Invasive Species Really Don't Belong Here

In September my brother and I drove through 12 ecozones from the Forest/Savannah Transition in Wisconsin through Tall Grasslands to the Western Short Grasslands in Colorado, my first time to see the American Prairie. For decades, I had read about conservationists’ efforts to restore its ecological integrity. At Blue Mounds State Park in Minnesota, we walked along a ridge at sunrise, saw bison in Northern Short Grasslands, and then stopped at the park office to chat with two conservation officers.

They described a 20-year long campaign against weeds in their bison range, but mentioned misgivings. They gave me a copy of an article about researcher Mark Davis of Macalester College, St. Paul. His research shows that exotic species often fit well into native ecosystems and contribute to ecosystem function and biodiversity.

Of course, some exotics are fine (e.g., exotic game birds and honeybees), but many are seriously ruinous to terrestrial or aquatic ecosystems or agriculture. Here in British Columbia, ranchers spend millions of dollars trying to limit the spread and reduce the density of knapweeds, for example, and farmers work hard to keep alien weeds out of their crops, as they do in Minnesota. Our aquatic biologists have likewise spent a small fortune trying to limit the growth of damaging aliens, such as the milfoil that fouls beaches in the Okanagan. But, although I have enjoyed hunting chukars and ring-necked pheasants in North America, it was much more of a thrill to see chukars in their native habitats in the Hashemite Kingdom of Jordan and ring-necked pheasants in the Peoples’ Republic of China. Clearly, aesthetics and values are valid components of the debate, if there is one. Some species just don’t belong here.

I agree with Davis that scientists have become more sanguine about the issue and it is usually non-specialists who have such an anti-invasive fervour. I don’t mind their zeal. In 1994, when I published the first comprehensive analysis of invasive species in this province , there was virtually no government or public attention to the damage caused by invasives. Now there are new laws to restrict importation and government staff, stakeholder committees, and citizens’ groups in every region that sponsor research, conduct campaigns to limit the spread of invasives, and mobilize volunteers to eradicate infestations in certain situations. This is all good for the environment.

Leaving Minnesota, we drove through South Dakota, Nebraska, and Colorado, stopping at state parks and National Grasslands all along the way. We saw pronghorn antelope, more bison, desert cottontails, prairie dogs, and other prairie wildlife in four more short-grass ecozones. Without conservation efforts like those at Blue Mounds State Park, these would have been degraded habitats empty of wildlife.

References
Harding, L.E, P.R. Newroth, R. Smith, M. Waldichuk, P. Lambert and B. Smiley, 1994. Exotic species in British Columbia. In: L.E. Harding and E. McCullum (eds.), 1994. Biodiversity in British Columbia: our changing environment. Environment Canada, Delta, B.C. p. 159-223.
DAVIS, M. 2003. Biotic globalization: does competition from introduced species threaten biodiversity? Bioscience 53:481-489.
World Wildlife Fund 2000, Terrestrial Ecoregions

Grooming and the Evolution of Language

Robin Dunbar’s interesting book, Grooming, gossip and the evolution of language (Dunbar 1996) proposes that language evolved in our primate progenitors as a social bond to promote group cohesion, essentially replacing social grooming. I’m not so sure.

His idea was that social grooming (which in primates goes well beyond that needed for health, for example, to remote ticks and fleas) evolved as societal “glue,” but became inadequate when group sizes became too large. Primate societies are based on relationships, which are usually hierarchical: whom you groom, who grooms you, both determine and demonstrate your place in society, which in turn determines your personal and consequently reproductive success. Hence, it is an evolutionary adaptation. But you can only groom and be groomed by so many partners. Beyond a certain group size, grooming becomes inadequate. Dunbar showed, based on a variety of paleontological, anthropological and physiological data and modern and extinct primates, including humans (for example, predicted group size based on ratio of group size to neocortex in primates) that group sizes grew from about 60 in australopithecines, to 80 in H. habilis, 100-120 in H. erectus, 110-130 in archaic humans, and 120-160 in modern humans. Modern human group size, whether as hunter-gatherers, military legions, or corporate operating units, is amazingly consistent and seems related to the number of people that anyone can know personally.

