Wood in the Water

Sunday, March 2, 2008

Delta Journal
by Bob Thomas

Folks often think of limbs and logs in water as obstructions, an undesirable condition. If there is any value, the wood is a nice place for turtles to sunbathe and for egrets to stealthily search for aquatic food.

Actually, wood is vitally important to the health of aquatic and marine ecosystems.

In bayous and rivers wood is a source of food energy for many forms of invertebrates. A simple snorkeling experience will reveal how important it is as habitat for vertebrates (catfish love to rest in their hollows). Many turtles spend their evenings clinging motionless to a submerged log.

In estuaries and the open sea, wood is necessary for the life histories of such marine organisms as ship worms (actually a bivalve mollusk that burrows into wood). Such activities result in the breakdown of the wood and the release of nutrients that support the base of the food web, including the essential microbial community that is normally overlooked.

Wood is also important along sea, lake, and river shores where it serves the same ecosystem functions mentioned above as well as serving to protect the shores from erosion.

Every fisher of coastal waters knows the value of flotsam. Fish simply cannot resist lurking under floating material, and wood serves to attract and concentrate all sorts of marine organisms, ranging from small prey to sought after game fish. Because the wood is floating, and usually infested with a community of dwellers and tag-alongs, it also serves to distribute a variety of organisms around the seas and their shores.

Back in the early 1800s, wood log-jams often occluded rivers where they converge. This was especially true of the beginning of the Atchafalaya River near Simmesport, Louisiana. These of course were extreme conditions, but the wood provided a wonderful platform for a living community, including life forms that lived in and upon the jams.

Easily overlooked is the value of wood that sinks and sits on the bottom of streams. They certainly provide habitat, but they also serve to protect the channels from excessive scouring.

The next time you consider cleaning up a waterway cluttered with limbs and logs, consider the ecosystem support and the living community served by the “worthless” wood.

Article Title: 
Wood in Water, Delta Journal, Times Picayune, P 3-2-08 C-9