镉对海湾扇贝的急性毒性研究

利用水生生物毒性试验方法,分5个浓度进行镉对日照海域海湾扇贝的急性毒性实验,以期对日照海域海湾扇贝养殖提供理论依据。利用概率单位和浓度对数作线性回归,得出镉对海湾扇贝(Argopectenirradiams)在24、48、96h的半致死量LC50,其值分别为5.85、4.52和3.45mg/L。并计算出镉对海湾扇贝的安全质量浓度为0.0345mg/L。实验证明,Cd对海湾扇贝是剧毒性的毒物,海湾扇贝发育越往后期,它对Cd的耐受性就越大。     

聚维酮碘对海湾扇贝等贝类幼虫的毒性试验研究

测定了聚维酮碘(PVP—I)对虾夷扇贝、海湾扇贝、牡蛎的壳预期幼虫以及牡蛎的眼点期幼虫的24h半致死浓度分别为：32．5mg／L，31．7mg／L，44．4mg／L；安全浓度分别为：3．25mg／L，3．17mg／L，4．48mg／L，4．44mg／L。     

消油剂对海湾扇贝(Argopecten irradians)的急性毒性效应

本研究以海湾扇贝(Argopecten irradians)为研究对象, 通过96 h半静水毒性实验,探讨了消油剂、0号柴油分散液(WAF)与0号柴油乳化液(CEWAF)对海湾扇贝24 h、48 h、72 h、96 h急性毒性效应。结果显示,消油剂对海湾扇贝的24 h、48 h、72 h和96 h半致死浓度(95%可信限)分别为1905(1570-2451 mg/L)、1293(1070-1556 mg/L)、1015(721-1348 mg/L)、846 mg/L(660-1020 mg/L);WAF对海湾扇贝的24 h、48 h、72 h和96 h半致死浓度(95%可信限)分别为36.57(29.42-48.96 mg/L)、23.10(21.07-25.39 mg/L)、14.99(13.66-16.41 mg/L)、11.31 mg/L(8.37-14.47 mg/L);CEWAF对海湾扇贝的24 h、48 h、72 h和96 h半致死浓度(95%可信限)分别为12.71(10.78-15.55 mg/L)、8.51 (7.99-9.07 mg/L)、6.56(4.46-7.74 mg/L)、5.42 mg/L(4.51-6.29 mg/L)。消油剂、0号柴油分散液、0号柴油乳化液对海湾扇贝96 h安全浓度分别为84.6、1.13、0.54 mg/L。随着实验时间的延长,消油剂、WAF和CEWAF对海湾扇贝的半致死浓度(LC50)均呈逐渐降低之势,半致死浓度与时间呈幂函数关系,其关系式分别为y=12242x–0.583、y=564.37x–0.848、y=89.987x–0.613。在受试溶液中暴露相同时间,海湾扇贝的半致死浓度从高到低依次为消油剂、WAF和CEWAF,说明CEWAF对海湾扇贝的毒性大于消油剂和WAF,这对于在养殖海区使用消油剂处理溢油事故具有重要的指导意义。     

消油剂对海湾扇贝(Argopecten irradians)的急性毒性效应

本研究以海湾扇贝(Argopecten irradians)为研究对象,通过96 h半静水毒性实验,探讨了消油剂、0号柴油分散液(WAF)与0号柴油乳化液(CEWAF)对海湾扇贝24 h、48 h、72 h、96 h急性毒性效应。结果显示,消油剂对海湾扇贝的24 h、48 h、72 h和96 h半致死浓度(95%可信限)分别为1905(1570-2451 mg/L)、1293(1070-1556 mg/L)、1015(721-1348 mg/L)、846 mg/L(660-1020 mg/L);WAF对海湾扇贝的24 h、48 h、72 h和96 h半致死浓度(95%可信限)分别为36.57(29.42-48.96 mg/L)、23.10(21.07-25.39 mg/L)、14.99(13.66-16.41 mg/L)、11.31 mg/L(8.37-14.47 mg/L);CEWAF对海湾扇贝的24 h、48 h、72 h和96 h半致死浓度(95%可信限)分别为12.71(10.78-15.55 mg/L)、8.51(7.99-9.07 mg/L)、6.56(4.46-7.74 mg/L)、5.42 mg/L(4.51-6.29 mg/L)。消油剂、0号柴油分散液、0号柴油乳化液对海湾扇贝96 h安全浓度分别为84.6、1.13、0.54 mg/L。随着实验时间的延长,消油剂、WAF和CEWAF对海湾扇贝的半致死浓度(LC_(50))均呈逐渐降低之势,半致死浓度与时间呈幂函数关系,其关系式分别为y=12242x~(–0.583)、y=564.37x~(–0.848)、y=89.987x~(–0.613)。在受试溶液中暴露相同时间,海湾扇贝的半致死浓度从高到低依次为消油剂、WAF和CEWAF,说明CEWAF对海湾扇贝的毒性大于消油剂和WAF,这对于在养殖海区使用消油剂处理溢油事故具有重要的指导意义。     

