Chaetoceros Muelleri Research Articles

Diatoms response to salinity changes: investigations using single pulse and cross polarisation magic angle spinning 29Si NMR spectra.

Diatoms Thalassiosira pseudonana and Chaetoceros muelleri (Bacillariophyceae) were cultured at three different salinities (26, 36 and 46 practical salinity units (PSU)) and their silica content examined using natural abundance 29Si magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectroscopy. The samples were investigated using both single pulse (SP) and cross-polarisation (CP) MAS experiments. In addition, samples of T. pseudonana were examined using variable contact time CP MAS experiments allowing the dynamics (TSiH and T1rρH) of CP to be determined. Comparison of SP and CP results revealed a change to a less condensed silica state when diatoms were cultured at salinities away from optimal (36 PSU). Further, an increased amount of organic material (but not its composition) was determined to be present for such samples affecting CP experiments. The location of the organic material, on the diatom surface or within the frustule, was unable to be determined.

Potential of refrigerated marine cyanobacterium Synechococcus elongatus used as food for Artemia franciscana

The aim of this study was to evaluate the performance of the cyanobacterium Synechococcus elongatus after refrigerated storage (4°C) and examine its potential as food for Artemia franciscana . Non-axenic semicontinuous cultures of S. elongatus were maintained at 4°C for 8 weeks. In our bioassay, we fed A. franciscana with refrigerated S. elongatus and fresh cultures of the diatom Chaetoceros muelleri as a control. The S. elongatus cultures could be refrigerated for up to 8 weeks without loss of its viability or alteration in its growth rate, cell size, and proximate composition. Fresh and eight week-refrigerated cultures of S. elongatus were similar with regard to fatty acid profiles. Significant differences in fatty acid profiles were found between refrigerated S. elongatus and fresh C. muelleri cultures. Vibrio bacteria were not detected in any of the S. elongatus cultures (fresh or refrigerated) or fresh cultures C. muelleri . This work demonstrated that refrigerated S. elongatus can be used to feed A. franciscana , maintaining similar growth rates and proximate composition compared with fresh C. muelleri cultures as feed. Thus, S. elongatus has potential aquaculture use as feed for A. franciscana .

Halo-adapted microalgae for fucoxanthin production: Effect of incremental increase in salinity

In order to commercially exploit microalgae for the production of fucoxanthin, species must remain productive in the increasingly saline environment typical in outdoor cultivation ponds. To this end, this study investigated the salinity range, growth, fucoxanthin content and productivity of two halotolerant and four marine microalgae under salinity increase condition. The semi-continuous cultivation followed by gradual salinity increase and slow adaptation helped saline microalgae to extend the salinity range up to 55%. Tested species showed about 12% to 90% more fucoxanthin content at their optimal salinity compared to when grown at non-optimal salinities. Fucoxanthin productivity was found directly linked to biomass productivity. Marine microalgae performed best at salinities <55‰ (ppt, parts per thousand) and halotolerant microalgae was best at salinities >55‰. Among marine species, the highest fucoxanthin content and productivity was observed in Chaetoceros muelleri which was 2.92mgg−1 and 0.072mgL−1d−1 of ash free dry weight (AFDW), respectively, at 45‰ and fucoxanthin content was relatively consistent over the range of salinity between 35 and 55‰. Between two halotolerants, Amphora sp. showed the highest content and productivity of fucoxanthin which was 1.2mgg−1 and 0.053mgL−1d−1 of AFDW, respectively at 85‰ salinity. The results indicate that it is most likely possible to achieve continuous production of fucoxanthin by cultivating marine and halotolerant species one after another when salinity rises due to evaporation. Details of fucoxanthin content and productivity for Chrysotila carterae, Chaetoceros muelleri, Amphora sp. and Navicula sp. are reported for the first time.

The role of external carbonic anhydrase in photosynthesis during growth of the marine diatom Chaetoceros muelleri.