Anthropologist do generally agree that our brain size grew to primarily accommodate the memory and analytical processing power needed to keep track of all the relationships in increasingly larger groups: from 450 cm3 in A. africanus to 750 cm3 in H. habilis, 1050 cm3 in H. erectus, and 1350 cm3 in H. sapiens (Pilbeam and Gould 1974). However, absolute size is not the whole story: in modern humans, body size was reduced somewhat, while the brain stayed the same or grew a little, meaning that relative brain size continued to increase and the biggest jump in relative brain size was only 100,000 years ago (Kappelman 1996). By Dunbar’s reasoning, therefore group size should have reached its peak then, not in archaic humans. This is, not surprisingly, around the time that most anatomists (if not linguists, who favour a later date) that language with complex evolved.

Dunbar reasoned that since gossip and other social commentary forms the bulk of human conversation—more, for example, that practical matters such as where to hunt kudu or when to propose a corporate merger—that it must have evolved as a replacement for grooming. He dismissed the previous notion, still held by many anthropologists, that language began as a way to communicate practical matters essential to survival, such as how to stalk a dangerous prey or warning of a predator.

But humans have a very different vocalization apparatus, including the shape and position of the hyoid bone, that lets us make a much wider range of sounds than any other primate, and this must have evolved much longer ago than the last 100,000 years. And even monkeys make a sufficiently wide range of vocalizations combined with commonly understood meanings, to give and distinguish among different warning calls for different predators. For example, vervet monkeys (pictured above) and many other colobine monkeys have give warning calls that distinguish among snakes, eagles, and leopards; in mixed species groups, all species of monkeys recognize and respond appropriately to each of the warning calls that the other species give. Surely, the roots of human language are much older than the beginning of larger group sizes.

Here’s how I think language started, and why I think it. Early in my career as a wildlife biologist, I worked with several Inuit and Dene (First Nations aboriginal people of Canada) hunters and trappers and at times camped with their families, few of whom could speak English. But our work required communication, and it was not long before, in each situation, my native counterparts and I knew each other’s words for the common animals we encountered, a few other nouns such as “track”, and a few verbs such as “hunt” and “follow”. Because I could write and kept notes, I perhaps learned these words more quickly than a hunter-gatherer who could not write. But that we learned, and quickly, shows how important in was for us, and how important it must have been for our hunter-gatherer ancestors. But there is more. My colleagues had a lot of gestures that they used to indicate different animals and verbs such as “hunt,” “track.” and “follow.” And the gestures were different from tribe to tribe. For example, Cree men from the Beaver Indian tribe of northwestern Alberta often pointed with their lips. To indicate where a caribou had gone, they would turn their face in that direction and pucker their lips, as if trying to kiss the direction. Clearly, hunters need non-verbal “words” so that they can coordinate a hunt without alerting the prey.

Archaeological evidence suggests that, since both H. neandertalensis and H. sapiens could speak, then their common ancestor, H. heidelbergensis, could, too. Rudimentary speech as described above: nouns describing everyday objects, no doubt dates from that time. Experts are divided as to when grammatical language with syntax developed, but estimates range from 300,000 to 50,000 years ago (see review in Ambrose 2001). This happened long before the development of modern humans.

Recent genetic evidence shows that we lost our hair at least 1.2 MYA(Rogers et al. 2004) , while archaeological evidence shows that we began using scraped hides as clothing about 300,000 years ago, and adopted sewn, well-fitting clothing around 20,000 years ago (see review in Rantala 2007). Language therefore coincides roughly with adoption of clothing, but not with nakedness. Since grooming would have been basically unnecessary for hygiene between 1.2 and 0.3 MYA, and it’s not possible to “groom” naked skin, it seems that Dunbar’s thesis is untenable. No, language started, if not with hunting per se, then with the general need to communicate about the exigencies of life among our ape ancestors who cooperated and coordinated their activities.

References
Ambrose, S. 2001. Paleolithic technology and human evolution. Science 291:1748.
Dunbar, R. 1996. Grooming, gossip and the evolution of language. Harvard University Press, Cambridge, Massachusets.
Kappelman, J. 1996. The evolution of body mass and relative brain size in fossil hominids. Journal of Human Evolution 30:243-276.
Pilbeam, D., and S. J. Gould. 1974. Size and scaling in human evolution. Science 186:892-901.
Rantala, M. J. 2007. Evolution of nakedness in Homo sapiens. Journal of Zoology 273:1-7.
Rogers, A. R., D. Iltis, and S. Wooding. 2004. Genetic variation at the MC1R locus and the time since loss of human body hair. Current Anthropology 45:106-108.

