Seawater acidification affects the immune enzyme activities of the Manila clam Ruditapes philippinarum

Ocean acidification leads to changes in physiological and immune responses of bivalves, but the eff ect on the immune enzyme activities of the Manila clam, R uditapes philippinarum, when the pH is lower than the normal value has not been studied in detail. In this study, experiments were conducted to determine how pH(7.4, 7.7, 8.0) affects the immune enzyme activities in the gill and hemocytes of the Manila clam. Membrane stability and phagocytosis increased with decrease of pH from 8.0 to 7.7 and then decreased at pH 7.4. The total protein content in the hemocytes and gills decreased with decreasing pH. Lysozyme content in the hemocytes increased with decreasing pH, and the diff erences were significant among the different pH groups(P 0.05). Adenosine triphosphatase activity at pH 7.4 was significantly higher than in the other two groups, but no significant diff erence was observed between pH 7.7 and 8.0. Catalase activity decreased from pH 8.0 to 7.7 and then increased at pH 7.4, and the dif ferences were significant among the experimental groups( P 0.05). These findings provide valuable information about the immune response of R. philippinarum to reduced water pH and insights for future research investigating exposure of bivalves to elevated CO_2 conditions.     

Effects of Seawater Acidification on Early Development of Clam Cyclina sinensis

Anthropogenic emission of atmospheric carbon dioxide(CO_2) has led to a rapid increase in atmospheric CO_2 concentration. Increasing atmospheric CO_2 can reduce seawater pH and carbonate ions, which may adversely affect the survival of the larvae of calcareous animals. Cyclina sinensis is a commercially and ecologically important species in several Asian countries. Living in coast shallow waters, this species has experienced the coastal environmental changes frequently throughout its life cycle. In this study, we simulated possible future seawater pH values including 8.2, 7.8 and 7.4 and examined the effects of ocean acidification on the early development of C. sinensis. Clam embryos were incubated for 48 h(2 d) in control and high-CO_2 seawater to compare embryogenesis, larval growth and swimming behavior. Fertilization rate was quite sensitive to pH, and moderate acidification could induce a significant decrease in fertilization rate. However, only extreme acidification could bring significant negative effect to hatching rate, body size, and average path velocity of trochophora. Moreover, with seawater acidification, C. sinensis needs much more time to reach the same developmental stage, which increases the risk of larva survival. Together with recent studies demonstrating negative impacts of high CO_2 on fertilization and larva swimming behavior, the results imply a future decrease of C. sinensis populations in oceans if its acclimation to the predicted environmental alteration does not occur.     

The potential of ocean acidification on suppressing larval development in the Pacific oyster Crassostrea gigas and blood cockle Area inflata Reeve

We evaluated the effect of pH on larval development in larval Pacific oyster(Crassostrea gigas) and blood cockle(Arca inflata Reeve).The larvae were reared at pH 8.2(control),7.9,7.6,or 7.3beginning 30 min or 24 h post fertilization.Exposure to lower pH during early embryonic development inhibited larval shell formation in both species.Compared with the control,larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3.Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3.However,when exposure was delayed until 24 h post fertilization,shell formation was only inhibited in blood cockle larvae reared at pH 7.3.Thus,the early embryonic stages were more sensitive to acidified conditions.Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves.Although the effects appear subtle,they may accumulate and lead to subsequent issues during later larval development.     

Effects of elevated seawater pCO<Subscript>2</Subscript> on early development of scallop <Emphasis Type="Italic">Argopecten irradias</Emphasis> (Lamarck, 1819)

To investigate the effects of elevated seawater pCO₂ on the early developmental stages of marine benthic calcifying organisms, we exposed the eggs and larvae of Argopecten irradias, an important bivalve species in Chinese aquaculture, in seawater equilibrated with CO₂-enriched (1000 ppm) gas mixtures. We demonstrated that elevated seawater pCO₂ significantly interfered with fertilization and larval development and resulted in an increased aberration rate. Fertilization in the treatment (pH 7.6) was 74.3% ± 3.8%, which was 9.7% lower than that in the control (pH 8.3) (84.0% ±3.0%). Hatching success decreased by 23.7%, and aberration rate increased by 30.3% under acidic condition. Larvae in acidified seawater still developed a shell during the post-embryonic phase. However, the shell length and height in the treatment were smaller than those in the control. The development of embryos differed significantly at 12 h after fertilization between the two experimental groups. Embryos developed slower in acidified seawater. Nearly half of the embryos in the control developed into D-shaped larvae at 48 h after fertilization, which were considerably more than those in the treatment (11.7%). Results suggest that future ocean acidification (OA) would cause detrimental effects on the early development of A. irradias.     

