This book is open access under a CC BY-NC 2.5 license. The Gulf of Mexico is an open and dynamic marine ecosystem rich in natural resources but heavily impacted by human activities, including agricultural, industrial, commercial and coastal development. The Gulf of Mexico has been continuously exposed to petroleum hydrocarbons for millions of years from natural oil and gas seeps on the sea floor, and more recently from oil drilling and production activities located in the water near and far from shore. Major accidental oil spills in the Gulf are infrequent; two of the most significant include the Ixtoc I blowout in the Bay of Campeche in 1979 and the Deepwater Horizon Oil Spill in 2010. Unfortunately, baseline assessments of the status of habitats and biota in the Gulf of Mexico before these spills either were not available, or the data had not been systematically compiled in a way that would help scientists assess the potential short-term and long-term effects of such events. This 2-volume series compiles and summarizes thousands of data sets showing the status of habitats and biota in the Gulf of Mexico before the Deepwater Horizon Oil Spill. Volume 1 covers: water and sediment quality and contaminants in the Gulf; natural oil and gas seeps in the Gulf of Mexico; coastal habitats, including flora and fauna and coastal geology; offshore benthos and plankton, with an analysis of current knowledge on energy capture and energy flows in the Gulf; and shellfish and finfish resources that provide the basis for commercial and recreational fisheries.

One of the most significant, energetic, yet not well understood, oceanographic features in the Americas is the Gulf of Mexico Loop Current System (LCS), consisting of the Loop Current (LC) and the Loop Current Eddies (LCEs) it sheds. Understanding the dynamics of the LCS is fundamental to understanding the Gulf of Mexico's full oceanographic system, and vice versa. Hurricane intensity, offshore safety, harmful algal blooms, oil spill response, the entire Gulf food chain, shallow water nutrient supply, the fishing industry, tourism, and the Gulf Coast economy are all affected by the position, strength, and structure of the LC and associated eddies. This report recommends a strategy for addressing the key gaps in general understanding of LCS processes, in order to instigate a significant improvement in predicting LC/LCE position, evolving structure, extent, and speed, which will increase overall understanding of Gulf of Mexico circulation and to promote safe oil and gas operations and disaster response in the Gulf of Mexico. This strategy includes advice on how to design a long-term observational campaign and complementary data assimilation and numerical modeling efforts.

The U.S. Gulf Coast provides a valuable setting to study deeply connected natural and human interactions and feedbacks that have led to a complex, interconnected coastal system. The physical landscape in the region has changed significantly due to broad-scale, long-term processes such as coastal subsidence and river sediment deposition as well as short-term episodic events such as hurricanes. Modifications from human activities, including building levees and canals and constructing buildings and roads, have left their own imprint on the natural landscape. This coupled natural-human coastal system and the individual aspects within it (physical, ecological, and human) are under increased pressure from accelerating environmental stressors such as sea level rise, intensifying hurricanes, and continued population increase with its accompanying coastal development. Promoting the resilience and maintaining the habitability of the Gulf Coast into the future will need improved understanding of the coupled natural-human coastal system, as well as effective sharing of this understanding in support of decision-making and policies. Understanding the Long-term Evolution of the Coupled Natural-Human Coastal System presents a research agenda meant to enable a better understanding of the multiple and interconnected factors that influence long-term processes along the Gulf Coast. This report identifies scientific and technical gaps in understanding the interactions and feedbacks between human and natural processes, defines essential components of a research and development program in response to the identified gaps, and develops priorities for critical areas of research.

As the Gulf of Mexico recovers from the Deepwater Horizon oil spill, natural resource managers face the challenge of understanding the impacts of the spill and setting priorities for restoration work. The full value of losses resulting from the spill cannot be captured, however, without consideration of changes in ecosystem services-the benefits delivered to society through natural processes. An Ecosystem Services Approach to Assessing the Impacts of the Deepwater Horizon Oil Spill in the Gulf of Mexico discusses the benefits and challenges associated with using an ecosystem services approach to damage assessment, describing potential impacts of response technologies, exploring the role of resilience, and offering suggestions for areas of future research. This report illustrates how this approach might be applied to coastal wetlands, fisheries, marine mammals, and the deep sea-each of which provide key ecosystem services in the Gulf-and identifies substantial differences among these case studies. The report also discusses the suite of technologies used in the spill response, including burning, skimming, and chemical dispersants, and their possible long-term impacts on ecosystem services.

Introduction -- Mesozoic depositional evolution -- Cenozoic depositional evolution -- Petroleum habitat.