Tidal Exchange
THE UNSEEN SLOUGH
What threatened amphibians reveal about hope and survival in the age of climate change
Ross Robertson, Communications Director
If you don’t know what you’re looking for, Rush Pond might not seem like much to speak of. A couple hundred square feet of murky water enclosed by a black metal pig fence, tucked into a hillside of twisted oaks. But for the Santa Cruz long-toed salamander, this is as good as it gets—a rejuvenating oasis in an arid sea. It’s a callback to a
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red-legged frog (by Evan Peers).
Elkhorn Slough Foundation
board of directors
Bruce Welden
President
Robert Hartmann
Vice President
Tara Trautsch
Secretary
Anne Secker
Treasurer
Anne Olsen
Past President
Gary Bloom
Judith Connor
Terry Eckhardt
Sandy Hale
Emmett Linder
Kent Marshall
Hon. Susan Matcham
Laura Solorio, MD
Becky Suarez
David Warner
Mark Silberstein
Executive Director
The mission of the Elkhorn Slough Foundation is to conserve and restore Elkhorn Slough and its watershed.
We see Elkhorn Slough and its watershed protected forever— a working landscape where people, farming, industry, and nature thrive together. As one of California’s last great coastal wetlands, Elkhorn Slough will remain a wellspring of life and a source of inspiration for generations to come.
PO Box 267, Moss Landing California 95039
tel: (831) 728-5939
fax: (831) 728-7031
elkhornslough.org
Tidal Exchange
Ross Robertson, Editor
RESERVE UPDATE
New Ponds, Old Friends
Dave Feliz, Elkhorn Slough Reserve Manager
Topped by several hundred feet of Pliocene Epoch sand dunes, the Elkhorn Slough watershed historically had several freshwater springs that percolated to the surface, some of which flowed profusely into the slough. There was ample habitat for a variety of amphibians in these hills. Today, with more than 20,000 people living in the area, associated groundwater wells have made freshwater marshes very rare. With the loss of freshwater habitats, breeding opportunities for amphibians with aquatic larval stages diminished dramatically. Yet species such as the California red-legged frog, California tiger salamander, and Santa Cruz long-toed salamander have persisted here.
We can help these animals by creating freshwater wetlands. Since there are few running streams in the area, we have devised means to capture rainwater and present it in constructed ponds. We started excavating ponds about ten years ago, fitting them with impermeable liners to prevent the water from soaking into the ground. Our first attempts were wildly successful. In a small 20’ x 20’ pond, both rare salamander species bred successfully.
Emboldened by these efforts, we continued building ponds. Every year, Reserve Biologist Susie Fork leads a team of researchers and volunteers to sample all the natural and created wetlands in the area. Participants are treated to large numbers of Pacific chorus frogs, but the real prize is finding salamander larvae. In 2021, Washington State University graduate student Mitch Ralson developed a protocol to detect the presence or absence of the Santa Cruz long-toed salamander by examining DNA in water samples. This technique allowed us to explore new areas and better understand the distribution of this endangered species.
© 2024 Elkhorn Slough Foundation
Constructed wetlands are now being created in areas above the tidal wetland footprint. In the past, inlets of the slough were diked off and managed as freshwater wetlands. As sea level rises, these areas will be vulnerable to becoming saline—and a logical place to restore valuable tidal wetlands. Looking forward, we can manage freshwater habitats above the reach of the increasing tides and secure a future for these amphibian species while providing habitat for many other species that depend on freshwater. n
THE UNSEEN SLOUGH
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time out of mind, before the land was chopped and dried and parceled out for people. Before plows and highways, homes and wells, concrete and strawberries. If you’re like me, overwhelmed by the scale and pace of the climate squeeze, it’s also a place to slow down. To listen. To marvel, even for a moment, at the delicacy of hope in a world of uncertainty.
It was early May when I first came up to Rush Pond this year. We followed two pickup trucks filled with biologists and grad students from the U.S. Fish & Wildlife Service and UC Santa Cruz. Down in the shade of the truck beds, sloshing around inside four or five plain orange, securely fastened Home Depot buckets, were the stars of the afternoon: 150 of one of the most endangered amphibians in the United States.
These tiny Santa Cruz long-toed salamanders, bred in captivity at UCSC’s Coastal Science Campus, were just four months old and a few inches long. Now at the tail end of their larval stage, they were ready to spread their feathery gills in the wild. The researchers set the buckets down in shallow water at the pond’s edge to start acclimating the larvae to the temperature of their new home, keeping an eye out for signs of stress. They poured a cupful of pond water into each bucket. We waited. Five minutes later, they poured a little more. This went on for half an hour.
