"Restoring life to S.F.'s long-blighted Mountain Lake"
2013-12-13 by David Perlman for "San Francisco Chronicle" [http://www.sfgate.com/science/article/Restoring-life-to-S-F-s-long-blighted-Mountain-5063394.php]:
Baby pond turtles growing at the San Francisco and Oakland zoos and water plants thriving in a transplant nursery are all waiting to repopulate the Presidio's long-polluted Mountain Lake, where decades' worth of toxic sludge has finally been dredged out.
The turtles and water plants, along with three-spined sticklebacks, freshwater mussels, forktail damselflies and more, once flourished at the lake, when Ohlone Indians drank from its spring-fed water and Spanish explorers camped along its banks.
But the surrounding city's rise and toxic exhaust from millions of passing cars degraded the lake over time beyond tolerance for its original plants and animals.
Pumps have now sucked up tons of polluted sediment from the lake's bottom, and while minor pumping will continue for a while, teams of scientists with expertise on the original plants and animals are preparing for their return.
"It's all a big field experiment," said Darren Fong, a National Park Service aquatic ecologist. "We're seeing if we can restore the lake's ecology, starting with the basics - the plants and then the fish and then all the other species that should make the lake as it once was."
Jonathan Young, a biology graduate student at San Francisco State University who leads the project, has worked hip-deep since before the dredging began to rid the water of many invasive animals - like carp, crayfish, large-mouthed bass and alien turtle species - that have wound up in the lake over the years, some abandoned by thoughtless pet owners.
Overgrowth along the lake's borders had also transformed the lake's ecology, but that's all about to change.
"We have a complete plan now," Young said, "but it's going to take the most careful step-by-step work, because it means introducing one organism at a time."
Restored vegetation -
The first step, once the lake's clarity has been fully restored next year, will be to plant it with the right vegetation.
At the Presidio's Native Plant Nursery, botanist Michele Laskowski has been bringing in a variety of infant water plants that will form the base of a new ecology at Mountain Lake.
"The plants that used to be there were never documented, so first you had figure out what they must have been, and then go out to find them," Laskowski said.
She and her team have collected the plants from all over the Bay Area, wading into dozens of places like the wetlands of Muir Beach and remote Abbotts Lagoon at the Point Reyes National Seashore.
Planting into Mountain Lake is expected to begin in March, and the first priority, Laskowski said, will be to introduce three of the lake's most important plants: sago pondweed (Stuckenia pectinata), coontails (Ceratophyllum demersum) and water nymphs (Najas guadalupensis).
Those plants will play many roles, Young and Laskowski said. They will form a leafy canopy to shield microorganisms on the bottom from sunlight and provide a source of food for the lake's dabbling ducks, as well as for the rare Western pond turtles that are being raised at the two zoos until they can be moved to the lake.
Once the plants are thriving, Young's team will introduce hundreds of fish called three-spined sticklebacks, (Gasterosteus aculeates), a 2-inch species with a crucial role in the lake's ecology.
The sticklebacks are abundant in Lobos Creek, near where it flows into the Presidio's water treatment plant near Baker Beach. The creek provides the park with a large share of its water supply, so there should be no problem transplanting the sticklebacks into the lake, said Fong, the Park Service ecologist, who is also an expert on the Presidio's fish.
Introducing mussels -
The sticklebacks will play a curious part in the life of the next animals to be restored to the lake: the freshwater mussels, or Anodonta californiensis, also known as California floaters.
The mussels are ideal filter feeders, able to clear a lake's water of polluting bacteria and algae at an astonishing rate, said Niveen Ismail, a Stanford graduate student in environmental engineering and the project's mussel specialist.
"A single mussel about the size of your thumb can clear a whole liter of mucky water every hour," Ismail said. "They'd have a field day if the lake is green with algae, because they're always hungry, so the plan to raise thousands of them, and getting them to thrive along the edges of the lake, will be a big deal."
No mussels grow in Mountain Lake now, and there's no evidence that the bivalves have existed there since 1948, Ismail said. So she collected test animals from pristine water in the south fork of the Eel River in Mendocino County.
She set up an improvised laboratory inside a small garage in Mountain Lake Park and has spent more than a month testing batches of the transplanted mussels in buckets filled with lake water for their water-clearing abilities. They did a fine job, she said.
Persuading the bivalves to reproduce won't be easy, she said, because their tiny larvae have a strange do-or-die relationship with fish. That's where the sticklebacks will come in. The lake will use them as ichthyological midwives: Once the female mussels spew out their larvae into the water, the larvae must quickly find the sticklebacks' gills to cling to or they will die.
