虾夷扇贝对牙鲆的粪便、残饵及网箱养殖区沉积物的摄食

采用室内静水法,研究了虾夷扇贝Patinopecten yessoensis对牙鲆Paralichthys olivaceus残饵、鱼类粪便、鱼类养殖网箱沉积物及微藻的摄食行为,分析了基于虾夷扇贝的鱼＋贝多营养层次的综合养殖（IMTA）模式的可能性。研究结果显示,虾夷扇贝对鱼粪、残饵及鱼类养殖网箱沉积物都可摄食,但对微藻的滤水率和摄食率最高,显著高于其他实验组(ANOVA, P<0.01);微藻组、残饵组和鱼粪组之间的吸收效率没有显著性差异,但都显著高于沉积物组。吸收效率（AE）与有机物比率（f）呈正相关关系：AE(％)＝38.84lnf+72.7 (R2=0.378);对有机物的吸收率（AR）与有机物浓度（POM）呈线性正相关关系：AR＝0.118×POM-0.555 (R2=0.329)。假粪产生时颗粒物TPM浓度的阈值为24.09mg/L。     

捕后干露对3种贝类活品品质的影响

为明确经济养殖贝类捕后早期干露耐受性,选取活力良好的菲律宾蛤仔、长牡蛎和虾夷扇贝在4 ℃条件下进行8 d的无水贮藏,以闭壳肌pH、糖原、腺苷三磷酸(ATP)关联化合物、磷酸精氨酸的含量和奥品脱氢酶活性为指标,研究3种贝类的品质变化规律。试验结果表明,无水贮藏期间,菲律宾蛤仔pH无明显变化( P <0.05),而长牡蛎和虾夷扇贝pH分别由7.23和7.39降至6.88和6.80。3种贝的糖原含量均呈下降趋势。ATP在菲律宾蛤仔和长牡蛎初始含量仅为0.41、0.42 μmol/g,且贮藏过程无显著变化( P <0.05);在虾夷扇贝的初始含量为4.05 μmol/g,且随着贮藏时间延长急剧下降。虾夷扇贝和菲律宾蛤仔闭壳肌中章鱼碱脱氢酶活性最大,且随贮藏时间呈增加趋势。长牡蛎中alanopine脱氢酶和strombine脱氢酶起主要作用。结合主成分分析推定,长牡蛎、菲律宾蛤仔、虾夷扇贝对干露耐受时间分别是8、4、2 d。试验结果表明,在活贝捕后流通过程中应结合干露耐受性差异建立品种针对性的管理措施。     

山东省8月份水产养殖动植物病情监测报告

8月份,全省各市共对27个养殖品种的病害发生情况进行了监测报告。 1病害测报情况分析 全省在八月共有草鱼、鲤等14个养殖品种发生了15种病害。鲂、罗非鱼、牙鲆、河蟹、海湾扇贝、栉孔扇贝、虾夷扇贝、牡蛎、菲律宾蛤仔、文蛤、中国蛤蜊、海带、中华鳖等13个养殖品种本月无病害发生。     

多棘海盘车(Asterias amurensis)对5种双壳贝类的摄食选择性及摄食节律

研究了多棘海盘车(Asterias amurensis)对虾夷扇贝(Patinopecten yessoensis)、栉孔扇贝(Chlamys farreri)、褶牡蛎(Ostrea plicatula)、贻贝(Mytilus galloprovincialis)、菲律宾蛤仔(Ruditapes philippinarum)5种双壳贝类的摄食选择性和对栉孔扇贝的摄食节律。结果显示,在有或无日本蟳、刺参等干扰饵料的条件下,多棘海盘车对于5种双壳贝类均可摄食,且表现出明显的摄食选择性。其中,多棘海盘车对菲律宾蛤仔的摄食选择性均显著高于其他4种贝类(P<0.05),分别为5.7、5.0、5.7、5.3、6.0只/d,干扰饵料的加入并没有对多棘海盘车的摄食选择性造成显著影响。同时,采用定时投喂饵料的方式,每隔4 h投喂一次栉孔扇贝,多棘海盘车表现出显著地昼夜摄食节律。其18：00–翌日06：00的摄食量显著高于06：00–18：00的摄食量(P<0.05),分别为60%和40%,多棘海盘车的摄食高峰出现在18：00–22：00,摄食频率达到58%,显著高于其他时段(P<0.05)。     

