Changes in temperature alters the toxicity of polycyclic aromatic compounds to American lobster (Homarus americanus) larvae.

Polycyclic aromatic compounds (PACs) present in the water column are considered to be one of the primary contaminant groups contributing to the toxicity of a crude oil spill. Because crude oil is a complex mixture composed of thousands of different compounds, oil spill models rely on quantitative structure activity relationships (QSARs) like the target lipid model (TLM) to predict the effects of crude oil exposure on aquatic life. These models rely on input provided by single species toxicity studies which remain insufficient. Though the toxicity of select PACs have been well studied, there is little data available for many, including transformation products like oxidized hydrocarbons. In addition, the effect of environmental influencing factors like temperature, on PAC toxicity is a wide data gap. In response to these needs, in the present study, stage I lobster larvae were exposed to 6 different understudied PACs (naphthalene, fluorenone, methylnaphthalene, phenanthrene, dibenzothiophene, and fluoranthene) at 3 different relevant temperatures (10, 15 and 20°C) all within the biological norms for the species during summer when larval releases occur. Lobster larvae were assessed for immobilization as a sublethal effect and mortality following 3, 6, 12, 24, and 48 h of exposure. Higher temperatures increased the rate at which immobilization and morality was observed for each of the compounds tested and also altered the predicted critical target lipid body burden (CTLBB), incipient LC 50 , and elimination rate. Our results demonstrate that temperature has an important influence on PAC toxicity for this species and we provide critical data for oil spill modeling. More studies are needed so oil spill models can be appropriately calibrated and improve their predictive ability.