Feb 25 2010 -- Apr 15 2010 Driftwood Plays a Key Role for Beaches and Estuaries
At Whiskey Run At McVay Rock(Editor's note: This is the second in our “Sightings” series, which provides background information about shoreline phenomena that CoastWatchers might observe. Again, the author is Bonnie Henderson, adopter of Mile 157 and author of Strand: An Odyssey of Pacific Ocean Debris.)
Have winter storms deposited new driftwood logs on your mile of beach? Treasure them. Drift logs haven’t actually been declared an endangered species, but as rare as they’ve become, and as critical as their role is in ocean, seashore and estuarine ecology, perhaps they should be.
CoastWatchers of a certain age may remember visiting the beach when they were kids and scrambling across huge piles of driftwood to reach the open sand and surf. Whatever your age, there was more driftwood on the beach before you were born, particularly before the advent of industrial-scale logging and dam-building and stream clearing for navigation and agriculture and salvaging of every possible tree for its economic value. For years, forest policy also called for clearing streams of slash from logging operations to “help” migrating fish.
Over the past three or four decades, scientists have developed a much clearer understanding of the essential role of woody debris—from needles and bark shreds to whole logs and their root wads—in the Pacific Northwest ecosystem. Most of us are aware of the current practice of putting logs back into streams to improve salmon and steelhead habitat. Perhaps less widely known is the role drift logs play in the ecology of beaches, estuaries and the open ocean. By blocking windblown sand, drift logs help build beaches and stabilize dune fronts (central coast mile adopters: look for buried logs emerging in eroding foredunes). Logs battering rocky shorelines contribute to the diversity of the intertidal community by opening up attachment sites for less dominant species.
In estuaries, drift logs serve many purposes: as perching spots for eagles, herons and other birds; as attachment sites for fish eggs; as nurseries for spruce seedlings; as cover for salmon and steelhead smolts as they adapt to seawater prior to entering the open ocean. Wood-boring gribbles and shipworms munch on driftwood, and their fecal pellets become food for certain worms, snails and other bottom-dwelling invertebrates, in the estuary as well as at sea. In the open ocean, drifting logs provide food and habitat for species ranging from tiny ocean striders (insects) to schools of tuna.
As Gearhart biologist Neal Maine puts it, the tree has pasted this giant energy bundle together and now is the basis of a critical food web that is being slowly taken apart with the precision of a surgeon’s scalpel. Check your local library for a copy of the informative and very readable From the Forest to the Sea: The Ecology of Wood in Streams, Rivers, Estuaries and Oceans by Chris Maser and James. R. Sedell for more specifics on this subject.
It’s illegal to build a beach fire in a pile of large driftwood on an Oregon beach. As a general rule, beach logging—removing logs from the beach for any reason—is also against the law here. Not that you’d want to, knowing what you now know about the importance of drift logs in marine ecology.
Contributed by Bonnie Henderson
Contact: Phillip Johnson, CoastWatch Director, (503) 238-4450, or EMAIL