Cellular oxidative stress may promote damage or death in biological systems and may be caused by production of pro-oxidant molecules known as reactive oxygen species (ROS). , 1987), a gill chamber parasite known for its capacity to cause host metabolic changes, including changes in oxygen consumption rates. Infested and non-infested shrimp were collected in the Patos Lagoon estuary (southern Brasil), where the prevalence of the paraslte may be as high as 70%. No significant differences were observed for either CAT or GPx activities However, SOD activity was significantly reduced in lnfected shrimp, suggesting that bopyrid isopod respiratory impairment resulted in reduced SOD enzyme activity

Pigment dispersion in chromatophores as a response to UV radiation was investigated in two species of crustaceans, the crab Chasmagnathus granulata and the shrimp Palaemonetes argentinus. Eyestalkless crabs and shrimps maintained on either a black or a white background were irradiated with different UV bands. In eyestalkless crabs the significant minimal effective dose inducing pigment dispersion was 0.42 J/cm(2) for UVA and 2.15 J/cm(2) for UVB. Maximal response was achieved with 10.0 J/cm(2) UVA and 8.6 J/cm(2) UVB. UVA was more effective than UVB in inducing pigment dispersion. Soon after UV exposure, melanophores once again reached the initial stage of pigment aggregation after 45 min. Aggregated erythrophores of shrimps adapted to a white background showed significant pigment dispersion with 2.5 J/cm(2) UVA and 0.29 J/cm(2) UVC. Dispersed erythrophores of shrimps adapted to a black background did not show any significant response to UVA, UVB or UVC radiation. UVB did not induce any significant pigment dispersion in shrimps adapted to either a white or a black background. As opposed to the tanning response, which only protects against future UV exposure, the pigment dispersion response could be an important agent protecting against the harmful effects of UV radiation exposure.

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