A drop in ambient temperature results in a transient reduction of interrenal ACTH responsiveness in the gilthead sea bream (Sparus aurata, L.)

This study investigated the effects of a drop in water temperature (18 °C to 9 °C in 24 h) on the pituitary and interrenal hormones of the gilthead sea bream Sparus aurata. The in vitro sensitivity of the interrenal tissue to ACTH, plasma levels of cortisol, ACTH, -MSH, GH, glucose, lactate and ions were determined. In vitro ACTH, stimulated the release of cortisol from isolated interrenal glands from control gilthead sea bream in a concentration dependent fashion. However, the interrenal cells were less sensitive to ACTH as soon as 24 h following the onset of the temperature drop. At this time, plasma cortisol and ACTH levels were raised, and plasma GH concentrations were decreased, whereas no significant changes were found in plasma -MSH. After 96 h plasma ACTH levels had recovered whereas plasma cortisol levels were still higher than controls after 8 days of the beginning of the experiment. Interrenal sensitivity had recovered after 8 days. The results may help to clarify the relationship between the stress response and the aetiology of the winter syndrome in sea bream.     

花鲈ncc、nkcc基因在海、淡水适应中鳃组织的表达与定位分析

为探究ncc、nkcc基因在花鲈渗透调节中发挥的作用,实验通过全基因组鉴定、多重序列比对、系统进化树构建以及蛋白结构预测对花鲈ncc进行了鉴定及序列分析,利用实时荧光定量PCR (qRT-PCR)检测ncc和nkcc在海水、淡水花鲈鳃组织中的表达水平,利用原位杂交技术确定ncc2和nkcc1a在海水及淡水花鲈鳃中的表达位置。结果显示,从花鲈中鉴定出2个ncc基因,即ncc1和ncc2,其编码序列(CDS)长度分别为2 691和3 120bp,编码896和1 039个氨基酸,在进化上具有保守性。ncc2在淡水花鲈鳃组织中的表达量显著高于海水,而nkcc1a在海水花鲈鳃组织中的表达量显著高于淡水,ncc1、nkcc1b、nkcc2在海淡水中的表达量则无显著差异。淡水适应过程中花鲈鳃组织中的ncc2的表达量逐渐上调,而nkcc1a的表达量逐渐下调;海水适应过程则呈现相反的表达趋势。此外,原位杂交结果显示,ncc2和nkcc1a基因分别位于淡水与海水中鳃组织的相邻鳃小片间的鳃丝上皮。以上结果表明,ncc2和nkcc1a基因分别编码淡水及海水花鲈鳃中重要的Na⁺及Cl     

Live microbial feed supplement in aquaculture for improvement of stress tolerance

Two bacterial strains, Lactobacillus fructivorans, isolated from sea bream (Sparus aurata) gut, and Lactobacillus plantarum, isolated from human faeces, were administered simultaneously, during sea bream development, using Brachionus plicatilis and/or Artemia salina as vectors. The probiotic treatment significantly affected gut colonization. To test the probiotic influence on stress responsiveness, sea bream fry, 47 days post-hatching (p.h.), were subjected to pH stress (from 8.6 to 6.3) and cumulative mortality, cortisol levels and HSP70 gene expression were analysed. Cortisol was selected, since under stress conditions its level increases. HSP70 was selected with consideration of its wide involvement in response to a great number of injuries, and because it protects cells probably by binding and refolding damaged proteins. The results obtained indicated that the administration of probiotic to sea bream fry induced higher HSP70 levels, indicating a greater potentiality to respond to the harmful conditions possibly present in fish farms. This hypothesis is supported by the fact that the levels of cortisol found were significantly lower (P < 0.05) in both groups under probiotic treatment. When pH was used as a stressor, it induced a higher cumulative mortality in the control; the mortality was found to be significantly lower in both treated groups. Interestingly, a significant increase (P < 0.05) in HSP70 gene expression was observed in all stressed groups. These results suggest an improvement in tolerance to acute stress of fry fed with probiotics.     