Agribusiness not a Panacea for Africa

Many people involved in aid and development programs for Africa think that science and agribusiness can reduce hunger and poverty. Governments, including Canada, promote this. They are wrong. Well, maybe in some hypothetical situation they can, but not in the real world. An example is Margaret Wente’s column about a year ago in The Globe and mail (Enviro-romanticism is hurting Africa, July 18, 2009). She said that in Africa, poverty and malnutrition are rising “largely because of primitive farming practices.” Nothing could be further from the truth. Poverty and malnutrition are rising because, among other factors, bad governance is ruining farmland, bad governments are leasing and selling farmland to foreign firms and governments, and bad international trade is preventing small farmers’ access to markets.

She said, “We could increase the global food supply by 80 per cent just by bringing the rest of the world up to the standards of modern agriculture.” This is pure nonsense. Many analyses of the global food situation, such as that of Lester Brown, “Plan B 3.0 Mobilizing to Save Civilization” (Earth Policy Institute, 2008), make it abundantly clear that global food production is on the decline. The improvements and innovations that gave rise to the “Green Revolution” during 1950–1990—mainly in large-scale irrigation, mass-production and distribution of fertilizers combined with plant breeding—have already been made and no amount of technological development can forestall the decline. Desertification (exacerbated by climate change), salinization of soils because of irrigation, and urban encroachment have reduced the global supply of farmland and rangeland. Water scarcity because of over-pumping of aquifers, over-use and degradation of surface water, and logging and other causes of more rapid runoff and erosion in watersheds are further reducing the amount and productivity of arable land. The world’s ocean catch of wild fish peaked at about 96 million tons in 2000. Aquaculture has allowed continued, modest increases in total fish production, but only at the expense of destruction of destruction of coastal ecosystems, especially mangroves, that support local shore-based fisheries and coastal farming.

Meanwhile, the increasing human population has meant that global per-person food supplies have declined. The wild seafood supply per person peaked at 17 kg in 1988 and now stands at 14 kg. The amount of grainland per person in 1950 was 0.23 ha, but in 2007 was 0.10 ha.

The global food crisis of 2007–2008 that saw food riots in several African countries, Indonesia, the Philippines, and Haiti because of dramatically increasing grain prices portends worsening food security. Today, in September 2010, people are rioting in Mozambique for the same reason.

Driving across Saskatchewan or Kansas, one sees Wente’s “modern agriculture”: vast distances of highly productive monoculture farmland with hardly any people. In our recent drive through four sub-Saharan African countries (Namibia, Botswana, South Africa and Swaziland), we saw a land densely dotted with small villages and single-family huts where people guarded their small herds and flocks, hoed their meagre maize and vegetable plots, and trudged by with heavy loads of firewood and water. Agribusiness may fit into the overall economic mix and productivity of these countries, but will not help the 60% of the population of sub-Saharan Africa who, as Wente notes, are “smallholder farmers, mostly women, who typically earn a dollar a day or less.”

Agribusiness is making their plight worse day by day. The report, “Land grab or development opportunity? Agricultural investments and international land deals in Africa” by the United Nations and the International Institute for Environment and Development, shows that big businesses in rich countries have been buying and leasing farmland in Africa at an alarming rate. Since 2004, governments of five African countries of re-allocated (sold outright or leased in long-term contracts) 2,492,684 ha of land (excluding allocations below 1000 ha) away from smallholders to big business, many of them foreign. They include governments or businessed in Saudi Arabia, Yemen, Kuwait, Qatar, India, Britain, South Korea, and China. The rate of farmland reallocation to foreigners has increased dramatically after the 2007–2008 food crisis as countries seek to increase their own food security. In May, the government of Madagascar fell because of a popular uprising against the government’s 99 year leases of almost 1.8 million ha of farmland to South Korean and Indian companies.

The biotechnology that Wendt and many others advocate as a panacea for African hunger is not bad by itself and may be an important part of the mix, but will not help the smallholders and often hurts them. What they need is for rich countries like Canada to tie its international trade and aid in poor countries to only those business deals and programs that help poor families.

