A new system for treating agricultural drainage water in the Delta could also help rebuild subsided islands.

A new system for treating agricultural drainage water in the Delta could also help rebuild subsided islands.

The approach—known as a Chemically Enhanced Treatment Wetland—combines chemical treatment with natural wetland processes; researchers tested it on Twitchell Island, which features corn and rice crops, as well as wetlands. They dosed agricultural ditch water with dissolved organic material (DOM), then treated it with a coagulant to precipitate the DOM, forming flocculant. The resulting water then passed though treatment wetlands, where the flocculant settled and blended with plant detritus in the sediment. The study, reported in the September 2019 San...
Read More

Manmade features in the Delta, including riprap-armored banks, water diversion pipes, pilings, and woody debris, may be sending juvenile native fishes into the jaws of finned invaders.

“We know from a decade of doing survival studies that migrating juvenile salmon are dropping out of the system pretty much everywhere in the Delta,” says UC Santa Cruz fisheries biologist Brendan Lehman. “Physical habitat features are potentially aggregating predators and prey in ways detrimental to salmon smolts and steelhead.” The scientists report in the December 2019 San Francisco Estuary and Watershed Science that artificial light and submerged aquatic vegetation pose the most severe and widespread risks to native fishes....
Read More

Levels of pyrethroid insecticides spike sharply in the North Delta’s Cache Slough during winter rainstorms, rendering the water so toxic that it decimates laboratory populations of a half-inch crustacean called Hyalella azteca.

However, according to a study reported in the September 2019 San Francisco Estuary and Watershed Science, Hyalella collected in the wild from Cache Slough are resistant to pyrethroids. Genetic analysis revealed that, collectively, Hyalella in the slough have four mutations for pyrethroid resistance. They also have a fifth mutation for resistance to organophosphates and likely carbamates, two additional major classes of pesticides that are applied extensively on agricultural and urban lands. “Hyalella are special,” explains co-author Helen Poynton, a molecular...
Read More

Researchers hope new computer models will help clarify the effects of entrainment on the population of endangered Delta smelt.

Entrainment at the South Delta pumps of the State Water Project and the Central Valley Project has been a concern for years, but disentangling its impact on the dwindling smelt population from those of other environmental and water management factors isn’t easy, and operational differences between the SWP and CVP facilities complicate analysis. Now, US Fish and Wildlife Service statistician Will Smith has developed computer models for entrainment effects on different smelt life stages, part of a larger Delta Smelt...
Read More

While the acreage of wetland restoration projects is growing throughout the Delta, scientists are still working to understand how best to help these areas become fully functioning, complex habitat as quickly and successfully as possible.

A study published in September’s San Francisco Estuary and Watershed Science shed light on some essential questions about what triggers seed generation in wetland habitat. “Wetland restoration practices can be enhanced by a solid understanding of basic plant life history and species ecology,” says co-author Taylor Sloey of Yale-NUS College in Singapore. The researchers looked at three questions: what seeds are present in the seed bank (the viable seeds that accumulate naturally in the soil), and how exposure to cold...
Read More

A recent test found more than 250 chemicals in the Delta’s Cache Slough, but “Dr Doom” says figuring out what they all are, and their concentrations, is beside the point in our efforts to understand stressors on native fish resilience.

“Knowing the effect on the fish is more informative than knowing which chemicals may be causing it,” says UC Davis’ Richard Connon (whose colleagues gave him his sinister title), referring to taking an ecological rather than regulatory perspective on fish health, and also to the less obvious sublethal effects of contaminants on fish behavior and reproduction. Connon is the lead author of a wide-ranging journal article in the December 2019 issue of SFEWS on how to better focus contaminants research...
Read More

Speakers discuss forward-looking science in a rapidly changing environment, and the neuroscience of persuading people to care about climate change.

Climate Change Planning Mark Gold made the ultimate comment in his opening plenary at the State of the Estuary Conference: “The age of incrementalism, and not moving forward in a bold way, is not getting it done in terms of climate change.” Gold, deputy secretary for ocean and coastal policy for the California Natural Resources Agency, outlined the state’s newly revised strategic plan for a bluer economy, coastal resilience, and rapid response to fisheries emergencies. Following his talk, Geeta Persad...
Read More

Not So Picky Marsh Mouse

The endangered salt marsh harvest mouse (informally “Salty”) is a poster child for tidal marsh restoration in San Francisco Bay. But recent research, presented by University of California at Davis postdoc Katie Smith in a State of the Estuary conference session on tidal wetlands, suggests we’ve misinterpreted what the mouse needs. “It’s been managed as a habitat specialist,” she said, based on assumptions that it requires tidal wetlands and a diet of pickleweed. However, hours of mouse-tracking around the Bay...
Read More

Speakers discuss issues facing Estuary wildlife and their wetland habitats, as well as drones and other new tools that will help future management.

Fish and Wildlife Check-up State of the Estuary Conference presentations featuring decades of data on fish, ducks, seabirds, and cetaceans revealed both hopeful and alarming trends. “The loss of federal funding for the midwinter waterfowl survey, usually conducted using small aircraft, has researchers looking at drone-based alternatives,” said waterfowl biologist Susan De La Cruz of the US Geological Survey. The overall community condition of the Estuary’s fish (abundance, distribution, diversity, proportion of native to non-native species) has declined, reported the...
Read More

Drones Pilot Vegetation Mapping

By Michael Hunter Adamson In the world of conservation, as attested to by multiple speakers at a late summer UC Davis event, drones, or UAVs (unmanned aerial vehicles) may be the vehicle of choice for mapping the future of invasive plant management in the Delta. The California Department of Water Resources began using UAVs in earnest after the Oroville dam failure in the winter of 2017, when drones offered visuals no one could get near on the ground. The Blacklock...
Read More

Invasive clams and freshwater exports from the Delta have created dramatic and unsustainable changes in the San Francisco Estuary’s foodweb over the past 50 years.

