Along the marsh’s edge at Cache Creek Nature Preserve, 20 miles northwest of Sacramento, Diana Almendariz harvests bundles of tule (Schoenoplectus acutus)— green, smooth cylinders up to 10 feet high. With a knife, she cuts the giant sedge, about as thick as a nickel, at their full height, while avoiding stalks where red-winged blackbirds and marsh wrens have built their nests. Sometimes, she stands nearly ankle-deep in the mud and looks skyward, imagining herself as a tiny ant in a grass lawn.
After taking only as much as she plans to use, Almendariz, an Indigenous cultural practitioner, dries the tule in the sun. She bends and binds them together with cattail reeds to make huts, dolls, and canoes, as her Maidu and Wintun ancestors had done. While many of their gathering sites are now gone, the preserve remains plentiful of tule—resilient and hardy, but also soft and flexible. And so, they make durable mats for sleeping and sitting, which Almendariz weaves every Sunday at her tule mat-making workshops. But more than 20 years ago, she discovered what happens when you float a small mat of tule on water.
“If it’s sitting on [water] for a long time, and it’s floating, then it gets slimy,” says Almendariz. “It’s food for invertebrates.”
While Almendariz has seen this slime for over 40 years gathering tule in the Sacramento Valley, she is now sharing her knowledge with UC Davis entomology associate professor Geoffrey Attardo, who has volunteered at her tule mat-making workshop for nearly three years. In November, Almendariz and Attardo began studying the life cycle of species living with the tule at Cache Creek Nature Preserve, a 130-acre sanctuary of wetland, oak woodland, and grassland habitat, once home to the Wintun people. In Attardo’s third year of a five-year grant from the Center for Disease Control to study invasive mosquito insecticide resistance and develop outreach programs with Native American stakeholders in California, Attardo, Almendariz, their students, and volunteers will determine whether tule mats can promote microbial biodiversity that limit mosquito populations in wetlands.
“My vested interest is coming up with control solutions that are ecologically oriented,” says Attardo. “Wetland restoration is really at the center of that, because wetlands are kind of like these fountains of life.”
Tule mats ready to go into the water, and PhD candidate Christofer Brothers bringing in a train of tule mats in from the marsh (Jillian Magtoto)
But Westerners have long demonized marshes as sources of “pestilence and disease,” says Attardo. “Drain the swamp!” American politicians like to say, when calling for the extermination of corruption and government waste in Washington. In nature, the mosquito is often to blame. Attracted to still bodies of water, mosquitoes often breed in marshes, ponds, and swamps, where they support their ecosystems as pollinators and food for fish, frogs, dragonfly nymphs, and birds. But as is the case with many villain origin stories, it’s not the mosquitoes themselves that create the threat, but rather the environment they are raised in. In wetlands with a lack of microbial and invertebrate diversity, natural predators of mosquitoes are absent, allowing mosquitoes to breed unchecked.
“A lot of vector-borne diseases really thrive in areas where the ecology has been disrupted,” says Attardo.
California’s wetland ecology has not just been disrupted, but largely eliminated. Just ten percent of the state’s historic wetlands remain, many of which are disturbed by agriculture, development, and dams. Amid this loss, California is seeing a rise in mosquito-borne diseases, including West Nile Virus and dengue. To make matters worse, chemicals entering waterways also create insecticide resistance in potentially deadly mosquitoes.
“You have a lot of this agricultural runoff that’s filled with remnants of pesticides, herbicides, and fertilizers these mosquitoes are being introduced into,” says Attardo. “So we’re seeing high levels of insecticide resistance in mosquitoes that transmit West Nile Virus.”
Cache Creek travels through swaths of farmland, abandoned mines, quarries, and golf courses before arriving at the preserve. The creek supplies just two percent of the water to the Sacramento River system, but up to 30 percent of the mercury as of 2017—a lingering remnant of the gold rush. Harmful algal blooms also persistently plague portions of the creek, likely due to fertilizer runoff.
