After 12 days of cultivation, A. franciscana wet biomass was 815.64 ± 18.74, 650.81 ± 83.98 and 40.76 ± 4.08 mg L−1 with C. muelleri, T. chuii and N. oculata (P

Microalgae have great biotechnological potential but the high cost of traditional formulae culture media is one of the limiting factors to their commercial cultivation. As an alternative, the use of residual water from other activities has been proposed as a culture medium. The goal of this study was to produce Chaetoceros muelleri, Nannochloropsis oculata and Tetraselmis chuii biomass using residual water from an intensive Litopenaeus vannamei biofloc cultivation system and to verify the ammoniacal nitrogen, nitrite, nitrate and orthophosphate consumption. The microalgae cultures were developed until the second day of their stationary phase in the following treatments: 100% f/2 culture media; 100% residual water; residual water diluted 50% with marine water. T. chuii and N. oculata presented the best relative biomass average (576 mg L � 1 ; 474 mg L � 1 ) (P > 0.05). All the species completely assimilated the orthophosphate in 2 days. In 10 days, T. chuii and N. oculata assimilated 87% and 85% of nitrate respectively. It can be concluded that residual water from an L. vannamei biofloc cultivation system can be used as an alternative culture medium for T. chuii and N. oculata biomass production. Moreover, the microalgae biomass proved to be very effective in recycling the dissolved nutritive salts.

The southern Australian whelk, Dicathais orbita, is a potential candidate for aquaculture, as both seafood and for bioactive compound production. Larval rearing experiments to determine the effects of temperature and diet on the growth and survival of D. orbita larvae under laboratory conditions comprised five different unicellular algal diets of two brown algal species; Isochysis galbana and Chaetoceros muelleri, two green algae; Tetraselmis seucica and Nannochloropsis oculata, and a mixture of all four strains for larvae maintained at 16 and 22°C. Absolute growth, specific growth rate (SGR) and survival were determined regularly. Larvae reared at 22°C on a mixed diet, or brown algae, performed significantly better than those reared on green algal diets alone. Preliminary trials with settlement cues were undertaken on different aged larvae to determine when larvae become competent. An array of natural cues (carrion, Xenostrobus pulex, adult mucus and Ulvella lens), as well as concentrations of KCl was tested. KCl(concentration of 20 mM) induced the greatest settlement, however, no larvae metamorphosed under the conditions provided. This study confirms long-lived planktotrophic larval development for Dicathais orbita with higher development rates at the higher water temperatures. Further studies will optimize culture conditions and cues for settlement and metamorphosis.

Mixotrophic metabolism was evaluated as an option to augment the growth and lipid production of marine microalgaTetraselmissp. FTC 209. In this study, a five-level three-factor central composite design (CCD) was implemented in order to enrich the W-30 algal growth medium. Response surface methodology (RSM) was employed to model the effect of three medium variables, that is, glucose (organic C source), NaNO3(primary N source), and yeast extract (supplementary N, amino acids, and vitamins) on biomass concentration,Xmax, and lipid yield,Pmax/Xmax. RSM capability was also weighed against an artificial neural network (ANN) approach for predicting a composition that would result in maximum lipid productivity,Prlipid. A quadratic regression from RSM and a Levenberg-Marquardt trained ANN network composed of 10 hidden neurons eventually produced comparable results, albeit ANN formulation was observed to yield higher values of response outputs. Finalized glucose (24.05 g/L), NaNO3(4.70 g/L), and yeast extract (0.93 g/L) concentration, affected an increase ofXmaxto 12.38 g/L and lipid a accumulation of 195.77 mg/g dcw. This contributed to a lipid productivity of 173.11 mg/L per day in the course of two-week cultivation.

The present work investigates the effects of Chaetoceros calcitrans, Nannochloropsis oculata, Tetraselmis tetrahele and Isochrysis galbana diets on the lifespan, growth, neonate production and the nutritional profile of Diaphanosoma celebensis. In addition, the effects of enriched D. celebensis on the survival and growth of Litopenaeus vannamei postlarvae (PLs) was compared with Artemia. Results showed that significantly higher (P 0.05) from PL fed only Artemia, indicating that D. celebensis has potential to be used as live feed for the hatchery rearing of L. vannamei PLs, in place of Artemia. This study illustrated that the quality of the D. celebensis production and proximate composition was highly correlated with the food type, and it can be used as a valuable live feed for shrimp larviculture.