多棘海盘车(Asterias amurensis)对5种双壳贝类的摄食选择性及摄食节律

研究了多棘海盘车(Asterias amurensis)对虾夷扇贝(Patinopecten yessoensis)、栉孔扇贝(Chlamys farreri)、褶牡蛎(Ostrea plicatula)、贻贝(Mytilus galloprovincialis)、菲律宾蛤仔(Ruditapes philippinarum) 5种双壳贝类的摄食选择性和对栉孔扇贝的摄食节律。结果显示,在有或无日本蟳、刺参等干扰饵料的条件下,多棘海盘车对于5种双壳贝类均可摄食,且表现出明显的摄食选择性。其中,多棘海盘车对菲律宾蛤仔的摄食选择性均显著高于其他4种贝类(P<0.05),分别为5.7、5.0、5.7、5.3、6.0只/d,干扰饵料的加入并没有对多棘海盘车的摄食选择性造成显著影响。同时,采用定时投喂饵料的方式,每隔4 h投喂一次栉孔扇贝,多棘海盘车表现出显著地昼夜摄食节律。其18:00–翌日06:00的摄食量显著高于06:00–18:00的摄食量(P<0.05),分别为60%和40%,多棘海盘车的摄食高峰出现在18:00–22:00,摄食频率达到58%,显著高于其他时段(P<0.05)。     

栉孔扇贝对春季桑沟湾颗粒有机物的摄食压力

由于养殖密度和产量较高，滤食性扇贝的养殖活动对海洋碳循环的影响引起人们的关注。不仅收获贝类能够从海域中移出大量的颗粒有机碳（particle organic carbon,POC），而且，在贝类养殖过程中（滤食、呼吸、排粪等生理活动）也对养殖海区的POC产生较大的影响。目前，国内、外学者就贻贝养殖的碳氮通量、虾夷扇贝的碳收支情况、生物沉降及其对底栖生物群落的影响、养殖贝类对浮游植物和悬浮颗粒物的摄食等方面进行了广泛的研究。但是，养殖栉孔扇贝对我国主要养殖海区桑沟湾POC的摄食压力未见报道。     

沉积再悬浮颗粒物对3种滤食性贝类摄食生理的影响

采用室内模拟实验法研究了不同浓度的沉积再悬浮颗粒物对3种经济贝类的滤水率、摄食率和吸收效率影响。结果表明,(1)沉积再悬浮颗粒物对3种滤食性贝类的滤水率、摄食率和吸收效率有明显的影响(P<0.05)。(2)在一定浓度范围内,3种贝类的滤水率和摄食率随沉积再悬浮颗粒物浓度的增大而增大,当再悬浮颗粒物浓度超过一定浓度后,滤水率和摄食率迅速下降。(3)实验期间(24h),随时间的变化,总悬浮颗粒物浓度为20～100mg/L时,3种滤食性贝类的滤水率呈现周期性的升降变化,总悬浮颗粒物对不同时间段3种贝类的滤水率的影响显著(P<0.05)。300和500mg/L时,总悬浮颗粒物对不同时间段栉孔扇贝和紫贻贝滤水率的影响不明显(P>0.05),而对菲律宾蛤仔滤水率的影响显著(P<0.05);在6～24h时间段,3种贝类的滤水值多次出现负值。(4)吸收效率随沉积再悬浮颗粒物浓度的增大而减小,与悬浮颗粒物有机质的百分含量的变化趋势相一致。本研究表明,沉积再悬浮颗粒物对3种滤食性贝类的摄食生理有显著的影响。     

多棘海盘车对四种贝类摄食率和选择性的初步研究

在水温为22～24℃,盐度29.6,溶解氧6.9 mg/L,pH 8.01的条件下,研究了多棘海盘车(Asterias amurensis)对4种贝类栉孔扇贝(Chlamys farreri)、贻贝(Mytilus edulis)、东方缝栖蛤(Hiatella orientalis)、菲律宾蛤仔(Ruditapes philippinarum)的摄食与食物选择性,以期了解多棘海盘车摄食生理生态学特性。结果表明:当只有一种贝类作为饵料时,多棘海盘车对不同贝类的摄食率差异极显著(P<0.01)。其中,对东方缝栖蛤的摄食率最大,为0.005 7～0.008 0 g干重/(h.只)(壳长为7～20 mm),其次是贻贝为0.003 5～0.004 9 g干重/(h.只)(壳长为10～21 mm),对栉孔扇贝的摄食率最小,为0.001 4～0.002 8 g干重/(h.只)(壳长为14～31 mm)。同时,多棘海盘车的摄食率还表现出一定的昼夜差异,夜间的摄食率大于白天,但差异并不显著(P>0.05)。当4种贝类同时作为饵料存在时,多棘海盘车对东方缝栖蛤的摄食率最大,为0.003 0 g干重/(h.只),其次是贻贝为0.001 7 g干重/(h.只),以摄食率评价摄食选择,多棘海盘车对于该4种贝类具有明显的选择性(P<0.05),其摄食选择性的顺序为:东方缝栖蛤,贻贝,菲律宾蛤仔,栉孔扇贝。     