Yet, life here appears to be undisturbed.
“All the testing I’ve done at Cache Creek, I’ve only found one mosquito larva, which indicates to me that the wetland is functioning, and its natural ability to control mosquitoes,” says Attardo. “So we’d like to kind of use this as an example of how you can go about practicing restoration in a less than ideal environment.”
In 1996, The Cache Creek Conservancy was born in an effort to restore the lower Cache Creek watershed. Now, flocks of about 30 white great egrets litter the preserve’s hillside full of deergrass, coyote brush, and purple needlegrass. Black-tailed deer frequently munch on grass that sprouts after burning during fire season. For Almendariz, the basis of the wetland’s success is clear.
“My grandmother taught that tule is important,” says Almendariz. “They provide healthy food. They provide healthy water.” And they provide shelter for Native people, animals, and bacteria.
Mule deer among stands of tule (Lauren Glevanik via iNaturalist, ^(https://www.blogquicker.com/goto/https://www.inaturalist.org/photos/170414069?size=original) CC by NC) and a redwing blackbird perched on a tule reed (Lauren Glevanik via iNaturalist ^(https://www.blogquicker.com/goto/https://www.inaturalist.org/photos/131144199), CC by NC) at Cache Creek Nature Preserve
More specifically, bacteria getting their fill on nutrient-rich tule are secreting a protective mucus—the slime Almendariz described. That slippery biofilm catches pesticides, nutrients, sediments, and other materials suspended in water. “It’s a filter,” says Almendariz. “It keeps the marsh clean.” Many other types of bulrushes and marsh grasses, such as cattails, also form biofilms in freshwater ecosystems. Some people have even turned biofilm into businesses, selling “floating wetlands” and “islands” that filter water and even prevent harmful algal blooms. Tule, in particular, is used in artificial wetlands to filter agricultural wastewater.
While Almendariz has long known about the importance of tule, placing dried tule mats on the water came to her over five years ago, when she was experimenting with a lone half-square foot tule mat, testing how long it could float.
“I was more into thinking about what happened to all the native boats that were probably everywhere,” Almendariz says. “Did they just break down?” But when the mat sank about six months later, she discovered tiny beings swarming in a slimy goo covering its underside.
“When you touch it with your finger, it feels kind of slippery,” says Attardo, and thicker than saliva. “Normally it just looks like slime, but when you zoom in… it really almost looks like a city,” a city where millions of bacteria eat and get eaten.
The slime is not just a filter, but also a micro-buffet for the rest of the food web. Single-celled ciliates with hundreds of hair-like limbs feed exclusively off of the bacteria. Multicellular organisms, like zooplankton, wiggle in to feast on decaying plant matter, single-celled organisms, and each other. Then the insects scuttle in, which get picked off by birds, fish, and frogs—all of which prey on mosquitoes.
“We’re weaving these mats as a way of providing habitat and nutrients to the animals that provide, generate, and form the foundation of the food web in the ecosystem,” says Attardo. Dried tule disintegrates into the water to produce substrate even more accessible to the bacteria, and the life that feeds on them. Almendariz and others have spotted birds, like a grey flycatcher, perched on the mat. A western toad, too, sat “fat and happy,” Almendariz says, a juicy meal for an egret or heron.
A common green darner (Lauren Glevanik via iNaturalist ^(https://www.blogquicker.com/goto/https://www.inaturalist.org/photos/156966291?size=original), CC by NC) and a widow skimmer (Lauren Glevanik via iNaturalist ^(https://www.blogquicker.com/goto/https://www.inaturalist.org/photos/77901059?size=original), CC by NC) at Cache Creek Nature Preserve
Attardo notices that the mats harbor one voracious mosquito predator in particular. Dragonfly nymphs sit in little nooks in the tule, hollowed out by microbes, where they sit and wait for their prey. Beautiful but deadly, dragonflies are among the most unforgiving predators in the animal kingdom. One wingless underwater larva can eat an average of 40 mosquito larvae per day—equivalent to a daily reduction of the mosquito larval population by 45 percent. When they grow to become airborne adults, they chase their prey with a catch rate of 95 percent.
