553
found of significant long-term environmental effects linked to the Ixtoc 1 oil spill
(Soto et al. 2014; Jernelöv and Lindén 1981; Yáñez-Arancibia and Sánchez-Gil
1986; García-Cuéllar et al. 2004). Amezcua-Linares et al. (2015) estimated a
decrease in diversity and changes in fish assemblages based on fisheries independent trawling surveys conducted before and after the Ixtoc 1 oil spill. They also
identified changes in commercial fisheries landing composition pre- and post-spill
and attributed these changes to impacts on larvae survival, although recognized that
variations could also be related to ecological, biological, and economic factors
(Amezcua-Linares et al. 2015). Natural variability in the ecosystem and lack of prespill baseline information are among the factors that limit the assessment of Ixtoc 1
effects (Soto et al. 2014; García-Cuéllar et al. 2004).
Applying a spatially explicit biogeochemical end-to-end ecosystem model,
Ainsworth et al. (2018) simulated impacts from the DWH oil spill and subsequent
recovery of fish guilds. Their results suggest that recovery of high-turnover populations may occur within 10 years, but some slower-growing populations may take
30+ years to fully recover (Ainsworth et al. 2018). Here we use a similar ecosystem
model, an Atlantis model focused on the Southern Gulf of Mexico (SGoM), to simulate impacts and subsequent recovery of fish guilds in the area affected by the Ixtoc
1 oil spill. We compare our results to the simulations done for DWH in the northern
Gulf to look at fisheries and ecosystem impacts.
32.2 Methods
32.2.1 Ecological Model
Atlantis is a deterministic modeling approach that simulates the structure and functioning of marine ecosystems by integrating physical conditions (salt, heat, and
water circulation), biogeochemistry (nutrient input, detritus, and bacterial dynamics), biological processes (primary production, growth, reproduction, movement,
mortality, and predator-prey interactions), and fisheries (Fulton et al. 2004, 2011).
The SGoM Atlantis model is derived from the implementation of the Gulf of Mexico
(GoM) model described in Ainsworth et al. (2015). The primary differences between
the GoM and SGoM Atlantis models are in the polygon geometry, the partitioning
of fisheries statistics between species groups and polygons, and the inclusion of a
functional group for octopus due to the relevance of its fishery in the southern Gulf.
In the Atlantis modeling framework, ecosystems are resolved spatially in three
dimensions using an irregular 3D polygon structure that saves computation time in
homogeneous space. For the SGoM model, 42 polygons were designed to capture
important biophysical and jurisdictional features (Fig. 32.1). Bathymetry, bottom
type, sediments, and riverine discharge were taken into account. In general, the
polygons reflect the continental shelf (from shore to the 200 m isobath), slope
(200 m to 3000 m), and abyssal regions (> 3000 m). Protected areas and major
32 Comparing Ecosystem Model Outcomes Between Ixtoc 1 and Deepwater...
found of significant long-term environmental effects linked to the Ixtoc 1 oil spill
(Soto et al. 2014; Jernelöv and Lindén 1981; Yáñez-Arancibia and Sánchez-Gil
1986; García-Cuéllar et al. 2004). Amezcua-Linares et al. (2015) estimated a
decrease in diversity and changes in fish assemblages based on fisheries independent trawling surveys conducted before and after the Ixtoc 1 oil spill. They also
identified changes in commercial fisheries landing composition pre- and post-spill
and attributed these changes to impacts on larvae survival, although recognized that
variations could also be related to ecological, biological, and economic factors
(Amezcua-Linares et al. 2015). Natural variability in the ecosystem and lack of prespill baseline information are among the factors that limit the assessment of Ixtoc 1
effects (Soto et al. 2014; García-Cuéllar et al. 2004).
Applying a spatially explicit biogeochemical end-to-end ecosystem model,
Ainsworth et al. (2018) simulated impacts from the DWH oil spill and subsequent
recovery of fish guilds. Their results suggest that recovery of high-turnover populations may occur within 10 years, but some slower-growing populations may take
30+ years to fully recover (Ainsworth et al. 2018). Here we use a similar ecosystem
model, an Atlantis model focused on the Southern Gulf of Mexico (SGoM), to simulate impacts and subsequent recovery of fish guilds in the area affected by the Ixtoc
1 oil spill. We compare our results to the simulations done for DWH in the northern
Gulf to look at fisheries and ecosystem impacts.
32.2 Methods
32.2.1 Ecological Model
Atlantis is a deterministic modeling approach that simulates the structure and functioning of marine ecosystems by integrating physical conditions (salt, heat, and
water circulation), biogeochemistry (nutrient input, detritus, and bacterial dynamics), biological processes (primary production, growth, reproduction, movement,
mortality, and predator-prey interactions), and fisheries (Fulton et al. 2004, 2011).
The SGoM Atlantis model is derived from the implementation of the Gulf of Mexico
(GoM) model described in Ainsworth et al. (2015). The primary differences between
the GoM and SGoM Atlantis models are in the polygon geometry, the partitioning
of fisheries statistics between species groups and polygons, and the inclusion of a
functional group for octopus due to the relevance of its fishery in the southern Gulf.
In the Atlantis modeling framework, ecosystems are resolved spatially in three
dimensions using an irregular 3D polygon structure that saves computation time in
homogeneous space. For the SGoM model, 42 polygons were designed to capture
important biophysical and jurisdictional features (Fig. 32.1). Bathymetry, bottom
type, sediments, and riverine discharge were taken into account. In general, the
polygons reflect the continental shelf (from shore to the 200 m isobath), slope
(200 m to 3000 m), and abyssal regions (> 3000 m). Protected areas and major
32 Comparing Ecosystem Model Outcomes Between Ixtoc 1 and Deepwater...