Effects of stocking density, diet, and water exchange on growth and survival of pearl oyster Pinctada maxima larvae

Three experiments were carried out to separately investigate the effects of stocking density (1.0, 2.0, 4.0 and 8.0 larvae ml^?1), diet (Isochrysis zhanjiangensis, Chlorella spp., Nannochloropsis oculata, 50 % I. zhanjiangensis/50 % Chlorella spp. and 50 % I. zhanjiangensis/50 % N. oculata), and water exchange (25 % once every other day and 25, 50 and 100 % once daily) on growth and survival of pearl oyster Pinctada maxima larvae. Results showed that there existed significant effects of stocking density, diet, and water exchange on the growth of pearl oyster larvae (P < 0.05). Larval survival was significantly affected by stocking density and diet (P < 0.05), but not by water exchange (P > 0.05). Larval growth decreased significantly with increasing stocking density (P < 0.05). A density of 1.0–4.0 larvae ml^?1 was optimal for larval growth of pearl oyster. Chlorella spp. and N. oculata could replace 50 % of I. zhanjiangensis as a food source for the pearl oyster larvae without affecting growth and survival. A water exchange of 25 % once daily provided optimum larval growth and survival.     

Pearl grafting: Tracking the biological origin of nuclei by straightforward immunological methods

French Polynesia is renowned for the production of Tahitian black pearl. These gems are obtained by grafting a nucleus into the gonad of a receiving oyster together with a graft, i.e. a small section of mantle tissue of a donor oyster. This procedure initiates the formation of a pearl sack around the nucleus, and subsequently, the deposition of concentric layers of nacre. The nucleus plays a key‐role in pearl formation and its characteristics influence markedly the quality of the final product. As it is manufactured from mollusc shells, it contains a small percentage of organics. In the present paper, we used a set of biochemical techniques to characterize and compare the organic matrices from two types of nuclei that are currently used in French Polynesia: that from the freshwater mussel Amblema sp., and that from the pearl oyster Pinctada sp. To this end, we extracted the matrices from nuclei and performed FT‐IR, monodimensional electrophoresis, and enzyme‐linked immuno‐sorbent assay (ELISA). Our data show that the matrix associated with Amblema nuclei has a very different biochemical signature from that of Pinctada nuclei, a fact that may explain the improved tolerance of grafted oysters to nuclei of Pinctada origin. In the absence of complex physical methods of investigation, simple immunological techniques and FT‐IR performed on the extracted organic matrix are extremely reliable and effective for discriminating nuclei from these two sources. We assert that such techniques can be used as a diagnostic test to track unambiguously the biological origin of nuclei to avoid fraud.     

Comparison of growth and pearl production in males and females of the freshwater mussel, Hyriopsis cumingii, in China

Growth and pearl production were compared for males and females in the freshwater mussel, Hyriopis cumingii, from a full-sib family. The results indicated that there was no significant difference (p > 0.05) on individual weight between male and female mussels of 1- or 2-year-old, while significant difference (p < 0.01) lay among 3- or 4-year-old mussels with male greater than female. The average shell width of the male mussels was less than that of the female individual (p < 0.05). 1- and 2-year-old males and females did not differ significantly with respect to the total weights, grain weights, or grain sizes of the pearls they produced, but these three parameters were all significantly greater in 3- and 4-year-old males (p < 0.05). The round pearl percent were similar between male and females at ages 1, 2, 3 and 4 years. Male and female mussels were separately and mixed cultured in enclosures, respectively. The rates of growth in shell width and body weight of females separated from males were 3.42 and 4.16 %, respectively, higher than in females mixed with males (p < 0.05). The total pearl weight per mussel, the average weight per pearl, and the average pearl size of females separated from males were 6.61, 7.10, and 3.59 %, respectively, greater than in females mixed with males (p < 0.05). There was no significant difference in the growth rate or pearl yield of males cultured with or without females (p > 0.05). Under traditional culture methods, male mussels have a better pearl performance, and artificial separation of females from males can improve the growth and pearl production of female mussels.     

