Legal Issues and Scientific Constraints in the Environmental Assessment of the Deepwater Horizon Oil Spill in Mexico Exclusive Economic Zone (EEZ) in the Gulf of Mexico

doi:10.4236/ijg.2013.45B007

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International Journal of Geosciences, 2013, 4, 39-45

http://dx.doi.org/10.4236/ijg.2013.45B007 Published Online September 2013 (http://www.scirp.org/journal/ijg)

Legal Issues and Scientific Constraints in the

Environmental Assessment of the Deepw ater Horizon Oi l

Spill in Mexico Exclusive Economic Zone (EEZ)

in the Gulf of Mexico

Luis A. Soto, Alfonso Vázquez-Botello

UA-Oceanic and Coastal Processes-Instituto de Ciencias del Mar y Limnología,

Universidad Nacional Autónoma de México, México, D.F., México

Email: [email protected]

Received July 2013

ABSTRACT

The largest accidental marine oil spill (4.9 million barrels) in the Gulf of Mexico (GoM) seabed (1600 m) caused by the

sinking of the Deepwater Horizon oil rig in 2010, put to the test once again the resilient capacity of the pelagic and

benthic realms of this Large Marine Ecosystem. Many are the ecological services provided by its waters (fisheries,

tourism, aquaculture and fossil fuel reserves) to neighboring countries (US, Mexico and Cuba). However, the unprece-

dented volumes of hydrocarbons, gas and chemical dispersants (Corexit) introduced in the system, represent ecological

stressors whose deleterious effects are still the subject of civil claims and scientific controversy. Presumably, the short

scale effects were confined to the Gulf’s northeastern shallow waters, and the combined actions of weathering, biode-

gradation, and oil recovery left the system almost under pre-spill conditions. Unfortunately, surface and subsurface oil

plumes were detected in the spill aftermath, and their dispersion trajectories threatened Mexico EEZ. Surface o il slicks

were detected in the pristine waters of northern Yucatán, while subsurface oil plumes from the Macondo’s well blow out

were dangerously advancing southwest towards key fishing grounds in the northwestern GoM. This disaster prompted

the Mexican government to implement an ambitious ocean monitoring program adopting a bottom-up approach focused

on building a base line for more than 42 physicochemical and biological variables for water, sediment and biota from

the continental shelf-slope region of the NW GoM. Technological constraints have precluded systematic observations in

the vast Mexican EEZ that could discriminate natural variability and oil seep emissions from antropic disturbances.

Therefore, preliminary risk analyses relied on seasonal and historical records. Two years of field observations revealed

subtle environmental changes in the studied area attributed to antropic disturbances. Waters maintained oligotrophic

conditions and zooplankton and benthic infaunal biomass were also poor. Biomarkers in sediments and biota did not

exceed EPA’s benchmarks, and sediment’s fingerprinting (δ13C) indicated marine carbon sources. Geomarkers revealed

an active transport fro m the Mississippi towa rds the NW GoM of phyllosilicates bearing a weathered oil coating. Con-

sequently, shelf and slope sediment toxicity begins to show an increasing trend in the region. The complexity of hydro-

carbons bioaccumulation and biodegradation processes in deep waters of the GoM seems to indicate that meso- and

large-scale observations may prove to be essential in understanding the capacity of the GoM to recover its ecological

stability.

Keywords: Deepwa t er Horizon; Macondo’s Oil Spill Accident; Mexic o ’s Exclusive Economic Zone; G ul f of Mexico

1. Introduction

The oil spill caused by the sinking of the Deepwater Ho-

rizon Platform (DWH) in the northern Gulf of Mexico

(GoM) is unprecedented in the history of catastrophic

events in the marine environment in both coastal and

deep-waters. The assessment of the environmental con-

sequences caused by this spill has represented a major

challenge for the scientific community of the neighboring

countries sharing the waters and resources of this Large

Marine Ecosystem.

