Effect of Temperature on Growth,Energy Budget,and Physiological Performance of Green,White, and Purple Color Morphs of Sea Cucumber,Apostichopus japonicus

As an intertidal species, Apostichopus japonicus is subject to diel and seasonal temperature fluctuations. Color variation is a distinct characteristic of A. japonicus, and a new color morph, purple A. japonicus, was recently found on the coast of Rushan, Weihai City. This study was conducted to compare the performance of green, white, and purple color morphs of A. japonicus at different water temperatures to help improving aquaculture technology and management. In this study, green, white, and purple color morphs of juvenile A. japonicus (1.5 ± 0.1 g) were cultured at 10, 14, 18, 22, and 26 C for 60 d, according to the suitable temperature range for sea cucumber growth. Temperature was shown to have a significant effect on growth, energy budget, and physiology of sea cucumbers (P < 0.05). Specific growth rates, feed conversion efficiencies, and the proportion of energy allocated to growth of all three color morphs were optimal at 18 C. Activities of the enzymes related with oxidative stress, immune response, and digestion were determined. Superoxide dismutase (SOD) and trypsin activities generally reached a maximum in all three color morphs at 18 C. The purple color morph of A. japonicus was higher in growth rate, food conversion efficiency, and proportion of energy allocated to growth than green and white color morphs at 18 and 22 C, consistent with its higher trypsin and SOD activity, indicating the mutual effect of growth and physiology. At 18, 22, and 26 C, the green color morph had the highest level of lysozyme activity and purple color morph had the lowest, indicating possible infection by external pathogens of green color morph, which might be caused by high temperature. These results suggested that the optimum temperature for culture of the three color morphs was approximately 18 C, the purple had a better adaption to high temperature, and the green and white color morphs may be more susceptible to thermal stress than the purple color morph.     

Effect of temperature on growth,digestion and immunity of green,white and purple sea cucumbers,Apostichopus japonicus (Selenka)

Three color morphs (white, green and purple strains) of Apostichopus japonicus (Selenka) were cultured in artificial seawater, for approximately 90 days, in three temperature ranges: 27–22°C (high), 22–17°C (mid) and 17–12°C (low). All strains grew in all temperature ranges. Temperature significantly affected growth rate, digestibility, digestive enzymes and immune‐related enzymes. Highest specific growth rates were exhibited in 4‐month‐old sea cucumbers at mid and high temperatures, and in 16‐month‐old sea cucumbers at mid and low temperatures. Specific growth rates of green and purple strains were not significantly different, but were significantly higher than that of the white strain at mid temperatures. The digestibility of each strain was significantly higher at 27°C, 22°C and 17°C than at 12°C. Green‐strain digestibility was higher than that of purple and white strains at specific temperatures. Protease and amylase activities of all strains followed bell‐shaped temperature curves with maximum digestive enzyme activity at 17°C. The activities of alkaline and acid phosphatases were higher in the guts of the green strain than in the white or purple strains at the same temperature. Superoxide dismutase activity was higher in the purple strain than in white and green strains.     

3种不同体色刺参体壁营养成分的比较研究

本研究分别对青色、紫色和白色刺参(Apostichopus japonicus)体壁的营养成分,包括蛋白、脂肪、粗多糖、氨基酸组成、脂肪酸组成及微量元素进行了比较分析。结果显示,青色刺参蛋白含量显著低于紫色和白色刺参(P<0.05),脂肪含量三者无显著差异(P>0.05),青色刺参和紫色刺参的粗多糖含量高于白色刺参(P<0.05)。3种体色刺参检测出17种氨基酸,白色和紫色刺参氨基酸含量相对较高,为48%左右,而青色刺参体壁氨基酸含量为44%左右。紫色和白色刺参的赖氨酸、苯丙氨酸、苏氨酸、缬氨酸等氨基酸的含量均显著高于青色刺参(P<0.05)。亚油酸(LA)、花生四烯酸(AA)、二十碳五烯酸(EPA)和二十二碳六烯酸(DHA)在3种刺参占较高比重,其中,LA作为重要必需脂肪酸在紫色和白色刺参中均显著高于青色刺参(P<0.05),为青色刺参的4.6倍左右;紫色和白色刺参的AA含量也显著高于青色刺参(P<0.05);而青色刺参中的EPA和DHA均显著高于紫色和白色刺参(P<0.05)。在检测的矿物质中,Fe在3种刺参中含量最高,紫色刺参Fe的含量显著低于青色和白色刺参(P<0.05);青色刺参Mn的含量显著高于紫色和白色刺参(P<0.05);白色刺参Cr的含量显著高于青色和紫色刺参(P<0.05)。研究表明,3种体色刺参的营养成分存在较大差异,均具有进一步开发利用价值。     