The influence of algal diet on survival, growth and development of hatchery reared flat oyster, Ostrea angasi , larvae was investigated in a series of uni, binary and ternary algal diet trials. Early stage larvae (140–230 μm shell length) generally grew faster than late-stage larvae (230–340 μm shell length) when fed unialgal diets. Of the 24 algal diets evaluated, larvae fed unialgal diets of Isochrysis sp. (T. Iso), Nannochloropsis oculata , Tetraselmis chuii or Pavlova lutheri ; a binary diet of T. chuii +T. Iso; or ternary diets of T. chuii +T. Iso combined with P. lutheri or N. oculata had the greatest larval growth, survival, development and metamorphosis, in the respective trials. The correlation between growth rate and spat produced in late-stage larvae was stronger when fed unialgal diets ( r = 0.75) than when larvae were fed either binary or ternary diets ( r = 0.44 and r = 0.45 respectively). Marked differences in proportion of spat produced (24 h post metamorphosis) were evident among diets producing similar growth rates. For hatchery production of O. angasi larvae, ternary diets of T. chuii +T. Iso combined with either P. lutheri or N. oculata were the best diets to maximize larval growth rate, development and survival 24 h post metamorphosis.

A series of laboratory experiments were conducted on the harpacticoid copepod, Euterpina acutifrons, to assess the influence of 10 different microalgal diets (four monoalgal and six mixed algal diets) on several parameters related to its productivity in culture. The four monoalgal diets were the Tahitian strain of Isochrysis sp. (T-Iso), Pavlova salina (Pav), Tetraselmis chuii (Tet) and the diatom Chaetoceros muelleri (Chaet), the five binary diets were T-Iso+Tet, Pav+Tet, T-Iso+Pav, Tet+Chaet and Pav+Chaet, while the tri-algal diet was T-Iso+Tet+Pav. All diets were fed to copepods at 1500 μ gC L−1 and in the case of binary or trialgal diets, carbon concentration was divided equally between the two or three algae offered. Among monoalgal diets, the diatom Chaet was excellent for E. acutifrons. Out of the 10 diets tested, the binary diet Tet+Chaet, which contained the diatom Chaet, was the best for naupliar production of single pair E. acutifrons (19.5±1.7 nauplii female−1 day−1), significantly (P 0.05). Similarly, in the group naupliar production trial (50 adult E. acutifrons per replicate), Tet+Chaet produced a significantly higher number of nauplii (405.8±18.6 nauplii day−1) than the other treatments (P

We examined the effects of 10 microalgal diets on a range of productivity-related parameters of Bestiolina similis. The diets tested included four monoalgal diets: Tahitian strain Isochrysis sp. (T-Iso), Pavlova salina (Pav), Tetraselmis chuii (Tet) and the diatom Chaetoceros muelleri (Chaet), five binary diets: Tet+Pav, T-Iso+Tet, T-Iso+Pav, Chaet+Tet and Chaet+Pav and a tri-algal diet: T-Iso+Tet+Pav. Except for sex ratio, microalgal diets significantly affected all parameters examined (P

This study examines the larval development, metamorphosis and postlarval stage of Venerupis pullastra in relation to growth, lipids content and fatty acid composition, specifically those believed to be essential for most bivalves (i.e. 20:5n-3 and 22:6n-3). Clam larvae were fed with two species of microalgae supplied individually or mixed –Isochrysis galbana and Tetraselmis suecica–species normally used in bivalve hatcheries. Larvae fed with T. suecica showed a progressive accumulation of lipids and fatty acids but did not survive to metamorphosis. Contrarily, larvae fed with I. galbana or mixed diet showed a progressive decline in lipids and essential fatty acids (20:5n-3 and 22:6n-3) from the pediveliger stage onwards, and a survival rate of 95% 1 until the start of metamorphosis. The lower content in n-6 and the absence of 22:6n-3 in T. suecica diet might contribute to the massive mortality observed for larvae fed with this diet. That diet seems to fail in the supply of some particular nutrient that allows energetic transformation of reserves for growth and metamorphosis. Nevertheless, larvae fed on mixture diet showed higher weight growth values at postlarval stage than those larvae fed on I. galbana diet.