3种珍珠贝精子发生及其超微结构的比较研究

在透射电子显微镜下观察合浦珠母贝（Ｐｉｎｃｔａｄａｆｕｃａｔａ）、大珠母贝（Ｐｉｎｃｔａｄａｍａｘｉｍａ）和企鹅珍珠贝（Ｐｔｅｒｉａｐｅｎｇｕｉｎ）的精子发生及精子形态．结果表明．大珠母贝从精原细胞到精子，核内都有数量不等的板层小体（ｎｕｃｌｅａｒｌａｍｅｌｌａｒｂｏｄｙ）；企鹦珍珠贝从精原细胞的晚期直到精子细胞早期，大多数细胞出现核内包含体（ｎｕｃｌｅａｒｉｎｃｌｕｓｉｏｎ）；而合浦珠母贝的生精细胞核无特殊结构．合浦珠母贝在初级精母细胞时由高尔基体分泌形成前顶体粒；企鹅珍珠贝的前顶体粒主要在次级精母细胞和早期精子细胞阶段形成。虽然大珠母贝的各级生精细胞中都没有出现典型的高尔基体，但前顶体粒仍在精母细胞时期形成。三种贝的精子结构均为典型的原生型，由头部、中段和尾部构成．合浦珠母贝精子的顶体最长，中段的线粒体数有变异；大珠母贝的精子核最高，其中含有板层小体；而企鹅珍珠贝精子中段的体积是最大的．     

The potential of ocean acidification on suppressing larval development in the Pacific oyster Crassostrea gigas and blood cockle Arca inflata Reeve

We evaluated the effect of pH on larval development in larval Pacific oyster （Crassostrea gigas） and blood cockle （Arca inflata Reeve）. The larvae were reared at pH 8.2 （control）, 7.9, 7.6, or 7.3 beginning 30 min or 24 h post fertilization. Exposure to lower pH during early embryonic development inhibited larval shell formation in both species. Compared with the control, larvae took longer to reach the D-veliger stage when reared under pH 7.6 and 7.3. Exposure to lower pH immediately after fertilization resulted in significantly delayed shell formation in the Pacific oyster larvae at pH 7.3 and blood cockle larvae at pH 7.6 and 7.3. However, when exposure was delayed until 24 h post fertilization, shell formation was only inhibited in blood cockle larvae reared at pH 7.3. Thus, the early embryonic stages were more sensitive to acidified conditions. Our results suggest that ocean acidification will have an adverse effect on embryonic development in bivalves. Although the effects appear subtle, they may accumulate and lead to subsequent issues during later larval development.     

华贵栉孔扇贝稚贝盐度适应性的研究

通过室内实验研究了水温28.5～29.4℃、pH值7.6～8.1条件下,华贵栉孔扇贝Chlamys nobilis(Reeve)稚贝(壳高9.77±0.19mm)对不同盐度的适应性。结果表明:华贵栉孔扇贝稚贝适宜生存盐度为24.27~37.18,最适生存盐度为26.91~32.13,适宜生长盐度为24.56~37.09,最适生长盐度为26.91~29.52。在适宜生存盐度范围内,当盐度变化超出最适范围时,低盐端变化对相对成活率、壳高日增长率、体重日增长率影响比高盐端明显。     

海水钙浓度对远海梭子蟹软壳持续时间与形态变化的影响

盐度30、pH7.5～8.5、温度27～30℃条件下,将刚刚蜕壳的远海梭子蟹放入不同钙浓度梯度(0～400 mg/L)的人工海水中,进行钙浓度对远海梭子蟹蟹壳硬化影响的实验。结果表明:0～12.5 mg/L浓度组的软壳持续时间在10.4～11.4 h之间,25～200 mg/L浓度组的软壳持续时间在6.1～7.7 h,400 mg/L浓度组的软壳持续时间为4.4 h;不同浓度组下,壳宽的增加差异不显著(P﹥0.05),壳长的增加差异也不显著(P﹥0.05);50 mg/L浓度组与400 mg/L浓度组体重增加差异显著(P<0.05),其它各浓度组之间体重增加差异不显著(P﹥0.05)。     

