【作者】 姜爱莉；

【导师】 王长海；

【作者基本信息】 大连理工大学 ， 生物化工， 2007， 博士

【摘要】 本研究采用室内静水培养系统，从生理生态学的角度对柄海鞘的摄食、代谢及能量收支进行了研究，建立了不同温度下柄海鞘的能量收支方程。应用半静态双箱式生物富集动力学模型，在室内研究了柄海鞘对Cd²⁺、Pb²⁺、Cu²⁺、Zn²⁺四种金属离子的生物富集作用，通过非线性拟合得到了相应的生物富集动力学参数。同时考察了四种重金属离子对柄海鞘代谢的影响，并探讨了柄海鞘及其代谢指标作为近海海域重金属污染指示物种和指标的可行性。柄海鞘代谢的研究结果表明：同一温度下，柄海鞘的各项代谢指标（耗氧率、排氨率、清滤率、摄食率和摄食强度）与体重的关系均可用幂函数R=aW^b表示；不同温度下同一规格柄海鞘的耗氧率随温度升高而增加，而排氨率、清滤率、摄食率、吸收率和摄食强度则在20～24℃出现峰值。柄海鞘的食物选择性研究表明，柄海鞘对较大规格的饵料藻（6μm左右）具有较强的选择性。当饵料藻浓度较低时，柄海鞘的摄食率和清滤率随饵料浓度增大呈幂函数增长，至10 mg POM·L^-1时达到最大值。在2.11～20.12 mg POM·L^-1的饵料浓度范围内，二项式R=aC²+bC+c可用来表示清滤率及摄食率随温度的变化。对柄海鞘的能量收支进行研究，发现同一规格柄海鞘的日常代谢明显高于标准代谢，耗氧率平均增加16.7～34.9％，排氨率增加34.0～61.9％。摄食能、吸收能、代谢能、排泄能和排粪能均随体重的增加而增加。实验温度范围内（12～28℃），柄海鞘的代谢能随着温度的增加而逐渐增加，摄食能、吸收能、排泄能和排粪能则在20～24℃出现峰值。能量收支中，排泄能占3.8～9.4％，排粪能占27～54％，代谢能占10～78％；各种能量组分所占的比例随温度变化较大。柄海鞘对重金属具有一定的富集作用，其中对Cd²⁺的富集作用明显高于Pb²⁺、Zn²⁺，而对Cu²⁺的富集作用很小。对四种离子的富集吸收速率常数k₁和富集系数BCF均随外部水体中金属离子浓度的增大而减小。富集平衡时，海鞘体内的金属含量(C_Amax)与外部水体中金属离子的浓度基本成正相关。柄海鞘不同器官中的金属浓度依次为：生殖腺＞消化腺＞其他部分＞外背囊。重金属在柄海鞘体内的生物学半衰期(B_1／2)为10～24d。柄海鞘富集金属的同时，这些金属离子也对柄海鞘的代谢产生了一定的影响，其中实验浓度的Cd²⁺、Pb²⁺、Zn²⁺均会使柄海鞘的耗氧率降低，0.1mg／L的Cu²⁺对柄海鞘的呼吸代谢有一定的促进作用，高于0.5mg／L则抑制柄海鞘的呼吸代谢。低浓度的Cd²⁺（0.01mg／L）、Cu²⁺（0.1mg／L）、Zn²⁺（0.1mg／L）和Pb²⁺（0.01mg／L）可促进柄海鞘的氮排泄，而高浓度下则使柄海鞘的排氨率降低。Cd²⁺对柄海鞘的清滤率表现出浓度相关的抑制作用；Zn²⁺则表现出浓度相关的促进作用；0.1、0.5和1mg／L的Cu²⁺及0.01和0.05mg／L的Pb²⁺可以提高柄海鞘的清滤率，而2mg／L的Cu²⁺和0.2mg／L的Pb²⁺则会抑制柄海鞘的滤水作用。四种金属离子对柄海鞘的氧氮比均表现出浓度相关的抑制作用。同时，四种金属离子也会影响到柄海鞘体内的几种代谢酶的活力。四种金属离子对柄海鞘的碱性磷酸酶和Na⁺-K⁺-ATP酶活力均有浓度相关的抑制作用。柄海鞘暴露于Cd²⁺和Pb²⁺溶液后，SOD活力均表现出先降低后回升的趋势；低浓度的Cu²⁺和Zn²⁺（0.1mg／L）提高了该酶的活力，高浓度的Cu²⁺和Zn²⁺则会抑制SOD的活力。结果提示，柄海鞘可以作为近海海域重金属污染的指示物种，而以柄海鞘的几项代谢指标（O／N、碱性磷酸酶、Na⁺-K⁺-ATP酶和SOD活性）作为海域污染的生物指标，具有一定的可行性。更多还原