The green water technique has been widely shown to improve fish larvae growth, survival and feed ingestion. Therefore, fish larvae (Sparus aurata L. and Solea senegalensis Kaup) feeding behaviour was studied through gut content analysis, when using different species of microalgae, as the ‘green water’ technique. Six treatments were used: Stain – food green stain; Tetra – microalgae Tetraselmis chuii; Iso – microalgae Isochrysis galbana; Tetra Sup –T. chuii supernatant (obtained from centrifugation); Phyto – a microalgae paste, Nannochloropsis oculata, (Phytobloom®); and C water – clear water, as control. At 9, 16 and 23 days after hatching (DAH) for S. aurata, and 4, 9 and 14 DAH for S. senegalensis, 40 unfed fish larvae were transferred to 3 L experimental tanks, filled with the different ‘green water’ technique. Fish larvae were sampled 2 h after being fed with live prey, anaesthetized and fixed in buffered formaldehyde for posterior gut content determination. Feeding was evaluated by the feeding rate, percentage of larvae with prey items in the digestive tract and feeding intensity, number of prey in each larva digestive tract. Fish larvae feeding ability was influenced by the interaction between light conditions and substances provided by the presence of microalgae during fish larvae development. Sparus aurata was more dependent on microalgae addition than S. senegalensis larvae, which may be related to the type of prey, larval behaviour, ontogeny and physiology. The presence of microalgae influenced the selection of larger prey (Artemia over rotifers) by S. aurata aged 23 DAH.

Activities of the digestive enzymes neutral lipase and phospholipase A2 were present in 2-mm scallop juveniles, indicating an endogenous ability to digest lipids. When determined in the dietary microalgae, lipolytic activities of both enzymes differed significantly, being highest in Isochrysis galbana and Tetraselmis sp. and lowest in Chaetoceros mulleri. Compared with the activities found in scallop juveniles, enzyme activities from the microalgae were rather low and did not seem to contribute considerably to their digestive process. However, ingested algae seemed to have a regulating effect on the phospholipase activity in scallops, as juveniles fed I. galbana had a significantly lower activity than juveniles of the other treatments. No such effect was evident for neutral lipase, indicating different regulation mechanisms for both enzymes. Dietary effects on digestive enzymes in scallop juveniles should be considered when choosing new potential algal species as feed or for future formulation of artificial diets.

The effect of different food items on growth and survival was assessed in four feeding experiments conducted consecutively using distinct Farfantepenaeus paulensis (Perez-Farfante) postlarval growing stages: (1) PL1–PL4 (i.e. from postlarvae 1-day old to postlarvae 4 days old); and (2) PL4–PL10; (3) PL10–PL18 and (4) PL18–PL30. For each trial, 10 feeding treatments were tested in triplicate: Unf, unfed shrimp; Tt, Tetraselmis chuii; Ch, Chaetoceros calcitrans; C, commercial diet; AC, decapsulated Artemia cysts; C+Ph, commercial diet and phytoplankton combination; FA, frozen Artemia nauplii; A, live Artemia nauplii; A+Ph, Artemia nauplii and phytoplankton combination and Mix, mixture of phytoplankton, live Artemia nauplii and commercial diet. Postlarvae feed phytoplankton (i.e. Tt or Ch) exclusively exhibited low growth and survival. The best results for growth and survival were observed in the A, A+Ph and Mix treatments. Frozen Artemia nauplii was found to be suitable for younger postlarvae (PL1–10), whereas AC may be offered from PL4 to PL30. In general, the present findings indicated that even at an early postlarval stage, F. paulensis presents a high degree of carnivory, and a diet containing Artemia is recommended.