Oxygen consumption and ammonia-N excretion of Meretrix meretrix in different temperature and salinity

Effects of temperatures and salinities on oxygen consumption and ammonia-N excretion rate of clamMeretrix meretrix were studied in laboratory from Oct. 2003 to Jan. 2004. Two schemes were designed in incremented temperature at 10, 15, 20, 25°C at 31.5 salinity and in incremented salinity at 16.0, 21.0, 26.0, 31.5, 36.0, and 41.0 at 20°C, all for 8–10 days. From 10 to 25°C, both respiration and excretion rate were increased. One-way ANOVA analysis demonstrated significant difference (P<0.01) in physiological parameters in this temperature range except between 15 and 20°C. The highestQ ₁₀ thermal coefficient value (12.27) was acquired between 10 and 15°C, and about 1 between 15 and 20°C, indicatingM. meretrix could well acclimate to temperature changes in this range. Salinity also had significant effects on respiration and excretion rate (P<0.05). The highest values of respiration and excretion rate ofM. meretrix were recorded at 16.0 salinity (20°C). These two physiological parameters decreased as salinity increased until reached the minimumQ ₁₀ value at 31.5 (20°C), then again, these parameters increased with increasing salinity from 31.5 to 41.0.M. meretrix can catabolize body protein to cope with osmotic pressure stress when environmental salinity is away from its optimal range. No significant difference was observed between 26.0 and 36.0 in salinity (P>0.05), suggesting that a best metabolic salinity range for this species is between 26.0 and 36.0. This work is supported by National High-Tech R & D Program of China. (863 Program) (2002AA603014).     

Effect of dietary potassium on growth,nitrogen metabolism,osmoregulation and immunity of pacific white shrimp (Litopenaeus vannamei) reared in low salinity seawater

An 8 weeks feeding experiment was conducted to determine the effect of dietary potassium on the growth and physiological acclimation of Pacific white shrimp(Litopenaeus vannamei) reared in diluted seawater(salinity 4). Six semi-purified practical diets containing 0.59, 0.96, 1.26, 1.48, 1.74, and 2.17+ g potassium K per 100 g diet were formulated, respectively. The survival and feed conversion rate did not show significant difference among groups of shrimps given these diets(P0.05). The shrimps fed the diets containing 0.96-1.48 g K+ per 100 g diet gained the highest weight, specific growth rate, and protein efficiency ratio. Their ammonium-N excretion rate as well as hemolymph concentration of Na+ and Cl- were significantly lower than those of the control(P0.05), but a reverse trend was observed for their gill Na+/K+-ATPase. Moreover, the shrimps fed with 1.48 g K+ per 100 g diet were the highest in hemolymph urea level, and the phenoloxidase and lysozyme activities were significantly higher than those of the control(P0.05). The growth and physiological response of the test shrimps suggested that diet containing 1.48 g K+ per 100 g diet improved the growth of L. vannamei in low-salinity seawater, and enhanced the physiological acclimation of the organism.     

Relaxation of Selective Constraint on the Ultra-Large Mitochondrial Genomes of Arcidae(Mollusca: Bivalvia)

The mitochondrial genomes(mitogenomes) are purportedly under selection for smaller size to improve their replication and translation efficiency. However, the mitogenomes of Arcidae species are larger than those of other bivalves, and are among the largest metazoan mitogenomes reported to date. In order to explore the differences of base composition and selective constraints between the large and small mitogenomes, we compared the mitogenomes of 9 large arcid mitogenomes and 77 small bivalves mitogenomes. Base composition analyses indicated that Arcidae mitogenomes have significantly greater GC skews in both their whole genomes and coding sequences. This result suggests that the replication of the large mitogenomes in Arcidae may be slower than those in other bivalves, exposing the parental strand to deamination for a longer time. Selection pressure analyses showed that the mitochondrial protein-coding genes of Arcidae species have significantly higher Ka/Ks ratios than other bivalves,suggesting that they have accumulated more nonsynonymous nucleotide substitutions. Seven protein-coding genes(atp6, cox1-3,nad1, nad4 and nad5) show significant difference for Ka/Ks ratios between the Arcidae and non-Arcidae groups. However, these divergences are not observed in the nuclear gene within histone H3. From these observations, we concluded that the large mitogenomes of Arcidae species experienced more relaxed selective constraints. As some Arcidae species are more tolerant to hypoxia that can lead to low metabolic rate, the relaxed selective constraints of mitogenomes may be energy-related. This study provides new insights into the evolution of Arcidae mitogenomes.     

