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

MARÍA CRUZ SUEIRO; CYNTHIA AWTUCH; MARIA GABRIELA PALACIOS

Buenos Aires

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

Fish inhabiting urban andindustrialized coastal areas are often exposed to high levels of complex mixesof anthropogenic pollutants. This exposure can lead to decreased disease resistance,with immunosuppression hypothesized as the main mechanism by which toxicantsmediate this decline. We present the results of a field study that evaluates whetherexposure to anthropogenic pollution impacts immunological and health-stateparameters of wild marine fish in the Peninsula Valdes region (an UNESCONatural World Heritage area) during the breeding and non-breeding periods. We assessedaspects of constitutive innate immunity (bactericidal competence, naturalantibodies, and leukocyte profile) and general health-related parameters (neutrophilto lymphocyte ratio, hematocrit, and condition factor) in the rockfish Sebastes oculatus. Individuals were sampledfrom polluted (exposed) and reference (control) sites during winter (i.e.,coolest temperatures and active reproductive period) and in summer (i.e., warmesttemperatures and non-reproductive period). Bactericidal competence, hematocrit,and condition factor were lower in fish from exposed sites independently ofseason. There was no effect of site or season on the percentages of neutrophilsand monocytes, whereas lymphocytes were higher at the exposed site only duringsummer. Natural antibodies were not affected by exposure to pollutants. Themechanisms involved in altered immune and health-related parameters associatedwith living in polluted sites could be elicited directly by toxicants, indirectlyby stress hormones, or by a combination of both. In addition, fish sampledduring winter displayed lower bactericidal competence, hematocrit, and conditionfactor than those sampled in summer independently of site, whereas the oppositepattern was found for natural antibodies. These results could be explained by life-historytheory, which predicts a re-allocation of resources between reproduction and otherphysiological functions (including immunity) during the most energeticallydemanding season. In conclusion, our findings show an alteration in immunologicaland health-state parameters of wild marine fish exposed to anthropogenicpollution independently of season, which could potentially result in highersusceptibility to disease and in turn population decline. Future studies willinclude an experimental approach and aspects of acquired immunity.