The precise volume of oil spilled and the trajectory of

surface and subsurface oil slicks are still controversial

issues. Similarly, the persistence in time and space of

weathered oil, its by-products, and their environmental

effects, constitute major research uncertainties for most

of the current studies hitherto accomplished. In the af-

termath of the oil spill accident, the reports released by

L. A. SOTO, A. VÁZQUEZ-BOTELLO

U.S. agencies NOAA and EPA [1,2] offered to the gen-

eral public a rather optimistic assessment on the percen-

tages of recovered oil, the volume burned and evaporated

from the Macondo’s well blowout [3,4]. Nonetheless,

there was a tacit admission about the severe environ-

mental damages caused by the accumulation of oil on

shorelines of the coastal zone of the northeastern GoM.

In spite of this environmental emergency, that lasted for

more than four months, there was a consensus among

experts [5-7], that while the expected damage in the

coastal zone was not as severe as anticipated, it was rec-

ognized that the Corexit dispersant injected near the base

of the oil well, promoted the formation of subsurface

hydrocarbon plumes, whose dispersion and degradation

in the deep sea was enigmatic given our limited know-

ledge on deep water circulation of the GOM.

Under this appalling scenario, the Mexican govern-

ment implemented in the summer of 2010, an ambitious

ocean monitoring program covering its own Exclusive

Economic Zone in the GoM. Initially a bottom-up ap-

proach was adopted in a multidisciplinary research pro-

gram focused on building a base line for more than 42

physicochemical and biological variables for water, se-

diment and biota obtained from the continental shelf-

slope region of the NW GoM. The present study high-

lights the most relevant environmental issues related to

the Macondo’s oil spill from a Mexican perspective .

Background

The GoM is one of the 61 Large Marine Ecosystems

(LME) recognized on the Planet. These ecosystems are

relatively large oceanic units characterized by environ-

mental properties such as bathymetric conditions, hydro-

graphic, productivity and trophically dependent popula-

tions [8]. In the particular case of the Go M, its waters

are shared by three countries, the U.S., Mexico and Cuba,

and much of the economy of these nations revolves

around energy and fishery resources from the coastal

zone and the ocean’s seabed.

The DWH well blow out located just off the Missis-

sippi River Delta spilled for nearly 84 days, 4.3 million

barrels of crude oil and an equivalent amount of methane

gas. As part of the first mitigation procedures it was de-

cided to employ 2.1 million gallons of chemical disper-

sants both on the surface, and at the base of the well [7].

This last action provoked the formation of hydrocarbon

subsurface oil plumes [9,10], approximately 100 m wide,

with a southwest trajectory and an estimated speed of 4

NM/ day [11,12 ].

According to our own projections [13,14], based on

the surface circulation models of the waters of the GoM,

the regions most likely to receive in the mid-term, the

impact of the oil slick from the Macondo’s blowout,

were the NE and SW coasts of Mexico. Our own re-

search efforts in the first two years of monitoring were

concentrated in the NW sector of the GoM (Figure 1).

This sector of the GoM is strongly influenced by the

cyclone and/or anticyclone gyres derived from the Loop

Current. When these processes are absent in the NW

Gulf, the surface oceanic circulation is predominantly

towards the north. Gyres in the NW Gulf are known for

their significant time/space variability. The salinity and

density vertical profiles obtained in winter indicated the

intrusion of cold and more diluted water originated from

the Louisiana-Texas continental shelf.

Figure 1. A. Location of the area of study in the NW. Gulf of Mexico. The extension of Mexico’s Exclusive Economic Zone

and the approximate position of the Deepwater Horizon Platform (DWH) are indicated. B. Position of the oceanographic

stations on the continental shelf and slope of the NW Gulf of Mexico (depth scale in meters).

Exclusive

Economic Zone

DWH

Area

Study

L. A. SOTO, A. VÁZQUEZ-BOTELLO

It is worth noting to ind icate at this point the technical

difficulties involved in the identification of Macondo’s

crude oil once it was over dispersed by surface and bot-

tom currents, and exposed to weathering and biodegrada-

tion processes. This situation seems augmented by the

facts that in the GoM there are natural emission of hy-

drocarbons and gas [15]. Sometimes the geochemical

record of GoM sediments reflects a composition of veg-

etable waxes, biofilms, and weathered hydrocarbons

from subsurface natural filtrations beneath the seabed. In

the particular case of the Macondo’s blowout, the envi-

ronmental damage assessment is also magnified by mix-

ing processes and fractionating of the oil components

[16-18].