A preliminary identification of genomic loci for body colour variation in the sea cucumber Apostichopus japonicus

The sea cucumber Apostichopus japonicus is one of the most economically important aquaculture species in China, which shows a distinct characteristic of body colour variation. A number of purple variants were obtained in the coast of China, which shows great potential to develop a niche market. In the present study, to understand the genetic basis of green‐purple colour variation, a genome‐wide association study based on the 2b‐RAD sequencing was conducted. As a result, 8,795 genome‐wide single nucleotide polymorphism (SNP) markers were obtained and then applied to the association analysis. Ten most associated SNP loci with p‐value <1.0 × 10^–8 were obtained, and they were assigned to 4 chromosomes (chr17, chr21, chr15 and chr05). In genomic regions neighbouring to those SNPs, 33 candidate genes with annotation were obtained and the endothelin‐converting enzyme‐1, which was reported to be involved in pigmentation variation, was identified. To our knowledge, this is the first report of the genetic locus for body colour variation in this species. These findings will be useful for the fine mapping of the determining gene for body colour variation of A. japonicus.     

Effect of shading colours on growth and pigment content of Gracilaria fisheri (Xia & Abbott) Abbott,Zhang & Xia (Gracilariales,Rhodophyta)

Sporeling and tissue propagation of agarophytic seaweed, Gracilaria fisheri, aimed to investigate the optimal shading colour for the preservation. This study was conducted under different shading colours indoor and outdoor experiments. The indoor experiment: tissues and sporelings of the seaweed were cultured in plastic chambers under fluorescent lights and were wrapped with white, green, blue and red colour PVC sheets of light intensity of 20 ± 1 μmol m^?2 s^?1. The outdoor tissues were cultured in the plastic tanks under different shadings of Saran sheets: white, green, blue and black covering the hoop‐houses with light intensity of 110 ± 10 μmol m^?2 s^?1. The results showed that different shading colours strongly influenced growth of G. fisheri sporelings and tissues but little effect on pigmentation. After 40 days, the highest growth rates of G. fisheri tissues and sporelings were found under red light with 1.44 and 1.89% day^?1 respectively. There was no significant difference (P > 0.05) on pigment content of tissues indoor, whereas it was found that chlorophyll concentration of the sporelings under green light with 416.8 μg g^?1 fresh weight was significantly higher (P < 0.05) than those in other treatments. After 8‐week culture, outdoor tissues showed the highest growth rate with 1.71% day^?1 in the green hoop‐house. The study has found that G. fisheri cultivation was less influenced by epiphytes in the back hoop‐house with 15%. This study showed the feasibility of successful cultivation of G. fisheri sporelings and tissues.     

Effects of light intensity on larval development and juvenile growth of sea cucumber Apostichopus japonicus

The growth rate, survival rate, development and setting rate of larval sea cucumber Apostichopus japonicus were measured under four light intensities (0, 50, 500 and 2,000 lx), and the growth rate and metabolism of the juvenile sea cucumbers were investigated under four light intensity treatments (0, 100, 1,000 and 2,500 lx). The light requirements (i.e. intensity) of the sea cucumber changed as they grew. Better growth performance, development and survival rate were observed in embryos and larvae under 500 lx treatment. However, reduced light intensity (50 lx) increased the settlement rate of the larvae. The highest specific growth rate occurred in juvenile sea cucumbers under 1,000 lx. The sea cucumbers in this group also had the lowest oxygen consumption rate and ammonia excretion rate, but the highest O:N ratio, indicating that the optimal light intensity for the juvenile sea cucumber culture was 1,000 lx. Therefore, appropriate light intensities were suggested to provide larval and juvenile sea cucumbers with better growth and development conditions.     