Growth performance and physiological responses in striped knifejaw, Oplegnathus fasciatus, held under different photoperiods

The growth performance and stress response in striped knifejaw, Oplegnathus fasciatus (body weight 100–300 g) reared under four photoperiods (6L:6D, 12L:12D, 16L:8D and 24L:0D) were investigated. Fish were fed a commercial diet to apparent satiation, two times a day for 8 weeks. A trial of acute handling and confinement stress was also carried out to investigate the stress-induced levels of different stress indicators in O. fasciatus. Blood was also collected from undisturbed fish which was considered as control. Although there were no significant differences in weight gain, specific growth rate (SGR) and feed conversion efficiency (FCE) in fish exposed to 6L:6D, 16L:8D and 24L:0D photoperiods, all parameters in these photoperiods were significantly higher than those of 12L:12D photoperiod (P < 0.05). There was no significant difference in protein retention efficiency (PRE) between fish exposed to 16L:8D and 24L:0D photoperiods, but PRE in both photoperiods was significantly higher than that of 12L:12D photoperiod.Acute stress significantly increased the plasma levels of cortisol (110.3 ng ml^− 1) and glucose (195.4 mg dl^− 1), and decreased plasma levels of total protein (0.8 g dl^− 1); however, all parameters were returned back to the levels indistinguishable from those of control, undisturbed fish within 24 h. The levels of cortisol, glucose and total protein in fish exposed to different photoperiods during the study were far from the stress-induced levels (P < 0.05). The results demonstrated that the growth performance of O. fasciatus reared from 100 to 300 g can be stimulated significantly by using the manipulated photoperiods where feeding time may be playing an important role to increase food intake and feed conversion efficiency. It also revealed that the artificial photoperiods did not cause significant stress response in fish.     

Effects of cortisol on hepatic carbohydrate metabolism and responsiveness to hormones in the sea raven,Hemitripterus americanus

The sea raven, Hemitripterus americanus, is a sit-and-wait, low metabolic rate, marine teleost. The objective of this study was to determine i) whether cortisol implantation (50 mg. kg^-1) for 7 days altered hepatocyte metabolism, and hepatocyte responsiveness to epinephrine, glucagon and insulin, and ii) whether 8 weeks of food-deprivation modified the above response. Cortisol implantation significantly increased hepatocyte total glucose production and oxidation from alanine compared to the sham group. There was no cortisol effect on glycogen breakdown, suggesting that the activation of other pathways, including gluconeogenesis, are required to account for the increased glucose production. Epinephrine-mediated (10^-5M) glycogen breakdown and insulin-mediated (10^-8M) total glucose production were enhanced in hepatocytes of cortisol implanted sea ravens, but there were no change in any glucagon (10^-7M) effects. The enhanced glycogen breakdown in the absence of similar increases in total glucose production with epinephrine indicates mobilization of carbohydrate reserves for endogenous use by the liver. Food-deprivation for 8 weeks significantly decreased condition factor, plasma cortisol concentration and liver glycogen content in the sea raven, but had no effect on plasma glucose concentration. Hepatocyte total glucose production and flux rates from alanine increased significantly with food-deprivation. Moreover, food-deprivation increased responsiveness of total hepatocyte glucose production to the actions of glucagon and insulin, but not to epinephrine; none of these effects were modified by cortisol implantation. Our results indicate that cortisol in the sea raven exerts both a direct and an indirect or permissive effect on hepatocyte metabolism by modifying hepatocyte responsiveness to epinephrine and insulin stimulation. Cortisol implantation did not modify the effects of glucagon or food-deprivation in this species.     

Survival and serum biochemical responses of spotted sea bass Lateolabrax maculatus during simulated waterless live transportation

Waterless live fish transportation is an alternative and promising transport strategy, which may reduce shipping costs, increase stocking density and improve survival of some species. Spotted sea bass is one of the most economically important marine fish in China. However, waterless transportation has not yet been studied on spotted sea bass. To explore the possibility of waterless transportation of spotted sea bass and its sublethal stress responses, the survival rate and dynamics of blood biochemical parameters were evaluated in the present study by preserving it under no water, less water and water (control) conditions for 9 hr. The serum biochemical parameters including total protein, cortisol, glucose, lactate, alanine aminotransferase (ALT), aspartate aminotransferase (AST), total carbon dioxide (TCO₂), creatinine, blood urea nitrogen (BUN), ammonia, superoxide dismutase (SOD) activity and malonaldehyde (MDA) were investigated. Results showed that the survival rates of fish in all groups gradually declined with time increasing. At the end of transportation, the survival rates in the control group, less‐water group and no‐water group decreased to 49.11%, 15.60% and 23.96% respectively. Significant changes were observed in several selected serum biochemical parameters, including glucose, lactate, ALT, TCO₂, BUN and ammonia during simulated waterless transportation, which might negatively affect the physiological homeostasis of fish, leading to the high mortality in present study. In general, waterless transportation of spotted sea bass was possible, but it might be rather suitable for short time than long time.     

