Derivation of toxicity thresholds for gas condensate oils protective of tropical species using experimental and modelling approaches

Toxicity thresholds for dissolved oil applied in tropical ocean risk assessments are largely based on the sensitivities of temperate and/or freshwater species. To explore the suitability of these thresholds for tropical habitats we experimentally determined toxicity thresholds for eight tropical species for a partially weathered gas condensate, applied the target lipid model (TLM) to predict toxicity of fresh and weathered condensates and compared sensitivities of the tropical species with model predictions. The experimental condensate-specific hazard concentration (HC5) was 167 mu g L-1 total aromatic hydrocarbons (TAH), with the TLM-modelled HC5 (78 mu g L-1 TAH) being more conservative, supporting TLM-modelled thresholds for tropical application. Putative species-specific critical target lipid body burdens (CTLBBs) indicated that several of the species tested were among the more sensitive species in the TLM database ranging from 5.1 (coral larvae) to 97 (sponge larvae) mu mol g(-1) octanol and can be applied in modelling risk for tropical marine ecosystems.

Automated summary

Toxicity thresholds for dissolved oil in tropical ocean risk assessments are largely based on sensitivities of temperate and/or freshwater species. Experimental data supported the use of TLM-modeled thresholds for tropical application, and identified several tropical species as more sensitive in the TLM database, which can be utilized in modeling risk for tropical marine ecosystems.