Carbon dioxide concentrating mechanisms (CCMs) act to improve the supply of CO2 at the active site of ribulose-1,5-bisphosphate carboxylase/oxygenase. There is substantial evidence that in some microalgal species CCMs involve an external carbonic anhydrase (CAext ) and that CAext activity is induced by low CO2 concentrations in the growth medium. However, much of this work has been conducted on cells adapted to air-equilibrium concentrations of CO2 , rather than to changing CO2 conditions caused by growing microalgal populations. We investigated the role of CAext in inorganic carbon (Ci ) acquisition and photosynthesis at three sampling points during the growth cycle of the cosmopolitan marine diatom Chaetoceros muelleri. We observed that CAext activity increased with decreasing Ci , particularly CO2 , concentration, supporting the idea that CAext is modulated by external CO2 concentration. Additionally, we found that the contribution of CAext activity to carbon acquisition for photosynthesis varies over time, increasing between the first and second sampling points before decreasing at the last sampling point, where external pH was high. Lastly, decreases in maximum quantum yield of photosystem II (Fv /Fm ), chlorophyll, maximum relative electron transport rate, light harvesting efficiency (α) and maximum rates of Ci - saturated photosynthesis (Vmax ) were observed over time. Despite this decrease in photosynthetic capacity an up-regulation of CCM activity, indicated by a decreasing half-saturation constant for CO2 (K0.5 CO2 ), occurred over time. The flexibility of the CCM during the course of growth in C.muelleri may contribute to the reported dominance and persistence of this species in phytoplankton blooms.

Evolutionarily distinct strategies for the acquisition of inorganic carbon from seawater in marine diatoms.

The acquisition of dissolved inorganic carbon (DIC) in CO2-limited seawater is a central issue to understand in marine primary production. We previously demonstrated the occurrence of direct HCO3- uptake by solute carrier (SLC) 4 transporters in a diatom, a major marine primary producer. Homologs of SLC are found in both centric and pennate marine diatoms, suggesting that SLC transporters are generally conserved. Here, the generality of SLC-mediated DIC uptake in diatoms was examined using an SLC inhibitor, diisothiocyano-2,2'-stilbenedisulfonic acid (DIDS), and an inhibitor of external carbonic anhydrase, acetazolamide. DIDS suppressed high-DIC-affinity photosynthesis in the pennate diatom Phaeodactylum tricornutum and the centric diatom Chaetoceros muelleri, but there was no effect on either the pennate Cylindrotheca fusiformis or the centric Thalassiosira pseudonana. Interestingly, the DIC affinity of DIDS-insensitive strains was sensitive to treatment with up to 100 μM acetazolamide, displaying a 2-4-fold increase in K0.5[DIC]. In contrast, acetazolamide did not affect the DIDS-sensitive group. These results indicate the occurrence of two distinct strategies for DIC uptake-one primarily facilitated by SLC and the other being passive CO2 entry facilitated by external carbonic anhydrase. The phylogenetic independence of these strategies suggests that environmental demands drove the evolution of distinct DIC uptake mechanisms in diatoms.

Publisher's Note: “Comparison of lipid and biodiesel properties of Chaetoceros muelleri cultured in deep sea water and surface sea water” [J. Renewable Sustainable Energy 9, 013104 (2017)

First Page

Isolation, culture and evaluation of Chaetoceros muelleri from the Caribbean as food for the native scallops, Argopecten nucleus and Nodipecten nodosus

The potential of the Caribbean strain Chaetoceros muelleri (CHA-C-04) to be produced and used as diet of two commercially important native scallops (Argopecten nucleus and Nodipecten nodosus) was assessed, using the non-indigenous Chaetoceros calcitrans strain, as a control. Growth and biomass of both diatoms were compared under different culture environments (indoor and outdoor) and culture media (F/2, organic fertilizer triple 15 and humus extract). In addition, their bromatological composition and effect on the physiological condition of the scallops fed with both diatoms were compared. The growth and biomass production of C. muelleri and C. calcitrans were higher under indoor conditions and using the F/2 media. Although the content of proteins, lipids and energy was higher in C. muelleri than in C. calcitrans, its size, organic content, growth and biomass values were not different. Scallops fed with both diatoms strains shows similar values for all of the physiological variables measured, including rates of absorption, oxygen consumption, ammonia excretion and scope for growth. Results suggest that the local strain C. muelleri can be successfully produced and used in the diet of A. nucleus and N. nodosus, but do not offer productive advantages.

