Looking on the wildflower-filled landscape of the National Wildlife Refuge along the Antioch coast, it's hard to assume that it was once a part of an unlimited sand dune system that stretched greater than two miles along the southern banks of the San Joaquin River.
Ancient deposits of glacial sand transported downstream from the Sierra Nevada formed the dunes, which were sculpted by winds and tides and once reached nearly 120 feet in height and prolonged about 800 feet inland. Until the early to mid-Twentieth century, the 400-acre site was Antioch's sandy gateway to the river – a spot to picnic, play and sunbathe.
But over a few years, natural processes and human intervention — starting within the late 1800s with large-scale sand mining — have isolated the Antioch Dunes to a much smaller area: 55 acres, plus a further 12 acres, with the recent addition of unused PG&E land in nearby. Nestled between a gypsum processing plant and the previous Fulton Shipyard, where World War II ships were once built, the now-isolated landscape is home to certain plants and a species of butterfly which might be completely unique to the dunes.
“I am very proud of the environment that Antioch is home to the only national wildlife refuge protecting plants and invertebrates,” said Julie Haas-Wajdowicz, Antioch Environmental Coordinator. “Because this (the long metalmark butterfly) is a species in great danger.”
Established in 1980, the Antioch Dunes National Wildlife Refuge – the primary of its kind dedicated to plants and insects – is the one home of the critically endangered Lange's metalmark butterfly, which has grow to be rare in recent times, and the first home of the Antioch Dunes -Evening primrose and the wallflower of Contra Costa.
The refuge is managed as a part of the San Francisco Bay National Wildlife Refuge Complex, a company of the National Fish and Wildlife Services.
Haas-Wajdowicz returned to the refuge last week together with about 30 public employees from various agencies to discuss sustainability and take away weeds comparable to winter vetch, star thistle, mustard and blackberry grass to enhance habitat for the endangered plants within the refuge Dunes often called trunk unit.
“There is a lot of invasive plant control in the spring,” Louis Terrazas, a wildlife refuge specialist and tour guide, told the volunteers. “Today we do it manually, but we also did a lot of spraying, mowing and weeding out here.”
“More rain means more plants. The endangered plants like it, but these non-native species like it too.”
Terrazas has worked on the refuge for nearly 20 years and has witnessed lots of the changes, including a long time of conservation work which have helped restore the land and make it a greater habitat for the endangered plants and butterflies. But in recent times, much more concerted efforts have been made to return the lost sand to the refuge, he said.
Two brick corporations opened near the positioning within the late nineteenth century, and after the 1906 San Francisco earthquake, freshwater sand was searched for high-quality bricks to rebuild the town with fire-resistant materials.
“It was a good location in the Bay Area where you could get sand material to make bricks quickly, and it was freshwater sand; It is easier to process freshwater sand into bricks,” Terrezas said.
Sand mining continued until 1980, when the U.S. Fish and Wildlife Service negotiated a deal for the property, which was almost sold to a developer to construct condominiums. The Long Metalmark butterfly and Antioch Dunes evening primrose were recently listed as endangered species.
Over the years, little of the endangered species' critical habitat remained; It suffered further damage from sand removal, trampling visitors, and accidental fires, prompting authorities to shut it to the general public in 1986.
Recognizing that the dunes were in dire need of restoration, the U.S. Fish and Wildlife Service began looking for sand in the next years. The answer got here from the Port of Stockton, which repeatedly dredges the nearby deep-water channel in search of a spot to dump sand.
The river has been dredged about every two years since 2012 from a spot within the predominant channel about 550 meters from the refuge, Terrazas said.
“It was a win-win situation where they needed a place to put it – and that saved them money,” he said. “They don’t have to pay a tip and they don’t have to transport it somewhere further away or pump it somewhere.”
Last October, the Port of Stockton dumped nearly 8,000 cubic yards of sand on the refuge, and Terrazas estimates that about 109,000 cubic yards of sand material has been added through the years at two different locations: the massive Trunk Unit to the west and the smaller Sardis Unit Eastbound.
“This area has been mined to the hard pan, and so a lot of the sand has disappeared,” Terrazas said. “An estimated 3.2 million cubic meters of sand was removed from the upper dune system and an estimated 1.7 million of this was on the protected area property that was removed from the sand dunes. We give a little of that back.”
To prevent the sand from blowing away, refugee staff placed bricks along the property line.
“It makes it easier for us to pick it up and put it somewhere else,” Terrazas said.
According to wildlife biologist Susan Euing, who keeps track of the plants, one resident of the refuge that loves the brand new sand is the endangered Antioch Dunes evening primrose.
“They’ve really started to take off in numbers,” she said.
Euing said there have been a median of 602 mature primroses within the reserve from 2006 to 2016, but by 2017 that number had increased to 1,735 after which to eight,506 in 2021 – a 390% increase.
The counts are carried out every three years, she said, adding that the following count will probably be in May. The recent sand “was a godsend,” she said.
Terraces agreed.
“Their numbers have skyrocketed here in the area where we have introduced new sand material because there is less competition for them,” he explained.
The endangered Contra Costa Wallflower, which is found primarily along the river, under oak trees and in shady areas, is just not faring quite as well.
“Their numbers didn’t respond the way the primrose numbers did,” Terrazas said. “Their numbers have gone down a bit, so we’re focusing on them now.”
This spring, staff are conducting pollination experiments on the Contra Costa Wallflower to grasp how this endangered species reproduces and to estimate its genetic diversity. According to Wildlife Services, the findings will help shelter staff learn the right way to higher protect and get better the endangered species.
The tiny Long Metalmark butterfly has also seen higher days, peaking in 2000 with a population of two,300 individuals. The butterfly has only been seen within the Sardis unit since a hearth devastated the refuge's predominant unit in 2007. Nevertheless, refuge staff proceed to plant Antioch Dunes buckwheat, the insect's host plant, within the hope that they may return.
Wayne Hayes, a wildlife service biologist, said the variety of long metalmark butterflies has declined over the past twenty years, however it's not clear why.
“It is most likely the result of a combination of stressors, including habitat loss and degradation, small population sizes, environmental pollutants, pesticides, wildfires and changing climatic conditions,” Hayes said.
The biologist noted that the US Fish and Wildlife Service is working with UCLA's California Conservation Genomics Project to review the metalmark butterfly's DNA. They wish to see how the Dunes metal tag pertains to other nearby butterfly populations, which could help them reproduce in captivity, he said.
Euing hasn't lost hope either.
“Their numbers have been declining and we didn't see any last year, but we're not counting them yet,” she said. “We’ll still be looking for them.”
Due to the sensitivity of the dune habitats, the refuge is just not open to the general public apart from regular monthly Second Saturday tours and other special events. The next tour takes place on May eleventh at 10 a.m. Please refer www.fws.gov/refuge/antioch-dunes.
image credit : www.mercurynews.com