379
DWH (2010) sediment interval (~10 mm depth). This suggested that the DWH interval, deposited in 2010, was buried by subsequent sedimentation of a sedimentary
organic carbon source similar to the source prior to DWH (Schwing et al. 2018a).
23.3 The Ixtoc 1 Oil Spill
23.3.1 Event Background
The Ixtoc 1 oil spill occurred over a period of 290 days in 1979–1980 at 51 meters
water depth (Jernelov and Linden 1981). The wellhead was located 80 km NW of
Ciudad del Carmen, Mexico, and released a total of 475 million liters of oil into the
southern GoM (Jernelov and Linden 1981). Approximately 50% of the spilled oil
evaporated (NOAA Oil Budget Calculator 2011), and 120,000 metric tons of oil
were deposited on the seafloor in the months following the event (Jernelov and
Linden 1981).
MOSSFA has been well documented following DWH in the northern GoM in
2010 (Thibodeaux et al. 2011; Passow et al. 2012; Ziervogel et al. 2012; Paris and
Hénaff 2012; Passow 2014; Brooks et al. 2015; Daly et al. 2016; Romero et al.
2017; Schwing et al. 2017a, Schwing et al. 2018b). Further, MOSSFA formation is
predicated on the presence of petroleum, dispersants, bacteria, phytoplankton, and
clay minerals (Daly et al. 2016). The area surrounding the Ixtoc 1 wellhead satisfies
each of these criteria. Vonk et al. (2015) suggest that MOSSFA was likely to have
occurred during Ixtoc 1 due to the particulate matter, algae, dispersants, and bacterial communities present. Gracia et al. (2013) documented the introduction of a
significant amount of suspended solids into the GoM from surrounding rivers, especially during the summer, a high-precipitation season. The duration of Ixtoc 1 coincided with the high-precipitation season. The setting for Ixtoc 1 supports the
occurrence of MOSSFA.
11
12
13
14
15
16
17
18
19
20
2011 2012 2013 2014 2015
2.3
2.5
2.7
2.9
3.1
3.3
3.5
2011 2012 2013 2014 2015
0
50
100
150
200
2011 2012 2013 2014 2015
Fishers Alpha Index
Species Richness (S)
Shannon Index
Heterogeneity (H)
Density
(indiv./cm 3 )
Fig. 23.3 Mean Fisher’s alpha index, Shannon index, and density (individuals/cm
3 ) for benthic
foraminifera from seven sites in the northern Gulf of Mexico from 2011 to 2015 consistent with
resilience rates of 3–5 years to achieve a steady state following the DWH event
23 Impact and Resilience of Benthic Foraminifera in the Aftermath of the Deepwater…
DWH (2010) sediment interval (~10 mm depth). This suggested that the DWH interval, deposited in 2010, was buried by subsequent sedimentation of a sedimentary
organic carbon source similar to the source prior to DWH (Schwing et al. 2018a).
23.3 The Ixtoc 1 Oil Spill
23.3.1 Event Background
The Ixtoc 1 oil spill occurred over a period of 290 days in 1979–1980 at 51 meters
water depth (Jernelov and Linden 1981). The wellhead was located 80 km NW of
Ciudad del Carmen, Mexico, and released a total of 475 million liters of oil into the
southern GoM (Jernelov and Linden 1981). Approximately 50% of the spilled oil
evaporated (NOAA Oil Budget Calculator 2011), and 120,000 metric tons of oil
were deposited on the seafloor in the months following the event (Jernelov and
Linden 1981).
MOSSFA has been well documented following DWH in the northern GoM in
2010 (Thibodeaux et al. 2011; Passow et al. 2012; Ziervogel et al. 2012; Paris and
Hénaff 2012; Passow 2014; Brooks et al. 2015; Daly et al. 2016; Romero et al.
2017; Schwing et al. 2017a, Schwing et al. 2018b). Further, MOSSFA formation is
predicated on the presence of petroleum, dispersants, bacteria, phytoplankton, and
clay minerals (Daly et al. 2016). The area surrounding the Ixtoc 1 wellhead satisfies
each of these criteria. Vonk et al. (2015) suggest that MOSSFA was likely to have
occurred during Ixtoc 1 due to the particulate matter, algae, dispersants, and bacterial communities present. Gracia et al. (2013) documented the introduction of a
significant amount of suspended solids into the GoM from surrounding rivers, especially during the summer, a high-precipitation season. The duration of Ixtoc 1 coincided with the high-precipitation season. The setting for Ixtoc 1 supports the
occurrence of MOSSFA.
11
12
13
14
15
16
17
18
19
20
2011 2012 2013 2014 2015
2.3
2.5
2.7
2.9
3.1
3.3
3.5
2011 2012 2013 2014 2015
0
50
100
150
200
2011 2012 2013 2014 2015
Fishers Alpha Index
Species Richness (S)
Shannon Index
Heterogeneity (H)
Density
(indiv./cm 3 )
Fig. 23.3 Mean Fisher’s alpha index, Shannon index, and density (individuals/cm
3 ) for benthic
foraminifera from seven sites in the northern Gulf of Mexico from 2011 to 2015 consistent with
resilience rates of 3–5 years to achieve a steady state following the DWH event
23 Impact and Resilience of Benthic Foraminifera in the Aftermath of the Deepwater…