The nutritional value of live and concentrated micro-algae for early juveniles of sandfish, Holothuria scabra

Information on the nutritional requirements and preferred diets of sea cucumber juveniles is extremely limited and this has hindered development of hatchery culture methods. This study assessed ingestion, cell wall digestion and relative nutritional values of two live micro-algae (Isochrysis aff. galbana (TISO) and Chaetoceros muelleri) and six concentrated micro-algae products (Instant Algae®, Reed Mariculture Inc.) for early juveniles of sandfish, Holothuria scabra. Seven of the eight micro-algae tested were ingested by juveniles with the exception of live TISO. Faeces excretion times varied between ingested diets that passed through the juvenile gut in less than 1h. The cell walls of five of the eight micro-algae tested were partially or mostly digested (Chaetoceros muelleri, TW1200®, Palova 1800®, Isochrysis 1800® and Shellfish 1800®), while the cell walls of Tetraselmis 3600® and 3H 1800® remained intact. Juvenile growth rates were significantly different between diet treatments over the duration of a 14day growth trial. Mean (±SE) length of early juveniles at the end of the growth trial was highest for those fed live C. muelleri (4.10±0.03mm) followed by TW 1200® (3.49±0.05mm). Juvenile survival did not differ significantly between diet treatments and was highest for those fed C. muelleri (79.33±6.11%) followed by TW1200® (78.33±1.20%). Pearson's correlation tests were used to identify key correlations between the levels of specific nutrients and juvenile performance (growth and survival). A significant positive correlation between growth and dietary protein content (P<0.05), and a highly significant positive correlation between growth and dietary EPA:DHA ratio (P<0.01) provide new information to inform diet selection for juvenile sandfish that will help improve juvenile performance and support improved hatchery production. Use of commercially available micro-algae concentrates as a replacement for live micro-algae in sandfish hatcheries supports development of cheaper, simpler post settlement rearing protocols for this species.

Comparison of lipid and biodiesel properties of Chaetoceros muelleri cultured in deep sea water and surface sea water

The growth rates, lipid characteristics, and fuel properties of fatty acid methyl esters (FAME) made from the microalgae cultured in deep sea water (DSW) were analyzed and compared with those made from the microalgae cultured in surface sea water (SSW). The mineral nutrients including nitrates, silicates, and phosphates contained in DSW were, respectively, 7.8, 4.6, and 5.2 times than those of the corresponding nutrients in SSW. The experimental results also show that the lipid content, growth rate, biomass formation, and production of fatty acid methyl ester (FAME) of the microalgae cultured in DSW were significantly greater than those of the microalgae cultured in SSW by 23.0%, 120.0%, 4.7%, and 9.5%, respectively. In addition, the microalgae cultured in DSW took additional 2 days to reach their maximum biomass quantity than those cultured in SSW. Biodiesel made from Chaetoceros muelleri grown in DSW had the highest content of saturated fatty acids and the lowest composition of mono-unsaturated fatty acids and iodine number among those three biodiesels studied here. DSW is thus a favorable medium for microalgae cultivation to generate lipid and biodiesel with adequate fuel properties.