Grizzly and Polar Bears Interbreeding is another threat to Polar Bears

It was one of the most awe-inspiring experiences of my wildlife career: in the autumn of 1975 a colleague and I watched a polar bear swim up an inlet toward us on Bathurst Island, then Northwest Territories (now Nunavut). We were near the head of an inlet on a high promontory, and were excited to watch the white bear swim for a mile or so until it reached the shore just below us. There it walked on the the shore and sniffed in the mud where we had walked moments before. We could see him sniffing in our individual footprints. He looked up and around, nose high, testing the wind. Then started following our tracks towards us.

My colleague ran, but since there was nowhere to hide and nothing to climb on the featureless tundra, I stayed put. In a few moments, the bear abandoned our scent trail and went on up the draw, passing out of sight among the rocks.

There are still polar bears throughout the Arctic and some populations are healthy, but some are declining, with low production of cubs and low survival of all age classes. Climate change is the main culprit, but now another threat has appeared.

The confirmation of a grizzly-polar bear hybrid (DNA confirms suspected rare grizzly-polar cross shot in High Arctic, Vancouver Sun, May 1, 2010) at Ulukhaktok, N.W.T, (formerly Holman, on Victoria Island) is part of a trend that began at least 20 years ago.

In the winter of 1951-1952, Frank Banfield, a government wildlife biologist, recorded a grizzly bear taken on Banks Island (Banfield 1974). This was so unusual that he reported it as an “extra-limital record,” that is, outside of the known range.

In the last 19 years, sighting of grizzly bears unusually far north have become common: Melville Sound (1000 km north of mainland) in 1991, Banks and Victoria Islands (160 km north of the mainland), Hudson Bay, and Melville Island in 2003 and again in 2007 (Kaufmann 2007; Struzik 2006). They have become so well established on Victoria Island as to be a significant predator of muskoxen (Gunn and Lee 2000) .
The one shot in May was a second-generation hybrid, the offspring female grizzly-polar hybrid mating with a male grizzly bear. It was the second known grizzly-polar bear hybrid. In April 2006 the first known hybrid polar-grizzly bear in the wild was shot on Banks Island (Roach 2006). DNA tests showed it had a polar bear mother and a grizzly bear father.

After I gave a talk on my grizzly bear research at an international bear conference in 1977, several Norwegian bear researchers rushed up to me. They had read my earlier paper in the Canadian Journal of Zoology on grizzly bear denning on the Arctic coast, in which I mentioned that polar bears also occurred in my study area (Harding 1976). It turned out that this was the first report of grizzly bear and polar bear ranges overlapping, and the Norwegians wanted to know how the two species interacted. Their interest was stimulated because a polar bear and grizzly bear had mated in a zoo and produced fertile offspring (c.f. Stirling 1999), and they wanted to know if this could happen in the wild. I had to disappoint them by explaining that, since polar bears only came ashore in winter when grizzly bears were asleep in their dens, they never had an opportunity to interact, even though they shared the same habitat temporarily.

How times have changed! The recent shrinking of the polar ice cap and withdrawal of seasonal ice from shore has driven many polar bears ashore in the summer, bringing them into contact with coastal grizzly bears. At the same time, more and more grizzly bears are taking up residence on the Arctic Islands. Such hybrids may become more common. Over many generations, this could, hypothetically, destroy the polar bear as a species by genetic contamination. That is, if they aren’t first destroyed by shrinking sea ice seal-hunting habitat.

References

Banfield, A.W.F. 1974. The mammals of Canada. National Museum of Natural Sciences, Univ. of Toronto Press, Ottawa.
Gunn, A., and Lee, J. 2000. distribution and abundance of muskoxen on northeast victoria island, n.w.t., august 1990. Government of the Northwest Territories, Department of Rresources, Wildlife and Economic Development Manuscript Report No. 119.
Harding, L.E. 1976. Den site characteristics of Arctic coastal grizzly bears (Ursus arctos L.) on Richards Islands, Northwest Territories, Canada. Canadian Journal of Zoology 54(8): 1357-1363.
Kaufmann, B. 2007. Grizzly sightings on northern Arctic island.
Roach, J. 2006. Grizzly-polar bear hybrid found -- but what does it mean?
Stirling, I. 1999. Polar Bears. University of Michigan Press.
Struzik, E. 2006. Grizzly bears on ice.

