Ian R Macdonald

Florida State University | FSU · Department of Earth, Ocean and Atmospheric Science

The Gulf of Mexico is a hydrocarbon-rich region characterized by the presence of floating oil slicks from persistent natural hydrocarbon seeps, which are reliably captured by synthetic aperture radar (SAR) satellite imaging. Improving the state of knowledge of hydrocarbon seepage in the Gulf of Mexico improves the understanding and quantification o...

Ocean oil slicks can be attributed to natural seepages or to anthropogenic discharges. To date, the global picture of their distribution and relative natural and anthropogenic contributions remains unclear. Here, by analyzing 563,705 Sentinel-1 images from 2014–2019, we provide the first global map of oil slicks and a detailed inventory of static-a...

In 2004, destruction of a Gulf of Mexico oil platform by Hurricane Ivan initiated a discharge of oil and gas from a water depth of 135 m, where its bundle of well conductors was broken below the seafloor near the toppled wreckage. Discharge continued largely unabated until 2019, when findings partly reported herein prompted installation of a contai...

We discovered a large field of cylindrically-shaped sediment chimneys at the seafloor along the flank of Farnella Canyon (water depth ∼2775 m) at the base of the Sigsbee Escarpment in the northwestern Gulf of Mexico. The chimneys are about 10 cm in diameter with 1 cm wide axial cavities; they rise about 0.5–1 m above the seafloor and continue down...

Hydrocarbon seepage plays an essential role in defining seafloor morphology and increasing habitat heterogeneity in the deep sea whereby asphalt volcanism ranks among the most complex and proliferous hydrocarbon discharge systems that have been described to date. In this study, seepage of hydrocarbon gas and oil as well as asphalt deposits were inv...

Physical transport processes such as the circulation and mixing of waters largely determine the spatial distribution of materials in the ocean. They also establish the physical environment within which biogeochemical and other processes transform materials, including naturally occurring nutrients and human-made contaminants that may sustain or harm...

Hydrocarbon seeps occur worldwide along continental margins and act as conduits for fluid discharge from the lithosphere to the overlying hydrosphere/atmosphere. The dynamics and rates of hydrocarbon release at cold seeps remain poorly constrained. Seepage enables a variety of processes that alter the seafloor morphology and affect the geochemistry...

Two video time-lapse cameras (VTLCs) were deployed by a remotely operated underwater vehicle (ROV) to observe the temporal and spatial variability of a natural hydrocarbon seep at 1180 m depth in the Green Canyon 600 lease block, Gulf of Mexico. The VTLCs were positioned approximately 60 cm and 90 cm away from the vent, each recording 15-s video bu...

Recent findings cap more than a decade of research on habitats for chemoautotrophic fauna that are generated by hydrocarbon seepage at abyssal depths in the southern Gulf of Mexico. Extensive pavements (3300 m²) of asphalt, created by repeated, slow discharges, are sparsely colonized by tubeworms that tap reduced sulfur compounds through cracks and...

This multi-disciplinary study of the hydrocarbon seepage system at Tsanyao Yang Knoll (TYK) in the southern Gulf of Mexico illustrates the amount and fate of hydrocarbons (mainly oil and methane) emanating from the seafloor structure and rising through a 3400 m water column. TYK forms part of the Campeche Knolls and was found to be one of the most...

Active seafloor hydrocarbon seepage from three distinct, positive seafloor features, termed knolls, in the Sigsbee Knolls area, Gulf of Mexico (GOM), was investigated in March 2015. The study sites included the Challenger Knoll, which was drilled by the Deep Sea Drilling Program (DSDP) in 1969 and showed the influence of salt tectonics on its evolu...

In September of 2004 hurricane Ivan, a category 3 storm at the time, passed through the northern Gulf of Mexico. Severe wave action attributed to the storm triggered a subsea mudslide that toppled Taylor Energy Company’s (TEC) oil Saratoga production platform A at Mississippi Canyon block 20 (MC20). The superstructure, also known as the jacket, cam...

Atmospheric methane (CH 4) concentrations at 3 m above the ocean surface were characterized for the first time for the Mississippi Canyon 20 (MC20) site. Fifteen years ago, Taylor Energy's production Saratoga Platform-A was destroyed when Hurricane Ivan triggered a mudslide off the Mississippi Delta, toppling and sinking the platform and moving it...

Sponges host a remarkable diversity of microbial symbionts, however, the benefit their microbes provide is rarely understood. Here, we describe two new sponge species from deep-sea asphalt seeps and show that they live in a nutritional symbiosis with methane-oxidizing (MOX) bacteria. Metagenomics and imaging analyses revealed unusually high amounts...

In 2003, the Chapopote asphalt flow was discovered in the southern Gulf of Mexico at a depth of 2,900 m. Subsequent exploration has expanded the known extent of asphalt volcanism across abyssal depths in much of this region. Aspects of asphalt flow morphology are analogous to ropy pāhoehoe flows known from eruptions of basaltic lava on land, but th...