We chatted some as they slowly moved the buckets deeper into the pond. Mostly, though, we were silent. Bits of iridescent algae floated on the surface. I listened to the wind. As though we hadn’t just met each other, we sank comfortably into the quiet. As though together, without words, we were casting a spell.
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Left: Amphibian sampling (by Dave Feliz).
Right: California tiger salamander larva (by Evan Peers).
Above: Long Valley Pond during and after construction.
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“Do you want to come say goodbye to your babies?”
Chad Mitcham, USFWS Senior Biologist and longtime partner of the Elkhorn Slough Foundation, paused while the researchers said their farewells. Then one by one, he tipped the buckets into the water and the next generation of “long-toeds” swam out to meet their destiny.
THE IMPERILED AMPHIBIANS OF ELKHORN SLOUGH
Three different amphibians in the Elkhorn watershed are listed as threatened or endangered under the state or federal Endangered Species Acts—the Santa Cruz longtoed salamander, the California tiger salamander, and the California red-legged frog.
The salamanders have a lot in common. Both spend the majority of their lives underground in small mammal burrows, either in riparian and oak woodlands (longtoeds) or valley and foothill grasslands (tiger salamanders). Both emerge on rainy nights during fall and winter, when they migrate to mate and lay eggs in ponds like Rush. Just 3-6 months after hatching, the larvae undergo metamorphosis and leave the water, only to return after they reach sexual maturity approximately 3 years later.
The California red-legged frog utilizes ponds like these, too, although it can also reproduce in streams, marshes, and lagoons. All three species co-occur, sharing similar habitat needs and benefitting from similar conservation actions. Yet while tiger salamanders and red-legged frogs occupy broader swaths of California, the long-toed is found only in southern Santa Cruz and northern Monterey counties, in an area just 16 miles long and 5 miles wide.
This minuscule range contributes to the long-toed’s more critical “endangered” status. It actually appeared on the first-ever list of endangered species issued by the U.S. Department of Interior in 1967, alongside the California condor, the bald eagle, and the grizzly bear.
THREATS FROM WITHOUT, THREATS FROM WITHIN
ESF Land Steward Ken Collins refers to these amphibians as “canaries in a coal mine”—species so sensitive they serve as early indicators of ecological trouble. Elkhorn
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Top row: California tiger salamander larva (left, by Inger Marie Laursen) and metamorph (right, by Anton Sorokin).
Middle row: Susie Fork and Inger Marie Laursen (left, by Evan Peers); California tiger salamander eggs (middle, by Susie Fork); Rush Pond (circle, by Ross Rob ertson); California red-legged frog eggs (right, by Susie Fork).
Bottom row: Santa Cruz long-toed salamander larva (left) and adult (right, by Evan Peers); dipnetting at Vista Pond (middle, by Inger Marie Laursen).
Teaching Sustainability
High above the Salinas River, at beautiful Dorrance Ranch, a group of conservation professionals gathers for a field workshop called “Biology and Management of the California Tiger Salamander.” Taught by Dr. Chris Searcy (University of Miami) and Dr. Pete Trenham (Penn State), participants test their knowledge of tiger salamander biology, workshop ideas for a hypothetical tiger salamander preserve, and learn how to perform surveys using a seine net.
It’s just one of a dozen similar courses offered each year by the Elkhorn Slough Reserve’s Coastal Training Program (CTP) to address critical environmental issues along California’s Central Coast, from habitat restoration and management to clean water and invasive species. “We run a number of workshops on the biology and management of sensitive species,” says CTP Coordinator Dan Brumbaugh, “including the California tiger salamander, the California redlegged frog, and the foothill yellow-legged frog.”
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Slough Reserve Biologist Susie Fork agrees: “At the same time, they’re steady steamers. They’re mysterious. For something that needs to keep their skin moist all the time, they can handle a lot.”
Of all the environmental pressures these animals face, the scientists I spoke with agreed that two loom largest—habitat loss and genetic isolation. “Historically,” freshwater ecologist Eric Palkovacs tells me, “the ancestors of today’s long-toed salamanders extended across much of California and the Pacific Northwest. But climatic changes over the last 10,000 years isolated the tiny relict population we now call the Santa Cruz long-toed salamander, and most of the suitable habitat within its remaining range was lost to development in the last 100 years.”
Foremost among their habitat needs is freshwater. Between groundwater depletion, saltwater infiltration, multi-year cycles of drought, and a future of climbing temperatures and rising seas, many ponds are drying up, and many of those closest to the estuary are getting saltier. These species also prefer ponds that are not just fresh, but vernal or ephemeral—ponds that come and go with the seasons—because year-round ponds eventually get colonized by invasive predators such as bullfrogs or mosquitofish.
The right kind of upland habitat for dispersal is equally important. “It has to have moisture and shade in it,” Fork says. “That’s why long-toeds are struggling more in north Monterey County than in Santa Cruz, because of all the areas converted to agriculture, and all of the roads.”