Exploration of the antibacterial proteins in pearl oyster <Emphasis Type="Italic">Pinctada fucata</Emphasis> induced by bacterial inoculation

The aim of this research was to characterize immune-related antibacterial substances from pearl oyster Pinctada fucata induced by bacterial invasion. Bacteria inoculation was performed by injecting 0.1 ml of 1.0 × 10¹² colony-forming units/ml Vibrio parahaemolyticus into adductor muscle. Acidic extracts were prepared with 0.1% trifluoroacetic acid from different tissues after 8 h of injection, and antibacterial activity against V. parahaemolyticus was determined via the microdilution broth method. The acidic extracts from gills of inoculated oysters (AEg) showed stronger antibacterial activity than those from non-inoculated ones. Based on this result, antibacterial proteins were purified from AEg via two-step gel filtration chromatography, followed by high-performance liquid chromatography using a TSkgel G3000 column. Protein components were analyzed by both sodium dodecyl sulfate and native polyacrylamide gel electrophoresis. As a result, two antibacterial proteins, APg-1 (with a molecular mass of approximately 210 kDa) and APg-2 (of approximately 30 kDa), were obtained from AEg. Matrix-assisted laser desorption/ionization time of flight mass spectrometry analysis and partial amino acid sequences revealed that these proteins might be novel antibacterial proteins. These results indicate that antibacterial proteins are potentially upregulated in the gill of pearl oysters or released therefrom for defense against bacterial invasion.     

Phenotypic indicators for cultured pearl size improvement in the black‐lipped pearl oyster (Pinctada margaritifera): towards selection for the recipient growth performance

The black‐lipped pearl oyster, Pinctada margaritifera, is the most important farmed species in French Polynesia and the basis of the most valuable export industry. Mass production of black pearls relies on a surgical operation requiring tissue from a donor pearl oyster to be grafted, together with a nucleus made of shell, into the gonad of a recipient oyster. Improving pearl size through family selection remains one of the main challenges for future aquaculture development. This study analyses the relative contribution of donor and recipient oysters to pearl size. To this end, hatchery‐produced donor oysters of two batches, large and small (based on shell height), were used to supply grafts for recipients, which were then monitored individually for their growth performance by recording shell height, width, and thickness, and total live weight (flesh + shells) every 6 months (four biometric measurement times) over 20 months of culture. Pearls issued from the two batches of donors showed no significant differences in nacre weight or thickness. In contrast, recipient oyster shell height and total weight were increasingly positively correlated with these pearl size parameters over the culture period, becoming significant at 8 months post‐grafting. Potential therefore exists to use shell height and oyster weight as phenotypic indicators for selective breeding of recipient oysters with high growth performance to increase pearl size in P. margaritifera.     

北海营盘新珍珠贝养殖区浮游植物现状调查

于2010-2011年按季节在北海营盘新珍珠贝养殖区海域进行了4次调查采样,对该海域的浮游植物进行了初步研究。结果表明：该海域共有浮游植物36属82 种,春季以细柱藻属占优,夏季以海链藻属占优,秋季以角毛藻属占优,冬季以菱形藻属和海链藻属占优。各季节各站位浮游植物数量变化范围在2.8×104～9.6×104cells/ml,均位于同一数量级,多样性指数范围在2.54～2.94之间,均匀度在0.47～0.55之间,水质处于轻度污染状态,作为规划的珍珠贝养殖区,该海域饵料生物数量偏低,是规划时需要考虑的因素。     

QTL mapping for glycogen content and shell pigmentation in the Pacific oyster Crassostrea gigas using microsatellites and SNPs

Glycogen content and shell pigmentation are two important economic traits of the Pacific oyster Crassostrea gigas. The first set of quantitative trait loci (QTLs) controlling the two traits was determined in an F1 full-sib family based on a sex-averaged linkage map. The linkage map was constructed using 120 SSRs, and 66 expressed sequence tag-derived single nucleotide polymorphisms (EST–SNPs). Two QTLs were found to be associated with glycogen content, explaining 0.27–79.05 % of the phenotypic variation. One QTL on LG9 were found to be related to shell pigmentation, the paternal and maternal alleles explaining 6.75 and 17.44 % of the phenotypic variation. The relationship of glycogen content with left shell depth and QTL linkage group analysis suggests that left shell depth and volume might be used to assist in indirect selection for glycogen content. The constructed linkage map and determined QTLs can provide a tool for further genetic analysis of the traits and be potential for marker-assisted selection in C. gigas breeding.     

