E-News WHITEBOARD

Pearls in the ocean of information that our reporters didn’t want you to miss
Vulnerable homes and office parks in San Mateo County.
August 6, 2017
Cariad Hayes Thronson

Simultaneous lawsuits filed against 37 fossil fuel companies by Marin and San Mateo Counties, along with the City of Imperial Beach, over sea level rise may open new front in climate battle.

The suits, filed in California Superior Court, seek compensatory and punitive damages and other remedies for the ongoing harm that oil, gas and coal cause by contributing to global warming and sea level rise. A 2009 Pacific Institute study calculated that San Mateo has more property and people at risk from sea level rise than any California county, while in Marin more than 12,000 homes, businesses and institutions, with an assessed value of $16 billion could be at risk from tides and surge flooding by the end of the century. The suits claim that the companies have known about the dangers posed by greenhouse gases for nearly fifty years and sought to conceal them from the public and encourage the use of fossil fuels while protecting the companies’ own assets and developing plans to profit from a warmer world. According to some legal experts, the suits may succeed where other efforts to hold fossil fuel companies accountable for climate change damage have failed, thanks to advances in climate science and recent revelations about what the companies knew about global warming and when they knew it. CHT

Man’s best friend is being enlisted in efforts to detect the soil-born pathogen responsible for sudden oak death and other rapidly spreading plant and tree diseases.

Phytophthora is difficult to detect in nurseries, plant materials, and planting sites until it has done its damage. To develop early-detection options, H.T. Harvey and Associates are training a female cattle dog/border collie mix named Bolt to sniff out Phytophthora. Part of the Harvey Dog ecological-scent detection program, Bolt has accurately identified four species of Phytophthora in the lab. If her training in a natural setting is successful, Bolt could get to work helping minimize the spread of Phytophthora. Potential beneficiaries would likely include those working to re-oak the parks, open spaces, and backyards of Silicon Valley to improve habitat for native plants and animals.  KMW

