The meltdown from the snows of 1996, moved enormous amounts of debris into streams, rivers and the Chesapeake Bay. An estimated 150,000 tons of debris, both natural and man-made, has been deposited along shorelines, in shallow water areas and in channels. Large obstructions to waterways can be a hazard to boaters and should be removed or flagged, if possible. Debris and garbage, clogging public beaches to the point of restricting access, also need to be removed. However, we should also acknowledge that some amount of woody debris is actually beneficial for wildlife.
Many researchers have documented the importance of woody, organic matter in streams and rivers. In streams, small pieces of driftwood are grazed upon by beetles, caddisflies, stoneflies and mayflies. Other insects use driftwood to crawl out of the water as they emerge from their larval forms into adults. In Coastal Plain streams, large woody debris provides the principal substrate for insects such as stoneflies, mayflies and dragonflies. These and other insects, in turn, are one of the most important food sources for fish, as well as, amphibians, reptiles and birds. Woody debris plays many other roles in aquatic ecosystems. Wood in streams can alter the flow of water, creating deep pools that are quickly inhabited by certain species of fish. In larger steams and rivers, turtles climb onto partially submerged logs to bask in the sun's warmth. After major storms and flooding, trees, branches and leaves are stranded along the edge of a river. These huge debris piles are quickly inhabited by a variety of mammals, including mice, voles and chipmunks. Rotting logs are a favorite place for many amphibians to deposit their eggs. Insect-eating birds forage on an abundance of insects and insect larvae in and on the debris.
During high discharges (flow), huge amounts of debris can be carried downstream in larger rivers and deposited in estuaries and marshes and along shorelines. This is nothing new. The natural abundance of large woody debris in estuaries of North America was, historically, so high that clearing it was one of the most important jobs assigned to the U.S. Army Corps of Engineers. More recent events, like Hurricane Agnes and the 1996 meltdown, continued to bring hundreds of tons of woody debris into the Chesapeake Bay. If left in place, larger pieces can persist for more than 200 years. Breakdown is more rapid in higher salinity areas where the debris is attacked by wood-boring worms, clams and crustaceans. The use of woody debris by wildlife in estuaries ha often been overlooked. This organic matter in shallow water areas, though unsightly to some people, provides habitat for aquatic wildlife. The driftwood in estuarine regions is often used as nest building material by ospreys, eagles, herons and muskrats. Partially buried logs and trees serve as perches for birds such as herons, gulls and shorebirds. This grounded debris may also help to stabilize eroding shorelines by trapping sediments. Decaying wood often serves as a nutrient-rich base on which other vegetation becomes rooted. Although large woody debris has probably always been a valuable part of aquatic habitat in the Bay, the importance of woody debris is especially critical today in areas where submerged aquatic vegetation and oyster reefs have declined. These natural physical structures provide a refuge for such species as blue crabs, mud crabs and grass shrimp. Fish, such as Atlantic croaker, killifish, mummichug, anchovy and striped bass, forage for food among submerged debris while hiding from predators. Plankton-eating fish, like Atlantic silversides and menhaden, also use the woody debris as a refuge from predators.
As many sport fishermen know, fallen trees in tidal creeks are excellent sites for catching perch, bass and croaker. Compared to areas without natural physical structures, both the variety and sheer numbers of aquatic wildlife increases in shallow water areas with woody debris. Boaters, whether in canoes, small motorboats, sailboats or racing craft, must remember that it is not possible to remove all the flood debris from waterways. Until much of the floating debris has been washed out of the Chesapeake Bay or permanently dumped on land, boaters will have to be more alert this season to avoid hitting submerged logs. We must also assume some responsibility for our own safety.
I learned that many years ago, as a novice canoeist, floating the Potomac River. My partner and I came upon a partially submerged tree in the river. We did not react fast enough to change our course and headed straight toward the tree that threatened to pin our boat. Luckily, we were able to paddle our boat toward one side where enough of the tree was sticking out of the water. Ducking, we gingerly slipped under the tree and continued downstream. The only thing the tree took that day was a tiny bit of skin scraped off my back. If you are a waterfront property owner, you probably regularly clear debris off the shore. Continue to remove objects that can pose a danger to both people and animals. But consider leaving some of the larger driftwood in the shalows and on the beach. This is especially important along bulkheaded shorelines where debris left in the shallows is probably the only natural habitat available to aquatic life. The habitat you provide will attract a variety of wildlife. The pleasure gained from watching birds, fish and crustaceans and the beauty they bring to your view will probably far outweigh the aesthetics of a "clean" shoreline.