池塘底泥生物组成的季节性变化对刺参食物来源的影响

为分析刺参养殖池塘底泥生物组成的季节变化及其对刺参食物来源的影响,本研究于2012年5—12月以16:1(n-7)/16:0及EPA作为硅藻的特征脂肪酸标志,20:4(n-6)作为褐藻的特征脂肪酸标志,DHA及DHA/EPA作为鞭毛藻或原生动物的特征脂肪酸标志,18:1(n-7)及奇数碳和支链脂肪酸(oddbr FAs)作为细菌的特征脂肪酸标志调查了荣成靖海湾刺参养殖池塘底泥和刺参脂肪酸组成的季节性变化特征。结果显示,硅藻、褐藻、多种异养细菌及鞭毛藻或原生动物为底泥的主要组成生物,且各类生物组成的季节变化显著,其中硅藻的特征脂肪酸16:1(n-7)/16:0及EPA最高值出现在冬季,褐藻的特征脂肪酸20:4(n-6)含量为秋季最高,细菌的特征脂肪酸18:1(n-7)及(oddbr FAs)最高值出现在夏季,鞭毛藻或原生动物的特征脂肪酸DHA含量为冬季最高。相关性分析显示,刺参食物中的硅藻、鞭毛藻或原生动物和细菌主要来源于底泥。研究表明,刺参养殖池塘底泥中主要生物组成季节性变化显著,进而引起刺参食物来源的季节性变化。     

Serum haemolytic and agglutinating activity as indicators of fish immunocompetence: their suitability in stress and dietary studies

Gilthead sea bream, Sparus aurata, were subjected to different stressful situations and the haemolytic activity mediated by the alternative complement and the agglutinating serum activity were tested as indicators of immunocompetence. The results show that both parameters were significantly compromised after chronic or repeated acute stress as well as in groups fed with vitamin E or 3 highly unsaturated fatty acids (HUFA) deficient diets and in infected fish. These results suggest that both haemolytic and agglutinating activity are suitable indicators for immunocompetence as they are non-specific responses induced by non-specific stressors. In addition, a comparison is performed with other immune indicators subjected to the same stressors.     

Enhanced production of the sea urchin Paracentrotus lividus in integrated open-water cultivation with Atlantic salmon Salmo salar

Survivorship and performance was investigated for two size classes of the sea urchin Paracentrotus lividus grown adjacent to open-water Atlantic salmon (Salmo salar) cultivation on the north-west coast of Scotland. Juvenile P. lividus were maintained for 12 months at 0 m, 50 m and 2.5 km from the mariculture activity. The sea urchins at the 0 m station showed higher survivorship than at the 50 m and 2.5 km stations and had significantly greater test diameter than at the 50 m station. Only urchins at 0 m developed gonads and, although small, these were of acceptable or excellent colouration in terms of their marketability. Adult P. lividus were maintained for 3 months at 0 m and 15 m from the mariculture activity, either with or without additional macroalgae Laminaria spp. Sea urchins at the 0 m station and fed additional macroalgae showed higher gonadal growth than sea urchins at the 15 m station held without additional food. Gonad colouration in the adult urchins, irrespective of the treatment, was acceptable or excellent. The 0 m station also received significantly greater quantities of particulate organic matter (POM) than the other stations in both the juvenile and adult experiments. At the 0 m station, the presence of the fatty acid 22:1n-11 and elevated levels of the long chain n-3 fatty acid DHA 22:6n-3 in the gonadal tissue of the urchins confirmed the consumption of fish farm derived POM and highlighted the potential human health benefits from consuming sea urchin roe.The results show that P. lividus can thrive in the salmon culture environment and suggests that the integration of P. lividus with Atlantic salmon can provide a viable means to culture this species, even at this northerly latitude. Salmon-sea urchin co-culture would enable fish farms to diversify into producing a second highly valuable product and would reduce the increasing worldwide pressure of sea urchin fisheries on wild stocks.     

