Bioaccumulation of heavy metals in the Sydney rock oyster, saccostrea commercialis (Iredale & Roughley)
- Publication Type:
- Thesis
- Issue Date:
- 1993
Open Access
Copyright Clearance Process
- Recently Added
- In Progress
- Open Access
This item is open access.
The suitability of the Sydney rock oyster (Saccostrea commercialis) as a monitor of
heavy metal contamination in estuarine and coastal waters was assessed. Case study I
examined the influence of body size (ie: soft tissue dry weight) on the tissue
concentrations of Cu, Zn, and Fe. Sampling was replicated both spatially and temporally
in order to determine whether the size-metal relationship for these elements varied with
geographical location (ie: differing levels of environmental contamination) or season. All
oysters were collected from 'wild' populations in the HawkesburyfNepean estuary.
Least-squares regression analysis indicated that Cu concentrations were independent of
body size at all times. Analysis of covariance (ANCOVA) showed that this relationship did
not change with either geographical location or season. Size-metal relalionships for Zn
indicated that concentrations for this element varied from being independent of size to
being size-dependent with proportionally greater concentrations present in the larger
individuals. Yet lests for homogeneily of slopes (ANCOVA) showed that no differences in
regression coefficients occurred with geographical location or season. Iron
concentrations were size-dependent with proportionally greater concentrations in the
smaller individuals. ANCOVA revealed that homogeneity of slopes with geographical
location occurred only on two of the four sampling occasions. Further examination of data
revealed that the size·range of the individuals sampled may be important in determining
size-metal relationship for iron.
Case Study II examined the concentrations of Cu and Zn in S. commercialis deployed into
the Georges River/Botany Bay and the Port Stephens estuaries. The influence of tissue
assimilation/loss on metal concenlralions was also examined. Organisms of a
homogenous genetic stock, of a similar size and age, and transplanted to a similar lidal
height were utilized. As all organisms were of a similar size and age at the time of their
deployment any differences in size during sampling were attributed to growth. Results
indicated that tissue loss (ie: 'degrowth') not accompanied by a similar loss of metal
resulted in an increase in metal concentrations. The assimilation of new tissue at a
greater rate than metal accumulation (ie: 'dilution') resulted in decreased metal
concentrations. From these relationships it was apparent that measures must be taken to
reduce, account for, or eliminate the effects of growth in bivalve monitoring programs.
Unless this problem is addressed, metal concentration values in S. commercialis are
likely to give an inaccurate estimation of the level of environmenlal contamination and
confound attempts to isolate pollution point sources.
Please use this identifier to cite or link to this item: