Selected tags: RedHerringSeries

“Red Herrings” in the Gulf of Mexico – Part 4: Persistent Effects?

This is the last post in a four part series discussing the ongoing – and "cascading" – effects in the Gulf, not from "oil," but rather its toxic components and their impacts on sensitive ecosystems. Read the rest of the series.

Once the more easily processed materials and their breakdown products have completed their complicated journeys through the Gulf ecosystems, that still leaves the toxins that don’t break down easily, both the polycyclic aromatic hydrocarbons (PAHs) and metals like arsenic that are associated with drilling accidents. By some estimates, as much as a quarter of the total volume of these toxins might end up back on the sea floor, and subjected to processing – and reprocessing – by sediment-eating "infaunal" invertebrates (worms and such), which are prey for bottom-feeding fishes and crustaceans. The same applies to marshes and beaches — foraging grounds for many sought-after fishes — as well as protected species, like migrating shorebirds.


These relationships provide re-entry points for toxins back into food webs that sustain seafood production.

It could be many years before those chemicals wend their way – much more slowly, and through different pathways – through both the ecological systems of the Gulf and their human counterparts.

The pathways for many of these longer-lived toxins will also be altered as human uses resume. Shrimp trawling, for instance, will stir up sediments, potentially exacerbating the impacts of both toxicants and oxygen-demanding substances.

Again and in conclusion, some elements of the complex ecology of the Gulf of Mexico may well get off scot-free from the disaster. But many others will be heavily impaired, at least for some time. Taken together, there will be a significant total effect on the ecological systems and on the productivity and safety of seafood from the Gulf, significant human population impacts are expected, and those impacts must be remediated.

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"Red Herrings" in the Gulf of Mexico – Part 3: Undersea Plumes?

This is the third post in a four part series discussing the ongoing – and "cascading" – effects in the Gulf, not from "oil," but rather its toxic components and their impacts on sensitive ecosystems. Read the rest of the series.

It could well be that the now-notorious subsurface plumes contained –or contain – a mixture of tiny oil droplets (both from oil spewing, hot, under pressure into cold water, and then being dispersed into even smaller droplets courtesy of Corexit) and dissolved or partly dissolved lower-molecular weight materials, like BTEX (benzene, toluene, ethyl benzene and various xylenes).

Components of these plumes broke down – and are breaking down – not in one felled swoop from oil to not-oil, but through a series of breakdown pathways, while it was transported in various directions as the currents shifted over several months of the active oil disaster. These materials would have been exposed to biological processing by bacteria. Bacterial populations were low initially, but have grown exponentially through time within the plumes as they drifted.

There is no free lunch in the sea: Did bacteria "eat" the oil?

Many people are sighing in relief that the apparent explosion of mid-water bacteria have processed much of the original oil load of the system. The cascading impacts of that phenomenon – if verified – have yet to be established. Perhaps the "oil," per se, is largely gone, but the array of produced materials, and their ramifying ecological effects must be fully accounted.

Full and final processing of this huge load of oil would both demand oxygen and produce carbon dioxide. While there have been some observations of adequate oxygen presence, there has as yet been no modeling of total oxygen demand and its implications for ocean ecosystems, including some already under oxygen stress. Moreover, the sea is already being subjected to acidification from absorbed carbon dioxide (the final breakdown product where oxygen is adequate from biotic degradation of hydrocarbons).

While an "Andromeda strain" scenario is far-fetched, many questions remain. What are the likely impacts of such massive loads of both oxygen-consuming organic substances and produced carbon dioxide, on oxygen levels and acidity patterns in the depths? What will happen to this large, new and artificial, biomass of bacteria, as they respire and then decompose? How will this major perturbation of mid-water biota cascade through ocean ecosystems? All unanswered questions.

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"Red Herrings" in the Gulf of Mexico – Part 2: Key Ocean Ecosystems at Risk

This is the second post in a four part series discussing the ongoing – and "cascading" – effects in the Gulf, not from "oil," but rather its toxic components and their impacts on sensitive ecosystems. Read the rest of the series.

I remain extremely concerned about what has happened to the out-of-sight, underwater ecosystems of the Gulf of Mexico, especially at middle depths and on the bottom. These little known but ecologically vital elements of the ocean have been heavily exposed to oil-based pollution, both rising from the bottom and sinking back down from the surface, and – at least in some places – bathed in persistent underwater toxic plumes.