For tu nately, there is valuable oceanographic informa-

tion [13,14,19-22] available from the regions under study

(SW marine ecosystem—Campeche Sound , and th e NW

sector—continental shelf of Tamaulipas and Veracruz)

that documents the pre-spill environmental conditions of

the GoM.

2. Main Oceanographic Features in Mexico’s

EEZ: NW Gulf of Mexico

The Gulf of Mexico is one of the most productive water

bodies on earth. Its area is about 1.5 million km2, with a

maximum depth of 3,800 m in the area known as Sigsbee

Abyssal Plain. It is relevant to note, that the valuable

natural resource of the GoM are also exposed to the ac-

tion stressful natural chemical and biological factors

whose synergy causes environmental changes with a

certain degree of predictability (seasonality). There are

also catastrophic weather events such as storms and hur-

ricanes, which modify the coastline, and can alter the

patterns of sediment transport, thus promoting erosion.

Its water chemical balance can also be altered by the ex-

traction of fossil fuels and gas beneath the seabed.

In recent years, excessive discharge of organic mate-

rials (fertilizers) in areas near the Mississippi River [23]

and Coatzacoalcos have generated the formation of hy-

poxic areas in which the O2 concentration level drops

alarmingly, threatening the survival of communities oc-

cupying the marine seabed. In reference to the Tamauli-

pas and northern Veracruz coasts (Figure 1), these are

highly influenced by river discharges (Bravo, Soto la

Marina, Pánuco) that enrich with nutrients and organic

matter the waters of the adjacent continental shelf. The

continental shelf in this region is narrow with a maxi-

mum length of 50 km and with steep and rugged slopes,

particularly off the coast of northern Veracruz. The se-

dimentary environment in the coastal strip is dominated

by terrigenous input from rivers and lagoons; sand and

biogenic muds predominate in deeper areas (Figure 2).

Other major physiographic features in the GoM are the

presence of extensive coastal lagoons namely Laguna

Madre and Tamiahua; both function as natural nursery

grounds for many estuarine-dependent species (penaeid

shrimp and oysters). The waters of the continental shelf

in this region of the GoM exhibit stratification and mix-

ing conditions from April to September and November to

March, respectively. During the rainy season (June-Sep-

tember), the rivers have a significant dilution and cooling

effects in the salinity (30 psu) and temperature of the

river plume (23˚C). Due to the intrusion of ocean water

toward the coast, these parameters are maintained at

23˚C and 36 psu, and shallow seasonal thermocline (18

m). Winter northern fronts promote the mixing of the

water column causing low salinity and temperature (34

psu and 15˚C) and the deepening of the thermocline (80

to 160 m). The waters of this region are considered well

ventilated to 100 m, with oxygen concentrations of 4 - 5

ml·L−1. The reference values of nutrients (PO4, NO3, NO2,

and SiO2) tend to be more enriched during the mixing

phase of the water column, reducing its concentration

values when stratified conditions are established. There

is a positive correlation between significant nutrient val-

ues and sites under the influence of river and lagoon dis-

charges. However, the rapid consumption of nutrients by

neritic phytoplankton maintains oligotrophic conditions.

The surface concentration values of chlorophyll a (>0.10

mg·m−3) correlate well with sites receiving low fluvial

influence, while oceanic environments are characterized

by poor chlorophyll concentrations (<0.05 mg·m−3).

A vital information in this study are the reference

concentrations of heavy metals and polycyclic aromatic

hydrocarbons (PAH’s) in surface sediments previously

recorded in the study area. Heavy metals such as Cr, Ni,

and Cd reach significant concentrations along the Ta-

maulipas’ shelf [24]. There are also high levels (26.9

μg·g−1) of PAH’s in sediments off Tamaulipas and Vera-

cruz attributable to chronic oil spills in the area.

