501
29.3.2 Noncardiac Developmental Effects on ELS
In addition to cardiac impairments, several other biological systems have demonstrated sensitivity to oil exposure. Mahi-mahi embryos exhibit yolk sac edema when
exposed to a low concentration (1.2 μg/L∑50PAH) of HEWAF for 48 hrs (Pasparakis
et al. 2016), and decrease in yolk sac depletion (nutrient uptake) was observed in
embryos exposed to higher concentrations (14.9–26.6 μg/L∑50PAH) of HEWAF
for 24 hrs (Mager et al. 2014). Other embryonic developmental impairments
observed in sheepshead minnows when exposed to 257 μg/L∑50PAH of CEWAF
for 48 hrs were retarded development and decreases in eye pigmentation and movement (Bosker et al. 2017). Both length and weight of larvae of several fish species
appeared to be influenced by exposure to CEWAF or HEWAF. Bosker et al. (2017)
observed a reduction in standard length sheepshead minnow larvae exposed for
48 hrs to 257 μg/L ∑50PAH CEWAF. A reduction in lenght was also seen in spotted seatrout exposed for 96 hrs (at much lower concentrations) of approximately
74 μg/L∑50PAH exposure solutions, whether HEWAF or CEWAF (Brewton et al.
2013), whereas a marked reduction in weight was measured in bay anchovy exposed
for 24 hrs to 0.24–1.23 μg/L ∑50PAH of CEWAF (Duffy et al. 2016). Data from
RNA-seq pathway analysis of oil-exposed larval mahi-mahi indicated that several
other biological systems were affected by a 48-h exposure to DWH source oil
(4.6 μg/L∑50PAH) or DWH slick oil (12 μg/L∑50PAH) HEWAF (Xu et al. 2016).
Particularly affected were genes involved in neurodegeneration of the central nervous system, eye degeneration, visual impairment, and abnormality of the vertebral
column. These studies highlight some of the potential consequences of oil exposure
on multiple biological systems leading to the likely increase in post-exposure
mortality.
29.3.3 Cardiac Function and Swim Performance
in Later Life Stages
While cardiotoxicity has long been a recognized effect of oil exposure in developing
fish, it was not until recently that the developed heart of adult fish was also identified
as a target for oil exposure. Yellowfin and bluefin tuna (Thunnus thynnus) myocytes
exposed to crude oil solutions showed prolonged action potentials through blockage
of the delayed rectifier potassium current and also decreased Ca
2+
current and Ca
2+
cycling leading to excitation-contraction uncoupling (Brette et al. 2014). Although
it is unknown at present how blood plasma PAH concentrations relate to environmental concentrations, the effects of PAH exposure on isolated tuna myocytes were
observed at low μg/L∑50PAH concentrations in the bathing salines, suggesting that
impacts to cardiac function may occur during environmentally realistic oil exposures. The first evidence of oil-induced impacts to cardiac function following exposures of adult GoM species came from a study exposing mahi-mahi to HEWAF
29 Digging Deeper than LC/EC50: Nontraditional Endpoints and Non-model Species…
29.3.2 Noncardiac Developmental Effects on ELS
In addition to cardiac impairments, several other biological systems have demonstrated sensitivity to oil exposure. Mahi-mahi embryos exhibit yolk sac edema when
exposed to a low concentration (1.2 μg/L∑50PAH) of HEWAF for 48 hrs (Pasparakis
et al. 2016), and decrease in yolk sac depletion (nutrient uptake) was observed in
embryos exposed to higher concentrations (14.9–26.6 μg/L∑50PAH) of HEWAF
for 24 hrs (Mager et al. 2014). Other embryonic developmental impairments
observed in sheepshead minnows when exposed to 257 μg/L∑50PAH of CEWAF
for 48 hrs were retarded development and decreases in eye pigmentation and movement (Bosker et al. 2017). Both length and weight of larvae of several fish species
appeared to be influenced by exposure to CEWAF or HEWAF. Bosker et al. (2017)
observed a reduction in standard length sheepshead minnow larvae exposed for
48 hrs to 257 μg/L ∑50PAH CEWAF. A reduction in lenght was also seen in spotted seatrout exposed for 96 hrs (at much lower concentrations) of approximately
74 μg/L∑50PAH exposure solutions, whether HEWAF or CEWAF (Brewton et al.
2013), whereas a marked reduction in weight was measured in bay anchovy exposed
for 24 hrs to 0.24–1.23 μg/L ∑50PAH of CEWAF (Duffy et al. 2016). Data from
RNA-seq pathway analysis of oil-exposed larval mahi-mahi indicated that several
other biological systems were affected by a 48-h exposure to DWH source oil
(4.6 μg/L∑50PAH) or DWH slick oil (12 μg/L∑50PAH) HEWAF (Xu et al. 2016).
Particularly affected were genes involved in neurodegeneration of the central nervous system, eye degeneration, visual impairment, and abnormality of the vertebral
column. These studies highlight some of the potential consequences of oil exposure
on multiple biological systems leading to the likely increase in post-exposure
mortality.
29.3.3 Cardiac Function and Swim Performance
in Later Life Stages
While cardiotoxicity has long been a recognized effect of oil exposure in developing
fish, it was not until recently that the developed heart of adult fish was also identified
as a target for oil exposure. Yellowfin and bluefin tuna (Thunnus thynnus) myocytes
exposed to crude oil solutions showed prolonged action potentials through blockage
of the delayed rectifier potassium current and also decreased Ca
2+
current and Ca
2+
cycling leading to excitation-contraction uncoupling (Brette et al. 2014). Although
it is unknown at present how blood plasma PAH concentrations relate to environmental concentrations, the effects of PAH exposure on isolated tuna myocytes were
observed at low μg/L∑50PAH concentrations in the bathing salines, suggesting that
impacts to cardiac function may occur during environmentally realistic oil exposures. The first evidence of oil-induced impacts to cardiac function following exposures of adult GoM species came from a study exposing mahi-mahi to HEWAF
29 Digging Deeper than LC/EC50: Nontraditional Endpoints and Non-model Species…