The combined effects of chemical and natural stressors on phosphagens and nonspecific immunity in two species of abalone.

摘要

While considerable information exists regarding the toxicity of xenobiotics for invertebrates in terms of lethality, comparatively little is known of the more subtle effects of chronic exposure to sublethal doses of toxicants. While concentrations of pollutants may be sufficiently high to cause acute injury or death, it is more likely that toxicants are present in low concentrations and have sublethal effects on aquatic organisms possibly predisposing them to debilitating disease. By examining phosphagen concentrations after exposure to sublethal levels of pentachlorophenol (PCP), it is possible to elucidate the subtle alterations in energy regulation vital for the survival of any organism. PCP is an EPA priority pollutant that is a potent biocide. PCP induced reduction in energy production might effect an organism's ability to forage, reproduce, and defend against predators as well as endure adverse environmental conditions. This thesis initially addresses how exposure to PCP combined with salinity stress effects concentrations of phosphagens among red ( Haliotis rufescens) and black abalone (Haliotis cracherodii ) using in vivo 31P NMR Spectroscopy. Black abalone have greater overall resistance to PCP exposure and salinity variations as confirmed by 14C PCP uptake analysis demonstrating their slower uptake of the biocide.;This study continues by examining how sublethal exposure to this biocide might effect an organisms ability to defend itself from microorganisms. Phagocytic and chemotactic function after in vivo exposure of abalone to PCP and salinity stress was examined. Black abalone demonstrate greater phagocytic ability overall as it took black abalone nearly twice as long to manifest toxic effects of PCP on phagocytic and chemotactic ability. High salinity, particularly in combination with PCP, had a dramatic effect on both species of abalone.;Mechanisms employed to kill microorganisms among abalone were examined including the quantification of reactive oxygen intermediates (ROIs). While exposure of red abalone to salinity variations plus PCP caused a stimulatory effect on ROI production the same exposure parameters caused an inhibitory effect on ROI production among black abalone. As aquatic organisms are rarely exposed to one stress at a time the research performed here has contributed to the understanding of the impacts of multiple environmental stresses.