“As crucial as these breeding ponds are for the longtoeds,” adds Mitcham, “they only spend a few weeks a year in them. The rest of the time they’re in oak woodlands and riparian habitats. But it’s not just the oaks— they need that thick, herbaceous understory beneath the canopy. During the dry, hot summer months, that’s what allows them to get up into areas that still retain soil moisture, and then they can find small mammal burrows and other things to get into.”
Perhaps the cruelest impact of habitat loss is on the genome itself. The most recent planning document, “Amphibian Conservation Strategy for Northern Monterey County” (2019), identifies six separate “metapopulations” of Santa Cruz long-toed salamanders
Workshop participants at Dorrance Ranch (by Ross Robertson).
that no longer interbreed. Even within these isolated areas, habitats continue to fragment, making “threats from genetic isolation . . . increasingly severe.” It’s a classic example of what’s known in conservation biology as an extinction vortex.
POPULATION MATTERS
The extinction vortex model describes how extinction risks accelerate as population size declines. In essence, shrinking populations decrease an organism’s genetic diversity, heightening its vulnerability to disturbance, which then leads to further population declines in a compounding, downward spiral. This means that some minimum population size is required for long-term survival.
Fork coordinates amphibian surveys in north Monterey County from her post at the Elkhorn Slough Reserve, along with a host of collaborators. We’ve been gathering data on sensitive amphibians in the Elkhorn watershed since the late 1990s. And as I learned when I joined her on several monitoring expeditions, this can be fun—but not easy—to do.
The unseen slough is a fragrant mystery, hidden from human eyes under mud, water, and vegetation. The most important tool in the surveyor’s kit is the dipnet, whose basic “pull through the water and see what comes out” utility is elevated in practiced hands to an elegant, almost martial art form. All manner of pond life shows up in the haul, from snails and aquatic insects to the ubiquitous Pacific chorus frog. Any salamander larvae or red-legged frog tadpoles are measured and recorded, along with water quality readings.
It’s a great way to keep tabs on amphibian populations, as well as on pond biodiversity in general. But nobody really knows how many long-toeds exist in the wild. “It’s hard to tell how they’re doing overall,” Fork explains. “You can’t base it on the larvae, because only one in a hundred make it from larva to adult.”
STRING OF PEARLS
The genetic bottleneck faced by the long-toed is extreme enough to justify one of conservation’s most disruptive interventions—captive breeding and reintroduction.
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Preservation Power Up
A new excavator arrives at Elkhorn Slough
Thanks to generous support from NOAA, CalFire, and a local family foundation, our new Kubota KX033 Compact Excavator is finally here! We’ve been anticipating this day for quite some time now. Stewardship and restoration projects that were just dreams before can finally become realities. This includes new and improved freshwater ponds for threatened amphibians, wildfire prevention, and cleanup projects at both ESF and Reserve properties.
Dragonfly exoskeletons (by Inger Marie Laursen).
Above: Ken Collins shows off Pig Pond (left, by Ross Robertson); Pacific chorus frog (top right, by Inger Marie Laursen); dragonfly closeup (bottom right, by Inger Marie Laursen).
Below: pond snail eggs (by Inger Marie Laursen).
Top: Susie Fork, Inger Marie Laursen, and Debie ChircoMacDonald (by Evan Peers).
Middle: spikerush (by Inger Marie Laursen).
Bottom: Santa Cruz long-toed salamander breeding tanks at UCSC (by Susie Fork).
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“The loss of this species would mean the loss of a critical link in forest and wetland ecosystems,” says Palkovacs, who oversees the program at UCSC.
Funded by USFWS, researchers started crossbreeding low genetic diversity populations from Monterey County with higher diversity populations from Santa Cruz County in 2021. They’re also building a genetic database of all the breeding pairs and all their larvae so that when wild-born long-toeds are captured in the future, they’ll be able to sample their DNA, see which lineages survived, and determine which are the most robust to guide future breeding efforts. It’s a daring attempt to improve both population size and gene flow.
Rush was among the first ponds where captive-bred long-toeds were released three years ago. (The Reserve’s Long Valley Pond was another; see page 2.) “It was the first time they’d been in these hills in probably 100 years,” Collins reflects. “We’re giving them a fighting chance to reclaim their native habitat.”
ESF Stewardship Director Dash Dunkell describes our long-term vision as building a “string of pearls”—a series of ephemeral freshwater wetlands for salamanders to move between that connects the dots from Carneros Creek in the north to ponds like Rush in the highlands and back down to the Reserve beside the slough. To knit the watershed together again—and boost the resilience of our whole water system in the process.