Lipid extraction from wet Chaetoceros muelleri culture and evaluation of remaining defatted biomass

Microalgae-based lipids are considered a good feedstock for various applications, including biodiesel and omega-3-rich oil production. However, developing new lipid extraction and recovery techniques are required to make microalgal oil a more economically competitive feedstock. To avoid the costly process of complete drying of algal biomass, extraction from wet slurry was improved. Potentially cost-effective and scalable processes were investigated and developed that enable total rupture of nutrient-starved microalgal cells to facilitate lipid recovery directly from wet algal slurry, including pretreatments (thermal treatment, UV-C light radiation and osmotic shock) and the use of a solvent mixture. Using hexane and ethanol on UV-C and thermally pre-treated algal slurries led to more than doubling of the total extractable lipids and total transesterifiable lipids, compared to biomass that was not pretreated and when hexane only was used as the solvent. Lipids (25% w/dry weight), triacylglycerol (13%) and fatty acid methyl esters (17%) were recovered from UV-C pre-treated algal slurry (1000mJ/cm2 UV-C). The residual defatted biomass was analysed for further applications and contained carbohydrates (≈15% w/dry weight) that may be suitable for bioethanol production through fermentation.

Effects of clam size, food type, sediment characteristic, and seawater carbonate chemistry on grazing capacity of Venus clam Cyclina sinensis (Gmelin, 1791)

Aquaculture in saline-alkaline water has a major problem: microalgal blooming causes the pH of water to increase dramatically, thereby causing damage to the reared organisms. To solve this problem, we set out to find a candidate filter-feeding bivalve species suitable for saline-alkaline water to graze on microalgae and to control the pH. In the current study, we investigated the effect of carbonate alkalinity (CA, 2.5, 10.0, and 20.0 meq/L) and pH (8.0, 8.5, and 9.0) on the grazing capacity (GC) of the clam Cyclina sinensis. Additionally, the effect of clam size (small, medium, and large) and microalgae species (Nannochloropsis oculata, Chaetoceros muelleri, and Isochrysis galbana), and the effect of bottom sediment characteristic (mud, sandy mud, and muddy sand) and thickness (3 and 6 cm) were analyzed as well. The results show that the GC on I. galbana was the highest and small size had the maximum GC/W (W: wet weight including body and shells). No significant differences were observed between sediment type and thickness. Regarding CA and pH, a significant decrease in GC by the pH or by their interaction was found. The GC of C. sinensis was not greatly reduced in the treatments of pH≤8.5 and CA≤20.0, and also not affected by bottom sediment type, indicating that this clam is capable to manage microalgal concentrations and might be a candidate species for pH reduction in saline-alkaline water ponds.

Exposure of marine mussels Mytilus spp. to polystyrene microplastics: Toxicity and influence on fluoranthene bioaccumulation

The effects of polystyrene microbeads (micro-PS; mix of 2 and 6 μm; final concentration: 32 μg L−1) alone or in combination with fluoranthene (30 μg L−1) on marine mussels Mytilus spp. were investigated after 7 days of exposure and 7 days of depuration under controlled laboratory conditions. Overall, fluoranthene was mostly associated to algae Chaetoceros muelleri (partition coefficient Log Kp = 4.8) used as a food source for mussels during the experiment. When micro-PS were added in the system, a fraction of FLU transferred from the algae to the microbeads as suggested by the higher partition coefficient of micro-PS (Log Kp = 6.6), which confirmed a high affinity of fluoranthene for polystyrene microparticles. However, this did not lead to a modification of fluoranthene bioaccumulation in exposed individuals, suggesting that micro-PS had a minor role in transferring fluoranthene to mussels tissues in comparison with waterborne and foodborne exposures. After depuration, a higher fluoranthene concentration was detected in mussels exposed to micro-PS and fluoranthene, as compared to mussels exposed to fluoranthene alone. This may be related to direct effect of micro-PS on detoxification mechanisms, as suggested by a down regulation of a P-glycoprotein involved in pollutant excretion, but other factors such as an impairment of the filtration activity or presence of remaining beads in the gut cannot be excluded. Micro-PS alone led to an increase in hemocyte mortality and triggered substantial modulation of cellular oxidative balance: increase in reactive oxygen species production in hemocytes and enhancement of anti-oxidant and glutathione-related enzymes in mussel tissues. Highest histopathological damages and levels of anti-oxidant markers were observed in mussels exposed to micro-PS together with fluoranthene. Overall these results suggest that under the experimental conditions of our study micro-PS led to direct toxic effects at tissue, cellular and molecular levels, and modulated fluoranthene kinetics and toxicity in marine mussels.