青、白刺参(Apostichopus japonicus)体壁营养成分的比较分析

通过对相同养殖环境条件下,青、白刺参(Apostichopus japonicus)体壁中营养成分(粗蛋白、粗脂肪、多糖、脂肪酸、氨基酸、微量元素等)的测定,比较两种剌参的营养品质与价值.结果显示,青、白刺参的出皮率,体壁中的水分、多糖和灰分含量差异显著(P＜0.05),粗蛋白和粗脂肪差异不显著(P＞0.05).青、白刺参体壁中均检测出20种主要脂肪酸,脂肪酸总量和多不饱和脂肪酸(PUFA)的含量差异不显著(P＞0.05),而青刺参饱和脂肪酸(SFA)含量显著高于白刺参,单不饱和脂肪酸(MUFA)含量显著低于白刺参(P＜0.05).MUFA中青刺参的花生四烯酸(AA)和二十二碳六烯酸(DHA)含量均显著低于白刺参(P＜0.05).青、白刺参体壁中检测出17种氨基酸,必需氨基酸(EAA)、鲜味氨基酸(FAA)和药效氨基酸(DAA)的含量均无显著差异(P＞0.05).青刺参体壁中天冬氨酸和精氨酸含量均显著低于白刺参(P＜0.05).青刺参体壁中Mn和Cr的含量显著低于白刺参(P＜0.05).重金属元素Pb、Cd、Hg、As的含量均符合相关食品卫生标准.综合评价认为,相同养殖环境条件下,白刺参的出皮率、多糖含量、脂肪酸中不饱和脂肪酸含量、AA和DHA的相对百分含量、氨基酸中天冬氨酸和精氨酸含量以及微量元素中Mn和Cr含量均优于青刺参.     

The effects of the tank colour on growth performance and physiological responses in fingerling grouper,Epinephelus coioides

In this study, the effects of different background colours on growth performance and physiological parameters of Epinephelus coioides were investigated. One hundred eighty E. coioides (average weight 18.16 ± 0.07 g) were distributed in black, white and blue 300‐L tanks and fed to satiation for 60 days. The tank colour had no significant effect on the weight gain, condition factor, hepatosomatic index and specific growth rate (p > .05). The lowest amount of viscerosomatic index and the highest carcass protein were recorded in the white tank (p < .05). Daily food intake, feed conversion ratio and plasma glucose were significantly higher in the blue tank (p < .05). The highest levels of haematocrit and plasma triglyceride were observed in the white tank, while the total protein and albumin were higher in the black tank compared to the other tanks. The tank colour had no significant effects on the plasma cortisol level (p > .05). Our findings showed that colours used in this study did not evoke stress and thus had no effect on growth, but some metabolic adaptation occurred in each colour to achieve optimum growth.     

Feasibility of Offshore Co‐culture of Abalone,Haliotis discus hannai Ino,and Sea Cucumber,Apostichopus japonicus,in a Temperate Zone

Feasibility of offshore co‐culture of abalone and sea cucumber was investigated in Northern China. Survival and growth of abalone, Haliotis discus hannai Ino, and sea cucumber, Apostichopus japonicus, co‐cultured in abalone cages from suspended longlines, in the offshore area, were examined. Abalone and sea cucumbers were co‐cultured at density ratios of both 3:1 and 6:1 for 1 yr. Abalone were fed with fresh kelp and no additional feed was given to sea cucumbers. Survival of abalone and sea cucumber was 100% for all treatments. Abalone and sea cucumber grew well; the body weight (BW) of abalone and sea cucumber was nearly doubled and had reached a commercial size. There were no significant differences in the growth rates for both abalone and sea cucumber between the two density treatments. The specific growth rate of BW of abalone (SGRbw) was highest in June, with a value of 0.536%/d. Growth rate of sea cucumber (SGRsc) was highest in December, reached 1.84%/d, with an annual average SGRsc of 0.182%/d. Results suggested that the offshore co‐culture of abalone and sea cucumber was feasible offshore. The co‐culture of abalone with sea cucumbers may provide an additional valuable crop without additional financial input.     

