This study examines the occurrence, distribution and storage of selenium in seagrass
communities of Lake Macquarie, which is a heavily industrialised area of NSW, where
notably high trace metal concentrations have been reported previously. Initially a suite
of organisms was collected from a seagrass bed (Zostera capricornia) in the southeastern
section of the lake to investigate the bioaccumulation and biomagnification of
selenium. All organisms contained selenium, with sediment-dwelling organisms
containing the highest Se concentrations. No consistent pattern of significant Se-metal
correlations with Cu, Zn and Cd was found. Biomagnification of Se was evident, as
concentrations increased from sediments and water to flora (algae and seagrass) to
bivalves to Crustacea. However, this trend was not continued to the higher trophic
groups of invertebrate predators and teleost fish.
The bivalve Anadara trapezia was further studied. Intrinsic and extrinsic factors
affecting the accumulation of Se were examined. Gender and mass were assessed in a
single day study, followed by a temporal investigation of the effect of gender,
reproductive cycle, temperature and salinity on Se accumulation. Gender had no effect
on the accumulation of Se in A. trapezia. Se was present in all tissues (adductor,
blood, foot, gills, intestine and mantle) and not immobilised or stored in a specific
tissue, indicating that it plays a structural role in the tissues of A. trapezia. Se burden
increased relative to size (shell length and dry mass) suggesting that Se is metabolically
controlled within the organism. Se concentrations were found to fluctuate temporally
because of: food availability in response to water temperatures; the reproductive cycle;
and associated metabolic activities responding to temperature changes and food
availability.
Subcellular selenium associations in A. trapezia were examined to assist in the
understanding of the fate of Se in marine tissues. Most of the Se was associated with
proteins, suggesting that Se has a metabolic role in this marine organism. Proteins
are intrinsically associated with the lipid bilayer of the cell membranes. A number of
proteins (94, 85, 43, 36.5, 30, 23.4, 17.4 and 15 kDa) were separated by SDS PAGE
from ethanol fractions. Determination of the Se concentration within individual
proteins was not possible because the ratio of Se to protein was too low for further
analysis.
These findings indicated that Se plays a metabolic role in the tissues of the marine
organism A. trapezia. The biochemical regulatory mechanism responsible for
maintaining Se concentrations within the tissues is currently unknown.
| Identifer | oai:union.ndltd.org:ADTP/219062 |
| Date | January 1999 |
| Creators | Jolley, Dianne F., n/a |
| Publisher | University of Canberra. Applied Science |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | ), Copyright Dianne F. Jolley |
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