{"id":16186,"date":"2016-11-15T00:11:00","date_gmt":"2016-11-15T08:11:00","guid":{"rendered":"http:\/\/live-hakamagwp.pantheonsite.io\/features\/slime-shorebirds-and-scientific-mystery"},"modified":"2019-03-29T16:01:48","modified_gmt":"2019-03-29T23:01:48","slug":"slime-shorebirds-and-scientific-mystery","status":"publish","type":"custom_features","link":"https:\/\/hakaimagazine.com\/features\/slime-shorebirds-and-scientific-mystery\/","title":{"rendered":"Slime, Shorebirds, and a Scientific Mystery"},"content":{"rendered":"
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\"\"This article is the first in a two-part series. The second installment is \u201cThe Questionable Science of Vancouver\u2019s Port Expansion.<\/a>\u201d<\/em><\/p>\n<\/div>\n

As the tide pulls out over British Columbia\u2019s Roberts Bank on an early October morning, it pools amid the hummocks, follows intertidal runnels seaward, and leaves a silvery-green sheen on the exposed mudflats where Canadian researcher Bob Elner walks. Thousands of southbound snow geese, propelled skyward by a hawk\u2019s approach, move in ever-shifting murmurations to Elner\u2019s right. Dunlin and ducks grub along the tideline to his left. But the western sandpipers, he observes, are gone. A scientist emeritus at Environment and Climate Change Canada, Elner has long studied the sandpipers, and he knows they have headed south on their 10,000-kilometer fall migration from the Arctic to Latin America.<\/p>\n

The big unspoken question hanging over these mudflats is how long the sandpipers and other shorebirds will continue to stop on the Fraser River estuary and fuel up, before flying onward. Beyond Elner, as he struggles to maintain his balance on the treacherous mud, rise the silhouetted loading cranes of Deltaport, which lies at the end of a causeway jutting into the Strait of Georgia. Trainloads of coal (bound for Asia, Europe, and South America) and containers of manufactured goods (bound for Canada) arrive there every hour, 364 days of the year. Now the Vancouver Fraser Port Authority is proposing to double the container capacity of this facility by building nearby an entirely new island, called Roberts Bank Terminal 2, at a cost of more than CAN $2-billion.<\/p>\n

Just what effect this mega development will have on the adjacent tidal flats and the sandpipers that flock here in the spring and fall is a point of contention in the environmental assessment that is now entering its final stages. At low tide, Roberts Bank\u2014slime covered and sulfurous smelling\u2014is a bleak expanse of shimmering, gray-brown mud. But the data that Elner and his colleagues have gathered here in the Fraser River estuary suggests that the sandpipers are extremely vulnerable if development proceeds. Indeed, the fate of these birds may now hinge on how regulators react to what Elner and his colleagues have learned.<\/p>\n

<\/a>

In late April, flocks of several hundred thousand migrating western sandpipers a day refuel on the mudflats at British Columbia\u2019s Roberts Bank. The future of the birds may be threatened by the Vancouver Fraser Port Authority\u2019s Terminal 2 project, a proposed expansion of the shipping terminal just offshore. Photo by Matthias Breiter\/Minden Pictures<\/p><\/div>\n

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Elner\u2019s research on sandpipers began more than two decades ago in his office at the Pacific Wildlife Research Centre, located a kilometer and a half from the Fraser River estuary. A raconteur and maverick by temperament, Elner was working for Environment Canada and studying shorebirds, when a new shipping facility was proposed in the early 1990s at Roberts Bank. The new container terminal, Deltaport, was slated to go in beside the existing Westshore Terminals coal export facility, on an artificial island at the end of a five-kilometer causeway into the ocean.<\/p>\n

Already, the causeway had begun impeding natural tidal flows on the southernmost flank of Roberts Bank, allowing eelgrass to spread over the muddy intertidal and subtidal zone. What effect would more construction have on the shorebirds? Elner happened to be studying one of the most numerous birds to migrate there: the western sandpiper. So he began looking in earnest into the relationship between sandpipers, their food, and Roberts Bank\u2019s mud. How, he wondered, did these little shorebirds\u2014no bigger than a human fist\u2014acquire sufficient energy during brief migratory stopovers to take 1,000-kilometer-long transits without refueling?<\/p>\n

<\/a>

The existing man-made island near the mouth of the Fraser River already hosts a coal terminal and a container terminal. In this artist\u2019s rendering, the island on the left is the site of the proposed Terminal 2 project. It could double the container facility\u2019s capacity. The sandpipers\u2019 primary feeding ground lies between the proposed new terminal and the shore. Image courtesy of the Government of Canada, Asia-Pacific Gateway and Corridor Initiative<\/p><\/div>\n

Examining the diet of western sandpipers during their layovers at Roberts Bank, Elner discovered, wasn\u2019t easy. On the vast mudflats, the birds move incessantly, hyperactively, heads bobbing, beaks dipping into the shimmering slime on the mudflats\u2019 surface, following the receding tide outward on spindly legs. Any approach sends thousands of birds airborne. Even through a telescope, it\u2019s impossible to discern what they\u2019re actually eating. So with a federal permit and a shotgun, Elner obtained several dozen sandpiper specimens to see what he could learn.<\/p>\n

