Could it be? The END?

CNN is reporting that the new device put on the wellhead of the BP oil rig Deepwater Horizon appears to have stopped the leak and is holding under the pressure, at least for now.  Lets all cross fingers that this marks the end of major leaking into the Gulf of Mexico.

Implications of the first sighting of whale sharks in the gulf oil slick

I recently experienced a moment of genuine dread regarding the oil spill in the Gulf of Mexico, and it was neither a familiar nor comfortable feeling. What is it that invoked such a powerful feeling after a disaster that has been underway for the last 80-odd days, now? Something that struck a little close to home, of course: the first direct impact to whale sharks. You may have seen this story coming across the wires over the past two days about NOAA scientists who, while on an aerial survey of the impacted area, observed 3 whale sharks swimming among ribbons of surface oil, not 4 miles from the epicenter of the Deepwater Horizon spill. This observation has serious implications; let me explain.

Whale sharks are widely-ranging tropical migratory sharks that are unusual among their more toothy relatives in that they eat plankton. Two of the adaptations they use to pursue this lifestyle – surface filter feeding and an exquisite sense of smell – make them especially susceptible to the impacts of the oil spill. I had all but convinced myself (perhaps wishfully thinking) that whale sharks would be able to sense the altered chemistry of the affected water bodies and avoid the area. It now seems that this is not the case; the observation by the NOAA scientists suggest that either whale sharks cannot tell the difference between polluted and unpolluted water, or they can tell the difference but do not alter their behaviour in such a way as to avoid the ribbons and plumes. As USM researcher Eric Hoffmayer states in the article, this is the realization of the worst fears of whale shark scientists, and I count myself among those.

How can it be that whale sharks are unable to tell the difference if their sense of smell is so good? One simple explanation is that the olfactory abilities may be extremely selective. Scientists don’t know exactly what sort of chemicals whale sharks are homing in on when they seek out patches of food in the ocean – indeed, addressing this question is one of the goals of this year’s whale shark research program at Georgia Aquarium – but we have some good candidate molecules. If the whale shark sense of smell is highly tuned to these compounds and relatively insensitive to other families of chemicals, like hydrocarbons (oil and gas), then it’s certainly possible that whale sharks simply cannot detect the problem.

That’s when the second adaptation, surface filter feeding, becomes a liability for whale sharks trying to negotiate the deadly emulsions and surface slicks in the Gulf. To fully appreciate why this is such a problem, we need to look a little more closely at the filtration apparatus whale sharks use to feed.

Like most plankton-feeding fishes, whale sharks use filters in the mouth/gill cavity to sift food particles from the water (see the exellent illustration by Emily Damstra at right). And like most plankton-feeding fishes, these filters develop from structures associated with the gills and gill rakers (cartilaginous rods that come off the leading edge of the gills and protect the gills from fouling and shape the current of water across the breathing surface). Where whale sharks differ radically from other planktivores like, say, anchovies, is that they do not have feathery interlocking gill rakers that serve to filter the plankton but can be disengaged from each other to allow bulk water flow out through the gill opening. Rather, their filters are so derived and so heavily branched that they form a single continuous pad that occupies the space between gill arches; it looks a lot like a black scouring pad. The gill arches cannot be disengaged from each other; thus, anything that goes in the mouth must be small enough to pass through the filters (less than 2mm, or about 1/12th of an inch), or it must be swallowed, or be spat back out through the mouth (something they are surprisingly good at!). In a paper currently in the review process, comparative anatomist Phil Motta from USF is describing the full functional anatomy of these structures; he took the photo of the filter pad surface shown hereabouts based on material samples from Georgia Aquarium.

The implication here is that oil that finds its way into the mouth, if it is not to be swallowed or to foul the filters, must be continually spat back. OK, I hear you say, perhaps if the whale sharks avoid feeding, there won’t be a problem. If only it were that easy. Whale sharks do not only use their mouths for feeding, they use them for breathing. They need to be passing water continually across the filters and thence across the gills, in order to keep the body supplied with oxygen. For the whale shark swimming in oil-affected waters, therefore, the animal’s breathing needs and the susceptibility of their feeding filters to fouling are in complete opposition.