The larvae will grow inside the fishes' gills until they are old enough, and then move to shore en masse to create new mussel beds.
"It's an astonishing display of evolutionary adaptation," said biologist and mussel authority Christopher Barnhart of Missouri State University, who advised Islmail and Young on the Mountain Lake project.
Western pond turtles -
Nearly 70 infant Western pond turtles (Clemmys marmorata), are now growing at the San Francisco Zoo under the watchful eye of assistant curator Jessie Bushell. Little more than the size of a quarter when they were born, they will follow the mussels into Mountain Lake.
The California native pond turtles were once abundant up and down California, their meat and eggs providing rich food for the Indians - and much later for North Beach folk, who craved their turtle soup.
Today, they are rare and listed as a "species of special concern" by the California Department of Fish and Wildlife. The turtles bound for Mountain Lake are part of a Bay Area effort to stem the turtle population crisis.
Nicholas Geist, a biology professor at Sonoma State University, and his students collected the turtle's eggs from a natural population thriving in a small protected pond in Lake County. The eggs were then hatched in Geist's lab at Sonoma State, and batches of the infant turtles were sent to both zoos to be reared.
When Mountain Lake is ready for them in 2014 or 2015, the turtles will take up residence to do their ecological job as highly efficient predators, Geist said.
"They have very catholic tastes, and whatever it is, if it's dead they'll eat it; if it's alive and they can catch it, they'll eat that," he said.
In the old dogma of eat-or-be-eaten, the same turtles can be prey for other predators, although with their hard shells they're difficult to consume, Geist said.
"Bullfrogs, birds, loose dogs and - most dangerous of all - humans grabbing them are all their predators," he said.
The entire project will continue for many years as new creatures come, others grow and still others are born in what will be Mountain Lake's shallow east arm, where passersby will be able to watch the process, said Young, the San Francisco State biologist.
"Restoring an entire aquatic ecosystem in the heart of this dense urban jungle is a new concept," he said. "I like to think of it as making a living museum."
Niveen Ismail is part of a team of scientists working on bringing back Mountain Lake's healthy ecology. Photo: Pete Kiehart, The Chronicle
2013-12-13 by David Perlman for "San Francisco Chronicle" [http://www.sfgate.com/science/article/Restoring-life-to-S-F-s-long-blighted-Mountain-5063394.php]:
Baby pond turtles growing at the San Francisco and Oakland zoos and water plants thriving in a transplant nursery are all waiting to repopulate the Presidio's long-polluted Mountain Lake, where decades' worth of toxic sludge has finally been dredged out.
The turtles and water plants, along with three-spined sticklebacks, freshwater mussels, forktail damselflies and more, once flourished at the lake, when Ohlone Indians drank from its spring-fed water and Spanish explorers camped along its banks.
But the surrounding city's rise and toxic exhaust from millions of passing cars degraded the lake over time beyond tolerance for its original plants and animals.
Pumps have now sucked up tons of polluted sediment from the lake's bottom, and while minor pumping will continue for a while, teams of scientists with expertise on the original plants and animals are preparing for their return.
"It's all a big field experiment," said Darren Fong, a National Park Service aquatic ecologist. "We're seeing if we can restore the lake's ecology, starting with the basics - the plants and then the fish and then all the other species that should make the lake as it once was."
Jonathan Young, a biology graduate student at San Francisco State University who leads the project, has worked hip-deep since before the dredging began to rid the water of many invasive animals - like carp, crayfish, large-mouthed bass and alien turtle species - that have wound up in the lake over the years, some abandoned by thoughtless pet owners.
Overgrowth along the lake's borders had also transformed the lake's ecology, but that's all about to change.
"We have a complete plan now," Young said, "but it's going to take the most careful step-by-step work, because it means introducing one organism at a time."
Restored vegetation -
The first step, once the lake's clarity has been fully restored next year, will be to plant it with the right vegetation.
At the Presidio's Native Plant Nursery, botanist Michele Laskowski has been bringing in a variety of infant water plants that will form the base of a new ecology at Mountain Lake.
"The plants that used to be there were never documented, so first you had figure out what they must have been, and then go out to find them," Laskowski said.
She and her team have collected the plants from all over the Bay Area, wading into dozens of places like the wetlands of Muir Beach and remote Abbotts Lagoon at the Point Reyes National Seashore.
