The shimmering, nutritious goo that fuels global migrations
In short: A few millimeters of greenish, slimy biofilm coats the mudflats of the world. This microscopic layer of algae and bacteria is far more than just mud; it is a vital energy source for long-distance travelers, powering the muscles of shorebirds and crabs alike.
In ecosystems like the mudflats of French Guiana, the food web begins with microscopic life. Fiddler crabs act as tiny engineers, scooping up sediment and sorting it within their mouths to extract bacteria, algae, and tiny animals. This nutrient-dense material builds the muscle mass necessary for survival, though the process is perilous; feeding outside their burrows leaves them vulnerable to hungry birds. The competition for resources is intense, as male crabs strive to secure higher burrows. These elevated positions are advantageous because they provide the crustaceans with increased opportunities to forage.
This energy transfer extends to migratory shorebirds, such as the Western Sandpiper (Calidris mauri). These birds rely on a 'shimmering goo'—a biofilm only millimeters thick—to refuel during grueling journeys that can span thousands of kilometers. At sites like Roberts Bank in British Columbia, these mudflats support over a million migratory birds during the peak weeks of April and May. The nutrient-rich material is found in places like Grays Harbor, Washington, where the mud is deep and pungent. These birds use specialized, bristly tongues to slurp up the material from the surface.
However, these vital stopovers are under threat. In recent decades, over 65 per cent of the mudflats situated between the Korean Peninsula and China have diminished. Should present trends persist, three types of migratory species might become endangered by 2026. In Canada, proposed industrial expansions, such as an offshore container terminal, threaten to alter water salinity and disrupt the delicate balance of these highly productive ecosystems. The decline is particularly evident along the Yellow Sea, spanning China and both North and South Korea. Such environmental shifts threaten the stability of the entire food chain, from microorganisms to larger predators.
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Sources
- Summary by Intellect · source: The Living Mud: How Microscopic Life Fuels Crabs and Birds | Part 3 | SLICE EARTH
- Also: Slimy Mudflat Biofilms Feed Migratory Birds--and Could Be Threatened
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