Heritability and phenotypic correlations of gonad sweetness in the sea urchin Strongylocentrotus intermedius

Gonad is the only edible part of sea urchins. Thus, a number of studies have been focusing on how to improve both quantity and quality of their gonads. However, as far as our knowledge, the genetic basis of gonad flavor remains totally unknown in sea urchins. In the present study, we found that the heritability of gonad sweetness was at a high level of 0.56, clearly indicating that it is, to a large extent, under genetic control. Gonad sweetness was significantly positively correlated with gonad weight (P < 0.05), a* (P < 0.01) and b* (P < 0.01), while significantly negative correlated with L* (P < 0.01), ΔE ₁ (P < 0.01) and ΔE ₂ (P < 0.01). The present study provides valuable information into the genetic basis of gonad sweetness and evidences that gonad sweetness is potential to be improved in sea urchin genetic breeding programs.     

Heat-shock protein 70 modulates apoptosis signal-regulating kinase 1 in stressed hepatocytes of Mugil cephalus

Oxidative stress causes damage at the cellular level and activates a number of signaling pathways. Heat-shock proteins (HSPs) play an important role in repair and protective mechanisms under cell response to stress conditions. HSP70 has been shown to act as an inhibitor of apoptosis. Apoptosis signal-regulating kinase-1 (ASK1) activity is regulated at multiple levels, one of which is through inhibition by cytosolic chaperons HSP70. The current study was aimed to investigate the alteration in signaling molecules that allow the fish to survive under stressed natural field conditions. The study also investigates the variation in biomolecular composition of hepatocytes by using Fourier transform infrared spectroscopy. The impact of stress on hepatocytes was assessed by measuring the level of lipid peroxides (LPO), catalase activity (CAT) and assessing the changes in hepatocytes of Mugil cephalus inhabiting Kovalam and Ennore estuaries. The expression of HSP70 and ASK1 were analyzed by immunoblot analysis and ELISA, respectively. The spectral analysis showed variations in biomolecular composition of hepatocytes at a wave number region of 4,000–400 cm^?1. There was significant decrease of CAT activity (p < 0.01) (25 %) with significant increase of LPO (p < 0.001) (35 %) and HSP70 (p < 0.001) and insignificant increase of ASK1 (p < 0.05) (16 %) in fish hepatocytes inhabiting Ennore estuary than Kovalam estuary. In conclusion, the present study suggests that the survival of fish in the Ennore estuary under stressed condition may be due to the upregulation of HSP70 that mediates the altered signal pathway which promotes cellular resistance against apoptosis.     

Molecular cloning,characterization, and expression analysis of luteinizing hormone receptor gene in turbot (Scophthalmus maximus)

The luteinizing hormone receptor (LHR) plays a crucial role in female reproduction. In the present study, full-length sequence coding for the LHR was obtained from female turbot (Scophthalmus maximus) by homology cloning and a strategy based on rapid amplification of cDNA end-polymerase chain reaction. The full-length LHR cDNA was 3,184 bp long and contained a 2,058-bp open reading frame which encoded a protein of 685 amino acids. Multiple sequence alignments of the turbot LHR manifested high homologies with the corresponding sequences of available teleosts and representative vertebrates, and significant homology with that of Hippoglossus hippoglossus. In addition, the turbot LHR showed typical characteristics of glycoprotein receptors, including a long N-terminal extracellular domain, seven transmembrane domains, and a short C-terminal intracellular domain. LHR mRNA was abundant in the ovary, but was deficient in extra-ovarian tissues. Furthermore, LHR mRNA gradually developed from previtellogenesis to migratory nucleus stage, with the highest values observed in migratory nucleus stage during reproductive cycle. However, LHR mRNA sharply decreased in atresia stage. These results suggested that LHR is a typical G protein-coupled receptor that is involved in the promotion of turbot ovarian development and may be related to the final maturation and ovulation of oocyte. These findings contribute to the understanding of the potential roles of LHR in controlling the fish reproductive cycle.     

Molecular cytogenetic study of genome ploidy in the German mirror carp Cyprinus carpio