3. Economic Damage Assessment

The estimation of natural resource damages caused b y oil

spills is extremely controversial. The main difficulty re-

sides in the complexity involved in assessing the ecolog-

ical services offered by the different biotic components

of the marine ecosystem. An event such as the Macon-

do’s oil spill is subject of legal claims from physical

damages, cleanup and preventative actions to the loss of

fishing grou nds and landscape prop erty value. Acco rding

to international agreements (International Oil Pollution

Fund) and US federal legislatio n (Oil Po llution Act, 1990)

addressing oil spill accidents, the responsible party, Brit-

ish Petroleum in this case, can be held accountable for

the caused environmental damages, while the affected

parties must provide sufficient evidence of the source of

L. A. SOTO, A. VÁZQUEZ-BOTELLO

98.0 97.0 96.0

22.0

23.0

24.0

25.0

26.0

12345

11 12 13 14 15

21 22

23 24 25

33 3435

0.3

0.8

1.3

1.8

2.3

Bravo River

Madre

Lagoon

Soto La

Marina

River

Pánuco

River

Tamiahua

Lagoon

Longitude O

Latitude N

(a)

98.097.096.0

22.0

23.0

24.0

25.0

26.0

12345

11 12 1314 15

21 22

23 2425

33 3435

Bravo River

Madre

Lagoon

Soto La

Marina

River

Pánuco

River

Tamiahua

Lagoon

Longitude W

Latitude N

98.0 97.0 96.0

22.0

23.0

24.0

25.0

26.0 12345

11 12 13 14 15

21 22

23 24 25

33 3435

Bravo River

Madre

Lagoon

Soto La

Marina

River

Pánuco

River

Tamiahua

Lagoon

Longitude W

Latitude N

(b)

Figure 2. Dis tr ibution and composition of surface sediments in the NW Gulf of Mexico. (a) Sand. (b) Silt. (c) Clay.

the spilled oil, and an economic quantification of the

alleged damages. Sumaila et al. (2012) have briefly ex-

plained some of the various attempts made in assessing

economic environmental damages due to oil spills. Ap-

parently, accidents caused by oil tankers are highly vari-

able in nature. They depend on the type of oil, the vo-

lume spilled and the area where the accident occurs.

While oil rig accidents like the Deepwater Horizon plat-

form, located in a “sensitive ecoregions” have substantial

ecological and economic damages [25].

L. A. SOTO, A. VÁZQUEZ-BOTELLO

4. General Discu ssi on

The Large Marine Ecosystem Gulf of Mexico is a

semi-enclosed basin whose hydrodynamic and topo-

graphic features may contribute to the confinement or the

dispersion of crude oil. Thus for instance, it was assumed

that the circulation system prevailing in the summer in

the northern gulf was responsible for the hydrocarbon

concentration towards the northeast [1], where oil slick

remains were then trapped into the Eddy Franklin, a ma-

jor gyre system of the Loop Current. Satellite images

obtained in June, 2010 revealed oil residues at 200 km

north of Yucatan [26] possibly transported by this circu-

lation system.

Perhaps, during the summer the surface transport of

Macondo’s crude oil was not as intense towards the

northwestern GoM. However, in the mid-term, such

transportation could have taken place through the sub-

surface layers below the mixed layer (~500 m). We were

able to detect in the winter of 2011, the transport and

deposition of oil mineral aggregates (OMA) in the EEZ

of Mexico on the slope (>1000 m) in front of Tamaulipas

(Figure 3). Presumably, the intrusion of water from

Texas-Louisiana shelf observed in winter, favored these

processes. Interestingly enough, at this time of year, an

increasing gradient in the levels of sediment toxicity was

also recorded in that region of the GoM [27].

The Mexican waters and coastal environments in the

GOM have been internationally recognized for its mega-

biodiversity. These habitats are home to over 15,000

species of flora and fauna and many of them have consi-

derable commercial value. That is the case of the penaeid

shrimp populations exploited in the offshore waters of

Tamaulipas, Veracruz, Campeche and Quintana Roo.

Other important fishing resources of high economic val-

ue are the pelagic stocks of red snapper, grouper and tuna.