5月份山东省水产养殖病害测报情况通报

5月份，全省各市对25个养殖品种（鱼类10种，甲壳类6种，贝类6种，藻类1种，棘皮动物1种，两栖类1种）的病害发生情况进行了监测报告。鲂、牙鲆、中国对虾、南美白对虾、日本对虾、罗氏沼虾、梭子蟹、海湾扇贝、虾夷扇贝、栉孔扇贝、牡蛎、缢蛏、菲律宾蛤仔、海带、中华鳖15个养殖品种没有病害发生。草鱼、鲤、鲫、乌鳢、鲢鳙、虹鳟、鲟、大菱鲆、河蟹、刺参10个养殖品种发生了14种病害，其中细菌性疾病7种，真菌性疾病1种，寄生虫疾病2种，藻类危害1种，其它病害3种。测报数据显示：随着气温和水温的不断提高，水产养殖动植物病害也逐渐呈现出上升趋势。     

虾夷扇贝稚贝海上保苗与商品苗运输

虾夷扇贝是一种大型冷水性贝类，营养价值高，养成效益好，自1980年引进我国后已在辽宁、山东开展大规模的育苗及养成。由于近年来海湾扇贝、栉孔扇贝、牡蛎等浅海贝类养殖效益极不稳定，虾夷扇贝的育苗与养成越来越引起重视。现将近几年从事虾夷扇贝稚贝海上保苗和商品苗运输的经验报告如下：     

Association between the interannual variation in the oceanic environment and catch rates of bigeye tuna (Thunnus obesus) in the Atlantic Ocean

The environmental processes associated with variability in the catch rates of bigeye tuna in the Atlantic Ocean are largely unexplored. This study used generalized additive models (GAMs) fitted to Taiwanese longline fishery data from 1990 to 2009 and investigated the association between environmental variables and catch rates to identify the processes influencing bigeye tuna distribution in the Atlantic Ocean. The present findings reveal that the year (temporal factor), latitude and longitude (spatial factors), and major regular longline target species of albacore catches are significant for the standardization of bigeye tuna catch rates in the Atlantic Ocean. The standardized catch rates and distribution of bigeye tuna were found to be related to environmental and climatic variation. The model selection processes showed that the selected GAMs explained 70% of the cumulative deviance in the entire Atlantic Ocean. Regarding environmental factors, the depth of the 20 degree isotherm (D20) substantially contributed to the explained deviance; other important factors were sea surface temperature (SST) and sea surface height deviation (SSHD). The potential fishing grounds were observed with SSTs of 22–28°C, a D20 shallower than 150 m and negative SSHDs in the Atlantic Ocean. The higher predicted catch rates were increased in the positive northern tropical Atlantic and negative North Atlantic Oscillation events with a higher SST and shallow D20, suggesting that climatic oscillations affect the population abundance and distribution of bigeye tuna.     

Growth performance,digestive enzyme activity and immune response of Japanese sea bass,Lateolabrax japonicus fed with fructooligosaccharide

