Effects of salinity, temperature, and cadmium on cadmium-binding protein in the grass shrimp,Palaemonetes pugio

Abstract

The combined effects of salinity, temperature, and cadmium on the accumulation of cadmium-binding protein (CdBP) were studied in the grass shrimp,Palaemonetes pugio. In 96-hr bioassays, shrimp were exposed either to zero or to one of three concentrations of cadmium, under one of six different salinity and temperature regimes. Cadmium-binding protein concentrations were quantified in survivors from the 24 exposure groups. Salinity and temperature did not affect survivorship unless the shrimp were also exposed to cadmium.P. pugio produced a 10,000-dalton metallothionein-like CdBP when exposed to at least 0.1 mg Cd2+/L for 96 hr. Accumulation of CdBP was elevated when either the level of cadmium or temperature was increased or salinity was decreased. Grass shrimp surviving the salinitytemperature-cadmium conditions associated with highest mortality exhibited the highest levels of CdBP. Thus, CdBP accumulation is not only related to cadmium exposure, but can be synergistically affected by environmental factors as well. The utility of metal-binding proteins to monitor physiological stress in estuarine biota that inhabit environments polluted with heavy metals is discussed.