If whale sharks are swimming into oil-polluted waters and fouling their filters with oil, what does that mean? In my best estimation, it means that the oil spill represents an extremely serious threat to whale shark health. I am by no means the first person to suggest this. Nature identified whale sharks as one of the 5 species most likely to be affected by the oil spill, and other scientists like Bob Hueter from Mote Marine Laboratory have also highlighted the risks. The true toll that the spill exacts on the Gulf of Mexico whale shark population will not be known for some time, but the thought of dead or dying whale sharks sinking silently into the depths (dead sharks generally sink, not float) is yet more motivation to put an end to the spill and to undertake immediate and extensive research and conservation programs to assess the damage and plan a road to recovery for the whale sharks – and all the other affected wildlife – in the Gulf of Mexico.

When acute gives way to chronic, Deep concerns for the Gulf set in

Just five days before the Deepwater Horizon oil rig exploded in the Gulf of Mexico, I wrote a piece for this blog about a different oil spill in Australia, when a Chinese coal ship called the Shen Neng1 ran aground in Queensland and spilled thousands of gallons of fuel oil onto a section of the Great Barrier Reef.  The gist of that post was that, horrible though they may be, there's no great cause to worry about acute events like that, because many marine ecosystems show remarkable resilience in the face of singular disturbance events.  About a week later when the BP spill started, therefore, I had confidence that the well would swiftly be capped, the oil would dissipate, Gulf life would return to normal and folks would all move onto the next media-hyped panic-fest.  But, as the days have dragged into weeks and the weeks are now dragging into two months and counting, and as the estimates rise of the amount of oil that continues to leak, and as successive attempts to cap the thing have failed, that confidence that the Gulf can recover to the same state it was in before the spill has started to get ever more shaky.

Now, I like to be a positive person; I try to see the upsides in most situations and not get caught up in negativity, which I consider one of the greatest and most utterly pointless malignancies of modern society.  But, following the coverage in the mainstream news and on excellent blogs such as DeepSeaNews and Observations of a Nerd and thinking about the problem in terms of ecological processes, it seems to me that we may well have passed a tipping point and that the ecosystems of the water column, benthic (bottom) habitat and coastal marshes may never return to their former states, even if they could stop the flow right now.  This principle has been elegantly captured by the "rolling ball" analogy, wherein an ecosystem has, by virtue of its structure and complexity, a sort of "potential energy" like a ball on a hill and that, if disturbed hard enough, you can start cascades that see the system diverge - the ball rolling down hill - until it settles in a new organisation - a dip in the hillside.  The important point is that getting the ball back up the hill to the former state is next to impossible, or at least requires inordinate amounts of energy and a thorough knowledge of the organising principles, which we lack.

What does all that mean for the Gulf, though? If a Spartina marsh isn't, then what is it?  What happens in the water column?  On the bottom?  That's where research comes in, and I was encouraged to read on the NSF website and by conversations I had with NSF and NOAA Fisheries Service program officers yesterday that they have spent all available money on rapid response grants, most recently an NSF multi-institutional cruise coordinated by UGA to study microbial responses in the water column.  Its not enough though, and the slowness of the peer review-based funding systems we have just can't meet the needs of a crisis of this magnitude fast enough, once the rapid response fund is tapped out.  It really needs executive intervention: if the White House can propose a Wall Street or Auto industry bail-out, why not a rapid response research and rehabilitation fund?  We can bill BP later!

Where is this all headed, and what should we expect to see in a "new" and different ecological regime in the Gulf of Mexico?  No-one can be certain at this point, but a hall-mark of such reorganisations is loss of diversity, and in any worldview, that is something to be lamented.  Lets hope it doesn't come to that, but at this point any concerns you may have that the damage to the gulf is irreparable could be forgiven, which is more than I can say for those responsible for this mess.