The blue crab, oysters, and clams, which are normally

exploited in the complex lagoon systems around the gulf

(Laguna Madre-Tamiahua-Alvarado), constitute vital

artisanal fisheries. All these marine living resources are

highly vulnerable to toxic compounds incorporated into

Figure 3. Microphotograph of oil mineral aggregates ob-

tained from surface sediments from the continental slope of

the NW Gulf of Mexico.

the crude oil molecules, such as naphthalene, phenanth-

rene, benzenes, and also the trace elements such as vana-

dium, cadmium, chromium, zinc, lead, and nickel.

From an ecological point of view, it is important to

recognize that the vast majority of organisms inhabiting

the GoM conduct, as part of their life cycle, circadian

and seasonal migratory movements at different spatial

scales that could seriously be disturbed by the presence

in the water column of spilled crude oil mixed with

chemical dispersants (Corexit). The direct exposure, the

disruption of breeding and spawning areas, or the transfer

of contaminants through the food web, are just some of

the deleterious effects one may expect to occur in the

GoM due to the Macondo’s blow out [28,29]. Consider-

ing the existing ecological connectivity within the GoM,

it is doubtful to accept the argument that the conditions

of environmental damage caused by the accidental oil

spill in the northern gulf were spatially and temporally

confined to that region.

The Ixtoc-1 (1979), Exxon Valdez (1989) and Prestige

(2002) oils spill accidents are painful remainders of the

lasting harmful effects to the marine ecosystem. Micro-

biologists were the first to report the unusual oil microb i-

al degradation that contributed significantly to minimize

the seriousness of the Macondo’s oil spill in surface wa-

ters [30,31]. However, it was difficult to reconcile the

bacterial degradation rate in deep-water with an average

temperature of 4˚C and possibly anaerobic conditions in

sediments. We presume that many of the toxic elements

of crude oil still remain bio-available in the sediments of

the GoM at sublethal levels mainly for benthic dwellers.

Our current toxicity analyses in tissues of shelf-fauna

inhabitants (mollusks, decapods crustaceans, and demer-

sal fish) from the northwestern GoM reveal concentra-

tions of HA P’s and heavy metals not exceeding the levels

to cause mortality [32,33]. However, the bioaccumula-

tion effects and possible magnification in the troph ic w eb

cannot be rul ed out.

On the other hand, prior to the accidental Macondo’s

oil spill, Mexican fisheries experts [34,35] have already

sent warning signs about the overexploitation levels

reached by demersal and finfish stocks traditionally ex-

ploited in Mexico’s EEZ waters. An additional stress

factor such as the presence of chemical pollutants in the

GoM may seriously undermine the immune capacity of

individuals and their bioenergetics balance (respiratory

metabolism-growth-rate-reproduction).

Bearing in mind the legacy left by accidental oil spills

occurred at different latitudes (IXTOC-1, 1979, SW Gulf

of Mexico; EXXON Valdez, 1989, Alaska; PRESTIGE,

2002, northern coast of Spain), we could expect that the

MACONDO massive oil spill effects will be present in

the GoM for several decades. The restoration of the eco-

logical stability of the GoM would depend on its resi-

L. A. SOTO, A. VÁZQUEZ-BOTELLO

lience capacity. Indeed, the existing natural oil and gas

seeps and the chronic contamination due to the current

extraction of fossil fuels in the north and south of the

GoM, increase the uncertainty in detecting the chemical

fingerprint from MACONDO. However, the seriousness

of the environmental damage of this unprecedented phe-

nomenon in the annals of contemporary science cannot

be met with hesitation or skepticism. An answer to this

challenging issue can be found in the implementation of

a modern observational system of oceanographic condi-

tions of the GoM and the periodic determinations of oil

biomarkers in sediments and biota (δ13 C, PAHs, hopanes,

steranes, and trace metals).