Dissolved air flotation and centrifugation as methods for oil recovery from ruptured microalgal cells

Solvent-free microalgal lipid recovery is highly desirable for safer, more sustainable and more economical microalgal oil production. Dispersed air flotation and centrifugation were evaluated for the ability to separate oil and debris from a slurry mixture of osmotically fractured Chaetoceros muelleri cells with and without utilizing collectors. Microalgal oil partially phase-separated as a top layer and partially formed an oil-in-water emulsion. Although collectors, such as sodium dodecyl sulphate enhanced selective flotation, by just adjusting the pH and cell concentration of the mixture, up to 78% of the lipids were recovered in the froth. Using centrifugation of fractured microalgal slurry resulted in removal of 60% cell debris and up to 68.5% of microalgal oil was present in the supernatant. Both methods, centrifugation and flotation provided options for separation of microalgal oil from C. muelleri slurry with similar fatty acid recoveries of 57% and 60%, respectively.

Effects of microalgae as diets on the survival, development and fecundity of a pelagic cyclopoid copepod Apocyclops borneoensis

It has been proposed that the feeding habit of cyclopoids is different from that of calanoid copepods in that they feed mainly on microalgae during early development but become carnivorous later. However, a different view also exists, believing that microalgae are the prime food for some cyclopoid copepods. In the present study, microalgae from various taxonomic groups, including a dinoflagellate (Prorocentrum micans), three diatoms (Chaetoceros muelleri, Skeletonema costatum and Nitzschia closterium f. minutissima), and a prymnesiod (Isochrysis galbana), were offered at different concentrations to the cyclopoid copepod, Apocyclops borneoensis, with survival, development and reproduction of the copepod closely monitored. The results showed that A. borneoensis is capable of utilizing any of the microalgae species tested for development and reproduction, but significant differences in survival, development rates of both nauplii and copepodites, and fecundity were detected among species. The results also showed that within a same algal species, food concentration also significantly affected various biological parameters measured. Overall, C. muelleri and I. galbana were the better diets for A. borneoensis and their optimal food concentration ranged from 8.50 to 17.00 µg C ml−1. The optimal food concentration of P. micans was also found to be 8.50–17.00 µg C ml−1, however for the other two algae, S. costatum and N. closterium f. minutissima, it was lower at 1.70–8.50 µg C ml−1. The present study provides novel information on the feeding habit of A. borneoensis and the effects of both quality and quantity of microalgae diets on a range of biological parameters are described.

Process Analysis of Alkaline Flocculation Harvesting for Chaetoceros muelleri and Scenedesmus quadricauda

Alkaline flocculation could be an attractive microalgae harvesting method, because it is low-cost, low energy consumption, and non-toxic to microalgal cells, and the high pH effectively sterilizes the microalgal biomass as well as the process water. In this paper, the mechanism of alkaline flocculation process and the difference between the two strains marine diatom Chaetoceros muelleri #862 and freshwater algae Scenedesmus quadricauda #507 were analyzed. The particle size of C. muelleri #862 cells increased linearly with the increasing pH value which increased dramatically by nearly fivefolds after alkaline flocculation. When pH was below 10.5, the absolute value of zeta potential on the surface of C. muelleri #862 increased rapidly, and also the conductivity of the solution declined quickly. The alkaline flocculation of C. muelleri #862 was mainly attributed to the production of Mg(OH)2 rather than calcium phosphate or calcium hydroxide. For the strain S. quadricauda #507, the cells still existed integrally as normal cells after alkaline flocculation. Firstly, with the increasing of pH in the solution, the absolute value of zeta potential had not declined. When pH was around 10.8, the absolute value of zeta potential had declined abruptly and the solution conductivity was increasing all the time. The cell wall of S. quadricauda #507 with the high content of cellulose Iα and low crystallization degree was good for the next step of saccharification or oil extraction.