This work presents food ingestion and digestibility analysis carried out by means of epifluorescence microscopy of 1-day-old Strombus gigas (Linnaeus, 1758) larvae fed five different algal cells: Tetraselmis suecica, T. tetrathele, Chlorella keslleri, Chlorella sp. and Chaetoceros cerastoporum. Absolute ingestion and digestion indices (AII and ADI) were used to compare larval feeding behaviour. Differences in efficiency of ingestion and digestion were observed, according to the diet: the highest AII and ADI were observed with T. suecica and T. tetrathele (>90% and 85–88% respectively). With C. cerastoporum and Chlorella sp. these indices were zero. We confirm the use of Tetraselmis as a suitable diet for S. gigas hatchery. On the contrary, Chlorella sp. and C. cerastoporum are not recommended during the early larval stage, due to their non-ingestion and digestion.

An artificial diet for shrimp larvae was microencapsulated with a polysaccharide blend [66% gum arabic, 17% mesquite gum and 17% maltodextrin 10 dextrose equivalent (DE)]. Microencapsulated diet (MD) was fed to mysis alone, as a co-feed with the microalgae Chaetoceros cerastosporum and Tetraselmis chuii (mixed) and compared with a live diet (control) of C. cerastosporum, T. chuii and Artemia nauplii. No significant differences (P > 0.05) were detected in growth rates, development and quality indexes of larvae fed the three experimental diets. All diets supported survival percentages of >90%. Shrimp larvae fed MD and mixed diets had higher specific trypsin activity and soluble protein content than those fed live diet. Amylase activity decreased in larvae fed the mixed and MD apparently due to the carbohydrate composition of the diet. The results indicate that it is possible to substitute a live diet with a microencapsulated one (with a wall composition made up of a polysaccharide blend) in Litopenaeus vannamei mysis.

The ability for food selectivity of rotifer Brachionus plicatiliswas studied in the laboratory by feeding mixtures of microalgae with various cell volumes. Chlorella sp. (≈22 µm3) was the reference algal species, and Asteromonas gracilis, (Chlorophyta) (≈2150 µm3), Tetraselmis suesica (≈268 µm3), Dunaliella salina (≈52 µm3) and Chaetoceros sp. (≈150 µm3) the experimental species. Each was mixed with Chlorella and fed in three experiments. In the first experiment, filtration and ingestion rates of rotifers each fed with algae revealed that the highest values were measured with the mixture of Chlorella + Asteromonas, and the lowest for Chlorella + Chaetoceros. In the second and the third experiments, by using several combinations of algal densities with the mixture of Chlorella + Asteromonas, a selectivity ability of the rotifers for Asteromonas was found. A hypothesis is presented that accounts for the preference of rotifers for Asteromonas, which is suggested as a new candidate species for use in live food production of fish hatcheries.

Larvae of Metapenaeus monoceros (Fabricius) at protozoea 1 (PZ1) stage were stocked in 2-L glass flasks to investigate the effects of various salinities (25, 30, 35, 40, 45, 50 and 55 ppt) on growth and survival until the post-larval (PL) stages. The PZ larvae were not able to tolerate a sudden salinity drop of over 10 ppt. Yet, an abrupt salinity increase of over 10 or even 15 ppt did not cause mortality. The PZ larvae were successfully acclimated to different test salinities at a rate of 4 ppt h−1. The larvae displayed better tolerance to high rather than low salinities. The lowest and highest critical salinities appeared to be 22 and 55 ppt respectively. Taking into account survival, growth and development results, the optimal salinity for the larval culture of M. monoceros inhabiting the Eastern Mediterranean was 40 ppt. At this salinity, the PZ1 larvae were successfully cultured until PL1 stage within 11 days with 68% survival on a feeding regime of Tetraselmis chuii Kylin (Butcher) (20 cells μ L−1), Chaetoceros calcitrans Paulsen (50 cells μ L−1), Isochrysis galbana Parke (30 cells μL−1) and five newly hatched Artemia nauplii mL−1 from M1 onwards at 28 °C.