鲢鳙混养对三角帆蚌生长和养殖水质影响的围隔实验

2008年4月23日—9月21日通过围隔实验,研究了不同鲢鳙混养比例对三角帆蚌生长及水化学指标的影响。实验中鲢鳙混养比例设置了6个水平,分别为0/0(对照组),100/0,70/30,50/50,30/70和0/100。实验开始和结束时测量三角帆蚌湿重,壳长和壳宽。每个月上下旬测量围隔水化学指标包括NO3N、NO2N、NH3N、TN、TP、PO4P和COD。实验结果表明,鲢鳙混养比例100/0的围隔蚌壳长相对生长率显著低于混养比例0/0,50/50和0/100的围隔(P<0.05),而不同混养比例下蚌的成活率、蚌壳宽及蚌重增长均无显著差异(P>0.05)。从水质来看,混养比例30/70围隔TP显著低于100/0(P<0.05),COD显著低于100/0及70/30(P<0.05),NH3N显著低于100/0(P<0.05)以及PO4P显著低于70/30(P<0.05)。因此,综合蚌生长及水质指标,混养比例30/70围隔对三角帆蚌养殖最有利。     

Cortisol and hematological response in Brazilian codling, Urophycis brasiliensis (Pisces, Phycidae) subjected to anesthetic treatment

The effects of benzocaine anesthesia on hematological parameters (erythrocyte and platelet number, hemoglobin concentration and hematocrit), plasma electrolytes (Na⁺, K⁺ and Cl⁻), cortisol, glucose and cholesterol levels in Brazilian codling (Urophycis brasilensis) exposed to a benzocaine bath solution were investigated. Cortisol and glucose levels 1 h after capture from the wild and on days 7 and 14 during the acclimatization period (20 days) were also determined. During the second week, cortisol levels reached to basal values (9 ng ml⁻¹). The use of benzocaine causes a significant increase in the erythrocyte number, in the concentration of hemoglobin and sodium and a decrease in chloride. Plasma cortisol and cholesterol levels were higher in fish exposed to the anesthetic, and glucose levels decreased significantly comparing with the control group, showing strong fluctuations between individuals in all the cases. These results show that the use of benzocaine causes an acute stress response that could be reverted quickly and it has to be considered during the evaluation of stress in fish.     

基于SSR-seq技术评估中间球海胆多代选育群体和普通养殖群体的遗传多样性

为明确不同选育群体中间球海胆的遗传多样性和遗传结构,利用SSR-seq技术和15个微卫星位点,对1个家系选育群体(FP)、1个群体选育群体(IP)和1个未经选育的普通养殖群体(CP)的遗传多样性及遗传结构进行了分析。结果显示,15个微卫星位点共检测出112个等位基因,FP、IP、CP 3个群体的平均观测等位基因数(N_a)分别为5.077、5.133和6.133个,平均有效等位基因(N_e)分别为2.816、2.873和3.638个,平均观测杂合度(H_o)分别为0.522、0.441和0.501,平均期望杂合度(H_e)分别为0.595、0.599和0.667,平均多态性信息含量(PIC)分别为0.546、0.543和0.623。家系选育群体(FP) H_e与H_o的差值(0.073)低于IP (0.158)和CP (0.166),平均固定指数(F)(0.115)低于IP (0.248)和CP (0.246)。3个群体间遗传分化系数(F_st)介...     

Physiological stress responses in spotted wolffish (Anarhichas minor) subjected to acute disturbance and progressive hypoxia

The spotted wolffish (Anarhichas minor) is considered a promising species for coldwater aquaculture. It is a sedentary, bottom-dwelling fish which exhibits a calm and “non-stressed” behaviour in captivity. There are, however, no reports on the physiological responses to stressors in this species. In the present study we investigated primary (cortisol secretion) and secondary (glucose mobilization) responses to common aquaculture stressors like disturbance and hypoxia. Pre-stress plasma cortisol levels were within those generally considered representative for unstressed fish (~ 10 ng ml^− 1), whereas basal glucose levels were unusually low (0.3–0.4 mM). After exposure to a short, but severe disturbance challenge (emptying the tank of water for 10 min), the increase in plasma cortisol level was slow and relatively weak, reaching a peak level of 25 ng ml^− 1 4 to 8 h after disturbance. When the fish were exposed to a gradually decreasing oxygen level in the tank, a significantly elevated plasma cortisol level (35 ng ml^− 1) was seen in the fish that remained in the tank until oxygen saturation had decreased to 20% oxygen saturation after 2.5 h. However, a two-fold higher plasma cortisol level (~ 70 ng ml^− 1) was seen in all fish exposed to reduced oxygen levels (60, 40 and 20% oxygen saturation) after 3.5 h recovery in normoxic water. Plasma glucose levels showed only moderate increases (~ 70%) following disturbance and hypoxia challenges. An in vivo injection of ACTH caused a strong elevation of plasma cortisol (peak level ~ 170 ng ml^− 1), demonstrating a high capacity for interrenal steroidogenesis in the spotted wolffish. The slow and relatively weak cortisol response to stressors, and low plasma glucose levels, may relate to the sedentary lifestyle of the spotted wolffish. The stress-response is characterised by a passive (reactive) coping style, which is considered adaptive for farming of this species.     

