深圳海域养殖牡蛎卫生质量状况(II)——农药、微生物及麻痹性贝毒的含量与评价

为了了解深圳海域养殖牡蛎体内的卫生质量状况,我们于2002年1月～2004年2月对该海域养殖牡蛎体内的污染物水平进行了检测,结果显示六六六(BHC)为ND(未检出)～0.100mg?Kg-1湿重,DDT为0.004～0.255mg·Kg-1湿重,细菌总数为ND～9.3104Ind·g-1,大肠菌群为ND～5.6104Ind·(100g)-1,PSP为ND～34礸·(100g)-1,副溶血性弧菌沙井和后海的近江牡蛎检测结果为阳性,其余站位未检出。参照GB18406.4-2001《农产品安全质量无公害水产品安全要求》,深圳海域养殖牡蛎的六六六、DDT、细菌总数和PSP完全符合要求,沙井和后海的近江牡蛎副溶血性弧菌超标,所有站位的大肠菌群均存在超标。综合重金属的检测结果发现,所有站位的牡蛎均有多个污染物超标,卫生质量欠佳,珠江口和深圳湾的近江牡蛎较大亚湾和大鹏湾的长牡蛎和褶牡蛎卫生质量更差。     

深圳海域养殖牡蛎卫生质量状况(Ⅱ)——农药、微生物及麻痹性贝毒的含量与评价

为了了解深圳海域养殖牡蛎体内的卫生质量状况,我们于2002年1月～2004年2月对该海域养殖牡蛎体内的污染物水平进行了检测,结果显示六六六(BHC)为ND(未检出)～0.100mg·Kg^-1湿重,DDT为0.004～0.255mg·Kg^-1湿重,细菌总数为ND～9.3×10⁴Ind·g^-1,大肠菌群为ND～5.6×10⁴Ind·(100g)^-1,PSP为ND～34μg·(100g)^-1,副溶血性弧菌沙井和后海的近江牡蛎检测结果为阳性,其余站位未检出。参照GB18406.4-2001《农产品安全质量无公害水产品安全要求》,深圳海域养殖牡蛎的六六六、DDT、细菌总数和PSP完全符合要求,沙井和后海的近江牡蛎副溶血性弧菌超标,所有站位的大肠菌群均存在超标。综合重金属的检测结果发现,所有站位的牡蛎均有多个污染物超标,卫生质量欠佳,珠江口和深圳湾的近江牡蛎较大亚湾和大鹏湾的长牡蛎和褶牡蛎卫生质量更差。     

三个牡蛎群体遗传多样性的AFLP分析

采用AFLP技术对太平洋牡蛎(Crassostrea gigas)、近江牡蛎(Crassostrea rivularis)和褶牡蛎(Crassostrea plicatula)3个牡蛎群体共60个个体进行了遗传多样性分析。结果表明,14对引物共扩增得到662个位点,其中多态性位点619个,多态性位点比例为93.50%。太平洋牡蛎、近江牡蛎和褶牡蛎多态位点比例依次为73.26%、70.54%和75.08%,Nei氏基因多样性指数分别为0.256 9±0.197 7、0.226 1±0.195 2和0.268 3±0.194 1,Shannon信息指数分别为0.382 3±0.276 2、0.341 4±0.274 1和0.398 8±0.270 9。上述结果表明,3个牡蛎群体的遗传多样性水平褶牡蛎最丰富,太平洋牡蛎次之,近江牡蛎最小。基因分化系数Gst和基因流系数Nm表明这3个牡蛎群体之间存在一定的基因交流。UPGMA聚类分析表明,太平洋牡蛎和近江牡蛎先聚为一支,而后与褶牡蛎聚在一起。     

混合暴露条件下近江牡蛎对重金属的积累与释放特征

选择近江牡蛎作为试验生物,研究了混合暴露条件下8种重金属在近江牡蛎体内的积累和释放特征.结果表明: 近江牡蛎对重金属Pb、Cu、Ni、Cd、Cr和Hg有很强的累积能力,可较好地指示溶液中的重金属浓度水平,但对重金属Zn和As的积累能力很小,不能真实反映溶液中重金属Zn和As含量的变化水平.在随后35 d的释放阶段,8种重金属在近江牡蛎体内的含量没有明显变化,表明近江牡蛎对重金属的释放能力较差.双箱动力学模型可较好地反映混合暴露条件下近江牡蛎对重金属的积累特征,但不适合对其释放特征进行描述.     

