title: Effects of Cd and Zn on oxygen consumption and ammonia excretion in sipuncula (Phascolosoma esculenta).
abstract: Physiological responses (oxygen consumption and ammonia excretion) of the sipuncula (Phascolosoma esculenta) exposed to four concentrations of Cd (0.45, 0.96, 2.04, and 4.46 mg L(-1)) and four concentrations of Zn (1.09, 2.34, 4.96, and 10.91 mg L(-1)) were monitored for 21 days, respectively. Oxygen consumption rates of sipuncula at all concentrations of Cd decreased from day 1 to day 6. At low concentrations of Cd (0.45 and 0.96 mg L(-1)), the oxygen consumption rate was promoted. Time and concentration were significant in affecting oxygen consumption rate, respectively. Oxygen consumption rate decreased significantly with time for Zn-exposed individuals and also decreased significantly with the interaction between the concentration of Cd and time for Cd-exposed individuals. Changes occurred in the ammonia excretion rates and O:N ratios with individual sipuncula experiencing different metal concentrations over time. Although low O:N ratios (<30) were obtained in most of the treatments, no predictable correlation was found between concentrations of metals and values of O:N obtained. The value of using O:N ratio as a stress index is questioned.
authors.affiliation: State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen 361005, China.
authors.forename: XiXiang
authors.initials: X
authors.lastname: Chen
authors.forename: ChangYi
authors.initials: C
authors.lastname: Lu
authors.forename: Yong
authors.initials: Y
authors.lastname: Ye
mesh_terms: D000641:Ammonia / Q000378:metabolism*; D000818:Animals; D002104:Cadmium / Q000378:metabolism / Q000633:toxicity*; D009348:Nematoda / Q000187:drug effects* / Q000378:metabolism; D009584:Nitrogen / Q000032:analysis / Q000378:metabolism; D010100:Oxygen / Q000032:analysis / Q000378:metabolism; D010101:Oxygen Consumption / Q000187:drug effects* / Q000502:physiology; D013997:Time Factors; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*; D015032:Zinc / Q000378:metabolism / Q000633:toxicity*
chemical_list: D014874:Water Pollutants, Chemical; D002104:Cadmium; D000641:Ammonia; D015032:Zinc; D009584:Nitrogen; D010100:Oxygen