Spontaneous captive breeding and larval development in the green and red variants of the Japanese sea cucumber Apostichopus japonicus (Selenka 1867)

We report the spontaneous spawning, larval development, survival rate and larval growth rate patterns observed in the green and red variants of the Japanese sea cucumber Apostichopus japonicus. The green variant adapted well to the captive conditions in the Sasebo City Fisheries Center and spontaneously spawned without any induction or stimulation. One hundred individual green variants spawned nine times and produced approximately 155 million eggs. In contrast, 50 individual red variants showed poor adaptation to captivity and spawned spontaneously only three times, producing about 12 million eggs. Larval development and growth rate pattern was almost identical between the two variants of A. japonicus. In contrast, the larval survival rate for the green variant was over 90% up to the auricularia stage (10 days), but much low (less than 30%) for the red variant. We demonstrated that the green variant of A. japonicus was easier to rear in captivity. This provides a useful method for maintaining sustainable harvests and eventually contributing to restocking and sea ranching of the existing population. Further studies about optimal ecological conditions and behaviour are needed to improve egg production and survival rate of the red variant of A. japonicus.     

Effect of salinity on growth and energy budget of red and green colour variant sea cucumber Apostichopus japonicus (Selenca)

Sea cucumber, Apostichopus japonicus (Selenca), tolerates salinity fluctuations inhabiting intertide zone. This study deals with growth, food intake, food conversion and the bioenergetic responses of the red variant (wet weight of 2.60 ± 0.11g) and green variant (wet weight of 2.56 ± 0.08 g) A. japonicus to different salinities of 22, 26, 30, 34, and 38 psu at 16.5 ± 0.5°C. The results showed that salinity had a significant effect on specific growth rate (SGR) of both green and red variants A. japonicus (P < 0.05). Both colour variants of sea cucumber had highest SGR at 30 psu, and then decreased when salinity below or above this point. Maximum SGR (the green 1.07 ± 0.08% day^?1, the red 1.14 ± 0.09% day^?1 respectively) is related with maximum food intake (FI) and highest food conversion efficiency (FCE) (P < 0.05) occurring at 30 psu. Only under 22 psu, the green variant grew faster than the red variant (P < 0.05), and under other four salinity treatments there was no significant difference between SGR of two colour variant holothruians (P > 0.05). Values of adaptable salinity scope for green and red variants sea cucumber survival are 18.5~39 psu and 20.9~38.6 psu respectively. The average energy budget formula of sea cucumber at 30 psu was: 100C = 6G +42F +3U+49R (C, energy ingested; G, energy for growth; F, energy loss as faeces; U, energy used for ammonia excretion; R, energy loss for respiration). The sea cucumber had maximum energy ingested (C) and highest proportion of energy for growth (G) at 30 psu, and then decreased when salinity is above or below this salinity. Both red and green variants of A. japonicus deposited for growth were very low, and the energy loss in faeces and energy for respiration accounted for the majority of assimilation energy. The result clearly showed that the optimum condition for farming green and red variants A. japonicus, both with respect growth and energy allocation, is the salinity scope of 26 ~ 30 psu.     

