392
whereas red snapper larvae were in poorer condition both during and after the spill
(2010, 2011, and 2013) as compared to larvae collected in years prior (2007–2009;
Ransom et al. 2016; Hernandez Jr et al. 2016). Studies are lacking on larval abundance of commercial species post Ixtoc 1; however, zooplankton biomass decreased
four orders of magnitude post-spill, and changes in the structure and organization of
zooplankton communities with a lower level of stability were detected (Guzmán del
Próo et al. 1986).
Laboratory studies exposing both model species and non-model species at environmentally relevant water concentrations (ΣPAH 3–14 μg/L) demonstrate adverse
cardiovascular responses of teleost embryos to petroleum-derived PAHs consistent
with field observations (Incardona et al. 2014). Exposures <15 μg/L resulted in
cardiotoxicity in large pelagic species (i.e., yellowfin tuna, Thunnus albacares;
bluefin tuna, Thunnus thynnus; and yellowtail amberjack, Seriola lalandi), suggesting that the survival of embryos and/or larvae will be potentially reduced in GoM
waters containing just a few micrograms of PAHs per liter. Moreover, Dubansky
et al. (2013) exposed Gulf killifish (Fundulus grandis) embryos to field-collected
sediments (~30–325 μg/g ΣPAH) from oil-impacted locations resulting in cardiovascular defects, delayed hatching, and reduced overall hatching success. As such,
these environmentally relevant levels could have implications for many species
within the GoM including highly valuable commercial and recreational species.
Laboratory exposure studies have also contributed evidence indicating oil exposures can result in growth declines (Kerambrun et al. 2012; Kerambrun et al. 2011;
Brewton et al. 2013; Brown-Peterson et al. 2017). However, data on the growth
impacts of oil on adult fish from field studies are generally lacking. To our knowledge, Herdter et al. (2017) were the first to evaluate the impacts of oil on the growth
rates of adult fish. They analyzed growth rates using back-calculated length-at-age
analysis from 822 field-caught red snapper otoliths collected post-DWH (2011–
2013). This study revealed significant growth declines in the dominant age groups
(4–6 years) of red snapper that were not strongly correlated with any other non-oil
spill-related environmental factors (e.g., wind, temperature, river discharge). Given
that size-at-age correlates with fecundity, changes in growth could have potential
population-level effects by negatively impacting reproduction and recruitment,
which is implicated in the declines in red snapper in years following DWH
(Murawski et al. 2018a, b; Fig. 24.1).
24.3 Diet and Trophic Level Shifts
The direct oiling of marine resources (i.e., phytoplankton, zooplankton, fish, birds,
and marine mammals) can result in adverse impacts on their abundances throughout
the water column, consequently altering food web trophic structures. The EVOS
resulted in delayed long-term trophic cascade effects that were in some cases devastating (Peterson et al. 2003; Harwell and Gentile 2006). The Gulf of Alaska kelp
ecosystem, comprised of killer whales (Orcinus orca), sea otters (Enhydra lutris),
E. L. Pulster et al.
whereas red snapper larvae were in poorer condition both during and after the spill
(2010, 2011, and 2013) as compared to larvae collected in years prior (2007–2009;
Ransom et al. 2016; Hernandez Jr et al. 2016). Studies are lacking on larval abundance of commercial species post Ixtoc 1; however, zooplankton biomass decreased
four orders of magnitude post-spill, and changes in the structure and organization of
zooplankton communities with a lower level of stability were detected (Guzmán del
Próo et al. 1986).
Laboratory studies exposing both model species and non-model species at environmentally relevant water concentrations (ΣPAH 3–14 μg/L) demonstrate adverse
cardiovascular responses of teleost embryos to petroleum-derived PAHs consistent
with field observations (Incardona et al. 2014). Exposures <15 μg/L resulted in
cardiotoxicity in large pelagic species (i.e., yellowfin tuna, Thunnus albacares;
bluefin tuna, Thunnus thynnus; and yellowtail amberjack, Seriola lalandi), suggesting that the survival of embryos and/or larvae will be potentially reduced in GoM
waters containing just a few micrograms of PAHs per liter. Moreover, Dubansky
et al. (2013) exposed Gulf killifish (Fundulus grandis) embryos to field-collected
sediments (~30–325 μg/g ΣPAH) from oil-impacted locations resulting in cardiovascular defects, delayed hatching, and reduced overall hatching success. As such,
these environmentally relevant levels could have implications for many species
within the GoM including highly valuable commercial and recreational species.
Laboratory exposure studies have also contributed evidence indicating oil exposures can result in growth declines (Kerambrun et al. 2012; Kerambrun et al. 2011;
Brewton et al. 2013; Brown-Peterson et al. 2017). However, data on the growth
impacts of oil on adult fish from field studies are generally lacking. To our knowledge, Herdter et al. (2017) were the first to evaluate the impacts of oil on the growth
rates of adult fish. They analyzed growth rates using back-calculated length-at-age
analysis from 822 field-caught red snapper otoliths collected post-DWH (2011–
2013). This study revealed significant growth declines in the dominant age groups
(4–6 years) of red snapper that were not strongly correlated with any other non-oil
spill-related environmental factors (e.g., wind, temperature, river discharge). Given
that size-at-age correlates with fecundity, changes in growth could have potential
population-level effects by negatively impacting reproduction and recruitment,
which is implicated in the declines in red snapper in years following DWH
(Murawski et al. 2018a, b; Fig. 24.1).
24.3 Diet and Trophic Level Shifts
The direct oiling of marine resources (i.e., phytoplankton, zooplankton, fish, birds,
and marine mammals) can result in adverse impacts on their abundances throughout
the water column, consequently altering food web trophic structures. The EVOS
resulted in delayed long-term trophic cascade effects that were in some cases devastating (Peterson et al. 2003; Harwell and Gentile 2006). The Gulf of Alaska kelp
ecosystem, comprised of killer whales (Orcinus orca), sea otters (Enhydra lutris),
E. L. Pulster et al.