In this experiment, a feeding trial was performed to determine the effects of fructooligosaccharide (FOS) on growth performance, digestive enzyme activity and immune response of Japanese sea bass, Lateolabrax japonicus juveniles (initial weight 38.3 ± 0.5 g), and the fish were examined following feeding with six levels of FOS (0, 0.5, 1, 2, 4 and 6 g/kg) for 28 days. Significant enhancement of weight gain (WG) and specific growth rate (SGR) was found in fish fed 1 g/kg FOS incorporated diets (p < .05), while the feed conversion ratio (FCR) in the 1, 2 g/kg FOS groups reduced significantly compared with the control (p < .05). Besides, the crude lipid in the 4, 6 g/kg FOS groups increased significantly compared with the control (p < .05). On the other hand, the erepsin and lipase activities significantly elevated in intestine of fish fed 2 g/kg FOS (p < .05) and the lysozyme activity in serum of fish fed 2 g/kg FOS were significantly higher than that in the control (p < .05). Moreover, the alkaline phosphatase activities in serum of fish fed 0.5, 1, 2 g/kg FOS were significantly higher than in control (p < .05). Regression analysis showed that the relationships between dietary FOS levels and either SGR, FCR, erepsin or lysozyme activities were best expressed by regression equations, and the optimal inclusion levels are 1.37, 1.80, 3.06, 3.11, 1.93 and 1.80 g/kg for SGR, FCR, erepsin, lipase, lysozyme and total superoxide dismutase activities, respectively. Overall, this study revealed that FOS incorporated diets could beneficial for L. japonicus culture in terms of increasing the growth, digestion and immune activities. Under the present experimental condition, the optimal supplementary level of FOS in the diet of L. japonicus is 1–3 g/kg.     

Involvement of gonadal steroids in final oocyte maturation of white perch (Morone americana) and white bass (M. chrysops): in vivo and in vitro studies

Plasma estradiol-17 (E₂), testosterone (T), 17,20-dihydroxy-4-pregnen-3-one (DHP) and 17,20,21-tri-hydroxy-4-pregnen-3-one (20-S) levels were measured by radioimmunoassay (RIA) in white perch (Morone americana) and white bass (M. chrysops) that were induced to undergo final oocyte maturation (FOM) with human chorionic gonadotropin (hCG). Plasma DHP levels increased in females of both species in association with oocyte germinal vesicle migration (GVM) and germinal vesicle breakdown (GVBD) and decreased thereafter. Plasma 20-S levels also increased with oocyte GVM in white bass, but were several-fold lower than DHP levels. Circulating E₂ and T levels were greatest during GVM and GVBD in both species and decreased to low levels during oocyte hydration and ovulation. Follicles from white perch and white bass which received a priming injection of hCG in vivo, produced both DHP and 20-S in vitro after exposure to hCG and their oocytes underwent GVBD. Ovarian incubates from unprimed fish of either species produced only E₂ and T and their oocytes did not complete GVBD. Oocytes from unprimed bass, but not perch, matured when follicles were exposed to hCG in vitro. Both trilostane and cycloheximide blocked in vitro production of DHP and 20-S and oocyte GVBD by white perch follices. DHP and 20-S were equipotent inducers of FOM in the GVBD bioassay. None of several other structurally-related steroids tested were effective within a physiological range of concentrations. These results indicate a role for DHP and 20-S in the control of FOM in white perch and white bass.     

Cardiac,ventilatory and metabolic responses of two ecologically dissimilar species of fish to waterborne cyanide

Changes in heart rate, ventilatory activity and oxygen consumption were determined in trout (Salmo gairdneri) and brown bullhead catfish (Ictalurus nebulosus) during exposure to a steadily increasing concentration of waterborne cyanide selected to produce death in 8–9 hours for each species. The lethal cyanide concentration for the bullheads was an order of magnitude higher than for trout. Trout developed an immediate and gradually increasing bradycardia throughout the exposure period. Cyanide produced tachycardia in the bullhead followed by a gradual onset of bradycardia as the concentration of cyanide was raised. Pericardial injection of atropine (a muscarinic cholinergic antagonist) indicated that bradycardia in the trout was due initially to increased vagal tone but later due to the direct effect of cyanide on the heart. Hyperventilation in the trout persisted throughout the exposure period, although the rate and amplitude fluctuated and was variable between individual fish. During the last hour of exposure (highest cyanide concentration), ventilation was characterized by rapid, shallow breaths followed by a sudden respiratory arrest. The bullheads exhibited hyperventilation during the first 3 hours of exposure followed by a gradual, linear drop in ventilation rate and amplitude until death occurred. Cardiac and ventilatory responses in both species were attributed to stimulation of central and peripheral chemoreceptors by cyanide. Evidence is presented which suggests the initial response in the bullheads was due, at least in part, to gustatory stimulation by the cyanide. Oxygen consumption of the trout remained above pre-exposure levels for the majority of the test period. Oxygen consumption in the bullhead paralleled the changes in heart and ventilatory rates. Whole-body lactate levels of fingerlings of both species during cyanide exposure were measured to estimate the extent of anaerobiosis. Whole-body lactate levels were much greater in the bullheads than the trout, indicating a higher capacity for anaerobiosis, possibly due to a greater fuel supply. Overall, the trout responded to cyanide in a manner similar to that produced by environmental hypoxia whereas the bullheads experienced a gustatory stimulus which masked the hypoxia-like response.     