There's a Hole in the Bottom of the Sea

With a tip of the Pirates Hat to Veggie Tales and Family Guy for the inspiration

There's a hole in the bottom of the sea,
There's a hole in the bottom of the sea,
There's a hole, there's a hole,
There's a hole in the bottom of the sea.

There's a pipe in the hole
In the bottom of the sea,
There's a pipe in the hole
In the bottom of the sea,
There's a pipe, there's a pipe,
There's a pipe in the hole
In the bottom of the sea.

There's some oil in the pipe in the hole
In the bottom of the sea,
There's some oil in the pipe in the hole
In the bottom of the sea,
There's some oil, there's some oil,
There's some oil in the pipe in the hole
In the bottom of the sea.

There's a hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a hole, another hole,
There's a hole in the pipe with the oil in the hole
In the bottom of the sea.

There's a cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a cone, an inverted cone,
There's a cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,

There's a leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a leak, ANOTHER leak,
There's a leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,

So NOW,

There's a plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a plume, a killer plume
There's a plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea.

There's a boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a boom, a floating boom
There's a boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea.

There's a gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a gap, just check a map!
There's a gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea.

There's a bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There's a bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a bird, a struggling bird
There's a bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea.

There’s a company responsible for the bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a company responsible for the bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea,
There’s a company, a Big Oil company
There’s a company responsible for the bird in the gap in the boom on the plume from the leak in the cone over the hole in the pipe with the oil in the hole
In the bottom of the sea.

...and we should never let up on them until they clean up the mess...

Oill spills and Tar balls – know thine enemy

One of the more intriguing aspects of oil spills, including the DeepWater Horizon spill currently unfolding in the Gulf of Mexico (DeepSeaNews has covered it well), is the formation of tar balls.  These are globby blobs of bitumen-like material that are found on the sea floor or washed up on beaches after a spill. There's a few theories about how they form, but the general concept is that as the more volatile parts of the oil mixture evapourate, the mixture becomes thicker, heavier and stickier, until eventually the blob becomes heavier than seawater and sinks. On the bottom, the sticky blob incorporates sediment and its ball-like shape is reinforced by the rolling actions of currents or surf, in much the same way as you roll cookie dough into balls before putting them on the baking tray (mmmmmm….cookies….ahem). Sometimes this process makes for a grainy crust on the outside and a soft center, a bit like a Ferrero Rocher (mmmmm....chocolate....why do my analogies always involve food?).  There’s some other theories of formation that concern flocculation (oil sticking to clay) and emulsion (oil and water making a mousse of sorts - again with the food), but the prevailing idea seems to be that of smaller blobs of weathered oil coalescing and incorporating sediment. The net results is a gooey mess that is characteristically hard to remove if it sticks to you (or an animal), pongs of petroleum and is generally unpleasant.  The photo at left from NOAA's image library shows a tarball on a beach in California

Other than their B-grade horror movie nature (The Blob – aiieeeeee!) and the formation process above, I confess not knowing much about tar balls, so I went to the literature to see what’s out there. The answer: not much. A Web of Science search for “(tar ball) or tarball” 1945-2010 gets you precisely 26 hits. Now that is interesting! I would have thought that there would be far more, given the attention that is focused on oil spills when they happen. Much of the research has focused on chemical fingerprinting to identify where a given tar ball originated. In other words, the presence and absence of certain chemicals in a tar ball can tell you what sort of oil the ball formed from, and pretty accurately too. This has allowed some other studies that have shown that you have to be careful about blaming all the tar balls on a beach on one spill; there’s often a pretty good background level of tar balls from previous spills and even natural sources of oily substances. This is especially so for really small tar balls in the mm size range.

So what’s the long-term prognosis on tar balls in the environment? It doesn’t look like that question has been thoroughly answered yet.  Clearly they persist long after many more obvious signs of oil are gone.  Its tempting to think that they may be largely inert, especially those that form a good crust on the outside that reduces stickiness and prevents chemical interactions with the outside. But really, it seems like there’s a lot more work that needs to be done to understand these curious byproducts of oil spill accidents.