The Deepwater Horizon (DWH) oil blowout in the Gulf of Mexico (GoM) led to the largest offshore oil spill in U.S. history. The accident resulted in oil slicks that covered between 10,000 and upward of 40;000 km2 of the Gulf between April and July 2010. Quantifying the actual spatial extent of oil over such synoptic scales on an operational basis an...

We report chemical characterization of natural oil seeps from the Gulf of Mexico by Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and Gas Chromatography/Atmospheric Pressure Chemical Ionization Mass Spectrometry (GC/APCI-MS), to highlight how FT-ICR MS can also be employed as a means to determine petroleum connectivity, in...

The mesophotic coral ecosystem (MCE) of the eastern Gulf of Mexico hosts diverse invertebrate and fish fauna across an array of hard-ground features. However, the extent of the potential MCE habitat in the region is poorly constrained. Maximum entropy modeling was used to predict the spatial extent of mesophotic azooxanthellate octocorals and antip...

This research quantifies the rate and volume of oil and gas released from two natural seep sites in the Gulf of Mexico: lease blocks GC600 (1200 m depth) and MC118 (850 m depth). Our objectives were to determine variability in release rates and bubble size at five individual vents and to investigate the effects of tidal fluctuations on bubble relea...

After the conclusion of emergency response efforts for the Deepwater Horizon (DWH) oil spill in fall of 2010, the National Oceanic and Atmospheric Administration (NOAA) initiated the natural resource damage assessment (NRDA) process. The NRDA guidance under the Oil Pollution Act requires trustees of natural resources, including NOAA, to assess the...

Offshore oil seeps occur in waters across the globe but locating them using in-situ methods requires a significant amount of time and cost. This motivated the design and implementation of an automatic method that can provide the location of offshore oil seeps from Synthetic Aperture Radar (SAR) data and resulted in the creation of the Automatic oil...

Detecting oil in the northern Gulf of Mexico following the Deepwater Horizon oil spill presented unique challenges due to the spatial and temporal extent of the spill and the subsequent dilution of oil in the environment. Over time, physical, chemical, and biological processes altered the composition of the oil, further complicating its detection....

Hydrocarbon seepage is a widespread process at the continental margins of the Gulf of Mexico. We used a multidisciplinary approach, including multibeam mapping and visual seafloor observations with different underwater vehicles to study the extent and character of complex hydrocarbon seepage in the Bay of Campeche, southern Gulf of Mexico. Our obse...

The Gulf of Mexico ecosystem is a hotspot for biological diversity and supports a number of industries, from tourism to fishery production to oil and gas exploration, that serve as the economic backbone of Gulf coast states. The Gulf is a natural hydrocarbon basin, rich with stores of oil and gas that lie in reservoirs deep beneath the seafloor. Th...

We studied asphalt deposits, oil seepage and gas venting during a multidisciplinary cruise in the Bay of Campeche, southern Gulf of Mexico. We conducted multibeam bathymetric mapping with an autonomous underwater vehicle and performed seafloor observations as well as sampling with a remotely operated vehicle. While previous studies concentrated on...

Natural hydrocarbon seeps occur on the sea floor along continental margins, and account for up to 47% of the oil released into the oceans. Hydrocarbon seeps are known to support local benthic productivity, but little is known about their impact on photosynthetic organisms in the overlying water column. Here we present observations with high tempora...

Animated Deepwater Horizon surface oil maps with response effort and wind: This is an animated set of 202 maps showing distribution and magnitude of surface oil at 12-h time-steps, with summary estimates of total area and volume, 24 April to 3 August 2010. Also animate are the average wind speed for the entire study area (right panel) and the relat...

Supporting Information S1

Data Set S1 Data Set S2A, S2B

Electronic supplemental material for Etnoyer et al 2015

Hard-bottom ‘mesophotic’ reefs along the ‘40-fathom’ (73 m) shelf edge in the northern Gulf of Mexico were investigated for potential effects of the Deepwater Horizon (DWH) oil spill from the Macondo well in April 2010. Alabama Alps Reef, Roughtongue Reef, and Yellowtail Reef were near the well, situated 60–88 m below floating oil discharged during...

Pathologies in over 400 octocoral and antipatharian colonies were quantified in the aftermath of the DWH oil discharge. Observations were made in September 2011 at water depths of 65 to 75 meters in the Pinnacle Reef trend area offshore from Mississippi and Alabama, Gulf of Mexico, using a digital macro camera deployed from an ROV to examine the co...

Taylor offshore platform 23051 in Mississippi Canyon Block 20 was damaged during Hurricane Ivan in 2004 and subsequently removed. Oil released from MC 20 rises to the surface and creates visible layers of floating material, called oil slicks or oil sheens. Based on my experience observing and measuring oil slicks, the long, contiguous rainbow color...