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.     

Antioxidative role of selenium against the toxic effect of heavy metals (Cd<Superscript>+2</Superscript>, Cr<Superscript>+3</Superscript>) on liver of rainbow trout (<Emphasis Type="Italic">Oncorhynchus mykiss</Emphasis> Walbaum 1792)

The main purpose of this study is to discuss the effect of Cd⁺², Cr⁺³ and Se metals on biochemical parameters in liver tissue of Oncorhynchus mykiss. The rainbow trout were exposed to heavy metal stress (Cd⁺², Cr⁺³) at 2 ppm dosage. The present study was undertaken to determine the protective effect of selenium treatment at the same dosage (2 ppm) on some biochemical parameters. The activity of catalase (CAT), glutathione peroxidase (GSH-Px), superoxide dismutase (SOD) and the changes in levels of malondialdehyde (MDA) from biochemical parameters were determined in liver tissue of the fish groups exposed to heavy metals, especially for the selenium-applied groups. Results of this study showed that the activities of CAT, GSH-Px and SOD in the tissues of fish exposed to the stress of Cd⁺² and Cr⁺³ were significantly lower than the control groups (P < 0.05). Meanwhile, the closer values to the control groups were obtained in selenium-added groups (Cr⁺³ + Se⁺⁴, Cd⁺² + Se⁺⁴). For the level of MDA, the last production of lipid peroxidation showed increases (P < 0.05) in the groups exposed to the metal stress, whereas significant decreases were obtained in selenium-applied groups. The result of the statistical evaluation showed that the negative effects occurring in the biochemical parameters of the applied groups exposed to the toxicity of heavy metal were significantly eliminated (P < 0.05) as a result of selenium treatment.     

Seasonal changes in pelagic fish biomass around the Chiswell Island Steller sea lion rookery in 2003

Fisheries acoustics surveys were conducted around the Chiswell Island rookery in the northern Gulf of Alaska at night in April and August 2003 to assess seasonal changes in prey available to Steller sea lions (Eumetopias jubatus) foraging around the rookery. Adult walleye pollock (Theragra chalcogramma) ≥28 cm fork length was the dominant biomass in the upper 50 m of the water column in both months, increasing from 122.8 kg/nmi² in April to 457.9 kg/nmi² in August. A similar pattern was observed for Pacific herring (Clupea pallasii), which averaged 2.8 and 65.6 kg/nmi² in April and August, respectively. Incidental trawl catch suggested the appearance of age-0 pollock and juvenile salmonids (Oncorhynchus spp.) around the rookery in August as well. The increased biomass of these key prey species is linked to increased foraging trip durations by lactating sea lions from Chiswell Island, and supports the general view that sea lions in the northern Gulf of Alaska are not food limited during summer months.     

Inhibition of HPI axis response to stress in gilthead sea bream (Sparus aurata) with physiological plasma levels of cortisol

This study investigates the effect of corticosteroid (cortisol) administration on the stress response of the gilthead sea bream Sparus aurata subjected to a 48 h confinement. The effect of (in-vitro and in-vivo ) cortisol administration on the in-vitro ACTH sensitivity of the interrenal tissue; the plasma levels and tissue concentration of cortisol; and the plasma levels of ACTH, -MSH, -endorphin and glucose were determined. Confinement caused a transient and concomitant increase in plasma cortisol and ACTH levels. However, in cortisol-fed fish the plasma ACTH levels were lower, indicating a suppresion of the ACTH release from the corticotropes by cortisol. In contrast to the activation of the corticotropes, the levels of plasma melanotrope derived peptides were not affected. In spite of the fact that interrenal cells of cortisol-fed gilthead sea bream released less cortisol than controls, the interrenal sensitivity to ACTH was not affected by in-vivo and in-vitro cortisol administration. This suggests that the interrenal sensitivity to ACTH in stressed (confinement) sea bream is probably not regulated by -MSH, N-ac--END, or by cortisol. Thus, in gilthead sea bream the interrenal sensitivity to ACTH could be regulated at the hypothalamus and/or pituitary and communicated via circulating ACTH levels.     

