SCIENCE NEWS: Eyes reveal life history of fish; California salmon deaths traced to thiamine deficiency; Corralling steelhead at the Carmel River Weir; Climate change will alter the position of the Earth’s tropical rain belt; and more …

Eyes reveal life history of fish

If you look deep into the eyes of a fish, it will tell you its life story.  Scientists from the University of California, Davis, demonstrate that they can use stable isotopic analysis of the eye lenses of freshwater fish — including threatened and endangered salmon — to reveal a fish’s life history and what it ate along the way.  They conducted their study, published today in the journal Methods in Ecology and Evolution, through field-based experiments in California’s Central Valley. The study carries implications for managing floodplains, fish and natural resources; prioritizing habitat restoration efforts; and understanding how landscape disturbances impact fish. … ”  Read more from UC Davis here: Eyes reveal life history of fish 

California salmon deaths traced to thiamine deficiency

The biologists working in a fish hatchery near Shasta Dam grew increasingly concerned last year when newly hatched salmon fry began to act strangely — swimming around and around, in tight, corkscrewing motions, before spiraling to their deaths at the bottom of the tanks.  Certain runs of chinook salmon in California are imperiled; the hatcheries and the fry raised there are the federal government’s last-ditch effort to sustain these ecologically and economically vital fish populations.  So, when scientists observed the young salmon’s screwball behavior, they reached out to their networks in oceanography, ecology and fisheries: Had anyone seen anything similar? Did anybody know what was going on? … ”  Read more from the LA Times here: Something was killing baby salmon. Scientists traced it to a food-web mystery

The ocean’s mysterious vitamin deficiency

Disoriented little fish caught the attention of staff members at the Coleman National Fish Hatchery in Red Bluff, California, in early January 2020. Looking down into the outdoor tanks, called raceways, the facility’s employees noticed that among the dark, olive-colored clouds of live fish, there were occasional slivers of silver from the undersides of tiny fry that were struggling to swim. The fish would roll onto their sides, sink to the bottom for a moment, spring back upright, swim a few strokes, and then roll over again.  Many were dying, too. While a few hundred mortalities daily in a facility containing millions of fish is normal, something was definitely amiss. … ”  Read more from Hakai Magazine here:  The ocean’s mysterious vitamin deficiency

Corralling steelhead: Carmel River Weir

One of the most fundamental challenges for freshwater fisheries biologists in California is monitoring the peaks in migratory fish movement that tend to happen shortly after rains lead to high river flows. More water makes fish passage possible, but also means deeper channels, swift flows, and turbid water, creating a catch-22 in which most fish movement occurs during the times when it is most difficult to detect fish. Fortunately, biologists and managers have a number of tools at their disposal to aid in this challenging task. One such tool is a weir, a kind of fence that spans the river and corrals fish into a passageway where they can be counted or captured and tagged. FISHBIO recently fabricated and installed just such a device on the lower Carmel River to prepare for the upcoming migration season for steelhead (Oncorhynchus species). … ”  Read more from FishBio here:  Corralling steelhead: Carmel River Weir

Tiny travelers and husky homebodies – genes tied to o. mykiss migration may modify growth

“Despite countless studies seeking to determine what makes an individual Oncorhynchus mykiss “decide” to migrate to sea and become a steelhead, or stay in freshwater and become a rainbow trout, the behavior of these fish continues to defy simple explanation. For example, some studies have found O. mykiss that grow most rapidly are more likely to migrate, whereas others have found the exact opposite. These inconsistencies result from the complex, numerous, and interconnected factors affecting migration. Migratory behavior is known to be influenced by genetics, but it’s not certain whether that influence is direct or indirect. In other words, it’s unclear whether an individual inherits genes from its parents that directly dictate its migratory status, or rather inherits genes that code for traits that may in turn play a role in its future life-history trajectory (an indirect relationship). … ”  Read more from FishBio here:  Tiny travelers and husky homebodies – genes tied to o. mykiss migration may modify growth

Genetic resiliency of Elwha River steelhead outlasts dams, new study finds

According to a new study examining the effects of removing dams on Washington’s Elwha River, dams do not impact the genetic diversity of steelhead. The findings indicate that steelhead populations cut off from the ocean by dams can rebound and maintain the same natural genetic diversity as fish populations below dams.  The study published last week in the journal Genes is part of a special issue on salmon and steelhead genetics.  Scientists from NOAA Fisheries’ Northwest Fisheries Science Center analyzed more than 1,200 genetic samples from both steelhead and resident rainbow trout in the Elwha River. … ”  Read more from NOAA here: Genetic resiliency of Elwha River steelhead outlasts dams, new study finds