5. Conclusions

In the aftermath of the unfortunate Macondo’s blowout

in which nearly 5 million barrels of crude oil were spilled

both in deep and surface waters of the northern GoM, a

heated debate emerged among experts on the fate and

persistence of the hydrocarbons in coastal and deep en-

vironments. The severe disruption of the ecological bal-

ance absorbed by the GoM due to this massive spill

tended to be officially underrated by the contention and

emergency procedures implemented during the acute

phase of the accident. Natural processes such as evapora-

tion, dispersion, dilution, and a significant microbial

biodegradation were largely credited for the substantial

loss of the released oil (>74%). The remaining percen-

tage still poses potential damages specially for the deep

sea environment since we ignore the degradation rates of

the different oil components, the areas of deposition, and

the dispersion trajectories of subsurface oil plumes. Un-

fortunately, our current knowledge on the deep circul a-

tion patterns and the deep sea biodiversity of the GoM is

not sufficient to foresee the degree and duration of the

environmental disturbance that an input of crude oil may

have in the Mexican EEZ. This is a challenging research

issue that requires the best available science and multila-

teral cooperation from neighboring countries in the GoM.

From a Mexican perspective, the answer to this riddle

can be found in the rescue of historical data, and the im-

plementation of a Monitoring Pr ogram of our coastal a nd

oceanic waters in order to ensure the sustaining devel-

opment of this LME.

6. Acknowledgements

We are indebted to the research group integrated in the

project “Marco Ambiental de las Condiciones Ocea-

nográficas en el Sector NW de la ZEE de México en el

Golfo de México (MARZEE)” for their invaluable sup-

port and tireless enthusiasm. The authors would like to

acknowledge the financial support of the Instituto Na-

cional de Ecología y Cambio Climático (INECC).

REFERENCES

[1] “Deepwater Horizon Oil Spill Principal Investigator

Workshop: Final Report,” National Science and Tech-

nology Council, Subcommittee on Ocean Science and

Technology, Washington, DC, 2012.

http://www.marine.usf.edu/conferences/fio/NSTC-SOST-

PI-2011/documents/SOST_2011_DWH_Workshop_Final

_Report.pdf

[2] J. Lubchenco, M. McNutt, B. Lehr, M. Sogge, M. Miller,

S. Hammond and W. Conner, “Deepwater Horizon/BP

Oil Budget: What Happened to the Oil?” Silver Spring,

MD: National Oceanic and Atmospheric Administration,

2010.

http://www.noaanews.noaa.gov/stories2010/PDFs/OilBud

get_description_%2083final.pdf

[3] P. S. Daling, “Weathering Properties at Sea of the Ma-

condo MC252 Crude Oil,” Gulf Oil Spill SETAC Fo-

cused Topic Meeting, Merida, 2011, p. 39.

[4] K. M. Kleinow, A. Bui, L. J. Thibodeaux and S. M. Fritz-

Kleinow, “Effect of the Dispersant Corexit upon Bio-

availability and Toxicity of Deep Horizon Light Crude

Oil Emulsion Components to Developing Fish,” Gulf Oil

Spill SETAC Focused Topic Meeting, Merida, 2011, p.

25.

[5] B. A, Muhling, et al., “Overlap between Atlantic bluefin

tuna spawning grounds and observed Deepwater Horizon

surface oil in the northern Gulf of Mexico,” Marine Pol-

lution Bulletin, Vol. 64, No. 4, 2012, pp. 679-687.

http://dx.doi.org/10.1016/j.marpolbul.2012.01.034

[6] P. D. Boehm, et al., “Polynuclear Aromatic Hydrocar-

bons from MC252 in the Water Column: Preliminary

Exposure Assessment, Weathering, and Biodegradation,”

Gulf Oil Spill SETAC Focused Topic Meeting, Merida,

2011, p. 40.

[7] S. E. Allan, B. W. Smith and K. A. Anderson, “Impact of

the Deepwater Horizon Oil Spill on Bioavailable Poly-

cyclic Aromatic Hydrocarbons in Gulf of Mexico Coastal

Waters,” Environmental Science & Technology, Vol. 46,

No. 4, 2012, pp. 2033-2039.

http://dx.doi.org/10.1021/es202942q

[8] K. Sherman, “Sustainability, Biomass Yield, and Health

of Coastal Ecosystems: An Ecological Perspective,” Ma-

rine Ecology Progress Series, No. 112, 1994, pp. 277-301.

http://dx.doi.org/10.3354/meps112277

[9] A. R. Diercks, et al., “Characterization of Subsurface Po-

lycyclic Aromatic Hydrocarbons at the Deepwater Hori-

zon Site,” Geophysical Research Letters, Vol. 37, 2010,

pp. 1-6. http://dx.doi.org/10.1029/2010GL045046

[10] T. C. Hazen, et al., “Deep-Sea Oil Plume Enriches Indi-

genous Oil-Degrading Bacteria,” Science, Vol. 330, No.