锌对海湾扇贝中镉累积和亚细胞分布的影响

采用室内模拟混合暴露方式,研究了在镉(Cd)质量浓度一定(0.05 mg/L)的条件下,添加不同质量浓度(0 mg/L、0.1 mg/L、0.5 mg/L、1 mg/L)的锌(Zn)对海湾扇贝整体、组织及亚细胞水平Cd累积和分布的影响。结果表明,Zn能显著抑制扇贝全贝对Cd的富集,并且这种抑制作用随暴露时间的延长和Zn浓度的升高而增强。在扇贝不同组织中Zn对Cd的富集均具有抑制作用,其中以鳃最为明显。在亚细胞水平,扇贝各组织累积的Cd主要分布在类金属硫蛋白(MTLP)和细胞碎片(CD)组分。在内脏各亚细胞组分中,Zn对Cd的抑制作用显著,且Zn的加入使CD中的Cd百分比从32%下降到21%~27%,而MTLP中的Cd百分比从57%增加到59%~67%。鳃组织中Zn对Cd百分比的影响更加明显,CD中Cd百分比从36%下降到14%~17%,MTLP中Cd百分比从59%增加到76%~79%;而性腺中MTLP和细胞器(ORG)组分中Cd百分比受Zn浓度影响较为明显,随着Zn浓度的升高,MTLP中Cd百分比下降,而ORG中Cd百分比升高;肌肉组织中Cd含量及百分比分布在亚细胞水平没有明显规律。     

三种扇贝种间血液生理指标比较及热胁迫对栉孔扇贝血液生理指标的影响

为了比较3种扇贝血液中的K⁺、Na⁺、Ca²⁺和Cl^-浓度，血氧(pO₂)和血二氧化碳(pCO₂)气体分压及血液酸碱度(pH)的差异情况，实验利用血气分析仪对栉孔扇贝、虾夷扇贝和海湾扇贝的血液生理指标进行测定。结果显示，扇贝的血液生理指标呈现显著的物种差异，其中栉孔扇贝血液的K+浓度[(15.74±1.47) mmol/L]、Na+浓度[(388.07±11.38)mmol/L]、Cl-浓度[(462.43±6.88) mmol/L]和p O2[(140.13±15.35) mmHg]最高。此外，栉孔扇贝和虾夷扇贝的Ca²⁺浓度和pCO₂含量较高，而海湾扇贝的pH最高。对相同月龄不同大小栉孔扇贝血液指标进行比较，发现栉孔扇贝的血液pH值与其壳高呈正相关(r=0.611)，而生理指标与壳高呈负相关。随着温度的升高，栉孔扇贝血液的Ca²⁺浓度显著增加，而pO₂显著下降，K<...     

拟除虫菊酯和有机磷农药对三种扇贝稚贝的急性毒性效应

采用静水实验法测定拟除虫菊酯类和有机磷类农药对三种扇贝稚贝的急性毒性效应.结果表明:联苯菊酯对海湾扇贝、栉孔扇贝和虾夷扇贝稚贝24 h的LC50的分别为1.460、1.662和2.909 mg/L;辛琉磷对海湾扇贝、栉孔扇贝和虾夷扇贝稚贝24 h的LC50的分别44.598、182.167和39.334 μg/L;马拉...     

栉孔扇贝对铜、铅、镉的累积效应

试验结果表明:当常规理化指标一致时,随着Cu、Pb、Cd质量浓度的升高,栉孔扇贝各组织的蓄积量明显升高;Cu、Cd在扇贝组织中蓄积量是内脏团>鳃>肌肉,Pb在扇贝组织中的蓄积量是鳃>内脏团>肌肉;当Cu、Pb、Cd质量浓度(0.1 mg/L)相同时,其鳃、内脏团、肌肉中重金属蓄积量的上升速率是Cu>Cd>Pb。     

Cu~(2+)和Cd~(2+)对克氏原螯虾幼虾的毒性效应研究

采用静水法生物测试,研究了Cu2+和Cd2+对克氏原螯虾幼虾(体重0.0142～0.0308g)的急性毒性作用。试验结果表明,克氏原螯虾对Cu2+、Cd2+均会产生较强的毒性效应,其对Cu2+、Cd2+的耐受性随接触时间延长而明显降低。Cu2+对克氏原螯虾幼虾24h、48h半致死浓度(LC50)分别为30.854mg/L、10.595mg/L;Cd2+对克氏原螯虾幼虾24h、48h、72h半致死浓度(LC50)分别为5.315mg/L、1.371mg/L和0.414mg/L。Cu2+、Cd2+对其的安全浓度(SC)分别为0.375mg/L、0.027mg/L,为相应渔业水质标准的3.8倍和5.5倍,表明克氏原螯虾具有较强耐受Cu2+和Cd2+污染的能力。     

Cu2+和Cd2+对克氏原螯虾幼虾的毒性效应研究

采用静水法生物测试,研究了Cu2+和Cd2+对克氏原螯虾幼虾(体重0 0142～0 0308 g)的急性毒性作用.试验结果表明,克氏原螯虾对Cu2+、Cd2+均会产生较强的毒性效应,其对Cu2+、Cd2+的耐受性随接触时间延长而明显降低.Cu2+对克氏原螯虾幼虾24 h、48 h半致死浓度(LC50)分别为30.854 mg/L、10.595 mg/L;Cd2+对克氏原螯虾幼虾24 h、48 h、72 h半致死浓度(LC50)分别为5.315 mg/L、1.371 mg/L和0.414 mg/L.Cu2+、Cd2+对其的安全浓度(SC)分别为0.375 mg/L、0.027 mg/L,为相应渔业水质标准的3.8倍和 5.5倍,表明克氏原螯虾具有较强耐受Cu2+和Cd2+污染的能力.     

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.