Dog Evolution: Camp Scavenger Hypothesis Denied

The photo of a Tundra Wolf first appeard in BC Outdoors, April, 1985. An abbreviated version of this post was published as a Letter to the Editor in the November/December 2010 issue of Archaeology.

In the September/October 2010 issue of Archaeology is an article, "More than Man’s Best Friend,” that summarizes theories about how dogs' domestication began. All dogs descended from wolves, although the exact location and hence subspecies of wolf is in doubt: some evidence points to China and some to the Middle East. One of these ideas is that wolves evolved as scavengers, hanging around human camps. Anyone who has lived in wolf country as I have would find this untenable. Wolves don't scavenge, unless they're starving, or if they opportunistically stumble upon another predator's kill. And human camps don't usually leave enough meaty refuse to attract a wolf, although they often visit camps out of curiosity. A hunting camp is a different matter: a large mammal carcass would attract a wolf; but humans have been using tools to clean meat from bones for more than 2 million years, and by about 15,000 years ago, when the first unequivocal dogs appear in the archaeological record, humans were very efficient at cleaning up the bones and extracting the marrow. The leftovers would not feed even one wolf, let alone a pack. Human settlements leave enough refuse; but these only appear about 10,000, just before agriculture.

Moreover, anyone who thinks the first dogs evolved as camp-periphery scavengers hasn’t spent enough time sleeping on bare ground where large carnivores might eat you. They can’t know the terror one feels upon hearing heavy footsteps in the dark after the campfire has died; nor can they realize how easy it is to obtain wolf pups. I have many times heard such footsteps and wished I had brought my dog, and later found grizzly bear or other predator prints. Once the footsteps stopped only a few meters away, and stayed. I lay petrified until the first light of dawn revealed a mountain lion watching me. In the Canadian Arctic and Boreal Forest, where I have worked as a biologist, hunted, and camped with Dene and Inuit and hunters and families for many years, every hunter finds wolf dens and many bring home the pups for the kids to play with. I’m too large to crawl into the wolf dens I have found, but the more lightly-built Dene hunters often can. It would not take long—about one night—for a family to realize how good a sentry the wolf can be. If it is a bitch that they have tamed, she’ll likely be bred by a wild wolf. It is not a great leap to think that the family will keep the most docile of the brood. From there to dogs is a short chain. In the Middle East, one of the places posited for dogs’ first progenitors, even into the last century there were wolves, lions, leopards, brown bears, striped hyenas, and wild boar, all of which can kill sleeping humans. After dogs were domesticated, sure, some no doubt became camp scavengers, but I feel in my bones, where terror lives, that they began as pets and sentries.

African Wildlife: The Big 5, Ugly 5 and Little 5

Preface

When Jeff and I were planning our trip to Africa in 2008, we searched hundreds of safari Web sites, and corresponded with perhaps 100 tour operators, some in person here in Vancouver, and began to suspect what I wrote above about tours. All of them advertised the “Big 5”. In Ernest Hemingway's day, when he wrote ”The Snows of Kilimanjaro”, these were the 5 most dangerous game animals to the hunter: lions, cape buffalo, white rhinoceros (black is more dangerous, but were nearly extinct by then), leopard, and elephant.



When non-hunting tourism began to take hold, the tour operators co-opted this phrase, implying that if you saw these 5 wildlife species, you had seen Africa.




Preamble

After some time with our guide, Lucky Garenamotse (www.luckyafricasafaris.com), and cook, Moses, on our private safari (which actually cost less than the all-inclusive tours), we discovered that the guides and other tour staff uniformly deride this “Big 5” notion. Our guide, when he understood that Jeff and I felt likewise, played a game: he began to show us the “Little 5” (one was a mouse) and the “Ugly 5” (for example, the Jaribou Stork).