We examined the polyploidy of Cyprinus carpio, the German mirror carp. Specimens were collected in the field in Hulan, China, and treated with phytohemagglutinin and colchicine before the chromosome spreads and the karyotype of kidney cells were examined using silver staining, chromomycin A₃ (CMA₃)/distamycin (DA)/4,6-diamidino-2-phenylindole (DAPI) staining, and fluorescence in situ hybridization (FISH) with a 5.8S + 28S rDNA probe. One to twosilver stained (Ag) nucleolus organizing regions (NORs) were detected during metaphase and interphase events, with 80 % of the metaphase spreads and 69 % of the interphase nuclei showing two Ag-NORs signals. One CMA₃ signal was detected on the terminus of the short arm of each submetacentric chromosome 8 (SMC8) homolog (n = 2). The 5.8S + 28S rDNA probe hybridized at the terminus of the short arm of each SMC8 homolog (n = 2). The results of the Ag-NORs, CMA₃/DA/DAPI, and 5.8S + 28S rDNA FISH analyses were consistent with regard to the total number and location of the SMC8 NORs in the chromosome spreads and karyotype, indicating that, at the molecular cytogenetic level, the German mirror carp is an evolutionary tetraploid with two sets of chromosomes after diploidization.     

A baseline study on lipid and fatty acid composition in the pearl oyster, <Emphasis Type="Italic">Pinctada fucata</Emphasis>

The pearl oyster Pinctada fucata is cultured for pearl production in China, but its germplasm is degenerated. Thus, lipid and fatty acids were investigated in P. fucata based on different tissues, body sizes and condition indexes using GC–MS to provide a lipidomic baseline for evaluation of breeding variety in terms of physiology. The major fatty acids over all samples included saturated (C16:0 and C18:0), monounsaturated [C16:1(n-7), C18:1(n-7) and C18:1(n-9)], and polyunsaturated fatty acids [arachidonic acid: C20:4(n-6), EPA: C20:5(n-3) and DHA: C22:6(n-3)]. Relative percentages of lipid contents of the mantle and visceral mass were, respectively, 40.75 and 42.03 %, significantly higher than adductor muscle (14.48 %) and gill (17.15 %). Fatty acid analysis showed that there were 15 types of fatty acids in adductor muscle, 17 types in mantle and gill, respectively, and 19 types in visceral mass. Meanwhile, total fatty acids, SFA, MUFA and PUFA were the highest in visceral mass (P < 0.05). Yet the lipid contents and fatty acid compositions showed no significant differences between body sizes or condition indexes based on visceral mass. The observations above suggested that visceral mass and mantle are the major tissues for P. fucata to store lipids and thus are important candidate tissues for lipidomic study.     

Schizothorax prenanti corticotropin-releasing hormone (CRH): molecular cloning,tissue expression,and the function of feeding regulation

Corticotropin-releasing hormone (CRH) is a potent mediator of endocrine, autonomic, behavioral, and immune responses to stress. For a better understanding of the structure and function of the CRH gene and to study its effect on feeding regulation in cyprinid fish, the cDNA of the CRH gene from the brain of Schizothorax prenanti was cloned and sequenced. The full-length CRH cDNA consisted of 1,046 bp with an open reading frame of 489 bp encoding a protein of 162 amino acids. Real-time quantitative PCR analyses revealed that CRH was widely expressed in central and peripheral tissues. In particular, high expression level of CRH was detected in brain. Furthermore, CRH mRNA expression was examined in different brain regions, especially high in hypothalamus. In addition, there was no significant change in CRH mRNA expression in fed group compared with the fasted group in the S. prenanti hypothalamus during short-term fasting. However, CRH gene expression presented significant decrease in the hypothalamus in fasted group compared with the fed group (P < 0.05) on day 7; thereafter, re-feeding could lead to a significant increase in CRH mRNA expression in fasted group on day 9. The results suggest that the CRH may play a critical role in feeding regulation in S. prenanti.     

Feeding,somatic condition and survival of sand lance <Emphasis Type="Italic">Ammodytes</Emphasis> sp. larvae in Mutsu Bay,Japan