热休克诱导近江牡蛎对高温的耐受性

设计6个温度组成的梯度,即38℃、39℃、40℃、41℃、42℃、43℃,对近江牡蛎加热处理1.5h后放回室温海水中连续观察3d,发现致死温度为42℃,半致死温度是40℃,亚致死温度为36℃。经亚致死温度36℃热休克1.5h后,在正常环境温度下恢复6h,再经受致死温度42℃处理1.5h后,放回室温海水中连续观察3d,发现三次重复的平均存活率为96.7%,显著高于对照组的存活率(0),结果表明预先的热休克极显著地增强了近江牡蛎对致死温度(42℃)的耐受力。     

吊养和底播两种养殖方式对扁平钳蛤生长的影响

扁平钳蛤具有蓝褐色珍珠层,是培育色泽特异珍珠的潜能品种,不同养殖方式的选择对扁平钳蛤的生长和存活具有重要的影响。本研究采用锥形笼吊养和底播养殖两种方式对扁平钳蛤进行为期半年的养殖,探讨两种养殖方式对扁平钳蛤壳长、壳宽、壳高和体重等生长性状以及其存活率的影响,以摸索一种适合扁平钳蛤的养殖方式。结果表明,养殖半年后,吊养扁平钳蛤(以小贝为例)的壳长、壳高、壳宽和体重的增长率分别为137.95%、143.84%、152.63%和92.68%,而底播贝则分别为110.30%、113.02%、115.85%和68.97%,吊养贝和底播贝之间存在显著差异(p0.05)。吊养贝在6个月的养殖期内总存活率分别为100%、75.56%、82.22%、91.11%、98.89%和82.22%,而底播贝总存活率则分别为100%、66.67%、74.44%、88.89%、100%和91.11%。在5、6、7、8四个月内吊养贝的存活率都显著高于底播贝(p0.05);9月份两者无显著差异(p0.05),在10月份因受台风影响则表现为底播贝的存活率高于吊养贝(p0.05)。这从生长性状和存活率两方面表明,锥形笼吊养与底播相比更适合于扁平钳蛤的养殖。     

牡蛎人工杂交的初步研究

牡蛎为重要的海洋养殖贝类之一,种类很多。单就福建厦门一带就有六种:密鳞牡蛎(Ostrea denselamellosa Lischke)、僧帽牡蛎(O.cucullata Born)、棘刺牡蛎(O.echinataQuoy & Gaimard)、复瓦牡蛎(O.imbricata Lamarck),以及大型的两种:住江牡蛎(O.rivularis Gould)和大牡蛎(O.gigas Thumberg),其中住江牡蛎和大牡蛎生活在咸淡水区,个体较大,生活力较强,惟肌肉粗糙,滋味很差。而密鳞牡蛎和僧帽牡蛎个体皆较前两者为小,生活力也较弱。但因其味鲜美,我国闽粤一带多以这些种类进行养殖。牡蛎棲息     

三种水产药物对近江牡蛎(Crassostrea ariakensis)的影响

用3种水产药物硫酸铜、孔雀石绿、甲醛分别设置浓度梯度,对正常和天然患病近江牡蛎进行处理,连续观察7d,发现3种药物对正常近江牡蛎的影响强度为孔雀石绿〉甲醛〉硫酸铜。对患病近江牡蛎的致死率显著高于对正常近江牡蛎的致死率,即使用同一药物的更低浓度处理患病近江牡蛎,其死亡率也显著高于更高浓度处理的正常近江牡蛎的死亡率。在患病近江牡蛎药物处理实验中,对照组有明显死亡,但死亡率低于药物处理组。实验结果表明水产药物残留对近江牡蛎,特别是对患病近江牡蛎有较大影响,会导致其死亡率明显上升,这也可能是引起近江牡蛎大规模死亡的原因之一。     

两种杀虫剂对近江牡蛎(Crassostrea ariakensis)的致死作用

为了阐明环境污染物在近江牡蛎死亡中的作用,设置两种浓度梯度的敌百虫和溴氰菊酯,分别处理正常和天然患病近江牡蛎,研究了这两种杀虫刺对近江牡蛎的致死作用。结果表明,浓度为0．005～0．1（mg／l）时,敌百虫对正常近江牡蛎不致死;0．001～0．5（mg/l）敌百虫对天然患病近江牡蛎致死,随浓度增加,死亡率从30％上升到65％。溴氰菊酯对正常和天然患病近江牡蛎均有致死作用,对患病牡蛎的致死作用比对正常牡蛎强,且随浓度增加,死亡率呈上升趋势。溴氰菊酯对近江牡蛎的致死作用远强于敌百虫的作用。     

