Immunological and health-state parameters in the Patagonian rockfish Sebastes oculatus. Their relation to chemical stressors and seasonal changes

SUEIRO, M. C.; AWRUCH, C.; PALACIOS, M. G.

Buenos Aires

Congreso; Society of Environmental Toxicology and Chemistry (SETAC) - Latinamerican 11th Biennial Meeting; 2015

Fish inhabiting urbanandindustrialized coastal areas are often exposed to high levels of complexmixesof anthropogenic pollutants. This exposure can lead to decreased diseaseresistance,with immunosuppression hypothesized as the main mechanism by whichtoxicantsmediate this decline. We present the results of a field study thatevaluates whetherexposure to anthropogenic pollution impacts immunological andhealth-stateparameters of wild marine fish in the Peninsula Valdes region (anUNESCONatural World Heritage area) during the breeding and non-breedingperiods. We assessed aspects of constitutive innate immunity (bactericidalcompetence, naturalantibodies, and leukocyte profile) and general health-relatedparameters (neutrophil to lymphocyte ratio, hematocrit, and condition factor) inthe rockfish Sebastesoculatus. Individuals were sampled from polluted (exposed) andreference (control) sites during winter (i.e.,coolest temperatures and activereproductive period) and in summer (i.e., warmest temperatures andnon-reproductive period). Bactericidal competence, hematocrit,and conditionfactor were lower in fish from exposed sites independently of season. There wasno effect of site or season on the percentages of neutrophils and monocytes,whereas lymphocytes were higher at the exposed site only during summer. Naturalantibodies were not affected by exposure to pollutants. The mechanisms involvedin altered immune and health-related parameters associated with living inpolluted sites could be elicited directly by toxicants, indirectly by stresshormones, or by a combination of both. In addition, fish sampled during winterdisplayed lower bactericidal competence, hematocrit, and condition factor thanthose sampled in summer independently of site, whereas the opposite pattern wasfound for natural antibodies. These results could be explained bylife-history theory, which predicts a re-allocation of resources between reproductionand other physiological functions (including immunity) during the mostenergetically demanding season. In conclusion, our findings show an alterationin immunological and health-state parameters of wild marine fish exposed toanthropogenic pollution independently of season, which could potentially resultin higher susceptibility to disease and in turn population decline. Futurestudies will include an experimental approach and aspects of acquired immunity.