An overview of stress physiology of fish transport: changes in water quality as a function of transport duration

This study brings an integrated analysis about the relationship between water deterioration and its physiological consequences in live fish transport. The analysis was focused on the transport water and its deterioration, and physiological challenges imposed on the fish. Usual commercial handling procedures employed to mitigate fish stress during transport were discussed. Future topics of research for the establishment of safer fish transport protocols were proposed. Transport was classified into short (≤8 h) or long transport (>8 h). The main issue in short transports should be the prevention of water pH reduction, while in long transports it is the increase in ammonia. Plasma cortisol is the most employed marker for stress and is acutely elevated upon short episodes of transport, but remains elevated even in long‐transport events. Plasma glucose is perhaps a better marker for handling stress. Plasma lactate, pH, osmolality CO₂ and ions should be more often evaluated. Plasma Na⁺ and Cl^‐ are very useful markers of acidosis, due to their respective exchange for H⁺ and , for acid–base regulation. The establishment of species‐specific transport protocols should be preceded by such combined analyses of water and physiological parameters.     

Are hatchery‐reared abalone naïve of predators? Comparing the behaviours of wild and hatchery‐reared northern abalone,Haliotis kamtschatkana (Jonas, 1845)

Abalone populations have declined worldwide, generating interest in enhancement using hatchery‐reared individuals. In many cases, such restoration efforts have met with limited success due to high predator‐induced mortality rates. Furthermore, the mortality rates of outplanted hatchery abalone are often considerably higher than for wild individuals. This study uses northern abalone (Haliotis kamtschatkana) as a case study to determine whether hatchery‐reared abalone behave differently than their wild counterparts. In the field, outplanted hatchery‐reared abalone were significantly less responsive than wild abalone, in terms of number of abalone responding and intensity of response, to nearby movement and to physical contact with an inert probe. Also, when encountering a cue to which all abalone responded (a seastar predator), hatchery‐reared individuals remained subdued. Anti‐predator behavioural deficits in hatchery‐reared abalone were more pronounced in 4‐year‐old individuals than in 1‐year‐old individuals, suggesting an influence of either age or amount of time spent in the hatchery environment. These behavioural differences are expected to increase the vulnerability of hatchery‐reared abalone to predators, and are likely a major cause of their elevated predator‐induced mortality when outplanted.     

Effects of cadmium on the kinetics of calcium uptake in developing tilapia larvae, Oreochromis mossambicus

The toxic effects of Cd²⁺ on Ca²⁺ influx kinetics in developing tilapia (Oreochromis mossambicus) larvae were evaluated. Addition of 20 µg l^-1 of Cd²⁺ to the environment of 0 and 3 day-old larvae competitively inhibited the Ca²⁺ uptake within 4h resulting in a great increase in K_m values for Ca²⁺ influx (19.3 and 17.4 fold, respectively) as compared with their respective controls. Consequently, the actual Ca²⁺ influx of larvae in solutions of 0.2 mM Ca²⁺ are suppressed by 32–45%. Also, 3 day-old larvae were more sensitive to internally accumulated Cd²⁺ than 0 day-old larvae. Although the Ca²⁺ influx in 0 and 3 day-old larvae may be restored to the levels of their respective controls with 24h of being transferred to a 20 µg l^-1 Cd²⁺ solution, total body Ca²⁺ content was significantly reduced in 3 day-old larvae. Increased Ca²⁺ uptake efficiency ensures sufficient Ca²⁺ for normal growth. However, rapid increase in Ca²⁺ influx after hatching also leads to higher Cd²⁺ uptake. Exposure to Cd²⁺ will lead to a drop in body Ca²⁺ content resulting in retardation of larval growth. Therefore, we conclude that if Ca²⁺ uptake is interfered with at this critical stage of development, larvae will not be able to maintain normal levels of body Ca²⁺ and will show signs of Cd²⁺ poisoning.     