Contribution of bioflocs to the culture of Litopenaeus vannamei post-larvae determined using stable isotopes

The aim of this study was to use preselected quality indicators for Litopenaeus vannamei post-larvae and the stable isotopes technique with δ13C and δ15N to determine the influence of bioflocs in shrimp feeding during the nursery phase, between PL1 and PL30. A control treatment (CT) with water renewal was compared to a biofloc treatment (BT) that received organic carbon fertilizations. Different types of commercial feed (Stresspak and Flake-INVE™, PL40-GUABI™), microalgae (Chaetoceros muelleri) and Artemia sp. nauplii were used as food sources. The physical and chemical parameters of water and ammonia were monitored daily, and nitrite, nitrate and alkalinity were measured weekly. Suspended solids and the microorganisms of bioflocs were characterized. At the end of the experiment, fifteen shrimps of each replicate were collected to evaluate nine larvae quality indicators. Isotopic values of 13C and 15N of food sources and shrimp tissues were collected on days 10, 20 and 30, and a Bayesian model of isotopic mixture measured the contributions of these sources to the shrimp biomass. Salinity, alkalinity and nitrite differed significantly between the treatments but were appropriate for post-larvae production. The larvae quality conditions in the CT treatment were ranked as “good,” whereas the BT conditions were considered “excellent” according to the analysis of larval quality parameters. The stable isotopes analysis showed that the PL40 GUABI™ feed was the most important food source throughout the experimental period in the CT. In the BT (10th and 20th days), the bioflocs and commercial feeds (Flake-INVE™, PL40-GUABI™) did not present significant variations in their contribution ratios; however, on the 30th day, the contribution of the PL40-GUABI™ feed was higher when compared to bioflocs. In general, the commercial feed played a more important role as a food source for Litopenaeus vannamei larvae during the nursery phase, although the consumption of bioflocs led to a better larvae quality.

Effect of different dietary microalgae combinations on growth and survival of black-lip pearl oyster (Pinctada margaritifera) larvae and the feasibility of replacing microalgae with a dietary lipid emulsion

A 10-day experiment was performed to examine different mono, binary and ternary dietary combinations on survival and growth of D-shaped and umbone black-lip pearl oyster, Pinctada margaritifera, larvae. The three tropical microalgae species were the flagellate Isochrysis galbana clone T. Iso (CS-177) and diatoms Chaetoceros calcitrans (CS-178) and Chaetoceros muelleri (CS-176) which were fed to D-shaped and umbone larvae at a density of 7000 and 14 000 cells mL−1, respectively. A second experiment was performed to investigate the feasibility of replacing T. Iso with a lipid emulsion for both D-shaped and umbone larvae for 10 and 12 days, respectively. The treatments included only T. Iso, unfed and lipid emulsion to substitute T. Iso at levels of 10% (LIP10), 30% (LIP30) and 100% (LIP100). In the first experiment, results showed that a monospecific diet of T. Iso led to significantly higher (P 0.05) from the unfed treatment. For D-shaped larvae, no significant growth difference was detected (P > 0.05) between the T. Iso and LIP10 fed treatments while for umbone larvae, the T. Iso, LIP10 and LIP30 were not significantly different (P > 005). These results indicate that microalgae combinations appear more necessary for later staged P. margaritifera larvae. In addition, the use of a lipid emulsion appeared to provide some nutrition to the larvae, although more research should be conducted to improve the use of such replacements.