Attardo and Almendariz’s optimistic observations are now being tested as part of Attardo’s work at the Pacific Southwest Center of Excellence in Vector-Borne Diseases at UC Davis, one of four Center for Disease Control (CDC)-funded centers nationwide conducting research on mosquito and disease control. With the freezing of federal grants ^(https://www.blogquicker.com/goto/https://baynature.org/article/trump-confusion-chaos-impacts-on-san-francisco-bay-area-conservation-work/), however, Attardo is unsure if funding for his projects will continue after this year.
They placed their first batch of mats in the marsh in late October, harvested from Cache Creek and a local wetland at the Yolo Bypass. One week later, they pulled in a 60-foot cattail-twisted rope through the marsh, followed by a train of about a dozen tule mats. After the mats landed on the grass, Attardo cut the tule into a handful of pieces, about one to three inches each. He was wearing a T-shirt picturing a giant mosquito with the caption “So many campers, so little time.”
At a nearby barn, Attardo covered a picnic table with microscopes, accompanied by identification sheets of invertebrate species he expected to find. About five volunteers looked through the microscopes at the tule partitioned into one-inch pieces on petri dishes. One was a PhD student from UC Davis in his fifth year of studying dragonflies, depicted in all colors and sizes on his shirt and shorts. Other volunteers belonged to Native American tribes from California to Wyoming. Once they fiddled with the knobs to focus their lenses, it didn’t take long to find wriggling worms, midges, snails, and mites, which the volunteers were encouraged to record on their identification sheets.
“We’re all going to be scientists after this,” says Melissa Mitchum-Brown of the Cachil Dehe Wintun Tribe in Colusa, to the other volunteers.
“Being able to see these living things in the water is something I believe is amazing,” says Mitchum-Brown, who regularly volunteers with her 16-year-old daughter. “Being a basket weaver and a land steward, I think it’s important that there are small beings and small worlds. The microscopes allowed us to be part of that world.”
Volunteers at Cache Creek Nature Preserve looking through microscopes, with Geoffrey Attardo, Diana Almendariz, and PhD Student Christofer Brothers peering over their shoulders (Jillian Magtoto)
The study is a group effort. An undergraduate student in Attardo’s lab has already been tracking the microorganisms entering and leaving the marsh, by extracting the microbial DNA from water samples—a helpful piece of context for the marsh’s baseline productivity for their study. Students as young as 14 years old in Almendariz’s Traditional Ecological Knowledge program help harvest tule and weave the mats themselves. “We wouldn’t be able to do it without them,” says Almendariz.
Science is not Attardo’s only goal. While he is unsure what data collection will look like, part of his grant’s purpose is inviting Native American people to participate in the merging of cultural and scientific knowledge in vector-borne disease. That, and he likes seeing the joy on people’s faces. Above all, he wants Almendariz to continue taking the lead.
“My approach was to talk with Diana and see what her primary interests were,” says Attardo. “Native practices and native knowledge are really going to be critical for proper ecological management… So my goal is to just provide anything that I can that will facilitate that.”
Almendariz eventually plans for Attardo to place a sheet of mats over a small island in the marsh, about a 40 by 60 feet piece of soil covered in tule. As for her future plans with Attardo, they plan to write a paper on their work as an example of marrying cultural with biological information—the outcome of a partnership built on trust and collaboration.“It’s a very complementary relationship,” says Almendariz, who remains cautious about the rest of the scientific community. “We’ve got to keep a lot of the knowledge we’re getting close to us… because it needs to be done right.”
#Lives #Dies #Tule #Mats
