There is no author summary for this article yet. Authors can add summaries to their articles on ScienceOpen to make them more accessible to a non-specialist audience.
Abstract
The role of algal concentration in the transfer of organic contaminants in a food
chain has been studied using the ubiquitous model polycyclic aromatic hydrocarbon
benzo[a]pyrene (BaP) as the contaminant, Isochrysis galbana as the phytoplankton food
source, and the common mussel (Mytilus edulis) as the primary consumer. The effect
of algal concentration on BaP uptake by M. edulis was determined by feeding M. edulis
daily with I. galbana which had previously been kept in the presence of BaP for 24
h. Four combinations of concentrations of algae and BaP were used to give final exposure
concentrations of 30,000 or 150,000 algal cells ml(-1) in combination with either
2 or 50 microg BaP l(-1). BaP concentrations were determined fluorometrically in rest
tissues (excluding digestive glands) and digestive gland microsomal fractions of M.
edulis after 1, 7 and 15 days exposure, and also in isolated algae. Potentially toxic
effects of BaP on M. edulis were examined in terms of blood cell lysosomal membrane
damage (neutral red dye retention assay) and induction of digestive gland microsomal
mixed-function oxygenase (MFO) parameters [BaP hydroxylase (BPH) and NADPH-cytochrome
c (P450) reductase activities]. BaP bioaccumulation in rest tissues (and to a lesser
extent in digestive gland microsomes) of M. edulis increased with both increasing
BaP and algal exposure concentrations, and over time, producing maximal bioconcentration
factors in rest tissues after 15 days exposure to 150,000 algal cells ml(-1) and 50
microg BaP l(-1) of 250,000. The five-fold higher concentration of algae increased
BaP bioaccumulation by a factor of approximately 2 for 50 microg BaP l(-1) at day
15. Blood cell neutral red dye retention time decreased linearly with increasing log(10)
tissue BaP body burden, indicating an increased biological impact on M. edulis with
increasing BaP exposure possibly due to a direct effect of BaP on blood cell lysosomal
membrane integrity. An increase was seen in NADPH-cytochrome c reductase activity,
and indicated in BPH activity, with 1 but not 7 or 15 days exposure to BaP, indicating
a transient response of the digestive gland microsomal MFO system to BaP exposure.