To clarify the recruitment process of sand lance Ammodytes sp., we investigated larval condition factor, relative gut fullness (%GF), prey abundance and oceanographic structure in Mutsu Bay, Japan, during 1999–2001. Ammodytes sp. larvae, which were collected by horizontal hauls of Motoda nets and a ring net at depths of 1, 10, 20, 30 and 40 m, were mainly distributed at 10–30 m. Larvae at the first feeding time until 12 mm in body length (BL) fed predominantly on copepod nauplii, whereas large larvae with BL of 12.1–14.0 mm fed on a mixture of copepod nauplii, copepodites and appendicularians from late February to April. A path analysis showed that difference in water density between 35- and 5-m depths negatively affected naupliar abundance at 10–30-m depth (standardised path coefficient β = ?0.71, p = 0.005 for 3.3–8.0-mm BL larvae and β = ?0.78, p < 0.001 for 8.1–12.0-mm BL larvae). Naupliar abundance positively affected the %GF of Ammodytes sp. larvae (β = 0.75, p < 0.001 for 3.3–8.0-mm BL larvae and β = 0.66, p < 0.001 for 8.1–12.0-mm BL larvae), whereas it was negatively affected by water temperature (β = ?0.45, p = 0.008 for 3.3–8.0-mm BL larvae and β = ?0.56, p = 0.002 for 8.1–12.0-mm BL larvae), and the temperature effect was weak compared with that of naupliar abundance. In turn, %GF positively affected larval somatic weight (β = 0.91, p < 0.001 for 6.0-mm BL larvae and β = 0.70, p = 0.005 for 10.0-mm BL larvae). The recruitment failure in 1999 was likely caused by a reduced condition factor, which resulted from low naupliar abundance. In contrast, the abundance of nauplii and Oithona similis copepodites was high in 2000 and 2001. It is possible that the higher recruitment success in 2001 was because of the higher water temperatures in Mutsu Bay, sustaining faster growth of the larvae than in 2000 under the high-prey abundance conditions.     

Dynamic expression pattern of corticotropin-releasing hormone,urotensin I and II genes under acute salinity and temperature challenge during early development of zebrafish

Corticotropin-releasing hormone (CRH), urotensin I (UI) and urotensin II (UII) are found throughout vertebrate species from fish to human. To further understand the role of crh, uI and uII in teleosts during development, we investigated the expression pattern of crh, uI, uIIα and uIIβ genes, and their response to acute salinity and temperature challenge during early development of zebrafish, Danio rerio. The results reveal that crh, uI, uIIα and uIIβ mRNA are detected from 0hpf, and the expression levels increase to a maximum at 6 days post fertilization (dpf), with the exception of uIIα that peak at 5dpf. Exposure of zebrafish embryos and larvae to acute osmotic (30ppt) stress for 15 min failed to modify expression levels of crh, uI, uIIα and uIIβ mRNA from levels in control fish except at 6dpf when uIIα and uIIβ were significantly (P < 0.05) modified. Exposure of embryos and larvae to a cold (18 °C) or hot stress (38 °C) generally down-regulated mRNA levels of crh, uI, uIIα and uIIβ apart from at 3dpf. The results indicate that the contribution of crh, uI, uIIα and uIIβ genes to the stress response in zebrafish may be stressor-specific during early development. Overall, the results from this study provide a basis for further research into the developmental and stressor-specific function of crh, uI, uIIα and uIIβ in zebrafish.     

Molecular cloning and expression of the heat shock protein 70 gene in the Kumamoto oyster <Emphasis Type="Italic">Crassostrea sikamea</Emphasis>

Episodes of summer mortality of the Kumamoto oyster Crassostrea sikamea are a major problem for its cultivation. Expression of the heat shock protein 70 (HSP70) is induced by various environmental stresses, including heat. We cloned and sequenced hsp70 complementary DNA from C. sikamea to investigate the relationship between hsp70 expression and heat tolerance in this oyster. Quantitative real-time polymerase chain reaction was performed using gill tissue dissected from oysters before and after heat shock for 1 h. The results showed hsp70 expression was faster and greater in oysters cultured at 20–22 °C than at 10–12 °C, and survival was lower among oysters cultured at 20–22 °C than at 10–12 °C. Moreover, heat tolerance was investigated by a 1-h pre-heat treatment, followed by exposure to heat shock conditions 5 days later. Survival was higher and hsp70 expression was notably lower in oysters that received the pre-heat treatment compared with those that did not. We conclude that a pre-heat treatment of only 1 h may be useful for inducing heat tolerance in C. sikamea, and that a low level of hsp70 expression after heat shock is an important index in selecting for high heat tolerance in these oysters.     

北海珍珠养殖区与非养殖区春、秋季磷的形态特征及其相关性

利用2008年9月和2009年4月对北海珍珠养殖区和非养殖区的调查资料,对该海区磷的循环特征及其生态效应进行了分析研究.研究结果表明,该海区磷的储量不高,无论是养殖区还是非养殖区均表现为有机态磷和无机磷含量明显偏低.除颗粒态磷外,所有形态磷均表现为秋季明显高于春季,突出体现了生物释放的补充影响作用.在磷的形态转化上,春...     

