Goal & Themes

Goal

Our primary goal is to integrate ongoing studies and develop new ideas and collaborations to promote a comprehensive view of the factors controlling the formation and deposition of oil-associated marine snow and its accumulation as flocculants on the seafloor, in the context of oil and gas release and dispersant application in the marine environment.

Specifically, we aim to understand:

1. Which factors (either alone or coupled) led to the formation of oil-associated marine snow, its rapid deposition and the subsequent accumulation of flocculent material at the sea floor, which occurred on the continental shelf and slope of the northern Gulf of Mexico in association with the Deepwater Horizon oil spill?


2. What were the consequences of this flocculation and sedimentation event for the distribution of oil, the oil budget and for ecosystems condition, structure and function?

Themes

Breakout groups held on Day 2 of the working group meeting will address the following three themes:

1. Processes and Pathways
   The goal of the first breakout group is to define the processes and pathways in the water column that govern oil-associated marine snow sedimentation. Participants will combine in situ and experimental data with modeling approaches to hind cast in a spatially and temporally explicit manner, the formation and distribution of oil contaminated marine snow after the DWH spill. Formation, modification and loss rates (due to microbial degradation, feeding or sinking) as well as possible impacts of fresh water input to the GoM, or the presence of minerals or phytoplankton, for the occurrence and distribution of oil-associated marine snow should be assessed. By using a mechanistic understanding of the formation and degradation of oil associated marine snow, combined with the spatial- temporal distribution of oil, dispersant and particles, like phytoplankton and minerals, we hope to be able to generate marine "oil snow” distribution maps.


2. Accumulation Rates
   The goal of the second breakout group is to assess - in a spatially and temporally explicit fashion - the accumulation rates of oil-associated material at depths > 1000 m (traps) and on the sea floor, and to characterize the biogeochemical signature of this flocculent material. Ideally, the sedimentation event after the GoM spill in 2010 will be put in a historical context of sediment accumulation rates within recent geological timescales. Using a mathematical or conceptual model, we hope to be able to relate marine snow formation events in the water, with patterns of sedimentation and accumulation events at the seafloor.


3. Effects
   The goal of the third breakout group will focus on the effects of such oil-associated marine snow formation, sedimentation and accumulation events on pelagic and benthic organisms. Sinking marine snow provides substrates for microbes, and food for zooplankton and fish, thus entry of fossil carbon into the pelagic food chain via oil-associated marine snow is a distinct possibility. Upon arrival at the seafloor this flocculent material may provide food and/or cover mega fauna and smother benthic organisms. The effects will most likely depend on biogeochemical characteristics of the sinking material, e.g. oil, dispersant or clay content, and degree of degradation of organic matter and oil.

We anticipate that all three groups will combine experimental, field and modeling data to achieve a better understanding of the dominant sedimentation pathways resulting from oil spills and subsequent effects on ecosystem processes.