Linking Oil Fate and Ecological Effects

In the sessions that addressed Ecosystem Effects, a wide range of topics were covered.  These included issues that have been researched for some time, such as what are the concentrations of Oil (WEF) and oil plus dispersant (CEWAF) used in toxicity tests versus concentrations actually measured in the Gulf.  Are they comparable?  This was raised several times and responses were inadequate (hence the repeated questions) mostly due to the challenge of defining exactly what is meant by ambient concentration.  A related and equally spirited discussion was had in several of the sessions on measurements.  The hydrodynamic and biological exposure conditions in the Gulf are highly heterogeneous.  Sampling and in-situ monitoring systems were operating in some cases at or beyond the limits of their design capability.  Measurement techniques, such as laser particle size distribution measurement (LISST), do not address the entire size range of particles, focusing only on the smaller sizes.  Dispersant mass balances and material budgets for fate models have added uncertainty as a result.  Combining the particle size measurements with other chemical measurements, including fluorescence, dissolved oxygen, gas chromatography-mass spectrometry, provides a more complete, but still imperfect, picture of the fate of the oil, including processes such as microbial biodegradation.    

Biologically mediated pathways of oil transport directionally have been minimally studied and consequences for in-situ transport are still essentially unknown – for example copepod ingestion of oil droplets and subsequent sedimentation of fecal pellets.  Was it observed in-situ and how significant is it in relation to other transport pathways?

A wide variety of biological response testing and ecosystem effects evaluation is yet to be performed.  Examples of questions raised during the discussion include different sensitivities of flora impacted by the oil and the mechanism of those impacts, especially on beaches and marsh areas.  Impacts to the beaches and marshes were not addressed very thoroughly.  This is an important question that has the potential to be addressed by SETAC.  This meeting has focused on the aquatic species (inclusive of water- and marsh-dwelling avifauna). An attendee commented that it would be constructive to have a meeting that focused on the impacts to the marshes and beaches (and potentially inclusive of pro and cons of various remedial techniques).  Other, more subtle effects, also need to be further investigated, such as multi generational impacts on avian species, delayed effects of juvenile exposure on adult organisms, and enhancements to primary, linear toxicity mechanisms – phototoxicity, as well as synergisms and antagonisms.  None of this work was included in the spill response testing, but is expected to be in the next set of research studies supporting resource damage assessments. 

A underlying issue was the “but for the dispersant” question.  The issue raised by one of the panelists is can we quantify the potential increase in the impact of oil to the beaches and marshes that would occur without the use of dispersants? In fact, is it a good idea in any case? 

It appears to have been decided that oil dispersal is a net environmental benefit.  This is being challenged, at least on the political level.  Presently the “responders” do not have adequate information to fully weigh the environmental benefits and costs of dispersant use (how, where, and when).

Perception vs. Reality — Which is Which?

Dispersed Oil - 0 to 10,000 mg/L (courtesy of Scott Miles, LSU)

As mentioned in the previous blog, the goal of the focus topic meeting is integrative – gathering lessons learned; sharing experiences and having a candid, even critical, discussion. The opening forum lived up to expectations. Given the variety of disciplines and perspectives represented, questions were asked about a number of comments made by the plenary panel participants. Many of these had to do with differences between what the analytical data seemed to be showing and what was visually observed (or thought). For example, the dispersal of the oil droplets – visually was not what the majority thought. Beakers of various dispersed oil concentrations were shown. Most local observers of these prepared samples had thought the dispersion would be a dark brown highly concentrated plume (containing 1000′s of parts per million of hydrocarbon) when actually it was translucent and concentrations were actually in the 1-10 part per million range.

This type of information triggered some great questions like – how was it decided that the use of dispersants would be preferable to allowing the oil to reach shore or even trying to mechanically collect as much as possible at sea? The unified command structure and the decision making processes coming from the environmental unit and the various on-site experts provided a glimpse into how the rapidly evolving situation was actually being handled. Although all agreed that improvements and enhancements in how the science was brought to bear on these decisions could and need to be made, the perceived chaotic nature of the operations did not reflect response procedures in place which operated as intended.

Still, the reality is that residuals are less but present, especially in outer beach areas. Oil mats continue to generate tar balls that can be found on shorelines at up to one meter of depth. One of the technology aspects that was not fully appreciated was the fact that mechanical cleaning cannot be used in all areas. Each decision on a shoreline cleanup technology recommendation needed to be evaluated on its own requirements. Even within a technology category significant variations exist and provide different results. Some 50 different machines have been employed. Examples of phragmites (marsh grass) cleaning indicate that even with a tailored approach – cleaning and subsequent recovery more successful in some areas (Pass a Loutre vs. other marshes).

Sampling effort during the response period was spread out over thousands of square miles and the summary statistics (percent positive) do not give a true picture of problems that exist. The current work is focussed on a more deliberate sampling and interpretation strategy. The summary information from the OSAT (Operational Science Advisory Team) reports was not intended to be used to interpret consequences for long term impact or remediation, really being intended for operational decision support. But it neverless has been cited in this longer term context.  As one panelist noted scientists need to emphasize how data should be used. Whatever is known tends to be seized upon and used even in instances where it is not appropriate. Trying to control this tendency in a social media-enabled world is problematic because if no data are available speculation and fabrication fill in the gaps.

The fact is whatever is presented on the web by perceived neutral or reliable parties tends to be believed.  As scientists we need to understand the current situation better and actively deal with today’s “always on” world. The notion that providing essentially raw data very quickly addresses our responsibility for communication to the public (or even to other scientists) during an event of this nature needs to be reevaluated.

The Gulf Oil Spill – A One Year Science Status Report

The one year anniversary of the massive Gulf Spill has passed with perhaps more questions than answers about the effects of the oil and attempts to control and abate it.   The size of the spill, the lack of definitive knowledge of what exactly should be done, the relatively old control and abatement technology available, and yes, even the regulatory-based damage assessment process have all contributed to the challenges inherent in understanding what happened and more importantly will happen to complex ecosystems and habitats in and along the Gulf. 

Still, it is critical we assess where we are today, what we think we know or don’t know, and what and how we need to organize our scientific resources going into the future. 

The basis for the SETAC Gulf of Mexico Focused Topic Meeting is to provide a multi-stakeholder forum for exchange of current and developing knowledge on key aspects of the spill not only from a traditional scientific meeting standpoint, but also in a more conversational way.  The format as a combination of platform presentations, posters, and panel discussions is intended to facilitate exchange and joint learning.     

If you want to make a contribution to this blog during or even after the meeting, here’s a link to an input form to capture your thoughts: http://www.surveymonkey.com/s/GWMRZRQ.

Further, the idea that the meeting will have immediate impact only happens if the key learnings are taken away and used to modify research projects and proposals and even to rethink strategies and policies within companies and agencies based on the exchanges at the meeting.  In short, we want this to foster thinking and acting at various levels.  The idea to include a session on “Communications Challenges and Solutions” is to address the fact that we as scientists and those we need to be communicating with, don’t always interact, preferring to stay in our own narrow universe, and even when we do try, we don’t necessarily speak the same language.  We must change that!