 A study by UC Davis researchers found a 97% decline in phytoplankton, the microscopic foundation of the food chain. “Understanding the causes for the decline in the pelagic [water column] community is essential so that efficient solutions can be implemented,” says Bruce Hammock, a research scientist at the UC Davis School of Veterinary Medicine’s Aquatic Health Program. The invasive clams (Potamocorbula amurensis), originally from Asia, have been over-consuming phytoplankton and zooplankton for more than 30 years, and have long been...
Read More

New shoreline strategies piloted in Puget Sound could help young fish in urbanized estuaries elsewhere.

When Seattle rebuilt its seawall in 2017, they hoped to make the hardened shoreline a little less daunting for the young salmon that hug it closely on their journey to the ocean. Project managers took a three-pronged approach. First, they added texture and complexity into the new concrete seawall to encourage invertebrates, food for the young fish, to settle in nooks and crannies and on horizontal “shelves” built into the wall. Mussels, ecosystem engineers, have settled on the shelves and...
Read More

Tailing a Thrush

By Joe Eaton Researchers like Point Blue Conservation Science ecologist Tom Gardali have equipped Swainson’s thrushes, weighing just over an ounce, with tiny, one-gram GPS tags. If recovered, the tag shows the thrush’s exact winter destination, information vital to border-crossing conservation efforts. “You only get a few readings,” says Gardali, “and you still need to get the tag back. But GPS goes to a spot on the map. This is Holy Grail stuff.”  Sierra/Cascade thrushes were presumed to migrate to...
Read More

Louise Conrad sees the Delta Stewardship Council’s science program, which she now leads, as poised to shift into a new gear – from breaking down the science landscape and building a new foundation for Delta science to actually doing it.

 “With the update of the Delta science plan done, we can now can sink our teeth into some topical issues our scientists can be passionate about, such as aquatic invasive vegetation, microcystis and climate change, for example,” says the former Department of Water Resources (DWR) fish biologist. Conrad grew up in Philadelphia and developed an interest in conservation on summer road trips to western national parks in their family’s Dodge Ram. “My mom sewed us individual seat covers with pockets...
Read More

A marriage of robotics and artificial intelligence promises to automate the detection of harmful algal blooms, which can trigger shellfish harvesting bans and fill wildlife rescue centers with sickened animals.

The Imaging FlowCytobot (IFCB) takes water samples around the clock and photographs phytoplankton cells floating within. “It’s got a huge amount of potential for figuring out what plankton is in the water column and monitoring for HABs,” says Alexis Fischer, a postdoctoral fellow at the University of California, Santa Cruz with Raphael Kudela. Fischer and colleagues are building a phytoplankton image classifier already capable of identifying more than 90 percent of cells photographed by IFCB at the Santa Cruz Wharf. The...
Read More

Sleuthing Sturgeon Snags

Local green sturgeon are struggling. The population that spawns in the Sacramento –San Joaquin River Delta was declared federally threatened in 2006. Researchers at UC Davis, which hosts the world’s only green sturgeon rearing program, are now trying to figure out why the fish is in trouble. “If we knew how large they are when they’re moving through each portion of the system, we’d know a lot more about the threats they face at each life state, and where we...
Read More

Recent discoveries are promising new weapons against red tides, the massive blooms of microscopic marine algae that are notorious for playing havoc with marine ecosystems.

The culprit behind poisoned seabirds, closed crab fisheries, stranded sea lions, and shellfish poisoning in humans are often diatoms producing the neurotoxin domoic acid. Now, scientists have identified the genes and biochemical processes responsible in diatoms of the genus Pseudo-nitzschia. The finding, published in the journal Science, opens the door to rapid genetic monitoring of algal blooms as a means to spot nascent harmful blooms and track their spread. “By identifying the genes that encode domoic acid production, we are...
Read More

Floods and droughts can cause pools and riffles—and the bugs that live in them—to become more homogenous.

For years, scientists monitoring water quality in streams and rivers have collected mixed samples of aquatic invertebrates from riffles, pools, and transition zones. But UC Santa Barbara stream ecologist David Herbst and his colleagues recently finished a 15-year study of the benthic life in small streams of the central Sierra that examined pools and riffles separately. They found that during flood and drought events, these habitats and their inhabitants become more uniform. But while floods come and go, droughts can...
Read More

MEGA-PEARLS, Oct 2018

A Stream of Science Takeaways. ESTUARY News sent reporters to the biennial Bay-Delta Science Conference in September. This special edition of Pearls shares more than 20 takeaways.
Read More

SF State Launches New Floating Sentinel

Two banana-yellow buoys anchored along the Tiburon shore will be San Francisco Bay’s sentinels against shifts in water chemistry due to climate change. Known as the Bay Ocean Buoy (BOB) and the Marine Acidification Research Inquiry (MARI), the permanent moorings will provide long-term monitoring of acidity and carbon dioxide levels—key indicators of how the changing ocean will impact Bay chemistry. “It’s taken over three years of perseverance and partnership building to get these instruments into the water, but now we’ll...
Read More
1 2