Marine life in the mid-waters is so rich and profuse in places that sonar waves bounce back as a "deep scattering layer" and provides key food for many familiar, surface-diving animals, including whales, dolphins, billfishes and giant tunas. Deepwater coral reefs and other bottom dwellers have been at great risk all along, and not even the initial explorations have yet been done to assess the impacts of reefs less than twenty miles from the broken well bathing in oil-based pollution.

An actual track of a sperm whale diving through rich mid-water feeding zones (shown in green) from the northern Gulf of Mexico. Credit: Modified from Azzara, 2006.

The oil and oil-derived pollution that made it to the surface followed – and is following – one set of pathways through the Gulf ecosystem, exposing and injuring not just sea turtles and sea birds, but also near-surface marine animals and plants, large and small, and entering foodwebs through a complicated series of entry points, which we don’t yet fully understand.

Fine droplets of dispersed pollution are more likely to be adsorbed onto particulates, sinking back through the midwaters and into the abyss. The moreresistent elements, like tar balls, either float away or sink back into the abyss, and follow a different set of pathways.

The total "dump" of highly toxic oil components, including low-molecular weight aromatic hydrocarbons (known familiarly as "BTEX" – benzene, toluene, ethyl benzene and various xylenes), could have been up to 50,000,000 gallons. These are heavy-duty pollutants in their own right, including known carcinogens and reproductive toxicants, with a fair solubility in sea water. In a surface spill, pollution mostly evaporates, and the only real concern relates to emergency response workers that are exposed while on duty. In this underwater case, scientists simply do not know – yet – exactly how the massive load of pollution is being processed in the Gulf.

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“Red Herrings” in the Gulf of Mexico – Part 1: It Ain’t the Oil

This is the first post in a four part series discussing the ongoing – and “cascading” – effects in the Gulf, not from oil, but rather its toxic components and their impacts on sensitive ecosystems. Read the rest of the series.

In recent weeks, nearly every discussion about the BP Oil Disaster in the Gulf of Mexico has focused on the question: “how much of the oil from the broken well is left in the Gulf?” 

The answer is simple:  “None – it ain’t the oil, stupid!”    

For some time now,  the problem hasn’t been the oil in the Gulf,  it’s the complicated series of impacts caused by the diverse substances that made up the oil as they are degraded in stages, both biologically and chemically. Each step along the way – and even the final breakdown products – poses important threats to a different suite of living things.  The total damage done by this complex array of shifting impacts on the sensitive ecosystems  and the people of the Gulf remains largely unknown.


Sure, some elements of the complex ecology of the Gulf of Mexico may get off scot-free from the disaster.  But many others have been or will be heavily impaired, at least for some time.  Taken together, there will be a significant total effect on the ecological systems of the Gulf, including the productivity and safety  of seafood, and significant  bottom-line impacts will be felt  on human health and social and economic well-being. 

Oil or Not Oil?

From the beginning of the disaster back in April, as “Gulf Light Sweet Crude” oil spewed  into the depths of the Gulf, the components of that oil – a “toxic soup” of hundreds of different chemicals – have been subjected to intense physical, chemical and biological sorting and processing, and to transportation by currents both towards and away from shore. 

This is an underwater look at one of the oil plumes in the Gulf of Mexico in late May. Click to watch the video.

By the time the well was capped in mid-July, a significant amount  of the approximately 200,000,000 gallons of liquid flowing from the broken well made it to the surface as recognizable oil.  But from the very beginning, the various “toxic soup” ingredients have followed radically different pathways through the complex oceanographic and living systems of the Gulf, spreading and being processed in different directions at different depths, and at different rates.

It is clear that all layers of the sea in a large zone around the well have been exposed, from bottom to top, as the spreading and rising cone (or “plume”) of oil-based materials spewed from the well. In contrast to a more typical oil spill on the water’s surface, where the transport and ecological fate of oil components are well-known, there are still many unknowns related to how the various chemicals have moved and are breaking down underwater, including the biochemical pathways and timetables.  Intense scientific investigation and complicated modeling are necessary before these complex relationships can be understood fully.

The addition of dispersants, both at the bottom and the top of the water column, has further altered the chemicals’ pathways through the ecosystem,  likely lessening some kinds of impacts and exacerbating others.It may well turn out that chemicals derived from oil spread over a much larger area because of the addition of dispersants, both at the bottom and the top.  The final accounting of the ecological and human winners and losers has yet to be made.

At the end of the day, the complex set of effects on the living systems of the Gulf from the oil and its chemical components will be understood, more or less.  The impacts on the human populations will be estimated, if not fully understood.  It is grossly premature to declare victory, though, until we understand the ways in which the basic fabric of the ecosystems of the Gulf has been altered, and what might be required to restore its weave.

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