The Story

After I’d been in Africa about 4 ½ weeks (3 with Hannah) and Jeff 1 ½ weeks, and had seen 24 species just in the family Bovidae (the antelopes and buffalo), 2 species of zebra, 2 of giraffe, 2 of rhinoceros, hundreds of hippopotamus including one that ran through our camp between our tents, plus nearly every other big game animal in southern Africa, not to mention almost all of the medium-sizes and large carnivores (bat-eared fox, 6 species of mongoose, 2 kinds of civets, spotted hyena--had actually looked up from my sleeping bag on the ground into the eyes of a hyena looking down at me--hunting dogs, leopards, and lions), and counted 344 species of bird; and had leapt aside as hyenas actually chased impalas between our tents, we came to the resort down of Kasane on the Zambezi River. This is just above Victoria Falls in Zambia, where tourists fly in on 3- or 5-day tours, see the falls, and then take a day’s detour so they can say they were in Botswana. Jeff and I went into the biggest resort for coffee while Lucky and Moses tinkered with the Land Rover and refilled our fuel and food supplies. On the verandah overlooking the Zambezi River, I put up my ‘scope and found an African Finfoot, a rare grebe-like bird with no relatives on Earth (except for the Asian Finfoot) and that that only occurs in Botswana at this one spot. Jeff and I were thrilled, as we wouldn’t get another chance. As we were turning to re-join Lucky and Moses, we encountered a young woman in safari tour-leader garb, with “Naturalist” on her name patch, who asked us if we had “got lucky” that morning. Not knowing what she meant, Jeff mentioned the Finfoot as being quite a prize. Then it was her turn to look perplexed. She had no idea what a Finfoot was. Finally we understood that she had been enquiring whether we had been lucky enough to see a hippopotamus on the morning’s boat ride!




The Epilogue

For the rest of the trip, when Jeff or I saw a new species, the other would say, “Got lucky there!”

The Sequel

Jeff and I are thinking about a trip to Borneo. Reading the tour operators' and lodge literature, it seems that people only go there to see orang-utans, which Jeff and I have labeled "The Big One." Worth seeing, to be sure, but Jeff and I agreed that we could be happy not seeing captive orang-utans being fed bananahs in rehabilitation centres. We've seen them in zoos, after all. If I (a primatologist, partly) miss them in the wild, but see a reasonable diversity of gibbons, leaf monkeys and perhaps a tarsier or two, and if Jeff adds 200 or 300 birds to his life list, we can live without seeing The Big One.

The Oil in the Gulf of Mexico and Canada's Whooping Cranes

The first good news is that the 247 whooping cranes that wintered at Aransas National Wildlife Refuge on the Texas Coast—all the wild ones remaining in the world—left for their nesting area in Wood Buffalo National Park before the oil began spilling into the Gulf of Mexico. The bad news is that some of the oil will be there when they come back.



Oil is not just oil. It starts out as a complex mixture off hundreds of compounds, some of which are lighter than others. The lighter fractions are more “volatile”, meaning that they go from a liquid to a gas more easily than the heavier fractions. This is what gives fresh oil its stink. Volatilization is temperature-dependent: the hotter the day, the more it volatizes. Immediately after spilling into the Gulf of Mexico, the lighter fractions began volatizing. From 30% to 50% of the oil spilling into the Gulf will be lost to the air within a few days. Since the Gulf of Mexico oil is relatively light, a higher proportion is being lost than if it were, for example in Alberta.

The second good news is that because the lightest fractions are the most toxic, as oil ages it becomes less toxic.

What is left is heavier. It still floats, but not for long. The rainbow sheens seen from the air are composed of lighter fractions separating from the heavier mass that have not yet volatized. Sheens are only a few molecules thick: thinner than the diameter off a human hair. Every sheen seen means a heavier mass of oil is lurking unseen.

A “slick” is a layer of oil usually a few millimetres thick. It is more difficult to see from the air and contains a much larger volume of oil per unit of surface area than a sheen. Since it is heavier and has lost much of its lighter fraction, it rides lower in the water. Seawater sloshes over it, making it impossible to see from the air, although infrared sensors can still pick it up.

As it is churned by the choppy seas, water molecules get into the oil, changing its physical appearance and chemical properties. It becomes weathered. It begins to look like chocolate mousse (though far less appetizing), and clean-up specialists call it that. Mousse doesn’t form slicks as readily; it tends to coagulate into “pans”, flat blobs several centimetres thick that ride under the surface of the water, although it still gives off sheens as the lighter fractions continue to volatize. Weathered oil and mousse become progressively harder to contain in booms and to clean up.
Although pans are even heavier than slicks, they still float—at first. The churning of the waves mixes dirt, phytoplankton, and other debris into the mousse until it finally becomes heavier than water. Then it sinks to the bottom.