Responses to ROS inducer agents in zebrafish cell line: differences between copper and UV-B radiation

Fish are commonly exposed to environmental pollutants, which in turns could induce an oxidative stress. So, it is important to understand the effects and the responses elicited by these toxicants in fish species, being fish cell lines important tools for this purpose. Thus, the aim of the present study was to compare the effects of copper and UV-B radiation exposure on zebrafish hepatocytes (ZFL lineage) in terms of reactive oxygen species (ROS) levels, sulfhydril groups content and mRNA levels of important genes related to cellular response to toxic agents. Exposure of ZFL cells to UV-B radiation (23.3 mJ/cm²) significantly increased levels of intracellular ROS and mRNA of both superoxide dismutase isoforms (sod1 and sod2), three glutathione S-transferase isoforms (gstα, gstµ and gstπ) and a heat shock protein (hsp70). However, no changes in nonprotein sulfhydryl groups (NP-SH) content, as well as in the mRNA levels of genes related to glutathione (GSH) synthesis and recycling, were observed. Contrary to this, copper exposure (20 mg/L) diminished NP-SH content and increased the levels of mRNA of genes related to GSH synthesis (gclc and gs). Moreover, copper exposure increases the mRNA levels of some genes related to antioxidant defenses (gpx and gstπ), biotransformation reactions (cyp1a1) and protein repair (hsp70). In conclusion, these results demonstrated that both toxicants could increase ROS levels in ZFL cell line, but the responses are different, which could be related to activation of different signaling pathways.     

Observations on the increase of wild gilthead seabream,Sparus aurata abundance,in the eastern Adriatic Sea: problems and opportunities

The recent increase of the local population of gilthead seabream, Sparus aurata, in three areas along the southeastern Adriatic Sea: Malostonski Bay (Croatia and Bosnia and Herzegovina), Neretva Estuary (Croatia) and Boka Kotorska Bay (Montenegro) and its adverse effects on shellfish culture by preying on Mediterranean mussels, Mytilus galloprovincialis, and the European flat oyster, Ostrea edulis, are studied. The results from the analysis of the existing information show that the main reason for the recent increase is the escapes from local fish farm which enrich the local population constantly with new gilthead sea bream. The existence of practically endless food in the area of the shellfish farms allows the concentration of the population in the region instead of its dispersion along the Adriatic coast. Moreover, ecological analysis indicates that the gilthead seabream is facing a very low competition from other local species which enhances its capacity to further populate the region. While the impact on the ecosystem is not yet known, the socio-economic impact of the increase of the gilthead seabream population is evident today. Many shellfish farms are closing today in the region since the damages may reach over 90 % of the production.     

Growth performance and biochemical composition of juvenile pearl oyster <Emphasis Type="Italic">Pinctada martensii</Emphasis> fed on artificial diets

The effects of three artificial diets (S1, S2 and S3) on survival, growth and biochemical composition of one-year-old pearl oyster Pinctada martensii were investigated. Six experimental groups (EG1, EG2, EG3, EG4, EG5 and EG6) and one control group (CG) were set up. EG1, EG2 and EG3 were solely fed on S1, S2 and S3, respectively. EG4, EG5 and EG6 were fed on mixed diets, as follows: S1 and Platymonas subcordiformis; S2 and P. subcordiformis; and S3 and P. subcordiformis, respectively. CG was fed on only P. subcordiformis. All groups were continuously fed for 60 days. Survival, growth and biochemical composition of soft tissues were compared across the groups. Results showed that survival rate, the absolute growth rate (AGR) and relative growth rate (RGR) of shell length did not differ significantly across the groups (p > 0.05). The AGR and RGR of total weight differed significantly among the groups (p < 0.05). AGR and RGR of shell length and total weight were the highest in EG5 and the lowest in EG1. Gross fat content showed insignificant differences among the groups (p > 0.05). However, gross protein content and ash content showed significant differences across the groups (p < 0.05). The gross protein of the groups solely fed on artificial diets was lower than those of the groups fed on mixtures of artificial diets and microalgae or single microalgae. The contents of other amino acids, total amino acids (TAAs) and essential amino acids (EAAs) showed significant differences across the groups (p < 0.05). TAA, EAA and delicious amino acids of the groups fed solely on artificial diets were lower than those of the groups fed on mixtures of artificial diets and microalgae or single microalgae. Results indicated that the artificial diet (S2) can serve as substitutes of microalgal diets for P. martensii.