厦门大嶝岛海域贝类的养殖容量

对厦门大嶝岛海域叶绿素a、初级生产力、浮游植物有机碳含量、潮下带、潮间带和吊养区非养殖滤食性动物生产量、养殖贝类的滤水率、有机碳含量和贝类含壳重与鲜组织重的比值等模型参数的调查测定和检测分析,采用营养动态模型和沿岸海域能流分析模型估算该海域贝类生态容量,进而扣除野生滤食性动物生产量,估算贝类养殖容量;同时应用方建光模型估算贝类的养殖容量;采用统计分析法估算贝类及其各养殖品种的适养殖面积,以控制该海域贝类的养殖量和对各种贝类养殖量进行优化配置.结果表明,3种模型估算的贝类养殖容量为35248～39990t(平均37488t),140008～158850×10⁴个(平均148903×10⁴个);适养面积2145hm²,其中牡蛎1900hm²、缢蛏81hm²、泥蚶20hm²、凸壳肌蛤144hm².2000年贝类及其各养殖品种的养殖面积已超过了估算的适宜养殖面积,应予以削减.     

长期垄作稻田腐殖质稳定碳同位素丰度(δ13C)分布特征

研究了四川盆地丘陵区连续16年垄（宽垄）作稻田土壤稳定碳库腐殖质组分的稳定碳同位素(δ¹³C)分布特征.结果表明： 稻田土壤有机碳含量为宽垄作＞垄作＞水旱轮作.腐殖质碳以胡敏素为主,占土壤碳含量的21%～30%,提取碳以胡敏酸为主,分别占土壤有机碳和腐殖质的17%～21%和38%～65%.土壤有机碳的δ¹³C值介于-27.9‰～-25.6‰,20～40 cm和0～5 cm土壤有机碳δ¹³C值之差约为1.9‰.土壤胡敏酸δ¹³C值比土壤有机碳低1‰～2‰,更接近于油菜和水稻秸秆及根系的δ¹³C值.土壤富里酸δ¹³C值分别较土壤有机碳和胡敏酸高2‰和4‰.耕作层和犁底层胡敏素δ¹³C值分别介于-23.7‰～-24.9‰和-22.6‰～-24.2‰,δ¹³C值的变化反映了耕层中腐殖质的新老混合现象.各有机组分δ¹³C值递减顺序为：胡敏素＞富里酸＞土壤有机碳＞稻草（油菜）残体＞胡敏酸.长期水稻种植有利于增加土壤有机碳含量,同时,耕作方式影响土壤腐殖质δ¹³C在耕作层和犁底层中的分布格局.     

Development of a quantitative real-time polymerase chain reaction targeted to the toxR for detection of Vibrio vulnificus

The TaqMan assay, a quantitative real-time polymerase chain reaction (PCR), was developed to target the ToxR gene (toxR) of Vibrio vulnificus. The toxR of V. vulnificus was cloned and sequenced. Based on these results, we designed specific primers and a probe for use in the quantitative PCR assay. Twenty-nine strains of V. vulnificus that were obtained from various sources produced a single PCR product. The amount of final amplification product and threshold cycle number were the same among the strains. We used the method to detect V. vulnificus in seawater and oyster samples. We developed standard curves to quantitate V. vulnificus numbers using the PCR from seawater and oyster samples. The standard curves were not different from that of the pure culture of V. vulnificus. We found the assay was very sensitive detecting as few as 10 microbes per milliliter of seawater and oyster homogenate. Moreover, we evaluated the TaqMan assay to detect V. vulnificus in seawater samples. The numbers of V. vulnificus counted by the TaqMan assay were similar to those by a culture method in almost samples. The TaqMan assay was performed within 2 h compared to days using the culture method. The results indicate the TaqMan assay method used in this study was rapid, effective and quantitative for monitoring V. vulnificus contamination in seawater and seafoods such as oysters.     

Does saltwater flushing reduce viability of diapausing eggs in ship ballast sediment?