The goal of the studies that are reported in this thesis was to develop adequate methods for the production of good quality fry of Atlantic halibut (Hippoglossus hippoglossus L.). In this connection, prey preferences of the Atlantic halibut larvae is important. When giving en the choice between rotifers and short term (ST) enriched nauplii, the Atlantic halibut larvae showed no preferences for any of these the first two days of the live feed period. From day 3 and onwards the larvae preferred ST nauplii. When the larvae had the opportunity to select between different size classes of A. franciscana, the preferred size was the newly hatched nauplii during the first 3 weeks. Around day 20 at 3-4 mg dry weight (DW), the larvae showed a pronounced shift in their preferred size of A. franciscana, and they started to select for individuals of 1.2-1.4 mm length or longer. The size corresponds to A. franciscana cultivated for 3 days.The larvae apparently digested the newly hatched nauplii better than the ST nauplii during the first weeks, this presumably because of the high lipid content of the latter. Also, the bigger size classes of A. franciscana seemed to be more effectively digested that the ST nauplii by larvae of less then 2.4mg DW. Bigger larvae showed almost equal and very efficient digestion of all size classes of A. franciscana. The larvae never selected positively for ST nauplii, and use of newly hatched nauplii for some time may be beneficial based on the selection and digestion patterns of the larvae. However, the newly hatched nauplii do not contain DHA (docosapentaenoic acid) and are therefore nutritionally inadequate for the larvae. This size class of Artemia may be beneficially used for a few days after onset of exogenous feeding provided that the nutritional status of the larvae at the onset of exogenous feeding is adequate and that the nutritional quality of the feed used later is satisfactory. The larvae selected positively for larger A. franciscana in a period before the reached the size when they normally start to accept formulated food. Prey of the size 1.2-1.4 mm (i.e. 3-day-old A. franciscana) seemed to be the optimal size for the larvae after about day 20 in the lived feed period. It was possible to produce 3-day-old A. franciscana with 18 mg DHA g-1 DW and a DHA/EPA ratio > 1.0 by using a diet containing more than 39% lipids and 10% DHA, respectively. A high DHA/EPA ratio (>1.0) is needed after the production because A. franciscana appears to transform DHA to EPA (eicosapentaenoic acid) relatively efficiently. Attempts were made to stabilise the content of DHA in A .franciscana in the larval tanks by incubating them with the DHA rich microalgea I. galbana. However, 6 mg C 1-1 or higher levels of this alga were negative for the DHA contents of ST A. franciscana which then decreased more rapidly during the first 24 h than at lower algal concentrations. This was most likely due to a replacement of lipids by algal cells in the gut of the nauplii. In the case of 3- and 4-day old A. franciscana, the effect of addition of I. galbana on the DHA level in the animals was small for the algal levels normally used in the larval tanks (1-2 mg C1-1). The microalgea Tetraselmis sp. was used to reduce bacterial level and change bacterial flora associated with the live feed. During a 4 h incubation of 2-day-old A. franciscana with this alga, the number of associated bacteria and Vibrio spp. were reduced significantly. This effect was even more pronounced after transfer to first feeding conditions. The composition of the microbial flora associated with the animals became more diverse, and less dominated by Vibrio alginolyticus, which was the dominating species associated with 2-day-old A. franciscana. The results also showed that the algae indirectly affected the larvae through changing the associated bacterial flora of the live feed. Larvae which received algal-treated 2-day-old A. franciscana had significantly lower numbers of Vibrios and bacteria with haemolytic activity compared to larvae fed non-treated- feed. In another first feeding experiment, 4-day-old A-franciscana had high numbers of associated bacteria, and especially of bacteria exhibiting haemolytic activity, even if the procedure for algal incubation was used. Differences in bacterial flora associated with the live feed may lead to differences in growth of larvae.Atlantic halibut juveniles with better quality was obtained with 20% perfect larvae when juvenile A. franciscana was used as feed compared to about 4% with the use of St nauplii. The 3-day-old A. franciscana seems to be the optimal size of the larvae from about day 20 after first feeding because this size has many useful properties. It is the most preferred size by larvae from this time in the live feed period, it is effectively digested by the larvae and it can be produced with a relatively high DHA content (

