472
species including commonly used standard test species may serve as suitable surrogates for deep ocean species. However, there are number of challenges that need
to be addressed before test species from shallow-water environments can be confidently used as surrogates for deep ocean species. Consequently, studies need to be
expanded to confirm these generalizations, including determining the influence of
low temperature and high pressure (Beyer et al. 2016; McConville et al. 2018).
27.3.2 Genomic Insights into Species Sensitivity
Impacts on gene expression following petroleum exposure in deep ocean communities are not well understood, making evaluation of some sublethal effects in these
communities additionally complex. The protected status of sea turtles and marine
mammals also limit genomic toxicity research endpoints on effects of petroleum
exposure in these taxa. Fish and invertebrates that reside in the euphotic zone elicit
different responses at the gene level to petroleum. Petroleum exposure can impact,
for example, reproductive success and cardiac function and affect stress response
sensitive genes (Whitehead et al. 2011; Incardona et al. 2014; Chiasson and Taylor
2017). Most taxa differentially express general stress markers in response to polycyclic aromatic hydrocarbon exposure (e.g., Cytochrome P450). Expression of
more specific markers (e.g., indicators of endocrine disruption) is evident in fish but
absent in, for example, crustaceans (see Portnoy et al. 2020). Genomic markers for
vertebrate aquatic species are relatively well understood, whereas markers for invertebrate species are often extrapolated from vertebrate studies and may not reflect
comparable responses between these taxa (Short et al. 2014). Early life stages are
generally more sensitive to sublethal effects than adults, but comparative genomic
sensitivity studies of oil exposure between larval and adult stages are scarce
(Whitehead et al. 2011). Genomic fingerprints due to petroleum exposure can persist for decades in an aquatic population residing in a spill area without a significant
population decline (Jewett et al. 2003).
27.4 Toxicity Extrapolation Approaches
27.4.1 Available Tools
In recent years, a number of tools and applications have been developed to help
characterize what is known about the toxicity of crude oils. One data visualization
tool that has gained acceptance in hazard assessments of chemicals, including crude
oil and spill mitigating agents such as dispersants, is the species sensitivity distribution (SSD). SSDs describe the probability distribution of the sensitivity of an assemblage of taxa to a particular chemical by ranking toxicity data (i.e., geometric mean)
M. G. Barron et al.
species including commonly used standard test species may serve as suitable surrogates for deep ocean species. However, there are number of challenges that need
to be addressed before test species from shallow-water environments can be confidently used as surrogates for deep ocean species. Consequently, studies need to be
expanded to confirm these generalizations, including determining the influence of
low temperature and high pressure (Beyer et al. 2016; McConville et al. 2018).
27.3.2 Genomic Insights into Species Sensitivity
Impacts on gene expression following petroleum exposure in deep ocean communities are not well understood, making evaluation of some sublethal effects in these
communities additionally complex. The protected status of sea turtles and marine
mammals also limit genomic toxicity research endpoints on effects of petroleum
exposure in these taxa. Fish and invertebrates that reside in the euphotic zone elicit
different responses at the gene level to petroleum. Petroleum exposure can impact,
for example, reproductive success and cardiac function and affect stress response
sensitive genes (Whitehead et al. 2011; Incardona et al. 2014; Chiasson and Taylor
2017). Most taxa differentially express general stress markers in response to polycyclic aromatic hydrocarbon exposure (e.g., Cytochrome P450). Expression of
more specific markers (e.g., indicators of endocrine disruption) is evident in fish but
absent in, for example, crustaceans (see Portnoy et al. 2020). Genomic markers for
vertebrate aquatic species are relatively well understood, whereas markers for invertebrate species are often extrapolated from vertebrate studies and may not reflect
comparable responses between these taxa (Short et al. 2014). Early life stages are
generally more sensitive to sublethal effects than adults, but comparative genomic
sensitivity studies of oil exposure between larval and adult stages are scarce
(Whitehead et al. 2011). Genomic fingerprints due to petroleum exposure can persist for decades in an aquatic population residing in a spill area without a significant
population decline (Jewett et al. 2003).
27.4 Toxicity Extrapolation Approaches
27.4.1 Available Tools
In recent years, a number of tools and applications have been developed to help
characterize what is known about the toxicity of crude oils. One data visualization
tool that has gained acceptance in hazard assessments of chemicals, including crude
oil and spill mitigating agents such as dispersants, is the species sensitivity distribution (SSD). SSDs describe the probability distribution of the sensitivity of an assemblage of taxa to a particular chemical by ranking toxicity data (i.e., geometric mean)
M. G. Barron et al.