Dispersal

Timing of larval dispersal from individual families (2007)

Larval lake sturgeon varied in dispersal time, ranging from 5-36 days (n = 833 observations). Dispersal time was significantly different among three groups of larvae whose parental females spawned in early, later or latest in the season. Temperature- dependence of larval dispersal time was expressed as the cumulative thermal unit (CTU), averaged 314 ± 84 degree-day (n=833). Difference in CTU among larval groups indicated that dispersal time did not only depend on water temperature but also on when a larva was produced. Water discharge and spawning date associated with temperature were equally important predictors of larval dispersal time.

Dispersal Timing Graph

 

 

Larval Capture Chart

 

Dispersal and Temperature Graph

 

Dispersal and Flow Graph
  • Multiple peaks in numbers of larvae captured generally correspond to different peaks in numbers of spawning adults
  • Environmental features such as water temperature and flow are predictive of dispersing larval numbers

 

Section SeparatorSection SeparatorSection Separator

 

 

 

 

Experimental design used to estimate rates of mortality of larvae from different females. Two locations were used for larval sampling.  Larvae were collected at upstream and down stream sites below the spawning areas.  Genetic data were used to determine parentage and thus the numbers of larvae from each female andrates of loss per adult female.

Dispersal Experimental Design
Larval Size Chart

 

 

 

Larval size at the time of dispersal.  Paired sizes represent larvae collected at upstream and down stream nets.  Red and black boxes indicate nights where significantly smaller or larger larvae were collected in downstream nets indicating differential survival by body size.

 

 

Mean and standard deviation of embryonic and larval developmental time until dispersal among siblings from the same female parent. Dispersal duration indicates the period that siblings from the same female stay in the spawning areas. Dispersal duration across families varied from 2 to 17 days (n = 55 families). Females whose offspring dispersed for longer periods were those had higher number of offspring.

Larval Dispersal Chart

 

Larval Hourly Dispersal Graph

 

 

 

 

 

 

Hourly pattern of larval dispersal based on collections at sampling site D1 on 2 nights (May 28 and 29). Larval numbers are cumulative totals over all females spawning at upstream (Site B) and downstream (Site C) locations (Duong et al. 2011).

 

 

Proportions of offspring produced by each female estimated based on collections at two larval sampling sites on two consecutive sampling nights. Female ID includes reference to spawning locations (B vs. C) and are presented in order of spawning date (Duong et al. 2011).

 

May28 Sample Chart

 

May29 Sample Chart

 

Larval Loss Chart

 

 

 

Relative larval loss among females (bars represent 1SD between two nights). The order of females was as the same as in the figure above.(Duong et al. 2011).