Laboratory experiments and field studies were conducted to investigate lysosomal destabilization, a biomarker of cellular damage, in bivalves (e.g., mussels, oysters) exposed to environmental contaminants [e.g., polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), organochlorine pesticides, tributyltin (TBT), metals].

In order to test the usefulness of lysosomal destabilization, oysters (Crassostrea virginica) were collected along a contamination gradient in Galveston Bay, Texas. A strong positive correlation (r^2 = 0.78) was observed between lysosomal destabilization and body burden of organic contaminants in oysters. Lysosomal destabilization assay was further evaluated as part of the large scale biomonitoring, NOAA¡¯s NS&T ¡°Mussel Watch¡± Project. Results indicated that lysosomal destabilization was greater than 50% (less healthy) at sites where organic contaminants or metals exceed the ¡°high¡± concentration (mean + SD) obtained from the NS&T Year 14 Mussel Watch data. Lysosomal destabilization and chemical concentrations showed better correlation when multiple contaminants were considered together.

To investigate recovery of lysosomal destabilization, oysters from a contaminated site were placed in clean aquariums. After 23 days of depuration, lysosomal destabilization returned to healthy levels (34%). The lysosomal recovery is likely related to the elimination of stress caused by PAHs, PCBs, DDTs, and chlordanes, or other contaminants (e.g., metals). In residue-response experiment, the lysosomal destabilization and PAH concentrations in oysters showed a positive relationship (r^2 = 0.89). Critical body residue of PAHs, in terms of lysosomal destabilization, was found at around 1,100 ng/g, which is 200 -700 times lower than reported chronic lethal body burdens. Bioconcentration factors had a better linear relationship with membrane-water partition coefficients than with octanol-water partition coefficients.

Lysosomal destabilization in bivalves showed a positive relationship with body burdens of contaminants. This indicates that lysosomal membranes are damaged by contaminants and that this method can serve as an early warning tool to assess ecosystem health. When degraded areas are detected with lysosomal destabilization, more expensive chemical analysis or sophisticated biological measurements can be used to determine possible causative agents.