Clean-up companies often hasten mousse-formation by adding detergent. This is like putting dish detergent into a sink full of greasy dishes. It emulsifies the oil, making it miscible in water, so you can empty it down the sink and have clean dishes. But the oil is still somewhere. After dish-washing, it is in the sewer system. In the Gulf of Mexico, it is on the sea-bottom.

The marine life that doesn’t live suspended in the water lives on the sea bottom. Many sea-bottom organisms, from crabs to corals, have eggs or life stages that live suspended in the water, and these are food for others, including the fish and shrimp that make up the bulk of the huge commercial fisheries of the Gulf of Mexico. Oil sinking to the sea-bottom, through its toxic and physical properties (such as smothering) will continue to kill marine animals and plants and affect productivity of the whole marine ecosystem for years.

Sunken oil is rarely visible to scuba divers or to cameras in remotely-operated vehicles that clean-up crews use to look for it. It gets covered quickly with sand and debris. Eventually it forms a sort of pavement.

When slicks and pans land on a beach, they look like chocolate-brown pancakes. Pans range in size from a loony to the shadow of a Volkswagen bus; a slick can cover many kilometres of shoreline. On a flat, sandy beach, pans are easy to pick them up. Clean-up people can roll them up and put them into a garbage bag…if they get there quickly enough.

Mixed in with the oil on the beaches are the dead and dying birds that have floated in with it. They represent only a fraction of the oiled birds. Depending on circumstances, more may die and sink at sea, and others, less heavily oiled, fly off to die in some coastal thicket. Wildlife management authorities know that, on a percentage basis, it is useless to try to clean oiled birds. So few are found alive in a condition that they can be cleaned, and so few of them survive anyway, that public funds would be ill-spent to clean them. The Canadian Wildlife Service, for example, does not provide staff for oiled-bird cleaning.

Wave action breaks up the slicks and pans on the beach into smaller and smaller blobs and covers them with sand. Within a couple of days, a heavily oiled beach can look clean. In one spill I worked on, a woman on our staff had white rubber boots and we sent her onto the beaches to do a “white boot test”. If she walked across a beach and the boots stayed clean, there was no oil. But if there was invisible oil, it turned her boots black.

In a coastal marsh, which is most of the shoreline of the northern Gulf of Mexico, instead of lying there in flat blobs, the oil coats the vegetation and gets worked into the mud. There is no hope of cleaning up much of the oil in marshes. Clean-up crews can use absorbent material, but not without physically damaging the plants they are trying to protect.

Rocky shorelines are a different matter, but these are few in the Gulf of Mexico.
Like the sunken oil on the sea bottom, the heavy pans and slicks of oil on beaches and marshes eventually become a more or less permanent pavement buried in the mud.
The last good news is that the environment is amazingly resilient. Besides the physical action of waves and grinding with sand, chemical processes including photolysis (from sunlight) and oxidation continue to break down the oil. Within weeks or a few months, the pavement-like layers, although continuing to have a physical effect, will have lost their most toxic components. Plants can put roots through them, worms can tunnel into them, and crabs can walk across them. Certain microbes can consume oil, and oil-eating bacteria populations flourish. They feed other organisms. On a hot day, oil still becomes viscous and can continue to generate sheens and oil birds and other shoreline life for years. These effects diminish gradually. After a few years for a moderate-sized spill, few traces of oil can be seen on wildlife, in beach sands, or on marsh plants. Although the beaches and marshes look clean, plant and animal productivity may be depressed for years and oil in the sediments can still be detected with chemical analysis more or less indefinitely.

With luck, by the time that Whooping Cranes leave Wood Buffalo National Park and arrive back on the coast of the Gulf of Mexico next fall, they will not encounter any oil.

References
I published a series of Environment Canada technical reports and conference presentations on the fate and effects of the Nestucca (name of barge) oil spill that occurred at Grays Harbour, Washington, in late December 1988, drifted north, and oiled about 180 km of beaches on the west coast of Vancouver Island. We (Environment Canada) took the polluter to court and won a a settlement of about $3.5 million for clean-up costs and $6.5 million for environmental damages, which were used primarily to restore seabird population on Langara Island by eliminating the introduced rats that had decimated the nesting birds. Please contact me if you would like references.