Photo: H.T. Harvey

In a paper published in September’s issue of San Francisco Estuary and Watershed Science, a research team proposes that diseases—caused by viruses, bacteria and other microbes—could be suppressing juvenile salmon survival in a river system that once hosted millions of adult spawners each year. According to tracking studies, nearly all juvenile Chinook born from natural spawning die before they reach the Golden Gate Bridge; habitat enhancement efforts have failed to mitigate this mortality rate. Short-term studies of Central Valley salmon have indicated high rates of infectious diseases, which lead author Brendan Lehman of UC Santa Cruz says demonstrates the need for ongoing systemwide monitoring. This could involve sampling fish directly for infections or conducting DNA testing of water samples. A monitoring program might also involve using so-called sentinel fish. Born and raised in the controlled environment of a hatchery, a sentinel fish is temporarily released into the wild, then retrieved and screened for diseases or infections. Lehman notes that pathogens occur naturally in river systems. “But the way we’ve changed their environment can exacerbate the effects on the fish,” Lehman says.
“They don’t represent current operations,” says Ukiah-based consultant Andrew Jahn, lead author of the analysis reported in the September 2020 issue of San Francisco Estuary and Watershed Science. Current operations at the State Water Project (SWP) and the Central Valley Project (CVP) can reverse flows in the Old and Middle rivers, diverting salmon on their way to the ocean towards the projects. Existing salmon loss estimates also fail to account for a likely Old River hotspot for predators, drawn to the influx of salmon and other fish near the two water projects. Evidence of this hotspot lies in the numerous acoustic tags from young salmon to be found in the sediment, which were presumably defecated by striped bass, as well as the fact that it is a popular spot for striped bass fishing. The hotspot is a two-kilometer stretch of Old River between the radial tide gates at the entrance of Clifton Court Forebay, which leads to the SWP, and the trash boom just before the CVP. “The state says ‘our impacts begin at the radial gates’ and federal officials say ‘our impacts being at the trash boom,’ ” Jahn explains. “But you know predators wouldn’t concentrate upstream at the bend...
Historically, most fish passages have been designed to help native salmon return to their upstream habitat and spawning grounds, with little consideration for other migrating species such as sturgeon and lampreys. “There is an assumption that if you just build a fish passage structure, fish will go thorough it, but that is not always the case,” says Department of Water Resources fisheries biologist Zoltan Matica, who conducted the review. “The challenge is to understand that this isn’t only a physical barrier, it can be also a mental barrier.” For example, some species that engage in schooling behavior, such as shad, may refuse to even enter a structure if it limits them to passing one at a time. According to the review, which appears in the September issue of San Francisco Estuary and Watershed Science, other factors that may affect fish passage access include water depth, velocity and turbulence. The key, says Matica, is to take the needs of different species into account from the outset. “You can build a structure that is multi-species friendly in many circumstances,” says Matica.
In a recent study, a team of scientists found that in a dry year, Pacific herring and longfin smelt larvae occurred farther up the Estuary than in a wet year, when spawning and recruitment was pushed seaward. The results suggest that the fish have broader geographic ranges than previously believed, a finding that could inform efforts to manage and protect their habitat. Biologists have long assumed that longfin smelt, a protected species in steep decline for decades, spawn strictly in upper reaches of the Estuary. But by towing a weighted hoop net behind a research vessel during the dry year of 2016 and again in the following year of heavy rainfall, the authors of the new study, published in October’s San Francisco Estuary and Watershed Science, put this assumption to rest. In the wet study year, they captured many larval smelt in the shallows of San Francisco Bay. The small size of the young fish indicated that spawning could not have taken place far away. The scientists saw similar patterns among larvae of Pacific herring. The fish spend most of their lives in the open ocean but spawn in coastal estuaries, and the team’s net surveys produced evidence that in...
As described by US Fish and Wildlife Service fish biologist Brian Mahardja and his co-authors in San Francisco Estuary & Watershed Science, the newcomer is an inch-long, minnow-like fish called the bluefin killifish (Lucania goodei), indigenous to Florida and adjacent southeastern states. It was first detected in the Delta Cross Channel during a beach seine survey in October 2017, and subsequently found in Beaver and Hog sloughs and at Decker, Sherman, and Brannan islands. With surveys curtailed by the coronavirus pandemic, current data is sparse, although 13 were caught before March and one was caught in June. Bluefin killifish are popular in the freshwater aquarium trade, and the authors suspect the founders of the Delta population were released by a former owner near the Sacramento River, which connects with the Delta Cross Channel in summer and fall. “It’s highly likely that the species is established in the Delta,” says Mahardja. Its life history suggests strong potential: it requires fresh water and submerged aquatic vegetation, has survived temperatures as low as 8.9 degrees C (48 degrees F), and is a fecund spawner with a long reproductive season. Climate change may improve the killifish’s overwinter survival, and planned tidal wetland restoration in the...