Flushing of ballast tanks with seawater has been proposed to reduce the risk of invasion associated with residual ballast in 'no ballast on board' ships. The efficacy of this procedure, however, has not been determined. Using diapausing eggs isolated from ballast sediments — as well as from Lake Erie sediment — this study investigated the impact of salinity (0, 8 and 35‰) and temperature (10, 20 and 30 °C) on the cumulative abundance and species richness of hatched zooplankton taxa. The rate and amount of hatching varied dramatically between sediments and across salinity–temperature regimes. Although exposure to saline water inhibited emergence of freshwater taxa during the exposure phase of all trials, mixed results were evident after diapausing eggs were returned to freshwater. The efficacy of salinity as a ballast treatment method was temperature dependent, although the direction of the effect was case-specific. Exposure of eggs to saline water was less effective at 10 and 30 °C than at 20 °C. Although flushing ballast tanks with open ocean water is expected to significantly reduce the number of active invertebrates living in residual ballast water (a potentially larger source of invaders), our results indicate that the most effective treatment conditions for reduction of diapausing egg viability is 8‰ salinity at 20 °C.     

Giraudia sphacelarioides (Phaeophyceae) at the Canary Islands and in Danish waters: a study in ecotypic differentiation and its biogeographical implications

Comparative culture studies on isolates from Lanzarote (Canary Islands) and from Danish waters of Giraudia sphacelarioides show that temperature plays the key role to determine its geographical distribution. Experiments show that the upper lethal temperature is the same for both isolates 26.5—-31.1°C for microthalli, and formation of macrothalli is inhibited between 23.2 and 26.5°C. The lower lethal temperature for both micro- and macrothalli in the Lanzarote isolate is between 10.8° C and 7.6°C, while the Danish isolate survives 54°C. The microthallus is thus the more persistent stage in relation to temperature, while the macrothalli occur only when more suitable conditions exist in nature. In the North Atlantic Ocean G. sphacelarioides is distributed over approximately 30° latitudes with severe winter temperatures especially in Danish waters. This distribution can only be explained by ecotypic differentiation. In Danish waters salinity decreases from c. 30 ‰ in the northern Kattegat to below 8 ‰ in the inner parts and therefore becomes an important factor for the immigration of species into the Baltic Sea. Combined salinity (30–20–10–5 ‰) and temperature (4 to 30°C) experiments show that the Lanzarote isolate only grows at 20 ‰ in an attenuated temperature interval and at 10 ‰ only fertile microthalli are observed, however, with limited liberation of swarmers. The Danish isolate grows and reproduces also at salinities from 20–5 ‰ both as microand macrothalli, but in a still more attenuated temperature interval, and the morphology of the macrothalli becomes increasingly aberrant vs. decreasing salinity. This is in agreement with the fact that G. sphacelarioides is reported from the northern part of Kattegat with salinity from 28—-25 ‰, and it is only recorded a few times in the southern part of Kattegat and limited by the 10 ‰ isohaline.     

Removal of Toxoplasma gondii Oocysts from Sea Water by Eastern Oysters (Crassostrea virginica)

SUMMARY. Toxoplasma gondii infections have been reported in a number of marine mammals. Presently it is not known how these animals acquire T. gondii from their aquatic environment. The eastern oyster, Crassostrea virginica , has been shown to remove Cryptosporidium oocysts from seawater and a similar phenomenon may be occurring with T. gondii oocysts and marine invertebrates. The present study was done to determine if eastern oysters could remove and retain T. gondii oocysts from seawater. Oocysts of the VEG strain of T. gondii (1 × 10⁶ oocysts) were placed in seawater (32 ppt NaCl) containing live eastern oysters. The infected seawater was removed one day postinoculation (PI) and replaced with fresh seawater. Selected oysters were removed at 1, 3 and 6 days PL Hemolymph, gill washes, and oyster tissue were collected separately at each observation time. The oyster tissue was homogenized and all 3 samples fed separately to mice. Toxoplasma gondii positive mice were observed at each time period. The results indicate that T. gondii oocysts can be removed from seawater by eastern oysters and retain their infectivity. Contaminated raw oysters may serve as a source of T. gondii infection for marine mammals and humans.     

Short-term bioaccumulation, circulation and metabolism of estradiol-17β in the oyster Crassostrea gigas

