COLLECTIONS, RESEARCH PAPERS AND SPECIAL PROJECTS CONSERVATION ANTHROPOLOGY MODERN HISTORY NATURAL HISTORY SPECIAL PROJECTS

pdf version Natural History Mud, Glorious Mud Philip Lambert Curator of Invertebrates First published in Discovery 23(4). The horizon's edge, the flying sea-crow, the fragrance of salt marsh and shore mud, These became part of that child who went forth every day, and who now goes, and will always go forth every day. from There Was a Child Went Forth by Walt Whitman He lurched toward me. His feet sucking like two giant toilet plungers. The stench of rotten eggs wafted over me as the hot sun beat down. A mirror-like eye stared at my forehead. It was aimed right at me: this was it! "I'm stuck! he wailed, "Give me a hand. I'm going to lose my boot." I inched forward and reached out my hand. "Pretty sticky isn't it?" I offered. The cameraman was not quite prepared for this gumbo. He was trying to line up the best angle for shooting a scene about the value of mud flats. I could see he wasn't too convinced about its value. It was going to be a hard sell! I guess he hadn't heard Flanders and Swan's "Mud, mud, glorious mud! There's nothing quite like it for cooling the blood". Or if he had, he didn't agree with them. We were pre-taping a piece about the micro-organisms that live in mud. I was about to do my imitation of David Attenborough. Later, in the lab, I would combine images of live animals under the microscope with this location shot for a television broadcast. Users of the Tsawwassen ferry terminal may have noticed the expanses of mud beside the causeway. This is typical of estuaries and shallow bays along the coast. I suspect that most people view it as a wasteland of mud, assuming that it's not much good for anything. But this apparently useless mud is a prime habitat in the marine ecosystem -- and worthy of preserving. An annual cycle of life plays out, largely unseen to all but the closest observers. It starts in the summer. During the growing season, marine plants such as eelgrass and single-celled diatoms flourish in these warm, shallow expanses. They convert sunlight and carbon dioxide into plant tissue. The weight of plant growth per square metre that is added in one year is a measure of productivity. Shallows like this can produce twice as much plant growth as an average farm field. Alas, acres of seaweed, march grasses and diatoms submerged beneath the sea tend to go unnoticed. But if these acres of mud produced loaves of bread instead, we would be very impressed! In the fall, plants that have not been eaten, die and settle to the bottom. Then, bacteria take over and begin the decay process. Oxygen penetrates only the top few centimetres of mud. Below this oxygenated layer, bacteria decompose the dead plants by converting them to hydrogen sulphide (the rotten egg smell), ammonia, methane and hydrogen. As these small molecules seep upward towards the surface, other types of bacteria oxidize them as an energy source. One study estimated up to 17 billion bacteria per cubic centimetre live in the surface layers of this organic mud. Without them, dead animals and plants would not decompose into simple compounds that can be used by other organisms. The system would come to a grinding halt, as few of the nutrients locked up in plants would become available. Nematode worms feast on these swarms of bacteria. Each worm species has mouth parts designed for a particular prey. Without the worms, much of the bacterial production could not be transferred to the larger predators at the surface of the mud. Some biologists believe that nematodes are the most abundant multi-celled animals on earth. In salt marshes, up to five million nematodes per square metre have been recorded. Biologists also estimate there are more species of nematodes than any other group of organisms. In a single 10-square-cm core, we may find 50 or more species. Along with nematodes, single-celled animals called ciliates are a major part of the diet of mud-dwelling animals. Ciliates (named for the hairy covering of cilia) can number up to 20 million per square metre in mud flats. Like nematodes, they prey on bacteria, diatoms, blue-green algae and flagellates (single-celled organisms named for their whiplike tail). Tiny crustaceans crawl around in the mud: copepods, sand fleas, isopods, small shrimp and crabs sift out the worms and ciliates with their hairy mouthparts. The crustaceans are eaten by juvenile fish and many types of birds. These food chains in the mud distribute the energy captured by plants to all the users of this habitat, and create the great productivity of this ecosystem. The delayed release of energy by these food-webs in the mud provides nutrition for birds and other winter users of the estuary long after the growing season. This double peak of energy -- first from plants in summer, then from bacteria in the fall -- contributes to the high productivity of mud flats. The energy consumed here radiates out into other habitats via transient animals or those that spend their youth in these nursery areas then migrate away. More than 130 species of birds from 20 countries and 3 continents breed, over winter or migrate through the Strait of Georgia region. Juvenile salmon pause here and consume up to 13% of their body weight every day. A mud flat is a source of energy, a starting point and a birthplace of future generations. So please don't despise mud. Enough of: "a pox damn you, you muddy rascal", "here's mud in your eye" and "yuck". Let's celebrate mud. Give mud its rightful place in our value system. Without that glorious mud, our environment would be a much poorer place.

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