Growth of Hatchery‐reared Juveniles of the Australasian Sea Cucumber,Australostichopus mollis,Fed with Artificial and Natural Diets

Australostichopus mollis is the most common and valuable sea cucumber species on the coasts of New Zealand and southern Australia. However, information supporting the development of artificial diets to advance the aquaculture of this species is scarce. In this study, the nutrient absorption, growth, pigmentation, and survival of small (111 mg) and large (434 mg) early juveniles were measured. The juveniles were fed with mussel biodeposits (MB); a commercial hatchery diet‐powdered macroalgae (HD); and artificial diets with different protein levels, 5% (5P) and 10% (10P), respectively. During the experiment, survival was greater than 66% in all diet treatments, with the juveniles feeding actively and absorbing all major macronutrients. The small juveniles, which were starting pigmentation, had higher growth rates (0.8–2.5%/d) than the large juveniles (0.2–1.2%/d), which were completing pigmentation. Growth was higher with the MB and HD diets than with the 5P and 10P diets, which could be explained by differences in the food consumption and nutrient absorption among the diet treatments. This study shows the feasibility of developing artificial diets without depending on naturally available ingredients; however, palatability and consumption need to be improved in order to make artificial diets for this species more effective and commercially available.     

N and P budgets of Haliotis discus hanai,Apostichopus japonicas,and Sebastes schlegeli in a polyculture system

The viability of placing abalones (Haliotis discus hannai), sea cucumbers (Apostichopus japonicas) and rockfish (Sebastes schlegeli) in a polyculture system, the effect of this mixed species group on the system's nitrogen (N) and phosphorous (P) budgets, and the growth and food intake of the organisms in the system were examined using a recirculating aquaculture system. Four replicates were set up for each of three treatment groups (abalone only (C), abalone‐sea cucumber (AS) and abalone‐sea cucumber‐rockfish (ASF)) with an experimental period of 60 d. Compared with the C group, in the AS group the abalone survival rate and specific growth rate (SGR) of body weight increased and the harvested abalones from the polyculture system became the main source of N and P output of the polyculture system. However, the N and P output in the water layer did not differ significantly from that in the C group (p > 0.05), and the N utilization rate was significantly higher than that in the C and ASF groups (p < 0.05). Compared with the AS group, in the ASF treatment the SGR of body weight as well as the protease and amylase activities of sea cucumbers were significantly higher (p < 0.05), the water layer and faeces became the main sources of N and P output in the system. These results showed that the AS polyculture mode significantly improved the N and P utilization rates in the system and led to increased aquaculture production.     

Increasing the stocking density in Paracentrotus lividus larviculture: Effects on survival and metamorphosis rates

The development of sustainable methods for sea urchin juvenile production is currently constrained by high mortality rates during larval growth and the high costs of larval rearing systems management. With the aim of developing a method for the production of juveniles of the purple sea urchin Paracentrotus lividus in a medium‐scale recirculating system, the present study focused on the effects of high stocking densities on larval growth. Plutei larvae were reared at three different densities (up to 7 ind/ml) in a semi‐static culture system. Larval survival and metamorphosis success were evaluated in order to identify the most effective density range. The highest metamorphosis rates (80%–95%) were obtained at 4 and 7 larvae/ml. These results are comparable with (and in some cases higher than) those reported for the same species at much lower larval densities. In conclusion, the rearing conditions tested here show for the first time that a significantly higher (4 ind/ml) stocking density than those of traditional P. lividus rearing methods (based on large volumes and low densities) can be adopted, thus supporting the feasibility of an increase in the final output of competent larvae with no increase in rearing volumes.     

Digestibility,growth and pigmentation of astaxanthin,canthaxanthin or lutein diets in Lake Kurumoi rainbowfish,Melanotaenia parva (Allen) cultured species