Steroids are active signal transmitters in Vertebrates. These roles have also been hypothesized in other Phyla and endocrine disrupting effects have been reported for different estrogen-like compounds in fishes and some marine invertebrates. As estradiol-17β has shown some physiological activities in the oyster and as estrogens or estrogen-like molecules can be present in water, we have investigated the bioaccumulation and metabolism of this estrogen in vivo in the oyster Crassostrea gigas. When dissolved in seawater, in less than 48 h estradiol-17β concentrated up to 31 times in the soft tissues of the suspension-feeder mollusc. Injected in the adductor muscle, estradiol-17β circulated from muscle to the gonad, the gills, the mantle, the labial palps, and to a lesser extent to the digestive gland. After 2 h, estradiol flow increased specifically towards this gland. Different hypotheses were raised concerning the circulation paths. However, in all cases estradiol metabolism primarily evidenced an in vivo transformation into estrone in the whole oyster and in its digestive gland. This strong 17β-hydroxysteroid-dehydrogenase activity confirms our previous in vitro results. In conclusion, it is proposed that oyster is able to take in charge estradiol as a potential contaminant in seawater. Therefore, its bioaccumulation and transformation into estrone could be studied as potential biomarkers of endocrine disruption. Furthermore, the experimental approach with dissolved steroids in the seawater combined to an anatomical screening appears as an interesting tool to investigate the bivalve endocrinology.     

Osmoregulation in juvenile Rhabdosargus holubi (Steindachner) (Teleostei: Sparidae)

Juvenile Rhabdosargus holubi (Steindachner), one of the commonest teleosts in south east African estuaries, are strong osmoregulators, showing little change in their internal osmotic concentration over an extremely wide salinity range. In 35‰ seawater the internal osmotic concentration is held at 370 mosmol/1. At a salinity of 1‰ the internal osmotic concentration falls to 216 mosmol/1 and at a salinity of 65‰ rises to 381 mosmol/1. When exposed to a new salinity the internal osmotic concentration does not change until after 10 h; this may be of considerable importance to fish living in areas subject to short term changes of salinity.     

基于碳氮稳定同位素技术研究辽东湾海蜇的食性和营养级

应用稳定同位素技术分析了渤海辽东湾海蜇及其可能摄食饵料生物的碳、氮稳定同位素比值,对其食物组成和营养级进行了研究.结果表明： 辽东湾海蜇的δ¹³C值范围是-20.27‰～-23.06‰,跨度为2.79‰,平均值为-21.33‰;δ¹⁵N值范围是6.82‰～10.03‰,跨度为3.21‰,平均值为8.25‰.海蜇的饵料生物主要包括悬浮物、浮游植物、鱼卵、≤1000 μm 浮游动物、1000～1500 μm 浮游动物和＞1500 μm 浮游动物,其中以≤1000 μm 浮游动物为主,贡献率高达71%～88%;其他饵料生物的重要性由高到低依次为>1500 μm浮游动物、1000～1500 μm浮游动物、悬浮物、浮游植物和鱼卵,其平均贡献率分别为6%～19%、0%～22%、0%～10%、0%～8%、0%～2%.经检验发现,海蜇伞径长与δ¹⁵N的相关性不显著(P >0.05),而与δ¹³C呈显著负相关(P<0.05).以悬浮物为基准的辽东湾不同伞径组海蜇的营养级范围为2.79～3.88,平均营养级为3.28.本研究结果说明,海蜇作为大型浮游动物在辽东湾生态系统中对小型浮游动物的能量传递起着关键的调控作用,研究结果将为深入研究辽东湾生物群落的营养结构及整个生态系统的物质循环与能量流动提供基础资料.     

模拟增温对长白山北坡垂直样带森林土壤有机碳稳定碳同位素的影响

分析了长白山北坡垂直样带3种典型原始森林地表凋落物及不同粒径土壤组分中有机质的δ¹³C值,并将在岳桦林样地(EB,海拔1996 m)采集的20 cm土柱分别置换到云冷杉林(SF,海拔1350 m)和阔叶红松林(PB,海拔740 m),云冷杉林样地采集的土柱置换到阔叶红松林中,进行为期1年的野外模拟增温试验.结果表明：3种林型土壤的δ¹³C值均显著高于凋落物的δ¹³C值,凋落物和土壤有机质中的δ¹³C值由地表凋落物向土壤下层逐渐增加,而土壤粒径中有机质的δ¹³C值随粒径减小而增大.3种林型中,凋落物δ¹³C值变化趋势为云冷杉林(-28.3‰)>阔叶红松林(-29.0‰)>岳桦林(-29.6‰),而土壤有机质的δ¹³C值变化趋势为岳桦林(-25.5‰)>阔叶红松林(-25.8‰)>云冷杉林(-26.2‰).在土壤温度增加0.7 ℃～2.9 ℃条件下,土壤及其各粒级的δ¹³C值均呈下降趋势,而且<2 μm粘粒和2～63 μm粉粒δ¹³C值的降幅(0.48‰和0.47‰)高于>63 μm砂粒δ¹³C值的降幅(0.33‰).未来气候变暖可能对储藏在细小颗粒中年龄较长的有机碳带来较大的影响.