Bivalve Monitoring: Figure 4.30

Tables

Figure 4.30. Total PCB accumulation or depuration in parts per billion dry weight (ppb) in three species of transplanted bivalves for eleven sampling periods from 1993-1998 (mean of all stations). The vertical bars represent the range of values of all stations where species were deployed. Note different y-axis scales. * In 1996, the reference population of "clean" Corbicula fluminea at Lake Isabella crashed and disappeared. Despite exploring several other potential reference sites, field staff was unable to find sufficiently large populations suitable for transplantation into the Estuary. Beginning with the 1996 data, C. fluminea bioaccumulation could no longer be compared with previous years due to the initial high concentrations of some contaminants, particularly trace organics, which biases bioaccumulation estimates toward the low end. Trends could not be calculated for the 1998 dry season since M. californianus had no T-0 value..

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