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Join the Friends of Dyke Marsh Wednesday, March 7, 7:30 p.m., at the Huntley Meadows Park Visitor Center, 3701 Lockheed Boulevard, Alexandria, VA 22306, for our quarterly membership meeting. The meeting is free and all are welcome.
Greg Zell will lead a visual tour of some of the champion trees of northern Virginia and discuss tree conservation. He'll describe how trees
provide environmental services like storm water
and erosion control, cleaner air and food and shelter for wildlife and help make our houses more efficient. President's Message, Fall 2011 - Glenda C. Booth Late summer brought a rare 5.9 earthquake, Hurricane Irene and five days of heavy rain from Tropical Storm Lee. As far as we know, none of these weather events caused major damage in Dyke Marsh, but as Dottie Marshall told FODM in June, “Every hurricane has a big impact on Dyke Marsh.” Marshall is the Superintendent of the George Washington Memorial Parkway for the U.S. National Park Service. As we previously reported, a U.S. Geological Service study has concluded that strong storms are major contributors to the wetland’s erosion. Between 1937 and 2009, as many as 24 tropical storms or hurricanes (winds over 39 mph and 74 mph, respectively) may have affected Dyke Marsh. USGS scientists found, “. . . storm waves driven northward up the Potomac River valley, from tropical storms and hurricanes in the summer and nor’easters in the winter, were the primary agents of marsh erosion." Our November 16 USGS speakers will give a not-to-be-missed presentation on this important study.
In our ongoing effort to minimize adverse environmental impacts on Dyke Marsh’s boundaries, FODM is partnering with Belle View Elementary School’s teachers, administrators and parents who are working to create an outdoor classroom to consist of wetlands, a meadow and a forest. Their goal is improve students’ scientific literacy and community stewardship, among other goals. They need around $4,000 and volunteer labor so I hope you can help either with a donation or time. As for the fauna of our favorite wetland, a paddle with Chris Hobson, the biologist conducting a dragonfly and damselfly survey in Dyke Marsh, opened my eyes to these beautiful and agile aerialists. They flitted, zoomed, patrolled and procreated. Hobson called the abundance “amazing” and observed, “There’s a whole lot of reproduction going on out here!” You can read about our survey here http://bellehaven.patch.com/articles/dragonflies-and-damselflies-abound-in-dyke-marsh and look forward to his presentation to FODM in the coming months. Looking toward winter, the U.S. Fish and Wildlife Service released preliminary statistics on breeding ducks and reported that total duck populations are estimated at 45.6 million breeding ducks on the surveyed area, an 11 percent increase over last year’s estimate of 40.9 million birds and is 35 percent above the 1955-2010 long-term average. We will no doubt see some of them visiting and wintering in Dyke Marsh. Thank You NPS and Volunteers We had several volunteer efforts this summer and fall. Be sure to read our article (below) on the Eagle Scouts’ bench project. Thank you, Ben Luce and your colleagues for your excellent work and for four new places to sit, observe and ponder.
Erik Oberg, National Park Service biologist, led a September 17 cleanup and a September 25 invasive plant attack along the parkway (see photo). Thank you, Erik, and volunteers. A big thank you to our Sunday morning bird walk leaders organized by Kurt Gaskill. Our knowledgeable guides engage walkers and offer interesting information about the birds and other natural resources of Dyke Marsh. Our faithful weed warrior team, led by Ned Stone, continues to whack at invasive plants. Please volunteer a few hours. The native plants we put in between the “dog leg” and the boardwalk are making quite a difference and demonstrate how a little bit of volunteer work can produce rewarding results and a healthier environment. Volunteers are all the more important given the NPS’s annual operating deficit of nearly $800 million and a $7.9 billion maintenance backlog, estimates the National Parks and Conservation Association. Invasive Catfish On the troubling news front, fishery managers say that the non-native blue catfish is “exploding” in the Potomac River, reports the September Bay Journal. This fish, introduced in the 1980s, can weigh over 100 pounds and can impact native species like shad, river herring, striped bass and American eels, says the article. And remember, the non-native snakehead fish is “here to stay,” according to John Odenkirk from Virginia’s Department of Game and Inland Fisheries. The snakehead has made itself at home in the waters of the Potomac, Dyke Marsh, Pohick Bay and Little Hunting and Dogue Creeks, Odenkirk maintains. Belleview Elementary School Students Learn All about Dyke Marsh
Eagle Scouts Install New Benches at DMWP - by Ben Luce On September 17, Eagle Scout candidate Ben Luce of Boy Scout Troop 135 in Alexandria organized and oversaw the installation of four benches along the Haul Road trail. The project was completed in conjunction with the National Park Service as its sponsor, under the supervision of Erik Oberg. Scouts began digging the two-foot deep bench support excavations at 9:00 a.m. with more than thirty volunteers present throughout the course of the day by 6:30 p.m. Three benches were installed along the trail and one bench was fastened to the wooden observation deck at the end of the trail. Additionally, many invasive plants were cleared to create a vista of the marsh at the third bench location.