On the basis of initial harvesting efficiency trials and screening trials to evaluate apparent cell damage and viability, high-speed centrifugation was selected as the most appropriate microalgae harvesting method for developing extended shelf-life concentrates that would collectively meet the requirements of marine hatcheries and nurseries. Bioassay evaluation of stored microalgae concentrates revealed major discrepancies between closely related species of microalgae with regard to the impact of harvesting method on both short-term nutritional quality and shelf-life of stored concentrates. At one extreme, very good retention of nutritional quality was exhibited by high-speed-centrifuged concentrates of Tetraselmis spp. and Chaetoceros calcitrans beyond 8 weeks storage. In contrast, the naked flagellates Pavlova lutheri and Tahitian Isochrysis and the diatom Chaetoceros muelleri exhibited rapid and profound losses in nutritional quality as a consequence of supercentrifugation. Likewise, the impact of storage conditions and the effects of preservatives and other common food additives on the quality and extended shelf-life of stored concentrates was found to be unpredictable and highly species specific. Accordingly, optimum combinations of harvesting and storage, including optimum cell densities, presence or absence of food additives, temperature and, in some cases, gaseous atmosphere and light, had to be specifically tailored to individual species of microalgae in order to maximize the effective shelf-life of their concentrates. Data are presented demonstrating that the best binary concentrate diets developed during the course of this study could sustain growth and survival of larval and juvenile bivalves at rates similar to fresh microalgae culture even after storage periods of 6–8 weeks.

Concentrates of nine microalgae widely used in marine hatcheries were prepared by centrifugation, stored chilled for either 9 or 14 weeks and then compared with their fresh counterpart as feeds for Penaeus monodon larvae. The nine species –Chaetoceros muelleri, C. calcitrans, Isochrysis sp. ‘Tahitian’ (T-ISO), Nannochloropsis oculata, Pavlova lutheri, Skeletonema costatum, Phaeodactylum tricornutum, Tetraselmis chuii and Thalassiosira pseudonana– in fresh and centrifuged forms were fed at high and low cell densities. The Larvatron, a computer-controlled apparatus for rearing planktonic animals, was used for the experiments. Fresh C. muelleri and T. pseudonana promoted the highest survival and fastest development of P. monodon to mysis 1. Although the survival rate of larvae fed concentrated C. muelleri, P. lutheri and T-ISO was comparable with those fed the fresh C. muelleri diet, the larvae fed these concentrates generally developed more slowly. The higher cell density, whether of fresh or concentrated algae, usually produced both higher survival and faster development of larvae. Nannochloropsis oculata and P. tricornutum were poor diets, regardless of their form or feeding density. Concentrating C. calcitrans and S. costatum markedly reduced their efficacy as diets. The centrifuged concentrates were unsuitable as complete replacements for fresh algae in larval culture when stored for either 9 or 14 weeks. However, the concentrates may be more successful in combination with other concentrates, fresh algae and/or artificial diets, or when stored for a shorter time.

The aim of the study was to investigate the effects of two light regimes that independently had shown positive effects on feeding and growth in cultures of Atlantic halibut, Hippoglossus hippoglossus (L.), larvae. The regimes were low-intensity overhead light and submerged light at intermediate light intensities. Secondly, an alleged beneficial effect of algae was investigated. An experiment was designed to include four different regimes in the larval cultures: low-intensity overhead light with and without algae (Tetraselmis sp.), and submerged light with and without algae. The results showed that submerged light was superior to overhead light with respect to larval growth, survival and feeding incidence. It was further indicated that algae improved larval growth and survival, but no effect was shown on feeding incidence. There was, however, no interaction between the effects of algae and those of the light regime. The causal effect of the algae may be ascribed to indirect factors, such as light attenuation as well as a direct and indirect nutritional effect.