【Abstract】 The ingestion and metabolism of ascidian Styela clava were studied in static water system, oxygen consumption rate, ammonia-N excretion rate, filtration rate （FR）, clearance rate（CR）, ingestion rates （IR）, ingestion intension （II） and assimilation efficiency （AE） were measured under different temperatures, and the energy budget equations were established in lab. Based on the semi-static two-compartment model, the bioaccumulation of four heavy metals (Cd²⁺, Pb²⁺, Cu²⁺ and Zn²⁺) by S. clava were investigated, the kinetic parameters (K₁, K₂, BCF, B_1/2) were obtained by non-linear regression. The effects of four heavy metal ions on metabolism were discussed at the same time. The feasibility of S. clara and its metabolizable parameters were explored used as markers of heavy metal pollution in offing marine space.The study on metabolism of S. clava showed that metabolizable parameters increased with increasing individual weight as a power function R=aW^b including oxygen consumption rate, ammonia excretion rate, filtration rate（FR）, clearance rate（CR）, ingestion rate（IR） and ingestion intensity（II）; Oxygen consumption rate increased with increasing temperature, while peaks were found in the range of 20～24℃for ammonia excretion rate, FR, CR, IR, II and AE.The study of food selection indicated S. clava had selectivity to the sizes of particles and could retain more particles around 6μm. In low concentration range, FR and IR of S. clara increased with increasing algal cell concentrations as described by the equation R=aW^b until 10 mg POM·L^-1. Within the range of diet concentration from 2.11 to 20.12 mg POM·L^-1, the relationships between POM and CR as well as IR changed to quadratic as R=aC²+bc+c.The study of energy budget revealed that routine metabolism of S. clava with same size was obviously higher than standard metabolism at different temperatures, oxygen consumption rate increased by 16.7～34.9％, while ammonia excretion rate increased by 34.0～61.9％. Ingestion energy, absorption energy, metabolism energy, excretion energy and feces energy all increased with increasing body weight at different temperatures. Respiration energy increased with increasing temperature within the range of temperature from 12℃to 28℃, but critical values were found at 20～24℃for energy of ingestion and absorption, and energy in feces and excretion. In the energy budget equations of different sized ascidians obtained at different temperatures, excretion energy shared a minimal fraction in ingestion energy （3.8～9.4％）, the ratios of feces energy and respiration energy to ingestion energy were 27～54％and 10～78％, respectively. The proportion of various energies changed with temperature.S.clava could accumulate heavy metals, and its accumulative action of Cd²⁺ was distinctly higher than that of Pb²⁺ and Zn²⁺, while the accumulation of Cu²⁺ was quite small. The absorbing rate constant k₁ of four heavy metals increased with increasing metal concentration in water as well as bioaccumulation factors （BCF）. When the accumulation achieved balance, metal concentrations in organism showed positive correlation to metal concentrations in water. Concentrations of four metals in different organs of S. clava were in the order: germen＞digest gland＞others＞crust. The biological half-life (B_1/2) of four heavy metals were 10～24 days.S. clara’s metabolism was influenced by heavy metal ions at the same time of accumulation. Cd²⁺, Zn²⁺ and Pb²⁺ could depress oxygen consumption rate of S. clava, 0.1mg/L Cu²⁺ could improve its respiratory metabolism, while restraint effect occurred when the concentration of Cu²⁺ exceeded 0.5mg/L. Ammonia excretion rates increased in 0.01mg/L Cd²⁺、0.1mg/L Cu²⁺、0.1mg/L Zn²⁺ and 0.01mg/L Pb²⁺, while obvious depress was observed when S. clara discovered in high concentration of metal. Cd²⁺ exhibited controlling effects on filtration rate of S. clava with concentration correlation, while Zn²⁺ boost FR with concentration correlation; 0.1, 0.5, 1 mg/L Cu²⁺ and 0.01, 0.05mg/L Pb²⁺ enhanced FR while 2 mg/L Cu²⁺ and 0.2mg/L Pb²⁺ depressed FR. Four heavy metals all showed restraining effect on O:N with concentration correlation.The four metal ions could affect energy of metabolizing enzymes in S. clara. Cd²⁺, Pb²⁺, Cu²⁺ and Zn²⁺ could depress the activities of alkaline phosphatase （AKP） and Na⁺-K⁺-ATPase with concentration correlation. The activities of SOD descended immediately and then increased again when S. clara exposed to Cd²⁺ and Pb²⁺. Cu²⁺ and Zn²⁺ could increase the activities of SOD at low concentrations, while restrain its activities at higher concentrations.The results suggested that S. clava and its metabolism parameters （O/N, AKP, Na⁺-K⁺-ATPase and SOD） could be used as markers of heavy metal pollution in offing marine space.更多还原