New cultured ornamental fish namely Lake Kurumoi rainbowfish Melanotaenia parva (Allen) run into reduced of colour performances when reared in the aquaria, consequently, fish feed must be added with carotenoids as a pigment source. The aim of this study was to evaluate the digestibility, growth and pigmentation of astaxanthin, canthaxanthin and lutein in diet. Apparent digestibility coefficients (ADC) of dry matter, lipid, protein, carotenoids, growth and pigmentation were studied in twenty fish after 14 and 56 days of observation. The single‐dose supplementation of 100 mg/kg of astaxanthin, canthaxanthin, or lutein diets on fish was fed by apparent satiation. The basal diet without carotenoids was used as control. The result showed that the ADC of carotenoids of test diets was higher compared to control. Fish fed astaxanthin diet had higher survival rate (96.67 ± 2.89%), colour measurements of lightness (57.60 ± 7.46%), a*‐values (4.66 ± 1.20), total carotenoids content in skin (33.75 ± 5.02 mg/kg) and muscle (2.16 ± 0.74 mg/kg). Astaxanthin also increased the growth after 14 days (2.00% ± 0.19%/days) but there was no significantly different at the end of experiment. The yellowish‐orange colour performance was more rapidly achieved by fish fed astaxanthin diet after 28 days experimentation. These values suggested that dietary carotenoids were required and astaxanthin diet was superior to other diets for skin pigmentation of Lake Kurumoi rainbowfish.     

Long-term effects of stocking density on somatic growth,gonad index and survival of the juvenile sea urchin, <Emphasis Type="Italic">Strongylocentrotus droebachiensis</Emphasis>

Juvenile Strongylocentrotus droebachiensis (average wet weight = 4.0 g) were held at three initial stocking densities (15, 30 and 60 animals per tray, which equates to 0.25, 0.5 and 1 kg sea urchins/m² surface area, respectively) under constant light and temperature conditions (LD 24:0 and 8.8°C) for 380 days. The somatic growth and survival of the urchins were monitored during this period, and the gonad index (GI) was measured at the conclusion of the experiment. The sea urchins in the two lowest stocking density groups had 100% survival after 380 days in contrast to the highest stocking density group, which only had 67% survival at the conclusion of the experiment. Somatic growth was significantly higher in the lowest density group than in the medium density group, and this in turn was significantly higher than in the high-density group. The injury occurrence was highest in the high-density group (20%), lower in the medium group (7%), and there were no injuries observed (0%) in the low density groups. There were no significant differences in GI between the groups at the end of the experiment. In conclusion, the present study showed that stocking density has significant effects on somatic growth and survival of juvenile green sea urchin, S. droebachiensis and should be taken into consideration when designing sea urchin holding systems.     

Effects of l‐tryptophan on the performance,energy partitioning and endocrine response of Japanese sea cucumber (Apostichopus japonicus Selenka) exposed to crowding stress

The effects of dietary tryptophan on growth performance, energy budget and endocrine response of sea cucumber Apostichopus japonicus (Selenka) were studied, to test whether the tryptophan could mitigate the crowding stress response of the sea cucumber. Four density treatments of the sea cucumber (i.e. 4, 8, 16 and 32 individuals per 40 L water, represented as L, ML, MH and H) were fed with diets containing 0 (control), 1%, 3% and 5% l ‐tryptophan, respectively, for 75 days. The results showed that the specific growth rate (SGR) and feed conversion ratio (FCE) of A. japonicus decreased with increasing in the stocking densities but increased after supplementation of 1% and 3% tryptophan. The energy allocation of the A. japonicus was affected significantly by stocking density and dietary tryptophan treatments (p < .05). In general, the energy consumed (C) and energy used for growth (G) decreased with the increasing in the stocking densities. The highest proportion of energy deposited to growth occurred in each 3% treatment (L, 6.38%; ML, 6.12%; MH, 4.56% and H, 4.14%), which were significantly higher than the controls (p < .05) respectively. Higher cortisol, glucose and lactate levels of A. japonicus were recorded in the control treatments of MH and H, but l ‐tryptophan supplementation could reduce the levels of cortisol, glucose and lactate of the test animals. The present results proved that the growth performance of the sea cucumber was inhibited by high stocking densities, while dietary supplementation of tryptophan could significantly mitigate the crowding stress, and improve the growth of sea cucumber.     