氧化应激对鲤抗氧化状态和免疫功能的影响

为探讨氧化应激对鲤抗氧化状态和免疫功能的影响,本实验以H_2O_2作为活性氧自由基(ROS),将鲤暴露于不同浓度的H_2O_2(0、0.25、0.50和1.00 mmol/L)中,诱导鲤产生氧化应激反应。连续暴露7 d后,采集鲤血液和肝组织,以检测相关生化指标以及基因表达量的变化。结果显示,与空白对照组(0 mmol/L)相比,随着H_2O_2浓度的升高,血清葡萄糖(GLU)、皮质醇(cortisol)和乳酸(LA)含量显著升高;而碱性磷酸酶(AKP)和酸性磷酸酶(ACP)活性仅在1.00 mmol/L H_2O_2处理组中显著高于其他实验组。氧化应激参数显示,与空白对照组(0 mmol/L)相比,0.50和1.00 mmol/L H2O2处理显著降低血清过氧化氢酶(CAT)活性,而提高还原型谷胱甘肽(GSH)、丙二醛(MDA)和总抗氧化能力(T-AOC)水平;在肝脏组织中,1.00 mmol/L H_2O_2处理显著降低了GSH含量,促进了MDA生成。基因表达结果显示,与空白对照组相比,1.00 mmol/L H2O2处理组显著上调了肝脏组织中cyp1a表达,而下调了cyp1b表达;同时0.50和1.00 mmol/L H2O2处理显著上调了hsp70、hsp90、c3、c-lyz和hep的表达。研究表明,氧化应激暴露可诱导鲤产生明显应激反应和脂质过氧化,降低机体抗氧化能力并激发免疫应答反应。     

玉足海参与凡纳滨对虾的混养效果

在室内条件下进行了玉足海参与凡纳滨对虾的混养实验,分析了单养与混养两种条件下养殖水体营养盐结构以及底质成分的变化,测定了对虾与海参的存活率与生长性能。结果显示,混养海参可以明显改变养殖系统的营养盐结构,可使水体中的磷酸盐和硝酸盐浓度有所升高,同时也可有效地控制系统中氨氮浓度。混养海参也可以大幅度地降低沉积物中有机质和硫化物含量,实验结束时混养组硫化物含量为(7.71±1.33)mg/kg,仅相当于单养组浓度的1/3。混养海参对对虾生长及存活具有明显的促进作用,其中混养组对虾体长特异增长率为(0.69±0.13)%/d,显著优于单养组(0.45±0.06)%/d;混养组对虾成活率可达72.5%±22.9%,显著高于对照组55.0%±17.5%。在混养系统内,对虾不会对海参的生存造成负面影响,海参能够有效地选择摄食和利用沉积物中的营养物质(对食物中有机质的同化率可达36.36%±13.79%),并以较快的速度生长。结果表明,在对虾养殖系统中混养玉足海参具有明显的环境与经济效益。本研究可为我国海水养殖业的可持续发展提供一定的科学依据。     

中华绒螯蟹雌性亲蟹血淋巴生化指标与盐度的关系

设定淡水对照组和两个盐度组(盐度12,盐度25),分别在第0、3、6、12、24、48、72、96、144小时取样,研究盐度对中华绒螯蟹雌性亲蟹6项血淋巴生化指标的影响。结果表明,在0~144 h内,盐度组中华绒螯蟹雌性亲蟹血淋巴总蛋白(TP)含量在前6 h显著高于对照组(P<0.05),96 h后高低盐度组TP水平趋于一致,并保持在略高于对照组的稳定水平。葡萄糖(GLU)含量随盐度的升高而增大,盐度组GLU均呈先升高后降低趋势,盐度25组GLU在72 h达到最大值且显著高于盐度12组和对照组(P<0.05)。盐度12组甘油三酯(TG)含量呈降低趋势且在6~144 h显著低于对照组(P<0.05),72 h后显著低于盐度25组(P<0.05),盐度25组TG呈先下降后上升趋势,且在72 h后恢复至对照水平。盐度组碱性磷酸酶(ALP)活性呈先升高后降低趋势,盐度组乳酸脱氢酶(LDH)活性均在3 h达到最大值,12 h取得最小值。分析认为,中华绒螯蟹雌性亲蟹由淡水进入咸水,其血淋巴TP、GLU、TG含量均发生显著性变化,推测其机体加强能量代谢,加速动用脂类和糖类作为能源物质以应对盐度突变刺激;并最先调节蛋白质代谢过程以响应外界坏境的渗透压变化进行渗透压调节,其机体最终能够适应外界较高盐度的水体。