A team of scientists analyzed 14 survey programs carried out by state and federal agencies, as well as UC Davis, and concluded that employing such a diverse variety of long-term surveys is essential for accurately tracking and assessing the overall health of San Francisco Estuary’s ecosystem and its resident fishes. The research is described in the June issue of San Francisco Estuary and Watershed Science. Lead author Dylan Stompe, of UC Davis, explains that the research arose from concerns that too many people – reporters included – have relied on the results of one annual survey, the California Department of Fish and Wildlife’s Fall Midwater Trawl, to make sweeping conclusions about the health and abundance of several fish species. The trawl, which samples 122 sites in San Pablo Bay and the Delta, has captured fewer and fewer individuals of several species almost every year. This has raised legitimate concern that these fishes, which include Delta smelt and longfin smelt, are nearing extinction. These species have undoubtedly declined dramatically, Stompe says, but when data from multiple surveys are analyzed together, “the story gets more complicated. We still see a long-term decline [in several fish species] but it’s much more muted,” he...
The trait – which cues fish when to spawn based on water temperature – isn’t syncing up with current conditions in the Sacramento River below Shasta Dam. A paper published in the June issue of San Francisco Estuary and Watershed Science, reports that cooler springtime river temperatures seem to prompt earlier winter-run spawning while warmer temperatures push back the peak spawning period by a week or two. Under historic conditions, when winter-run Chinook spawned in high-elevation streams now inaccessible to the fish, their behavioral adaptability would have helped the temperature-sensitive eggs and offspring in two ways—by ensuring “sufficient time for egg maturation in cool years, while secondarily preventing egg and alevin mortality in warm years,” write authors Eva Dusek Jennings, a quantitative ecologist with Cheva Consulting, and Noble Hendrix, a biometrician with QEDA Consulting. Excessively cold water significantly slows egg development, Jennings explains in an interview, while water much warmer than 56 degrees F will kill the eggs. But the winter-run Chinook no longer spawn in the river system in which they evolved: Shasta Dam forces them to spawn in the sun-baked Central Valley. The dam, and how it’s operated, has also reversed water temperature patterns during the summer spawning season. River water downstream...
That’s one key takeaway from a review of environmental management and the use of science during the 2012-2016 drought commissioned by the Delta Science Program and published in the June 2020 issue of San Francisco Estuary and Watershed Science. “There are lots of mysteries about how to manage water to benefit species, agriculture, upstream and downstream users. I think science is going to be the best solution,” says lead author John Durand of UC Davis’ Center for Watershed Science. Durand and his team based their review on available reports and data, as well as discussions with agency staff, stakeholders and researchers. They focused on water management actions during the drought through the lens of four priorities identified by water managers: public health and safety, saltwater intrusion control, preservation of cold water in Shasta Reservoir, and protections for endangered species. “We’re really in sort of a brave new world of droughts,” says Durand, noting that water managers face new challenges as climate change creates more weather extremes. Durand believes that broad, ecosystem-level experiments that include predictions about, and monitoring the effects of, water releases from reservoirs, can provide needed guidance to water managers. He says his team’s research revealed a surprising—and disturbing—lack...
Hydrogeologist Fadji Maina and colleague Erica Siirila-Woodburn of the Lawrence Berkeley National Laboratory ran simulations of wildfire effects in the Cosumnes River watershed (see map). “We chose the Cosumnes because it’s one of the largest rivers that has no dam in California,” explains Maina. The most significant findings concerned the way wildfire affects groundwater recharge and storage. “It depends on where the wildfire occurs,” says Maina. The underlying rocks—foothill volcanics or High Sierra granites—make a difference. Consistent with earlier studies, the model also showed more snow accumulation after wildfire, but unexpected results include a post-fire increase in evapotranspiration in some downslope areas. Another study focused on the effects of forest thinning on snowpack on the west side of Lake Tahoe. A team led by University of Nevada, Reno ecohydrology professor Adrian Harpold used lidar (three-dimensional radar) to map a patch of forest, then simulated how removing trees of different heights affects snowpack accumulation and melt. “In forest that’s more dense relative to height, results show that taking out some of the smaller trees really can show a net benefit to the amount of snowmelt,” Harpold says. Effects of thinning vary with elevation and which way a slope faces, but thinning appears to have the greatest...

REBALANCING THE BAY

Former Chronicle reporter Jane Kay spent a year exploring the San Francisco Bay’s 1,000-mile shoreline, focusing on efforts to restore the balance of the bay she loves. She reports that the rising seas and intensified storm surges of climate change may be mitigated by natural buffers, including tidal marsh from reclaimed hayfields and commercial salt ponds as well as restored eelgrass and oyster reefs in subtidal zones. Kay also highlights the ecological role of freshwater flowing though Delta, which benefits species in the Estuary and helps flush treated sewage out of the South Bay. Her story was posted by National Geographic on June 13, 2017. Photo by Ariel Okamoto.

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