6001, 2010, pp. 204-208.

http://dx.doi.org/10.1126/science.1195979

[11] R. Camilli, et al., “Tracking Hydrocarbon Plume Trans-

port and Biodegradation at Deepwater Horizon,” Science

Express, 2010. http://dx.doi.org/10.1126/science.1195223

L. A. SOTO, A. VÁZQUEZ-BOTELLO

[12] C. M. Reddy, et al., “Composition and Fate of Gas and

Oil Released to the Water Column during the Deepwater

Horizon Oil Spi ll,” Proceedings of the National Academy

of Sciences, Vol. 109, No. 50, 2012, pp. 20229-20234.

http://dx.doi.org/10.1073/pnas.1101242108

[13] J. Zavala-Hidalgo, S. L. Morey and J. J. O’Brien, “Sea-

sonal Circulation on the Western Shelf of the Gulf of Me-

xico Using a High-Resolution Numerical Model,” Jour-

nal of Geophysical Research, Vol. 108, 2003, pp. 1-19.

http://dx.doi.org/10.1029/2003JC001879

[14] J. Zavala-Hidalgo, R. Romero-Centeno, E. Galvanovskis

Romero, M. L. Lagunas Modesto and M. E. Osorio Tai,

“Riesgo Ecológico y Modelo Predictivo de la Trayec toria

de la Pluma Submarina de Hidrocarburo Procedente del

Pozo Macondo (BP), Luisiana en la Zona Económica

Exclusiva de México, Golfo de México,” Rep. Tec.

CCA.UNAM, 2013, 35 p.

[15] I. R. MacDonald, “Natural Oil Spills,” Scientific Ameri-

can, No. 279, 2012, pp. 56-61.

[16] D. L. Valentine, et al., “Propane Respiration Jump-Starts

Microbial Response to a Deep Oil Spill,” Scienc e, Vol.

330, No. 6001, 2010, pp. 208-211.

http://dx.doi.org/10.1126/science.1196830

[17] D. L. Valentine, et al., “Dynamic Autoinoculation and the

Microbial Ecology of a Deep Water Hydrocarbon Irrup-

tion,” Proceedings of the National Academy of Sciences,

2012, in press.

[18] T. B. Ryerson, et al., “Chemical Data Quantify Deepwa-

ter Horizon Hydrocarbon Flow Rate and Environmental

Distribution,” Proceedings of the National Academy of

Sciences, 2012, in press.

http://dx.doi.org/10.1073/pnas.1110564109

[19] A. V. Botello, et al., “Golfo de México: Contaminación e

Impacto Ambiental: Diagnóstico y Tendencias,” Cam-

peche: Universidad Autónoma de Ca mpeche, Centro de

Ecología, Pesquerías y Oceanografía de l Golfo de Mé-

xico, Univ. Nal. Autó. Méx., Inst. Cien. Mar y Limnol.,

Inst. Nal. Eco l ., 2005, p. 696.

[20] L. A. Soto and C. González Macías, “PEMEX y la Salud

Ambiental de la Sonda de Campeche, México,” Luis A.

Soto y Carmen González Macías, Eds., Batelle-IMP-

UAM-UNAM, 2009, 336 p.

[21] L. A. Soto, et al., “Marco Ambiental de las Condiciones

Oceanográficas En El Sector NW de la Zee de México en

El Golfo de México (Marzee),” Rep. Tec. I. UNAM-INE,

2011, 430 p.

[22] L. A. Soto, et al., “Marco Ambiental de las Condiciones

Oceanográficas En El Sector NW de la Zee De México

En El Golfo De México (Marzee),” Rep. Tec. II. UNAM-

INE, 2012, 430 p.