Planting into Mountain Lake is expected to begin in March, and the first priority, Laskowski said, will be to introduce three of the lake's most important plants: sago pondweed (Stuckenia pectinata), coontails (Ceratophyllum demersum) and water nymphs (Najas guadalupensis).
Those plants will play many roles, Young and Laskowski said. They will form a leafy canopy to shield microorganisms on the bottom from sunlight and provide a source of food for the lake's dabbling ducks, as well as for the rare Western pond turtles that are being raised at the two zoos until they can be moved to the lake.
Once the plants are thriving, Young's team will introduce hundreds of fish called three-spined sticklebacks, (Gasterosteus aculeates), a 2-inch species with a crucial role in the lake's ecology.
The sticklebacks are abundant in Lobos Creek, near where it flows into the Presidio's water treatment plant near Baker Beach. The creek provides the park with a large share of its water supply, so there should be no problem transplanting the sticklebacks into the lake, said Fong, the Park Service ecologist, who is also an expert on the Presidio's fish.
Introducing mussels -
The sticklebacks will play a curious part in the life of the next animals to be restored to the lake: the freshwater mussels, or Anodonta californiensis, also known as California floaters.
The mussels are ideal filter feeders, able to clear a lake's water of polluting bacteria and algae at an astonishing rate, said Niveen Ismail, a Stanford graduate student in environmental engineering and the project's mussel specialist.
"A single mussel about the size of your thumb can clear a whole liter of mucky water every hour," Ismail said. "They'd have a field day if the lake is green with algae, because they're always hungry, so the plan to raise thousands of them, and getting them to thrive along the edges of the lake, will be a big deal."
No mussels grow in Mountain Lake now, and there's no evidence that the bivalves have existed there since 1948, Ismail said. So she collected test animals from pristine water in the south fork of the Eel River in Mendocino County.
She set up an improvised laboratory inside a small garage in Mountain Lake Park and has spent more than a month testing batches of the transplanted mussels in buckets filled with lake water for their water-clearing abilities. They did a fine job, she said.
Persuading the bivalves to reproduce won't be easy, she said, because their tiny larvae have a strange do-or-die relationship with fish. That's where the sticklebacks will come in. The lake will use them as ichthyological midwives: Once the female mussels spew out their larvae into the water, the larvae must quickly find the sticklebacks' gills to cling to or they will die.
The larvae will grow inside the fishes' gills until they are old enough, and then move to shore en masse to create new mussel beds.
"It's an astonishing display of evolutionary adaptation," said biologist and mussel authority Christopher Barnhart of Missouri State University, who advised Islmail and Young on the Mountain Lake project.
Western pond turtles -
Nearly 70 infant Western pond turtles (Clemmys marmorata), are now growing at the San Francisco Zoo under the watchful eye of assistant curator Jessie Bushell. Little more than the size of a quarter when they were born, they will follow the mussels into Mountain Lake.
The California native pond turtles were once abundant up and down California, their meat and eggs providing rich food for the Indians - and much later for North Beach folk, who craved their turtle soup.
Today, they are rare and listed as a "species of special concern" by the California Department of Fish and Wildlife. The turtles bound for Mountain Lake are part of a Bay Area effort to stem the turtle population crisis.
Nicholas Geist, a biology professor at Sonoma State University, and his students collected the turtle's eggs from a natural population thriving in a small protected pond in Lake County. The eggs were then hatched in Geist's lab at Sonoma State, and batches of the infant turtles were sent to both zoos to be reared.
When Mountain Lake is ready for them in 2014 or 2015, the turtles will take up residence to do their ecological job as highly efficient predators, Geist said.
"They have very catholic tastes, and whatever it is, if it's dead they'll eat it; if it's alive and they can catch it, they'll eat that," he said.
In the old dogma of eat-or-be-eaten, the same turtles can be prey for other predators, although with their hard shells they're difficult to consume, Geist said.
"Bullfrogs, birds, loose dogs and - most dangerous of all - humans grabbing them are all their predators," he said.
The entire project will continue for many years as new creatures come, others grow and still others are born in what will be Mountain Lake's shallow east arm, where passersby will be able to watch the process, said Young, the San Francisco State biologist.
"Restoring an entire aquatic ecosystem in the heart of this dense urban jungle is a new concept," he said. "I like to think of it as making a living museum."
Niveen Ismail is part of a team of scientists working on bringing back Mountain Lake's healthy ecology. Photo: Pete Kiehart, The Chronicle
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