Satellite-borne synthetic aperture radar (SAR) data are widely used for detection of hydrocarbon resources, pollution, and oil spills. These applications require recognition of particular spatial patterns in SAR data. We developed a texture-classifying neural network algorithm (TCNNA), which processes SAR data from a wide selection of beam modes, t...

Detection of floating oil on the ocean surface, and particularly thick layers, is crucial for emergency response to accidental oil discharges. While detection of oil presence on the ocean surface is relatively easy under most conditions with a variety of remote sensing techniques, estimation of the thickness of oil layers is technically challenging...

We developed a Textural Classifier Neural Network Algorithm (TCNNA) to process Synthetic Aperture Radar (SAR) data to map oil spills. The algorithm processes SAR data and wind model outputs (CMOD5) using a combination of two neural networks. The first neural network filters out areas of the image that do not need to be processed by flagging pixels...

Methane hydrates are stable at high pressure, low temperature, and saturated methane concentrations. However, natural hydrates exist at the seafloor where methane concentrations are well below saturation. Under such conditions, hydrate outcrops should shrink rapidly as they dissolve into the surrounding seawater. However, some natural hydrate outcr...

In this paper we use examples of Synthetic Aperture Radar (SAR) imagery collected during the Deepwater Horizon (DWH) oil spill and the Texture Classifier Neural Network Algorithm (TCNNA) to identify SAR image signatures that correspond to regions of emulsified (thicker) oil, which were verified by sea level observations and other remote sensing ins...

Detection of oil floating on the ocean surface, and particularly thick layers of it, is crucial for emergency response to oil spills. While detection of oil on the ocean surface is possible under moderate sea-state conditions using a variety of remote-sensing methods, estimation of oil layer thickness is technically challenging. In this paper, we u...

Natural hydrocarbon seeps have an important role in the carbon cycle and in the Gulf of Mexico (GOM) ecosystem. The magnitude of these natural oil seeps was analyzed with 3D-seismic attributes in combination with satellite and acoustic data. Hydrocarbon seepage in the deep water of the GOM is associated with deep cutting faults, generated by vertic...

The tragic explosion, which sank the Deepwater Horizon rig and caused a catastrophic oil discharge in the Gulf of Mexico, has set in motion an unprecedented response effort. A major concern throughout the 84-day emergency was finding and tracking the oil across the deep-ocean floor, and this required use of ROVs, AUVs and profiling instruments depl...

Analysis of Advanced Synthetic Aperture Radar satellite images in combination with water column and seafloor investigations documented natural oil seepage from Pechori Mound and Colkheti Seep in 1,000 – 1,200 m water depth in the eastern Black Sea offshore Georgia. Hydroacoustic imaging of the water column using multibeam echosounder evidenced nume...

A benthic species inventory of 1,125 taxa was compiled from various sources for the central Arctic deeper than 500m, and bounded to the Atlantic by Fram Strait. The inventory was dominated by arthropods (366 taxa), foraminiferans (197), annelids (194), and nematodes (140). An additional 115 taxa were added from the Greenland–Iceland–Norwegian Seas...

Three deepwater hydrocarbon seep sites in the northern Gulf of Mexico that feature near-seafloor gas hydrates, MC118 (depth = 900 m), GC600 (depth = 1250 m) and GC185 (depth = 550 m), were investigated during the Remote Sensing and Sea-Truth Measurements of Methane Flux to the Atmosphere (HYFLUX) study in July 2009. Continuous measurements of air a...

Analyzing the magnitude of oil discharges from natural hydrocarbon seeps is important in improving our understanding of carbon contribution as oil migrates from deeper sediments to the water column, and then eventually to the atmosphere. Liquid hydrocarbon seepage in the deep water of the Gulf of Mexico (GOM) is associated with deep cutting faults,...

Effervescent hydrocarbons rise naturally from hydrocarbon seeps in the Gulf of Mexico and reach the ocean surface. This oil forms thin (~0.1 μm) layers that enhance specular reflectivity and have been widely used to quantify the abundance and distribution of natural seeps using synthetic aperture radar (SAR). An analogous process occurred at a vast...

Kessler et al. (Reports, 21 January 2011, p. 312) reported that methane released from the 2010 Deepwater Horizon blowout, approximately 40% of the total hydrocarbon discharge, was consumed quantitatively by methanotrophic bacteria in Gulf of Mexico deep waters over a 4-month period. We find the evidence explicitly linking observed oxygen anomalies...

The deep-sea hydrocarbon discharge resulting from the BP oil well blowout in the northern Gulf of Mexico released large quantities of oil and gaseous hydrocarbons such as methane into the deep ocean. So far, estimates of hydrocarbon discharge have focused on the oil released, and have overlooked the quantity, fate and environmental impact of the ga...