According to Dunkell, the ponds in the highlands are special because they’re surrounded by such large tracts of high-quality habitat. “Over the last 40 years,” he says, “we’ve acquired and retired nearly 1,000 acres of steep, eroding farmland around the slough, while maintaining four certified organic farms. By reconfiguring farmlands to a sustainable footprint, we’ve hugely reduced groundwater pumping and planted thousands of native plants on the restored slopes and valleys, creating optimal habitats for these amazing little animals.”
“These lands are experiencing a renaissance,” Collins continues. “As climate change creeps up and temperatures are expected to rise, we are locking more freshwater in our hills than at any point in the last century.”
Collins half-jokingly refers to himself as a pond archaeologist: “In the process of removing erosive sands from historical farms, we sometimes find clay soil and
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THE UNSEEN SLOUGH
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old wetland features underneath. These ‘ghost ponds’ often make excellent restoration sites. The sediment layers and the hydrology are already there. There’s usually a dormant seed bank, as well.”
Pig Pond was one of these ghost ponds until Collins saw feral pigs repeatedly wallowing there. “They showed us where there was an open water seep, and when we removed the soil, the water just came up again.”
EVERYTHING IS A CANARY
I was lucky to be dipnetting with Fork on the first day we found new long-toed larvae in our ponds this year. So there was joy in the air to temper the exhaustion of fighting through thickets of arroyo willow and mud deep enough to contend with us for ownership of our waders.
Suck-stepping my way through slate brown water, I caught one myself—and sank, once again, into a blossoming expanse of unexpected stillness.
I lifted its gossamer body out of my net and into the small plastic bin I would use to convey it back to our rendezvous point. I can’t let it spill, I thought with each careful step through the crowded willows. So easy to tip. I kept dipnetting, one dip here, one there, step, shift my weight, step, dip again, all the while tending my floating bucket. I caught one more larva before I made it back to shore; altogether, we found 11. Each was weighed and
measured. 50 or 60 millimeters. Less than a gram or a little more. Their downy gills; their meager legs; their toes clutching our palms.
It’s not easy to convey what it’s like to bear witness to such a slender species—whether in the precise matrix of a captive breeding facility or the hidden wetlands above Elkhorn Slough. I’m moved by the people trying, in the runaway complexity of the world we’re in, to save something so small from a fate so permanent.
“Yes,” Mitcham replies when I ask him about the canary in a coal mine analogy. “But that’s really an appropriate metaphor for any species. I think it’s relevant, truly. It’s relevant for everything.”
Everything related. Everything dependent. Everything.
A week after I found two long-toed larvae myself, another group found 18 of them at Long Valley Pond on the Elkhorn Slough Reserve. This place is too far from any existing long-toed habitat for them to have migrated there themselves. We won’t know for sure until genetic studies are done, but the researchers are confident that these are our first returnees—the first captive-bred Santa Cruz long-toed salamander offspring known to have bred in the wild.
Mitcham, Collins, and the others expect to see our first returnees at Rush next year, as well. “We have to be hopeful as humans,” Fork says. “Otherwise, how do you move forward?” n
Susie Fork holds a Santa Cruz long-toed salamander (by Inger Marie Laursen).
Coming Home
I am honored to be invited to join the Board of the Elkhorn Slough Foundation. I was fortunate to spend two decades at the Reserve (1990-2010), first working for the Department of Fish and Wildlife in education and then as the Reserve Manager. One of my favorite aspects was collaborating with both the Reserve’s federal partner, NOAA, and its local partner, ESF. Each entity is distinct in its role and function, and yet together we could dream bigger and pursue more complex conservation goals than any one of us could do alone.
I was also lucky to live on the Reserve, just footsteps away from nesting birds, yipping foxes, and courting frogs. I loved being immersed in the estuary’s ever-
changing sights, sounds, and smells. I met my wonderful husband, Jorge, at Elkhorn Slough and made many lifelong friends.
Returning to Elkhorn Slough in this new role feels like coming home. Being involved with ESF means doing something positive for our local ecosystems, from the watershed to the bay. The expertise and enthusiasm of the staff and volunteers is inspiring, and it is exciting to be part of an organization in which I have the utmost confidence. I appreciate the trust that you, the ESF members, place in this organization as well, and I promise to do whatever I can to support a healthy future for the estuary and its inhabitants we all love. n
SLOUGH VIEW
Becky Suarez, ESF Board of Directors
Above: Suarez kayaking in Elkhorn Slough during her tenure with the California Department of Fish and Wildlife at the Elkhorn Slough Reserve. Inset (right) by Jorge Suarez.
In 2024, longtime slough champion Becky Suarez became the newest member of the Elkhorn Slough Foundation Board of Directors.
Dipnetting for amphibians at Blohm Ranch (by Inger Marie Laursen).