海星棘皮投喂仿刺参(Apostichopus japonicus Selenka)的效果

在饲料中添加海星棘皮,与两组商品饲料分别投喂体重为5.0–6.7 g的仿刺参(Apostichopus japonicus Selenka),进行60 d养殖试验,研究其对仿刺参平均增重率(AWGR)、特定生长率(SGR)、饲料系数(FCR)、摄食率(FR)和蛋白表观消化率(APD)的影响。结果显示,各组仿刺参生长良好,成活率无显著差异(P>0.05);60 d时,各组仿刺参的AWGR和SGR变化趋势相同,由高到低依次为市售2组、海星组、市售1组;海星饲料组仿刺参的FCR最低,与其他两组间差异不显著(P>0.05);海星饲料组与市售1组的FR间差异不显著(P>0.05),与市售2组FR间有显著差异(P<0.05);海星饲料组仿刺参的饲料转化率(FE)明显高于其他两组(P<0.05);海星饲料组仿刺参的APD最高,为67.28%,与市售1组的APD差异显著(P<0.05)。研究表明,添加海星棘皮可以较好地促进仿刺参的生长和提高饲料的利用,可添加到仿刺参幼参饲料中用作饲料源。     

Effects of tank colour and feed colour on growth and feed utilization of thinlip mullet (Liza ramada) larvae

The effects of aquarium background colour and feed colour on survival, growth rates and feed utilization efficiency of thinlip mullet (Liza ramada) larvae (0.035 g) were investigated in two experiments. In the aquarium background colour trial, 50 larvae were stocked in duplicates in 120 L glass aquaria filled with dechlorinated tap water. The outside walls and bottoms of each pair of the aquaria were covered with coloured paper sheets to achieve one of six colours (white, black, red, green, yellow and blue), while noncoloured aquaria served as a control. The fish were fed an experimental diet (35% crude protein) at a daily rate of 5% of their body weight (BW), twice a day for 8 weeks. The best growth rates, feed efficiency and survival were achieved in larvae reared in light‐coloured aquaria (white, noncoloured and yellow). Fish performance was significantly retarded in larvae reared in dark‐coloured aquaria (red, green, black and blue). Body composition was not significantly affected by aquarium colour. In a feed colour trial, duplicate groups of larvae (0.035 g) were stocked at 50 fish per 120 L aquarium and fed a test diet (35% crude protein) with six different colours [dark blue, red, yellow, light brown (control), light green and dark brown] at a daily rate of 5% BW, twice a day for 8 weeks. The best performance and survival were achieved in fish fed on dark‐coloured diets (red, dark blue and dark brown). Light‐coloured diets (yellow, light green and light brown) resulted in inferior performance. Body composition was not significantly affected by feed colour. These results suggest that light‐coloured tanks should be used for rearing thinlip mullet, L. ramada larvae, while dark‐coloured diets are more preferable to light‐coloured diets.     

投喂不同海藻饵料对海上网箱幼刺参生长及成活的影响

分别采用鲜孔石莼(Ulva pertusa)、鲜角叉菜(Chondrus ocellatus)、鲜裙带菜(Undaria pinnatifida)磨碎液及其混合液与25%海泥制成四种不同配合饵料,对2.25g±0.02g的幼刺参生长和成活进行了研究。结果表明:实验60d后,投喂鲜孔石莼的幼刺体重增长达到(4.86±0.54)g,特定生长率表现出最大值,为1.36%±0.13%/d,相比对照组(3.42g±0.62g,0.82%±0.34%/d)增长显著(P<0.05),鲜角叉菜次之,体重和特定生长率分别为4.37g±0.31g和1.22%±0.22%/d,两者差异不显著(P>0.05)。幼刺参摄食鲜孔石莼、鲜角叉菜、鲜裙带菜和混合藻液其存活率分别为62.2%±0.2%、58.7%±0.3%、55.3%±0.9%、56.3%±0.7%,与对照组(50.6%±1.3%)之间差异显著(P<0.05)。研究结果显示,投喂鲜孔石莼对海上网箱幼刺参的生长和成活效果最好。因此,在刺参海上网箱养殖阶段添加鲜孔石莼是经济可行的。