Meeting Dates
Mar 27 '08
Minutes for March 27, 2008
Present: Not noted.
On March 27, we gathered at the Library of the Edgecomb Eddy School to hear Dr. Peter Larsen of the Bigelow Laboratories and Dr. Karen Wilson , marine botanist of the University of Southern Maine on the restoration of salt marsh conditions to the former Sherman Lake area.
The meeting was opened by Vice President Roslyn Strong. The minutes of November 22, 2007, were approved as read. The Treasurer's report was approved as read.
Dr. Wilson showed a 2003 map of Sherman Lake, with the creek bed highlighted. Then a picture of the swing bridge which was in place from the early 1900s, which was heavily used for loading product from the local brickyards onto coastal boats. In 1934 an earthen dam was constructed to enable traffic on U.S. Route 1, which began the formation of Sherman Lake. In 1960 the old roadbed was covered by a new bridge and tarred. Then, in 2005, tremendous rains blew out the 1934 earthen dam, and turned the freshwater lake back into salt marsh overnight!
Dr. Wilson and graduate student Laura Jones have been studying the replacement of pickerel weed and waterlilies with salt marsh ecology, based on parameters of flooding frequency, elevation and salinity. The principal study species are Spartina alterniflora which flourishes in brackish water, also Spartina patens, "cowlick grass." Due to obstruction from what remains of the old dam, there has been no real low tide in the marsh to date. The tides are too slow to fill or thoroughly flush the 200 acre area. However, the wild rice left from the freshwater conditions has since died off, replaced by salt marsh goldenrod (Solidago sp.) And Juncus, apparently 70 years dormant, has reappeared! Cattails have taken over from the freshwater flora rapidly.
It was asked whether there was not still a freshwater stream coming through the marsh. Dr. Wilson explained the incomplete drainage in 2006, but the April 2007 floods opened up the channel wider, allowing in more salt marsh plants. She warned about an invasive species, Phragmites, which will require control or it will take the marsh over (a European species, used for roof thatching and packing material). Dr. Wilson also discussed the gradual entrance of marine zoology: marine worms feed on surface material and are, in turn, fodder for wading birds. They have found tiny horseshoe crabs (smaller than a quarter), mummichogs (a species of minnow), which feed striped bass and other larger fish species. Last summer they saw otters! And also, oysters were discovered.
The audience commented there have been reports of porpoise and seals in the marsh.
Dr. Larsen started with the big picture, glaciology of the Georges Banks, global warming of 7,000 years ago, when there were no animal species under ice. As the temperatures changed, species from farther south began to move in, although there were pockets of subarctic conditions in the Gulf of Maine but warm pockets in estuaries and around Prince Edward Island. Among these were Casco Bay, Quahog Bay and the Sheepscot Bay and River. This explains why oysters got here, witness the Damariscotta shell heaps. They died off when the Gulf of Maine grew cooler, tides became larger and the warm periods too short between the cold periods for them to thrive. Then came European colonies, and the influence of sawmills, brickyards, other coastal industries.
Sheepscot Falls near Sheepscot Village is an isolated colony of surviving native Maine oysters. Dr. Larsen wants to do genetic studies to track morphological changes among several such isolated colonies. He showed a map of the Marsh River (which is the lower end of Sherman Marsh, entering the Sheepscot), showing oyster sites near the railroad bridge and the entrance to Sherman Lake. These oysters are not clinging to the metal or concrete structures, but out in the mud.
Why are oysters so important? They are food for other species, and habitat for other species which attach to their shells. They stabilize the bottom surface, provide water filtration. For instance, during the colonial period, Chesapeake Bay was filtered every 3 days by oysters!
There are 214 species of New England oysters. The audience asked if they were isolated the way Darwin's finches are, throughout the Galapagos Islands. Dr. Larsen said the isolation was of interest not only for genetic changes but in face of climate changes. He wants to survey existing beds, place seettling panels in the marsh to see if juvenile oysters will settle, and then provide suitable habitat for the oyster spat (there can be 50 million eggs in a swarm of spat). Then, to monitor the growth of the population and the surrounding community of other creatures.
Benefits, he said, included increasing the oyster population size to increase their chances for survival; to provide a genetic bank; to accelerate development of the estuarine community, water quality improvement and the reduction of erosion.
Dr. Larsen is very concerned about Maine Department of Transportation's plans to enlarge the entrance to the marsh, which may interfere with restoration efforts. He suggested that those concerned should write their legislators, asking that no such enlargement be done. Dept. of Marine Resources has declared the area off-limits to harvesting, although landowners can hang strings for private consumption.
Ros Strong asked, Why are there no shell heaps here as there are on the Damariscotta? The probability is that there have been heaps, but mined by local people extensively for calcium and lime, and a kind of building concrete known as tabby. The Damariscotta shell heaps were preserved as an effort to stop such use. Northrup Fowler told how, as kids, Barry Hathorne and he would dive for oysters from the railroad bridge, some as big as your foot!
Are there any other clusters nearby? Yes, a few at the mouth of Dyer River and some samples from Deer [[??]] Brook. Dr. Larsen used to own the Newagen Inn. Once, when he drained its swimming pool, he found thousands of oyster spat, but of the European, commercial, species. Why in the Damariscotta River are there no native oysters? No natural spawning. What about in Great Salt Bay, the closest natural population, which is being expanded with varying success. Perfect conditions would be consistently warm water in the estuaries, high salinity.
Respectfully submitted,
Joanna M. Cameron
Secretary