ESTUARY PEARLS: Beavers, climate impacts, harmful algal blooms, juvenile salmon, phytoplankton production, and more …

California will spend big bucks on beavers to try to boost their numbers and reap some of the benefits—including slowing wildfire—these ecosystem engineers can provide.

After years of advocacy by beaver “believers,” the state has allocated funding for a beaver restoration program. The $1.67 million in license plate funds for fiscal year 2022-23 and $1.44 million the following year represents a new way of thinking about beaver management in California, says Kate Lundquist, of the Occidental Arts & Ecology Center.

Until recently, the Fish and Game Code has focused on recreational and commercial beaver trapping and permitting the depredation of nuisance beaver,” she explains. “I am excited that the Governor, the Natural Resources Agency, and the California Department of Fish and Wildlife are recognizing beaver and process-based restoration as legitimate nature-based solutions that can restore our watersheds, recover listed species, and make our state more resilient to droughts, wildfires, and climate change.

Lundquist’s organization was one of more than 100 groups—including conservation and agricultural organizations, tribes, and others—that advocated for the funding allocation and for recognizing the benefits of beavers. The beaver restoration line item funds five new permanent CDFW positions and equipment for managing and monitoring the health of the state’s beavers, as well as relocating beavers as necessary. Chad Dibble, Deputy Director with CDFW, is particularly excited about the potential for beavers to help stem wildfires.

Beavers are incredibly good at engineering dams that slow water down and spread it out,” he says. “This can help wet a larger area of land that is much greener and more lush than your typical side channel growth in water-restricted areas.”

That greening, says Dribble, can help stop wildfires moving through an area.

Author: Lisa Owens Viani | Photo: Brock Evans, OAEC

Climate change is heating, salinizing, and expanding the San Francisco Estuary, a review of nearly 200 scientific studies concludes.

Sea level rise, changing snow and rainfall patterns, and warmer waters are some of the changes already observed in the Estuary and expected to continue through the rest of the century as greenhouse gas concentrations rise. Changes to water are at the heart of the documented and further expected impacts; there’s less of it entering the system overall, but more arriving in torrential bursts, and more saltwater creeping inland from the Bay.
The scope of the research is expansive even for a review article, in part because climate changes aren’t happening in isolation from other threats and habitat impacts. Writing in San Francisco Estuary and Watershed Science, the authors attempt to summarize not only all known research about climate change impacts on several upper estuarine ecosystems, but incorporate examples of impacts on two native fish species, as well as caveats accounting for the compounded impacts of other modern disruptions to the Estuary.
Lead author Bruce Herbold expressed hope that instead of dealing with each subsequent drought, hot spell, and flood “on an emergency-by-emergency basis,” policymakers will shift to anticipating extreme conditions that threaten the Estuary’s ecosystems and species. The authors suggest focusing policy strategies on what the region can control: monitoring, habitat restoration, and to an extent, water flows. The larger issue at hand—the rapid pace of global change—is wisely counted outside the influence of Estuary managers and scientists.
“At the very least,” the paper concludes, “we need to consider our science and management in the context of environmental extremes as the new normal.”
Author: Sierra Garcia | Image courtesy of Bruce Herbold

In spite of the enduring drought, which has drained most of California’s water reserves, a trio of reservoirs in the Sierras remains flush with cold mountain water.

Some environmental advocates are accusing the San Francisco Public Utilities Commission of hoarding the water through an excessively conservative management plan they say harms the environment and benefits almost no one–not even the city dwellers who use the water. Read the story here.

In the absence of a government program to contend with harmful algae blooms (HABs) in the Delta, a loose coalition of academics and environmental and community groups has been studying their spread and potential health impacts both from ground level and from the air.

San Francisco Baykeeper has been sending up drones to monitor eight sites between Discovery Bay and downtown Stockton, as well as photo-documenting the spread and intensity of HABs from airplanes flown by Lighthawk Conservation Flying. At the same time, volunteers with Restore the Delta have been conducting water quality testing for HABs and the toxins they produce.

“The airplane and drones together allow us to get a really broad geographic understanding of where these neon green HABs are occurring, says Baykeeper’s Jon Rosenfield. “That paired with site specific water quality testing that Restore the Delta is doing allows us to get different spatial scales of analysis of this problem.”

These HABs, which Rosenfield says occur during the late-spring and summer in “really wide areas” of the southern Delta, are formed by cyanobacteria that thrive where high temperatures and slow moving water combine with a nutrient-rich environment, and can pump toxins that are dangerous for people and animals into the water—and possibly the air.

Click here to read more and view drone footage.