Today in his office, he extracts a collection of numbered glass vials from a cabinet and waves No. 104 in the air, its contents a clear liquid the color of sesame tea. \u201cOrnithologists believed sandpipers ate little crustaceans, worms, and mollusks,\u201d Elner says, sloshing more vials as he talks. \u201cBut the stomachs of the sandpipers were empty. Just this liquid, and some sand. Almost no crustaceans [or other prey],\u201d he says. \u201cIt was a complete surprise. It didn\u2019t make sense.\u201d<\/p>\n

So, if it wasn\u2019t crustaceans, worms, or mollusks, the biologist thought, what were<\/em> they eating that helped the northbound birds to fly nonstop until they reached the Stikine River estuary on the Alaskan panhandle?<\/p>\n

<\/a>

Bob Elner has spent more than two decades observing migratory sandpipers on the 21,703-hectare estuary of the Fraser River. What he\u2019s discovered there has revolutionized our understanding of the critical link between shorebirds and the mudflats on which they feed. Photo by Ron Watts<\/p><\/div>\n

In the search for answers, Elner headed out, sometimes accompanied by a team of research assistants, onto the Fraser River\u2019s slick tidal flats, often walking the southern swath that makes up Roberts Bank. The team struggled\u2014like characters in Monty Python\u2019s famous \u201cMinistry of Silly Walks\u201d skit\u2014to keep their balance on the treacherous mud. There were days in late April, when several hundred thousand shorebirds\u2014from dozens of species\u2014filled the air in high-pitched, trilling clouds. Elner\u2019s team would skim the veneer of slime from the mud\u2019s surface, collect sandpiper poop for evidence of nutrients, and try to document the birds\u2019 feeding patterns.<\/p>\n

\u201cWe spent hundreds of hours watching them,\u201d Elner recalls. \u201cWe noticed the sandpipers arrive regularly at the same time every year.\u201d They seemed to prefer the southernmost intertidal mudflats at Roberts Bank, as opposed to other parts of the Fraser River or delta. But he had no idea why. \u201cWe also saw\u2014as the tide went out\u2014some shorebird species kept following the retreating tideline all the way out. But the sandpipers went 300 meters out, and stopped.\u201d The birds knew something<\/em>, but Elner didn\u2019t know what that was.<\/p>\n

To find out exactly what<\/em>, he turned to Peter Beninger, now a professor of marine biology and ecology at the Universit\u00e9 de Nantes in France. In his lab, Beninger had a powerful scanning electron microscope capable of magnifications of up to 300,000 times. Elner shipped off several sandpiper heads to Beninger in 1997, to see if microscopic study could reveal something about the birds\u2019 feeding habits. The first thing Beninger noticed was that, unlike many shorebirds that feed exclusively by probing tidal flats for crustaceans and mollusks with their beaks, western sandpipers have feathery tongues, whose edges and tips are covered with keratinous bristles. Could these be used like a mop, he wondered, for slurping up the silvery gunk on the surface of the tidal flats\u2014a substance scientists call biofilm?<\/p>\n

<\/a>

As the tide recedes from the vast mudflats of Roberts Bank, millions of northbound shorebirds find nourishment each spring for the next leg of their journey to the Arctic. Each flight between stops can be more than 1,000 kilometers. Photo by Ron Watts<\/p><\/div>\n

Beninger shifted the microscope to 1,000-times magnification. There embedded in the bristles were tiny, single-celled algae called diatoms. With silica-glass cell walls, diatoms are crystalline, almost jewel-like, and plentiful beyond number. More importantly, they are carbohydrate-rich and therefore essential to marine ecosystems. They provide energy and vital nutrients for zooplankton and in turn\u2014moving up the food chain\u2014for as much as half of all ocean life. \u201cThis was our eureka moment. We couldn\u2019t believe it,\u201d says Elner. \u201cThe sandpipers appeared to be eating diatom-rich biofilm.\u201d<\/p>\n

Even today, Elner can barely contain his delight at this discovery. He laughs aloud. \u201cSnot. Biofilm. Mucous. Saliva. It\u2019s all the same thing: microbial goo<\/em>. Energy-rich goo<\/em>. It had never been reported before. It looked like the birds were eating slime.\u201d<\/p>\n

This \u201cgoo,\u201d says Elner, is ubiquitous, and develops naturally in very thin, opalescent layers, in varying concentrations, on intertidal mudflats worldwide. It\u2019s composed primarily of single-celled bacteria and diatoms, and a mucous-like carbohydrate that bacteria and diatoms produce to bind individuals together. The protein also allows the bacteria and diatoms to bond with the mud\u2019s surface, ensuring that the microbes remain unaffected by the ebb and flow of tides. Within this sticky, organic matrix, the photosensitive, single-celled diatoms thrive.<\/p>\n