不同温度下马氏珠母贝干露耐受能力及其免疫相关基因表达的变化

【目的】探究马氏珠母贝(Pinctada fucata martensii)对干露胁迫的响应,为马氏珠母贝健康养殖和遗传育种提供基础资料。【方法】在不同温度下对马氏珠母贝进行干露胁迫,探究温度对马氏珠母贝干露耐受的影响;筛选出马氏珠母贝干露胁迫敏感组和耐受组,比较两组的免疫相关基因表达量和植核后休养期存活率。【结果】(1)22~34℃条件下,马氏珠母贝干露耐受能力随温度升高及干露时间延长而降低;(2)22℃下,S组和T组的脯氨酸羟化酶(PHD)、葡萄糖转运蛋白(GLUT)、髓样分化因子(MYD88)、热休克蛋白(Hsp70、Hsp20)和凋亡抑制因子(cIAP)6个基因在干露过程中表达量基本呈上升趋势,组间差异显著(P<0.05);(3)植核试验结果表明耐受组植核后休养期的存活率显著高于敏感组(P<0.05)。【结论】马氏珠母贝在高温环境下干露耐受能力降低,在适温条件下耐受组比敏感组表现出较高的存活率。     

4种海洋贝类多糖提取和保湿性研究

以马氏珠母贝(Pinctada martensii)、企鹅珍珠贝(Pteria penguin)、翡翠贻贝(Perna viridis)和近江牡蛎(oyster)的内脏团为原料提取、纯化多糖,与甘油、聚乙二醇400(PEG-400)、丙二醇和1,3-丁二醇四种常规保湿剂进行比较.结果表明,在相对湿度为44%时,前12h 吸湿率顺序为:马氏珠母贝<近江牡蛎<企鹅珍珠贝<翡翠贻贝< PEG-400<1,3-丁二醇<甘油<丙二醇;在相对湿度为80%时,前12 h 吸湿率顺序为:近江牡蛎<马氏珠母贝<企鹅珍珠贝<1,3-丁二醇<翡翠贻贝< PEG-400<甘油<丙二醇.前12 h 的保湿率顺序为:近江牡蛎>翡翠贻贝>马氏珠母贝>企鹅珍珠贝>甘油>1,3-丁二醇>丙二醇> PEG-400.翡翠贻贝吸湿性多糖优于其他贝类多糖,稍低于常规保湿剂.在相对湿度为80%时,前12 h 翡翠贻贝多糖的吸湿率大于常规保湿剂1,3-丁二醇,翡翠贻贝多糖保湿性稍弱于近江牡蛎,但强于其他贝类多糖和常规保湿剂要强一些     

Comparative Studies on Uptake Pathway of Cadmium by Perna viridis

Experiments were designed to expose the filter-feeding bivalve Perna viridis to different Cd-contaminated water environments in order to compare the different pathways through which Cd is accumulated. Results show that mussels can accumulate Cd through seawater, food, sediment and suspended particle pathways in a short period of time. Mussels＇ uptake of Cd through the seawater pathway reaches the highest concentration approximately 3 and 9 times larger than through the algae and sediment pathways respectively after 7 d. This indicates that the Cd-accumulation through seawater is most efficient. Results also indicate that the uptake directly through contaminated algae, particles or sediments ingested by mussels is less important when compared with the uptake of Cd by mussels through the seawater pathway. Metal uptake pathways and mechanisms of bioaccumulation by marine bivalve are also discussed in this paper.     

