Jacqueline Michel

Extent and Degree of Shoreline Oiling: Deepwater Horizon Oil Spill, Gulf of Mexico, USA

The oil from the 2010 Deepwater Horizon spill in the Gulf of Mexico was documented by shoreline assessment teams as stranding on 1,773 km of shoreline. Beaches comprised 50.8%, marshes 44.9%, and other shoreline types 4.3% of the oiled shoreline. Shoreline cleanup activities were authorized on 660 km, or 73.3% of oiled beaches and up to 71 km, or 8.9% of oiled marshes and associated habitats. One year after the spill began, oil remained on 847 km; two years later, oil remained on 687 km, though at much lesser degrees of oiling. For example, shorelines characterized as heavily oiled went from a maximum of 360 km, to 22.4 km one year later, and to 6.4 km two years later. Shoreline cleanup has been conducted to meet habitat-specific cleanup endpoints and will continue until all oiled shoreline segments meet endpoints. The entire shoreline cleanup program has been managed under the Shoreline Cleanup Assessment Technique (SCAT) Program, which is a systematic, objective, and inclusive process to collect data on shoreline oiling conditions and support decision making on appropriate cleanup methods and endpoints. It was a particularly valuable and effective process during such a complex spill.

Heavily Oiled Salt Marsh following the Deepwater Horizon Oil Spill, Ecological Comparisons of Shoreline Cleanup Treatments and Recovery

The Deepwater Horizon oil spill affected hundreds of kilometers of coastal wetland shorelines, including salt marshes with persistent heavy oiling that required intensive shoreline “cleanup” treatment. Oiled marsh treatment involves a delicate balance among: removing oil, speeding the degradation of remaining oil, protecting wildlife, fostering habitat recovery, and not causing further ecological damage with treatment. To examine the effectiveness and ecological effects of treatment during the emergency response, oiling characteristics and ecological parameters were compared over two years among heavily oiled test plots subject to: manual treatment, mechanical treatment, natural recovery (no treatment, oiled control), as well as adjacent reference conditions. An additional experiment compared areas with and without vegetation planting following treatment. Negative effects of persistent heavy oiling on marsh vegetation, intertidal invertebrates, and shoreline erosion were observed. In areas without treatment, oiling conditions and negative effects for most marsh parameters did not considerably improve over two years. Both manual and mechanical treatment were effective at improving oiling conditions and vegetation characteristics, beginning the recovery process, though recovery was not complete by two years. Mechanical treatment had additional negative effects of mixing oil into the marsh soils and further accelerating erosion. Manual treatment appeared to strike the right balance between improving oiling and habitat conditions while not causing additional detrimental effects. However, even with these improvements, marsh periwinkle snails showed minimal signs of recovery through two years, suggesting that some ecosystem components may lag vegetation recovery. Planting following treatment quickened vegetation recovery and reduced shoreline erosion. Faced with comparable marsh oiling in the future, we would recommend manual treatment followed by planting. We caution against the use of intensive treatment methods with lesser marsh oiling. Oiled controls (no treatment “set-asides”) are essential for judging marsh treatment effectiveness and ecological effects; we recommend their use when applying intensive treatment methods.

Impacts of the Deepwater Horizon Oil Spill on Salt Marsh Periwinkles (Littoraria irrorata).

Deepwater Horizon was the largest marine oil spill in U.S. waters, oiling large expanses of coastal wetland shorelines. We compared marsh periwinkle (Littoraria irrorata) density and shell length at salt marsh sites with heavy oiling to reference conditions ∼16 months after oiling. We also compared periwinkle density and size among oiled sites with and without shoreline cleanup treatments. Densities of periwinkles were reduced by 80-90% at the oiled marsh edge and by 50% in the oiled marsh interior (∼9 m inland) compared to reference, with greatest numerical losses of periwinkles in the marsh interior, where densities were naturally higher. Shoreline cleanup further reduced adult snail density as well as snail size. Based on the size of adult periwinkles observed coupled with age and growth information, population recovery is projected to take several years once oiling and habitat conditions in affected areas are suitable to support normal periwinkle life-history functions. Where heavily oiled marshes have experienced accelerated erosion as a result of the spill, these habitat impacts would represent additional losses of periwinkles. Losses of marsh periwinkles would likely affect other ecosystem processes and attributes, including organic matter and nutrient cycling, marsh-estuarine food chains, and multiple species that prey on periwinkles.

BEACH CLEANING AND THE ROLE OF TECHNICAL SUPPORT IN THE 1993 TAMPA BAY SPILL

ABSTRACT This paper reports on the decision-making process and shoreline cleanup methods used following the oiling of 23 km (14 mi) of oceanfront sand beaches in the St. Petersburg, Florida, area i...

CHEMICAL TREATING AGENTS: RESPONSE NICHES AND RESEARCH AND DEVELOPMENT NEEDS

ABSTRACT Chemical oil spill treating agents—here meant to exclude chemical oil spill dispersants, burning agents, and bioremediation agents—are one type of countermeasure used to control the release and/or spread of spilled oil. They are infrequently used in the United States, in part because they have been inadequately tested and demonstrated for efficacy and environmental effects. A study planned and sponsored by the Marine Spill Response Corporation examined the potential utility of chemical treating agents during marine oil spills. Through an extensive literature search and market survey process, this study defined specific product classes and evaluated these classes in terms of operational use, efficacy, and environmental fate and effects. Individual products within each class were also evaluated in terms of these study parameters, and a resultant compendium of available products worldwide was produced. Based on the evaluation, as well as results from a workshop held in conjunction with this project,...

THE DECISION PROCESS TO SUPPORT SHORELINE CLEANING AGENTS IN THE FIELD

ABSTRACT Chemical shoreline cleaning agents (SCAs) are one option for cleanup of stranded oil on shorelines. However, site-specific variables, the properties of stranded oil, variations in the natu...

MECHANICAL PROTECTION GUIDELINES1

ABSTRACT The recently published Mechanical Protection Guidelines will: provide guidelines for identifying and prioritizing areas of economic, environmental, and cultural sensitivity, including form...

CASE STUDIES OF STANDARDIZED TECHNIQUES TO DOCUMENT SHORELINE OILING CONDITIONS

ABSTRACT The concept of standard terms and definitions, forms or checklists, and sketches is intended as the foundation for a variety of field programs or surveys designed and tailored to meet specific goals. The idea of standardized assessment procedures has developed over recent years to meet the requirements of spill response managers and planners prior to shoreline cleanup or treatment. The approach has been adopted by Environment Canada and the U.S. National Oceanic and Atmospheric Administration as a primary technical support tool for oil spill response. This paper presents eight case studies that illustrate a range of applications.