The Salt Marsh is an Ellipsis
Every marine shoreline constitutes a transition, a zone of change from dry land where most organisms breathe air, to water where the creatures are incorporated into their saline environment. But shorelines vary immensely in shape: some are abrupt and peremptory, while others can be so gradual that they are almost imperceptible. This shape affects the nature of the transition.
In a way, shorelines can be considered as the punctuation between sea and land. A steep sea cliff is an exclamation mark. The transition is exaggerated and absolute!
A narrow cobble beach is a period. The transition is definite, but it is not overstated.
A broad beach is a semicolon; it leads us gently from one environment to another.
Sometimes a beach could also be a colon, since it can sponsor other environments such as dunes, lagoons, or ponds:
But what is the salt marsh? Following this logic, the salt marsh must be an ellipsis … it is not so much an unfinished thought, as a trailing off. It is a place of poorly-defined changes, of transitions so gradational that to really recognize them one must stand in one place and observe the minutiae as they vary through the day, or through the year.
The salt marsh’s shape and features are transformed as the tides pump water in and out through its reedy channels. Within the marsh is a mesh of interwoven microenvironments: some saltier, some much less salty, some wet, some mostly dry. But these change through the day, as the marsh alternates between soaking by saline tides, drying by sun and wind, and wetting by fresh rain and stream water. This variation makes the salt marsh a place of immense richness and dizzying complexity, even within an area the size of a suburban yard.
On a slightly larger scale the salt marsh is itself often part of a series of interconnected environments. Beach, dune, barachois (lagoon), marsh, channel, and meadow can blend almost seamlessly, one into the next.
The salt marsh is different from many other shorelines in that it is a habitat that owes its existence to biological evolution. Cliffs, rocky shores, beaches, and tidal flats have been present on Earth almost as long as oceans have been here. They are environments defined and created by the action of waves and currents.
But the salt marsh is there because plants have evolved to live on protected tidal shorelines. More than 430 million years ago, there were no salt marshes. All the sorts of places where we now see tidal marshes would have been monotonous, unpleasant mudflats. Salt marshes developed as salt-tolerant vascular plants evolved, possibly as early as the mid Silurian Period, about 425 million years ago. Marshes became more and more complex as plants and animals evolved to fit into its myriad of niches. The modern salt marsh is the outcome of the long interval of co-evolution since the mid Paleozoic Era.
In recent times, the interaction between human society and salt marshes has also evolved. Sometimes we have offended against nature. Hundreds of years ago people drained salt marshes (such as those at upper end of Bay of Fundy) so that the fertile land could be used for agriculture. In modern times, salt marshes have been considered as ideal sites for container terminals and petroleum refineries.
But we also have a long history of respecting salt marshes, and of utilizing their resources for food and fibre. And now we recognize the marshes as natural filters, as nurseries for fish and other marine creatures, and as places where we can examine the boundless complexity of life.
© Graham Young, 2009