Effects of natural and anthropogenic stressors on lysosomal destabilization in oysters Crassostrea virginica

Abstract

ABSTRACT-Lysosomal destabilization indices (based on a neutral red retention assay) were evaluated for digestive gland cells of oysters Crassostrea virginica. Laboratory studies were conducted to evaluate the effects of variable salinity regimes (a natural stressor) and copper exposures (a pollutant stres-SOT) on lysosomal destabilization. Field studies were also conducted with native oysters and hatcheryreared juvenile oysters deployed in situ at reference and polluted sites. Lysosomal integrity was not affected by either short-term or longer-term variations in salinity during laboratory experiments, and the destabilization indices were similar to those of deployed and native oysters from reference sites characterized by a range of salinlties. However, laboratory Cu exposures (ranging from 2.5 to 20 pg Cu 1-') caused significant adverse effects on lysosomal destabilization after only 18 h, and the eiiecis were sustained or worsened with increasing exposure time and concentration. Hatchery-reared oysters deployed at or native oysters collected from polluted sites had significantly higher lysosomal destabilization indices. Estuanne habitats are characterized by variable sal~nity regimes, so cellular responses that are sensitive to salinity stress as well as contaminant stress would be difficult to interpret if salinity effects cannot be distinguished from pollutant effects. A robust biomarker of anthropogenic effects should be insensitive to natural stressors such as salinity, but should be sensitive to pollutants. The salinity and contaminant studies described in this paper indicate that lysosomal destabilization responses in oysters are insensitive to salinity variations and sensitive to pollutants, and are therefore potentially valuable biomarkers of anthropogenic stress.

It’s All in the Genes: How Genotype Can Impact Upon Response to Contaminant Exposure and the Implications for Biomonitoring in Aquatic Systems

“…In this study, C. virginica exposed to high salinities as well as copper solutions displayed higher levels of lysosomal destabilisation than control organisms. These results were also congruent with field studies of C. virginica deployed in contaminated estuarine sediments (Ringwood et al, 1998).…”

“…An example is the destabilisation of lysosomes in the oyster, Crassostrea virginica exposed to environmental stressors (Ringwood et al, 1998). Lysosomes are considered to be sensitive organelles to contaminant-induced stress as they are involved in a host of cellular repair and defence functions.…”

“…Other aquatic sentinel species include fish, frogs, molluscs, copepods and water fleas (e.g. Matson et al, 2006;Poynton et al, 2008;Rinner et al, 2011;Ringwood et al, 1998;Schizas et al, 2001). …”

Clearance effects of the Pacific oyster Crassostrea gigas on the fish-killing algae Chattonella marina and Chattonella antiqua

“…Direct exposure to C. subsalsa caused lysosome destabilization of C. virginica, as did exposure to at least 1 Chattonella toxin, brevetoxin (Keppler et al 2006). Lysosome damage can affect the ability of cells to survive various stressors, because this organelle is involved in cell defense and repair (Ringwood et al 1998). However, the lysosomal destabilization is a sensitive physiological indicator of several types of stressors in oysters in both field and laboratory settings (Ringwood et al 1998).…”

“…Lysosome damage can affect the ability of cells to survive various stressors, because this organelle is involved in cell defense and repair (Ringwood et al 1998). However, the lysosomal destabilization is a sensitive physiological indicator of several types of stressors in oysters in both field and laboratory settings (Ringwood et al 1998). Therefore, it is uncertain whether the lysosomal destabilization of oysters observed by Keppler et al (2006) was caused by C. subsalsa brevetoxin or the other stressors during incubation.…”