Using population demographic parameters to assess impacts of two @entity13727 ( XXXX , @entity13729 ) on the rotifer @entity29171 .

@entity13729 @entity137 @entity13727 @entity29171 @entity13728 @entity20062
@entity13727 ( @entity13727 ) are highly persistent anthropogenic contaminants found in the environment, posing a risk to aquatic ecosystems, whereas there is a lack of data concerning their impacts on marine invertebrates. The objective of this study was to assess the relative lethal and sublethal @entity137 effects of two @entity13727 , @entity20062 and @entity13729 congeners, on marine zooplankton rotifer @entity29171 associated with @entity13728 concentrations and time of exposure. Gas chromatography-mass spectrometry (GC-MS) analyses were performed to determine actual @entity13728 concentrations. Rotifer population demographic parameters from life tables, including age-specific survivorship (lx), age-specific fecundity (mx), net reproductive rate (R0), intrinsic rate of increase (rm), finite rate of increase (  ), life expectancy (E0) and generation time (T), were used as measures of treatment effects. Results from this study have revealed increasingly intense negative effects on many of the rotifer demographic parameters with elevated @entity13728 concentrations. The population growth curves of @entity29171 showed almost no lag phase and reached peak abundances within 11 days, while @entity29171 exposed to @entity13729 had a lag phase of about 5 days. In addition, increased @entity13728 levels reduced the population abundances and peak population densities of @entity29171 . The two @entity13727 have caused the carrying capacity (K) suppressed and the negative influence turned more serious as the concentration rose. Results also revealed that the time to reach growth curve inflection point (Tp) was shortened by @entity13727 to different degrees. This study not only indicated that life table demography and population growth curve studies were two important aspects used to evaluate toxicant @entity13728 effects, but also compared the two @entity13728 disruptions to the population growth and reproduction of the rotifer.
