Two years ago, environmental studies assistant professor Kristen Przyborski sent out birth announcements after most of about 5,000 plugs of dune grass planted by student volunteers at the Mitchell College beach the previous summer survived the winter and began growing.

"We were so happy," she said last week, as she and Mitchell College colleague Kim Blake walked the beach off Pequot Avenue in New London, a natural classroom for students and a favorite place for summer sunning and swimming for the college community. "It was such a success story."

Today, she and Blake, chairwoman of the science, technology, environmental studies and math program at Mitchell, use words like "catastrophe," and "tragic" to describe what they see on this stretch of sand near the mouth of the Thames River. A little more than a year after Tropical Storm Irene tore into the dunes that the college had worked so hard to restore, Hurricane Sandy swallowed an even larger chunk of what remained.

"Two-thirds of the dune is lost," said Przyborski, standing on a flattened spot that just 2½ weeks ago was occupied by a mound of sand 12 feet high and 30 feet across. "I don't know how we come back from this."

The portion of the beach between the water and the dunes is narrower, too, after Sandy carved off the top layer of sand and lowered the elevation below the water line.

At beaches across southeastern Connecticut, officials have been assessing the impacts of Sandy and what - if anything - should be done in response. Some beaches, like McCook Point Park and Hole-in-the-Wall in East Lyme, actually grew as a result of the hurricane, gaining sand stripped off another nearby beach. Others, like Griswold Point at the mouth of the Connecticut River in Old Lyme, shifted as sand was hauled off one end and deposited on another.

"From the birds' perspective, it might be better," said David Gumbart, assistant director of land management for the state chapter of The Nature Conservancy, which owns the barrier beach and adjacent tidal marsh. A nesting area for endangered piping plovers and terns, Griswold Point was breached near the only foot access point at its western end, meaning conservancy naturalists will now have to use kayaks and canoes when it's time to erect protective fencing for the birds. But, Gumbart said, that also means fewer people will be disturbing the birds.

"It's not as though it's lost," he said. "It's just moved around."

At another tern and plover nesting area, Bushy Point at Bluff Point Coastal Reserve in Groton, the dunes were flattened and sand was thrown into the Poquonnock River marshes on the backside of the barrier beach, said Jonathan Lincoln, park supervisor for the state Department of Energy and Environmental Protection. But, he said, there's still plenty of nesting area. Some repairs will take place naturally as winter storms carry in new sand, he said, adding, "We'll just let nature take its course."

Other public beaches will need some human intervention to accelerate the natural repair process. One of those is Waterford Town Beach, which has been closed since the hurricane.

"There's been significant alteration," said Maureen Fitzgerald, environmental planner for the town.

Last week, she led officials from DEEP and The Nature Conservancy on a damage assessment tour as she seeks input on what to do. Several channels along the barrier beach opened up across the dunes, as storm surge poured in from Alewife Cove on the north side and Long Island Sound on the south. A dune that once rose 12 feet high on the eastern end is gone.

Juliana Barrett, coastal habitat specialist for Connecticut Sea Grant, also toured Waterford Town Beach last week, among others. Barrett is trying to get an overall understanding of changes along the coast in order to pull together resources to help towns restore their public beaches. In about two weeks, she'll convene a meeting of local officials with experts who can help them figure out how to restore these public spaces in a way that allows for the dynamic forces of nature.

"I'm also trying to help find (financial) resources," she said.

In some areas, like Waterford beach, waiting for nature doesn't seem to be a realistic option. The dune breaches could become deeper and wider in future storms, ultimately severing one end of the beach from the rest.

Looking across a 15-foot wide breach, she said: "The issue here is, are you going to lose that much beach? It could also become a public hazard."

Peter Francis, supervising environmental analyst with DEEP's Office of Long Island Sound Programs, said towns all along the coast have contacted him for help with their beaches. He visited Waterford beach and recommended the town recapture the sand that flowed over the dunes and into Alewife cove, to keep water in the cove flowing and rebuild the dunes.

"It's a valuable property," he said.

In the coming weeks, he said, his office will get a better understanding of how Hurricane Sandy has reshaped the shore. An important part of that effort was scheduled to take place this weekend, when contractors for the U.S. Army Corps of Engineers would fly along the shoreline to gather data on changes in elevation and shoreline profile. Francis expects to see a host of significant changes, given that storm surge from Sandy measured 6 feet above normal high tide, about 2½ feet higher than the surge during Irene.

The challenge, said Adam Whelchel, director of science for The Nature Conservancy, will be to understand the unique characteristics of each beach and how recent storms are affecting it, before undertaking a restoration plan.

"How do we allow these systems to be dynamic, and yet continue to provide recreational value?" he asked. "Chances are that we will get another Sandy in the future."

State and local officials also need to account for the many alterations made over the years that prevent the natural movement of sand along the coast, Whelchel said.

"It's not a natural shoreline," he added.

Frank Bohlen, professor emeritus of marine sciences at the University of Connecticut's Avery Point campus, said each beach is affected differently by powerful storms like Sandy due to a complex set of factors - orientation to incoming winds and waves, offshore water depths, tidal currents and water flow from nearby rivers and streams among them.

"This storm should come as a lesson in the dynamics of shorelines," he said. "People should pay attention."

Understanding the physical characteristics of each beach, he said, will be critical as officials continue to cope with the effects of powerful storms and determine where rebuilding dunes and shorelines makes sense and where it doesn't.

"Sea level is rising, and it's pushing the inshore boundary in," he said. "We will be losing more and more shoreline in Connecticut."

j.benson@theday.com