Author: Cariad Hayes Thronson | Above: A bright green HAB in downtown Stockton. Photo: SF Baykeeper

Researchers are applying a novel genetic technique as part of the development of an annual estimate for the number of juvenile spring-run Chinook salmon entering the Delta.

The technique, spearheaded by geneticist Melinda Baerwald from the California Department of Water Resources, allows researchers to accurately distinguish young spring-run salmon from other runs by targeting DNA sequences specific to these fish.
In a paper published in San Francisco Estuary and Watershed Science, lead authors Baerwald and Peter A. Nelson explain some of the challenges of developing this estimate, called the spring-run juvenile production estimate. A key hurdle is differentiating spring-run fish from salmon that migrate during other seasons. Unlike juvenile salmon from the winter run, spring-run juveniles are hard to identify using the conventional length-at-date approach, which determines age and spawning migration season based on size.
“There’s nothing visually about a spring-run salmon that distinguishes it from a winter-run, fall-run, or late-fall-run salmon,” says Nelson. The spring-run Chinook population is at a historic low, and “the more we know about how this run is doing from one year to the next and across the different tributaries [where they spawn], the better we’ll be able to manage and hopefully bring this particular run back.”
Spring-run salmon have a specific genetic region that can reliably differentiate them from late-migrating (fall-run and late-fall run) salmon. The new genetic assays are based on the gene-editing technique CRISPR; they apply CRISPR’s ability to target unique DNA sequences and combine this with visualization techniques to allow a user to easily determine if a fish has this sequence. Using this method, researchers can identify spring-run salmon within an hour and with 90% accuracy.
Baerwald plans to expand the use of the method to other species, including the Delta smelt, and sees it as a valuable resource given the effects of climate change. “I think this technique provides the best of both worlds in terms of both speed and accuracy,” she says.
Author: Dianna Bautista | Above: Drained island pump stations adjacent to levee walls. Photo courtesy of Christina Richardson.

Light and nutrients are the staples of every phytoplankton production recipe, but wind and tides in the Delta affect phytoplankton production too, say researchers.

Several projects in the lower Sacramento River and Delta have been exploring strategies for increasing the quantity and quality of food for migratory and resident fish. As part of a broader whole-ecosystem experiment that added nitrogen into the Sacramento River Deep Water Ship Channel, Leah K. Lenoch and colleagues at USGS and UC Davis looked into the channel’s hydrodynamics to explore whether the environmental conditions there hold promise for increasing the quantity of phytoplankton (the microscopic algae at the base of the food web). They knew that turbid and well-mixed waterways, including parts of the San Francisco Estuary and Delta, are not very productive because phytoplankton don’t get enough light and are at the mercy of invasive clams. However, where the water column is stratified, phytoplankton can grow in the upper layers, where they are isolated from clam grazing and there is more light. They monitored the channel for 78 days during the summer of 2019 to understand how water mixing (vertical, lateral, and longitudinal) happens in the deepwater channel.
Lenoch and Jon Burau, another author of the study, say they were surprised by how much the wind—which blows in alignment with the Channel—affected the water column. “The channel is a lot more energetic than we thought,” says Burau. Nutrients added to the channel dispersed quickly due to the tidal currents, and wind mixed the water column vertically in an average of just one hour and six minutes. Such quick mixing doesn’t support greater phytoplankton growth before they are plunged into the dark and are eaten by clams. Periods of longer stratification were only observed on five days, when the wind speeds were low which reduced mixing. Burau now wants to study other processes happening in the DWSC, from how the morphology of the channel banks can contribute to fish food to how the organisms living at the bottom of the channel use this artificial habitat. Lenoch highlights that climate change will likely change the DWSC and Delta hydrodynamics, due to warmer days and nights and weaker winds creating more prolonged periods of stratified water and, potentially, more fish food. This only raises another question: will native fish be able to tolerate a warmer Delta?

Author: Pedro Morais | Above: A crop duster plane added nitrogen into the DWSC in August 2019 at the onset of the study. Photo courtesy of Leah E. Lenoch.

The latest plan to replumb the Delta is out, and the eternal debate about sending Sacramento River water south to California’s largest cities and richest farms has resumed.

On July 27, the Department of Water Resources released the Draft Environmental Impact Statement on the plan for a single 45-mile tunnel capable of moving 6,000 cubic feet of water per second. The plan raises myriad questions, some familiar, some new. How should we update old plumbing that is inefficient, hard on fish, and obsolescent in the era of climate change? How much water should continue to be moved? Will the plan make it harder to enact new regulations to protect sensitive species? Environmental historian John Hart has thought long and hard about many of these questions and shares his perspective here.

And elsewhere, to inform the debate with a bit of history, he reviews one hundred years of big plans, little plans, impassioned arguments, improvised solutions, unmet promises, changing attitudes, and ecological decline.

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