Stanford researchers develop a new way to forecast beach water quality

Less than two days of water quality sampling at local beaches may be all that’s needed to reduce illnesses among millions of beachgoers every year due to contaminated water, according to new Stanford research. The study, published in Environmental Science & Technology, presents a modeling framework that dependably predicts water quality at beaches after only a day or two of frequent water sampling. The approach, tested in California, could be used to keep tabs on otherwise unmonitored coastal areas, which is key to protecting the well-being of beachgoers and thriving ocean economies worldwide. … ”  Read more from Stanford News here:  Stanford researchers develop a new way to forecast beach water quality

A new era of debris flow experiments in the Oregon woods

Studying the physics of landslide initiation and the dynamics of debris flows is challenging, as these phenomena occur spontaneously, commonly in remote locations, and usually during inclement weather. Those who do this work trudge into the muck not only because the unpredictable natures of natural slope failures and landslide runouts are scientifically interesting in their own right, but also because illuminating these phenomena can help in hazard mitigation efforts. … ”  Read more from EOS here: A new era of debris flow experiments in the Oregon woods

Ocean toxin a heartbreaking threat for sea otters

Heart disease is a killer threat for southern sea otters feasting on domoic acid in their food web, according to a study led by the University of California, Davis.  The study, published in the journal Harmful Algae, examined the relationship between long-term exposure to domoic acid and fatal heart disease in southern sea otters, a threatened marine mammal.  “Sea otters are an amazing indicator of what’s happening in the coastal environment, not just to other marine animals, but to us, too, especially on the issue of domoic acid,” said Christine K. Johnson, director of the EpiCenter for Disease Dynamics in the One Health Institute at the UC Davis School of Veterinary Medicine and senior author of the study.  … ”  Read more from UC Davis here: Ocean toxin a heartbreaking threat for sea otters 

UCI researchers: Climate change will alter the position of the Earth’s tropical rain belt

Future climate change will cause a regionally uneven shifting of the tropical rain belt – a narrow band of heavy precipitation near the equator – according to researchers at the University of California, Irvine and other institutions. This development may threaten food security for billions of people.  In a study published today in Nature Climate Change, the interdisciplinary team of environmental engineers, Earth system scientists and data science experts stressed that not all parts of the tropics will be affected equally. For instance, the rain belt will move north in parts of the Eastern Hemisphere but will move south in areas in the Western Hemisphere. … ”  Read more from UC Irvine here:  UCI researchers: Climate change will alter the position of the Earth’s tropical rain belt

Groundwater runoff is changing the metabolism of the coral reef ecosystem

Submarine groundwater discharge — the flow of fresh water from land through the coastal seafloor into the ocean — is changing the metabolism of coral reef ecosystems, according to California State University, Northridge marine biologist Nyssa Silbiger, which can affect coastal economies around the world.  The findings by Silbiger and her fellow researchers, Megan Donahue with the Hawaii Institute of Marine Biology and Katie Lubarsky with the Scripps Institution of Oceanography, have implications for understanding human impacts on marine ecosystems, as well as informing the decisions of policy makers as they consider coastal development or anticipate the impacts of sea-level rise. … ”  Read more from CSUN here: Groundwater runoff is changing the metabolism of the coral reef ecosystem

Primer on carbon dioxide removal provides vital resource at critical time

Scientists say that any serious plan to address climate change should include carbon dioxide removal (CDR) technologies and policies, which makes the newly launched CDR Primer an especially vital resource, says Berkeley Lab scientist Margaret Torn, one of about three dozen scientists who contributed to this document.  “Atmospheric CO2 concentrations are already 50% over historic natural levels – 270 ppm (parts per million) in pre-industrial times vs 414 ppm today,” said Torn. “To slow climate change and avoid its worst impacts, climate scientists tell us that we need to restore atmospheric CO2 concentrations to about 350 ppm or less. To do that, we need CDR technologies and polices to remove excess CO2 from the atmosphere.” … ”  Read more from Berkeley Labs here: Primer on carbon dioxide removal provides vital resource at critical time

Maven’s XKCD Comic Pick of the Week …

 

 


About Science News and Reports: This weekly feature, posted every Thursday, is a collection of the latest scientific research and reports with a focus on relevant issues to the Delta and to California water, although other issues such as climate change are sometimes included. Do you have an item to be included here? Submissions of relevant research and other materials is welcome. Email Maven

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