Polyunsaturated fatty acids (PUFA) have a fundamental role in human metabolism. Here, a study was attempted to develop a commercially feasible technology to enrich eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) present in Isochrysis galbana, Chaetocerous calcitran, Chlorella marina and Tetraselmis gracillus using lipase source Candida cylinderacea. To the wet mass of algae added 4, 8 and 12 U of lipase enzyme concentration and was incubated at 37C for 4, 8, 16 and 24 h of hydrolysis. Control was taken without any added enzyme. The experiment investigated the optimum conditions of lipases as a function of time and enzyme concentrations. The study reveals that the uses of biolipases under standardized condition are useful for commercial production of PUFA in pharmaceutical industries. Practical Application Polyunsaturated fatty acids (PUFA) have a fundamental role in human metabolism due to their antibacterial, antiinflammatory and antioxidant properties, and play role in the prevention of cardiac diseases and inhibition of tumor progression. Marine fish oil is the richest source for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), but the limitations are its high susceptibility toward oxidation and consequent off-flavors and production of toxic compounds, as well as geographical and seasonal variations in quality and quantity. As marine algae is the primary producer of n-3 PUFA in the natural environment, replacing fish oil with n-3 PUFA enriched algae provides an excellent opportunity to develop alternative n-3 PUFA for nutraceutical and pharmaceutical purposes. Following this background, a study was attempted to develop a commercially feasible technology to enrich Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA) present in microalgae.

The effects of the density and type of food on oxygen consumption and ingestion rate of larvae of the white shrimp Penaeus setiferus fed diatoms Chaetoceros ceratosporum, flagellates Tetraselmis chuii and Artemia franciscana nauplii were analysed. Diatoms, flagellates and Artemia nauplii were fed at five densities from 10 to 5 × 103 cells mL−1, 0 to 4 × 103 cells mL−1, and 0.1, 0.5, 1.0, 1.5 and 2 nauplii mL−1, respectively. In three experiments, two of three types of food were maintained constant at concentrations of 30-40 × 103 cells mL−1 (diatoms), 2 × 103 cells mL−1 (flagellates) and 1 Artemia nauplii mL−1. The oxygen consumption in three experiments increased with larval stage, reaching maximum values in Mill except at lower feed concentrations. A maximum ingestion peak in MI was recorded in larvae fed diatoms, whereas that peak was observed in Mil in larvae fed flagellates. The maximum ingestion rate of Artemia nauplii was observed in Mill. Feed concentrations that produced an optimum metabolic rate as a consequence of equilibrium between ingested food and larval stages were obtained with 20 and 30 × 103 cells mL−1 of C. ceratosporum, 2 and 3 × 103 cells mL−1 of T. chuii, and 1.0 Artemia nauplii mL−1. These concentrations would be the most suitable for producing P. setiferus postlarvae.

The effects of three selected algal species, Tetraselmis tetrahele, Isochrysis galbana and marine Chlorella sp. on the population growth of Brachionus plicatilis was evaluated after 3, 5 and 7 days of culture. The rotifers fed on T. tetrahele showed superior growth with mean peak density of 92.5 individuals per ml to those fed on I. galbana (48.2 individuals per ml) and Chlorella sp. (47.2 individuals per ml) in 5 days. In another experiment, milkfish. Chanos chanos Forsskal, fry with initial mean body weight and standard length of 6.26 ± 1.07mg and 13.04 ± 1.40mm, respectively, were fed B. plicatilis reared on the three algal species for 30 days. Results showed that growth, measured in terms of gain in weight and length, was significantly different (P > 0.05) among treatments. Fastest growth was obtained in fry fed B. plicatilis cultured on T. tetrahele with mean gains in weight and length of 61.48 ± 8.40mg and 9.37 ± 1.68 mm, respectively, followed by fry fed B. plicatilis reared on I. galbana (43.56 ± 8.35mg and 6.25 ± 0.48mm). Milkfish fry fed B. plicatilis cultured on Chlorella sp. gave the poorest growth with mean gains in weight and length of 11.05 ± 1.82mg and 2.33 ± 0.29mm, respectively. Percentage survival ranged from 93.1 to 95.3 percent and was not significantly different between treatments (P < 0.05). The differences in population growth of B. plicatilis and consequently growth of milkfish fry was almost certainly attributed to the differences observed in the biological values of their algal diet, and in particular their protein and lipid contents. T. tetrahele and I. galbana improved the food value of B. plicatilis as live food for the milkfish fry. Their high dietary value was related to the higher algal protein and fat levels and contents of n-3 HUFA particularly 20:5n-3 and 22:6n-3 compared to B. plicatilis cultured on Chlorella sp. The results of the present study point to T. tetrahele as the most suitable food for the mass culture of the rotifer, B. plicatilis.