The installed benches remained taped off overnight as the concrete cured, and a small crew removed the bracing hardware the following Sunday. Just twenty-four hours after installation, visitors were already using the new benches. The scouts hope that the benches will not only serve the practical purpose of providing places to sit along the trail, but additionally, of creating more awareness of the Dyke Marsh Wildlife Preserve. They hope that the benches will make the area more visitor-friendly, which will in turn draw more visitors, and ultimately result in greater support for the preservation and restoration of Dyke Marsh. Photos by Ned Stone.
Earth Day 2011 in Dyke Marsh Raptors enraptured fans of all ages on April 23 when FODM joined with the Raptor Conservancy of Virginia and the National Park Service in a two-hour presentation featuring live raptors in Belle Haven Park. Kent Knowles and Liz Dennison from the Conservancy displayed and discussed six species of raptors, all of which posed patiently, while setting off a few avian alarms in the nearby trees. The event was part of Earth Day celebrations all around the Mount Vernon area organized by the Mount Vernon Council of Citizen Associations. Emily Zivot, NPS ranger, and Glenda Booth, FODM president, led a wetlands walk. The Raptor Conservancy’s volunteers handle around 240 birds a year, most injured by colliding with vehicles. Rehabilitators nurse the birds back to health, release them to the wild, or keep or find homes for those so disabled that they cannot survive on their own. "Our vets perform 150 surgeries a year. Our patients don't make appointments, don't pay their bills and they bite us," Knowles quipped.
Sandburg Students Learn About Wetlands Around 600 students from Kate Williams's science class at Carl Sandburg Middle School visited the Dyke Marsh Wildlife Preserve in April. National Park Service rangers set up four learning stations: human impacts on the watershed, watershed dynamics, invasive species and testing the waters. Fifteen FODMers volunteered over three days. This was the second year Ms. Williams's students have come to the preserve. FODM thanks all the NPS staff for welcoming the students and making presentations.
Research on Sediment Dynamics in Dyke Marsh Many of us have wondered, "Is the marsh growing or shrinking? Is it being rebuilt by the river, or are we losing it to erosion?" To provide some answers to these questions, research in the gain and loss of sediments in the marsh has been undertaken by Cindy Palinkas and David Walters of the Horn Point Laboratory of the University of Maryland Center for Environmental Science in Cambridge, MD, in cooperation with the National Park Service, building on earlier work by Katia Engelhardt. They reported their work in a poster paper at a recent conference of the American Geophysical Union. The goal of their study is more modest than predicting the ultimate fate of the marsh: "to better understand the spatial and temporal variability in sedimentary processes in a freshwater tidal marsh." There are competing effects at work in setting the level of the marsh relative to the river. The Potomac always carries a burden of sediment, which is greatly enhanced following heavy rain upstream. Two daily incoming tides flood parts of the marsh, and some of the river-borne sediment is left behind in those areas.
The following is a copy of a letter to the editor written by FODM President Glenda Booth and published in the August 26 edition of the Mount Vernon Gazette. Many newcomers view Northern Virginia as a suburban sea of tract homes, dense development, shopping malls and traffic jams. I hope they realize that we are blessed with a natural jewel, which former U. S. Senator John Warner called “a magnificent little oasis.” It is the Dyke Marsh Wildlife Preserve on the banks of the Potomac River in the Mount Vernon area of Fairfax County, just south of Old Town Alexandria. At 485 acres, the preserve is one of the last tidal wetlands on the river. Tidal freshwater marshes are rare, says Dr. Elizabeth Wells, a George Washington University wetland plant expert. This wetland complex is one of the most significant temperate, tidal, freshwater, riverine marshes in the national park system. Thus, it is a national treasure as well. Congress designated it as a preserve in 1959 “so that fish and wildlife development and their preservation as wetland wildlife habitat shall be paramount.” Today, it has 300 known species of plants, 6,000 arthropods, 38 fish, 16 reptiles, 14 amphibians and over 230 birds, Like all wetlands, Dyke Marsh provides ecological services: flood control, water quality enhancement, habitat, fish nursery, shoreline stabilization and recreational opportunities. It’s been excavated, dumped in and invaded by exotics. Commendably, the U.S. National Park Service is moving to restore damaged areas. The Dyke Marsh Wildlife Preserve is “the nearest thing to primeval wilderness in the immediate vicinity of the city,” wrote naturalist Louis Halle in 1947. Newcomers’ lives can be enriched by the few remaining natural areas like Dyke Marsh that have not fallen prey to the bulldozer and asphalt spreader.
Take a walk out the Haul Road in Dyke Marsh, and when you
round the bend you will be treated to an open view of the Potomac River on your
right, thanks to Don Robinson (pictured), Ned Stone and Mary Jo Detweiler. The
three meet Friday mornings to remove Bush (Amur) Honeysuckle and other invasive
plants from Dyke Marsh. After they cut invasives to the ground and flag the cut
stems, National Park Service personnel selectively apply herbicides to the
flagged plants. Stone and Robinson have been trained by NPS to identify and
remove invasives. To join this volunteer effort, please contact either Ned
Stone, 703-765-5441 or nedstone@verizon.net, or contact Elizabeth Ketz-Robinson
or Don Robinson at 703-768-1344.
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