Migratory dynamics of stream-spawning longnose gar (Lepisosteus osseus)

Abstract– Literature evidence suggests that lake-dwelling longnose gar (Lepisosteus osseus) enter tributary streams to spawn, Until the present study, the dynamics of this breeding migration had never been investigated quantitatively. During the summers of 1991 and 1992, longnose gar were captured as they entered Weaubleau Creek, Missouri, a tributary of Harry S. Truman Reservoir. The in-stream spawning migration began in early April and ended in late May, and was positively correlated with stream flow and water level, and negatively correlated with water temperature. In-stream residence times ranged from 15 to 94 days, with males exhibiting longer residence times than females. Once in-stream, longnose gar travelled as far as 10 km upstream and occupied certain pools at greater relative frequencies. Although the reason for this preferential utilization is not completely understood, it may relate to pool depth and riffle proximity. Longnose gar disperse from the spawning stream great distances, with gar captured in Weaubleau Creek being recaptured up to 48 km away. This information should provide fisheries biologists the means to consider the reproductive ecology of this species in their conservation and management decisions.     

Nutritional regulation of hepatocyte fatty acid desaturation and polyunsaturated fatty acid composition in zebrafish (Danio rerio) and tilapia (Oreochromis niloticus)

The desaturation and elongation of [1-¹⁴C]18:3n-3 was investigated in hepatocytes of the tropical warm freshwater species, zebrafish (Danio rerio) and Nile tilapia (Oreochromis niloticus). The hepatocyte fatty acid desaturation/elongation pathway was assayed before and after the fish were fed two experimental diets, a control diet containing fish oil (FO) and a diet containing vegetable oil (VO; a blend of olive, linseed and high oleic acid sunflower oils) for 10 weeks. The VO diet was formulated to provide 1% each of 18:2n-6 and 18:3n-3, and so satisfy the possible EFA requirements of zebrafish and tilapia. At the end of the dietary trial, the lipid and fatty acid composition was determined in whole zebrafish, and liver, white muscle and brain of tilapia. Both zebrafish and tilapia expressed a hepatocyte fatty acid desaturation/elongation pattern consistent with them being freshwater and planktonivorous fish. The data also showed that hepatic fatty acid desaturation/elongation was nutritionally regulated with the activities being higher in fish fed the VO diet compared to fish fed the FO diet. In zebrafish, the main effect of the VO diet was increased fatty acid Δ6 desaturase activity resulting in the production of significantly more 18:4n-3 compared to fish fed the FO diet. In tilapia, all activities in the pathway were greater in fish fed the VO diet resulting in increased amounts of all fatty acids in the pathway, but primarily eicosapentaenoic acid (EPA; 20:5n-3) and docosahexaenoic acid (DHA; 22:6n-3). However, the fatty acid compositional data indicated that despite increased activity, desaturation of 18:3n-3 was insufficient to maintain tissue proportions of EPA and DHA in fish fed the VO diet at the same level as in fish fed the FO diet. Practically, these results indicate that manipulation of tilapia diets in commercial culture in response to the declining global fish oil market would have important consequences for fish fatty acid composition and the health of consumers. Scientifically, zebrafish and tilapia, both the subject of active genome mapping projects, could be useful models for studies of lipid and fatty acid metabolism at a molecular biological and genetic level. This revised version was published online in August 2006 with corrections to the Cover Date.     

Protein and amino acid composition from the mantle of juvenile O ctopus vulgaris exposed to prolonged starvation

Protein and amino acid composition of the mantle of juvenile O ctopus vulgaris (Cuvier, 1797) during fasting for 27 days were determined. Average protein content of octopus mantle was of 711.19 ± 46.80 g kg^?1 DW, and it decreased with increasing fasting days. The non‐essential amino acids content was higher (486.18 ± 11.08 g kg^?1 protein) than essential amino acids (425.82 ± 9.15 g kg^?1 protein) at the start of the experiment (unstarved animals). The results suggest that the amino acid profile of the mantle where the most abundant amino acids are Arg, His, Lys, Gly, Leu and Pro could indicate a prolonged fasting condition (>20 days) or poor nutrition of O . vulgaris. This study supports the idea of using mantle for metabolic needs of starved O . vulgaris suggesting that the degradation pathway of amino acids to pyruvate and tricarboxylic acid cycle intermediates was favoured contrary to the degradation pathway of ketogenic amino acids. Special considerations should be taken concerning Thr, Ile, Ser, Ala, Asx (Asp, Asn), Glx (Glu, Gln) (because of their fast intake) and Lys and His (due to their stable contents) during a prolonged period of fasting.