氮源、磷源及重金属离子对绿色巴夫藻生长的影响

研究了不同氮源、磷盐、不同氮磷比以及培养液中3种重金属离子含量对绿色巴夫藻(Pavlovaviridis)生长的影响。结果表明:无机氮、有机氮共同提供氮源,以及磷酸二氢钠提供磷源,氮磷比5∶1时,绿色巴夫藻生长速度最快;铅、锌、铜离子可不同程度地影响绿色巴夫藻的生长,三者的毒性依次增大,三者的96hEC50分别为25.700、7 .079和1 469mg/L。     

Corrosion performance of zinc coated steel in seawater environment

Considering the continuous exploitation of marine resources,it is very important to study the anticorrosion performance and durability of zinc coated streel(ZCS) because its increasing use as reinforcements in seawater.Tafel polarization curves and linear polarization curves combined with electrochemical impedance spectroscopy(EIS) were employed to evaluate the corrosion performance of ZCS at Qingdao test station during long-term immersion in seawater.The results indicated that the corrosion rate of the ZCS increased obviously with immersion time in seawater.The corrosion products that formed on the zinc coated steel were loose and porous,and were mainly composed of Zn_5(OH)_8Cl_2,Zns(OH)_6(CO_3)_2,and ZnO.Pitting corrosion occurred on the steel surface in neutral seawater,and the rate of ZCS corrosion decreased with increasing pH.     

马氏珠母贝肠道及其养殖水体可培养细菌群落结构

【目的】了解马氏珠母贝(Pinctada fucata martensii)肠道及其养殖水体可培养细菌的群落组成。【方法】采用2216E平板涂布法研究海区养殖马氏珠母贝肠道与养殖水体的可培养菌群种类及丰度。【结果与结论】马氏珠母贝肠道及其养殖水体的可培养细菌归属于2门(变形菌门和厚壁菌门)3纲7目10科23属56种。属水平上,肠道中以弧菌属(74.7%)和假交替单胞菌属(18.7%)为主;养殖水体中α-变形菌纲的FJ943236_g属(40.7%)丰度最大,弧菌属(16.7%)相对肠道丰度较低。样品共有菌属为弧菌属、假交替单胞菌属、发光杆菌属和芽孢杆菌属;肠道特有菌属为希瓦氏菌属和盐单胞菌属;养殖水体特有菌属主要为FJ943236_g、鲁杰氏菌属和Nautella。在种水平上,7个种为二者共有;马氏珠母贝肠道和养殖水体特异性菌种分别为18个和31个。虽然门水平上马氏珠母贝肠道中可培养细菌群落与其养殖水体中的细菌群落大致相似,但在属、种水平上二者差异明显。     

The apparent copper complexing capacity of seawater and the interaction of copper with humic matter

The anodic stripping voltammetry with physically-coating mercury film electrode was used to investigate the complexing action of trace heavy metals in seawater with organic ligands. The apparent copper complexing capacity of seawater was determined by titrating the organic ligands in natural seawater with standard ionic copper solution. The complexing actions of copper in seawater with humic acid (HA) or fulvic acid (FA) were investigated by titrating copper in seawater with HA or FA solution. The equilibrium time, electrodeposition potential, and effect of pH etc. were investigated respectively. The results show that the interaction of copper in seawater with organic matter is a fast process. At natural pH, HA or FA tend to act with copper in seawater to form nonlabile complexes. During experimental electrode process, these complexes did not significantly dissociate. The experimental results were calculated according to 1∶1 complex formation.     

体重和温度对马氏珠母贝耗氧率和排氨率的影响

采用室内实验生态学方法对马氏珠母贝的耗氧率和排氨率进行了研究。结果表明:在温度13～33℃范围内,马氏珠母贝的耗氧率和排氨率均与体重呈负相关,可用Y=aW表示;在13～28℃温度范围内,马氏珠母贝-b的耗氧率随温度的升高而增加,28℃时,耗氧率达最大值,温度升高至33℃时,耗氧率反而下降,而排氨率在此温度范围内则呈持续升高趋势;在13～28℃温度范围内,马氏珠母贝呼吸和排泄Q10值分别为1.51～2.71和1.03～2.73,且在该温度范围内,马氏珠母贝的耗氧率和排氨率的比值范围为7.29～13.14。方差分析表明,体重、温度及二者的交互作用对马氏珠母贝的耗氧率和排氨率均有极显著影响(P<0.01)。马氏珠母贝的日常代谢高于标准代谢,耗氧率和排氨率平均值分别提高40.8%和59.1%。