Optimization of growth requirements of marine diatomChaetoceros muelleriusing Response Surface Methodology

The marine centric diatom Chaetoceros muelleri has been widely used as live feed in fish and shellfish aquaculture due to its excellent nutritional properties. The growth of microalgae is affected by various nutritional and environmental parameters, and species specific optimization of these parameters is essential for the development of cost-effective biomass production process. In this study, the growth of C. muelleri, was optimized using response surface methodology (RSM). The variables nitrate, phosphate, silicate, temperature, pH, salinity and agitation speed were initially screened for biomass production in C. muelleri using Plackett–Burman experimental design, and it was found that nitrate, phosphate, silicate, temperature and pH significantly influenced the biomass production. These variables were further optimized by central composite design of RSM for biomass production and nutrient composition, and the medium was re-constituted accordingly to have 180 mg L−1 nitrate, 7.5 mg L−1 phosphate, 30 mg L−1 silicate, with optimum growth conditions of temperature at 31°C and pH 6.46. At the end of 10 days culture period under the above conditions, biomass, protein, lipid and carbohydrate significantly increased from 0.360 ± 0.01 mg L−1, 9.41 ± 0.02%, 18.11 ± 0.01%, 0.6 ± 0.02% to 1.16 ± 0.01 mg L−1, 11.02 ± 0.01%, 19.58 ± 0.01% and 0.77 ± 0.01% respectively. The biomass production of C. muelleri could be increased 3.2-fold with an improved nutrient profile by modifying the growth factors, the study thus offering an optimized process for biomass production of C. muelleri.

Feeding rate responses of Babylonia formosae habei (Prosobranchia: Buccinidae) larvae on cultured algae

Babylonia formosae habei is a commercially important marine gastropod species. Food particles ingested by the planktotrophic larvae of B. formosae habei can be critical in maximizing the larval growth and survival of this species. In this study, feeding rate responses of B. formosae habei larvae on cultured algae were observed using a Coulter multisizer. Variations were recorded based on the changes of different factors of influence, including varied larval stoking density, varied types of algae, varied algae concentrations and selective feeding on mixed algae cells of different types. Results of this study reveal some facts on the feeding of B. formosae habei larvae: larval stoking density has negative effect on their feeding rates; larva has a higher feeding rate on big-sized algae than small-sized algae; larva has a higher feeding rate on diatom than green algae and flagellate; feeding rate of larvae increased when fed mixed algae cells. Optimal algal concentration of the cultured algae Chlorella sp., Chaetoceros muelleri, Isochrysis zhanjiangensis and Dunaliella tertiolecta was suggested at 20 × 104, 5 × 104, 20 × 104 and 10 × 104 cells mL−1 respectively. Results of the preset study can be important in understanding feeding ecology of B. formosae habei larvae, and applicable for the aquaculture of this species.

通气对角毛藻营养组分的影响

采用索氏提取法、考马斯亮蓝法、Somogyi法分别对静止培养和通气培养的牟氏角毛藻(Chaetoceros muelleri)内的脂肪、蛋白质、碳水化合物等营养组分的含量进行了测试分析。结果表明：静止培养的牟氏角毛藻营养物质含量高于通气培养的牟氏角毛藻营养物质含量。静止培养条件下牟氏角毛藻中脂肪含量为26.425%，蛋白质含量为0.816%，碳水化合物含量为10.7%；通气培养条件下牟氏角毛藻中脂肪含量为24.396%，蛋白质含量为0.474%，碳水化合物含量为7.840%。 Contents of lipids, proteins and carbohydrates in the cells of Chaetoceros muelleri, which cultivated in aerobic and anaerobic photobioreactors, were measured by the Soxhlet extraction method, Bradford method and Somogyi method, respectively. The results showed that the content of nutrimental substances in the cells of anaerobic cultures of C. muelleri is higher than them in the aerobic cultured cells. The content of lipid, protein and carbohydrate were 26.425%, 0.816%, and 10.7%, respectively in anaerobic cultured cells. While in the aerobic cultures they were 24.396%, 0.474%, and 7.84%, respectively.