Delta Journal
by Bob Thomas

Freshwater marshes are the most biodiverse of our wetlands. They reside between swamps and brackish or intermediate marsh. One of their principal characteristics is that they experience a unidirectional flow of water from inland toward the sea. Their water is always fresh, having virtually no salt content.

Their characteristic vegetation, consisting of hundreds of species over the coast of Louisiana, may be divided into five categories. First, the standing vegetation. These species are those that are rooted in the bottom and extend to or above the surface of the water (e.g., maidencane, spike rush, bulltongue, water lillies). Second, submerged vegetation that may or may not be rooted but is not typically exposed to the air (e.g., coontail, fanwort, bladderwort, water milfoil). Third, floating plants that are not rooted (water hyacinth, duckweed, water lettuce). Fourth, epiphytes (plants that grow on others) such as algae. During some seasons when the others experience low productivity, the epiphytic algae may out-produce all others and clearly establish its value to the ecosystem. The fifth category is the benthic algae, those algae that grow on the bottom of the marsh. During most of the year, their value is limited. But during the dead of winter when most other plants have died back and the water clears to allow deeper penetration of sunlight, they become invaluable to the marsh ecosystem.

Due to the extreme diversity of plant life, animal life is equally diverse. Many species of reptiles, amphibians, crustaceans, spiders, insects, mammals, birds, mollusks, and more depend on freshwater marshes. Each of these is linked to many others in the complex food webs that exist.

As Louisiana’s coastal wetlands are lost, overall diversity of both plant and animal species is diminishing. Who is to say how our children’s lives will be affected by the reduction of complexity and function in our marshes? We know that Mother Nature’s balance has maintained our lifestyle to date, but no one knows which pieces of the puzzle are most critical for our future.