[23] N. N. Rabalais and R. E. Turner, “Hypoxia in the North-

ern Gulf of Mexico: Description causes and changes, in

Coastal Hypoxia: Consequences for Living Resources

and Ecosystems,” In: N. N. Rabalais and R. E. Turner,

Eds., Coastal Estuarine Studies, Vol. 58, AGU, Wash-

ington, D. C., 2001, pp. 1-36.

http://dx.doi.org/10.1029/CE058p0001

[24] G. Ponce-Vélez, A. V. Botello and G. Díaz-González,

“Organic and Inorganic Pollutants in Marine Sediments

from Northern and Southern Continental Shelf of the Gulf

of Mexico,” International Journal of Environment and

Pollution, Vol. 26, 2006, pp. 295-311.

http://dx.doi.org/10.1504/IJEP.2006.009113

[25] U. R. Sumaila, et al., “Impact of the Deepwater Horizon

Well Blowout on the Economics of US Gulf Fisheries,”

Canadian Journal of Fisheries and Aquatic Sciences, Vol.

69, No. 3, 2012, pp. 499-510.

http://dx.doi.org/10.1139/f2011-171

[26] Sistema Satelital de Monitoreo Oceánico de la CON-

ABIO: Reporte No. 1 -CONAB IO.

http://www.conabio.gob.mx/informacion/geo_espanol/mo

dis/oceano.html

[27] S. S. Figueroa, “Evaluación de la Toxicidad de Sedimen-

tos,” In: L. A. Soto, Ed., Proyecto “Marco Ambiental de

las Condiciones Oceanográficas en el Sector NW de la

zee de México en el Golfo de México (Marzee II)”, Rep.

Tec. Ii. Unam. Inecc, México, 2012, 430 p.

[28] Greer, et al., “Is CEWAF Prepared in the Lab Suitable for

Predicting Toxicity to Herring Embryos?” Gulf Oil Spill

SETAC Focused Topic Meeting, Merida, 2011, p. 34.

[29] S. Mitra, e t al., “Macondo-1 Well Oil-Derive d Polycycli c

Aromatic Hydrocarbons in Mesozooplankton from the

Northern Gulf of Mexico,” Geophysical Research Letters,

Vol. 39, No. 1, 2012, pp. 1-6.

[30] T. C. Hazen, et al., “Deep-Sea Oil Plume Enriches Indi-

genous Oil-Degrading Bacteria,” Science Express, 2010,

pp. 1-10.

[31] D. L. Valentine, et al., “Response to a Deep Oil Spill

Propane Respiration Jump—Starts Microbial,” Science,

Vol. 330, No. 208, 2010, pp. 208-211.

http://dx.doi.org/10.1126/science.1196830

[32] A. V. Botello, et al., “Contaminación Marina,” L. A. Soto,

Ed., PROYECTO In: L. A. Soto, Ed., Proyecto “Marco

Ambiental de las Condiciones Oceanográficas en el

Sector NW de la zee de México en el Golfo de México

(Marzee II)”, Rep. Tec II. UNAM. INECC, México, 2012,

436 p.

[33] G. Núñez-Nogueira, et al ., “Determinación de Metales en

Biota” L. A. Soto, Ed., In: L. A. Soto, Ed., Proyecto “Mar-

co Ambiental de las Condiciones Oceanográficas en el

Sector NW de la zee de México en el Golfo de México

(Marzee II)”, Rep. Tec II. UNAM. INECC, México, 2012,

436 p.

[34] A. Díaz de León, J. I. Fernández, P. Álvarez-Torres, O.

Ramírez-Flores and L. G. López-Lemus, “La Sustentabi-

lidad de las Pesquerías del Golfo de México,” In: M.

Caso, I. Pisanty and E. Ezcurra, Eds., Diagnóstico Am-

biental del Golfo de México, SEMARNAT-INE -Harte

Res. Inst., Vol. I-II, 2004, pp. 727-755.

[35] Díaz-Guzmán, et al., “Posibles Efectos del Derrame de

Petróleo del Golfo de México en la Pesquería Mexicana

del atún,” El Vigía, Vol. 15, No. 37, 2010, pp. 11-16.