Day

August 31, 2022
31
Aug

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...
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31
Aug

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...
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31
Aug

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...
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31
Aug

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...
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31
Aug

Groundwater pumped from subsided islands back into Delta channels through 200 or more active outfalls can be laden with excess nitrogen transported from island soils, report the authors of a new study.

The Sacramento-San Joaquin Delta contains more than 50 peat islands. Most have subsided—some as much as three meters — as a result of drainage for farming, and must maintain artificial water tables below the land surface via managed pumping. According to researchers from the University of California at Santa Cruz and the US Geological Survey, these pump stations are an underappreciated source of nutrients in nearby waters, with potentially significant implications for habitat and water quality.   To get a sense of how much nitrogen is leaving the islands and when, the researchers measured monthly discharge along with nutrient and trace element concentrations in drainage from three Delta islands over the course of nearly a year and a half, then...
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31
Aug

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...
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