October 22-24, 2008, Sacramento Convention Center

It you want to talk to anyone about the Delta at the end of October, you will find them at this conference.

I counted 48 presentations (about 20% of the total) and 40 posters (about 50% of the total) by UC Davis faculty and students.  I think we can say that water quality, aquatic systems, environmental justice and land use and strengths for our campus. 

Climate change has a daylong session. One talk, not one of ours, is entitled, "Sea Level Rise, what is the water engineer to do with all those projections?"  Clearly there are those in regulation who aren't sure what do to with all this research.  Is science-based decision making still the exception rather than the rule?

Applied interdisciplinary research solves environmental problems, but might there be more interpretation of the volumes of data collected over decades of monitoring?  And those of you who read the Sacramento Bee know what that means, more data interpretation to fight over!

 

 

 

 

 

 

Delta smelt are fascinating. Not because they have been listed as threatened for fifteen years, or because they are found only in the San Francisco Bay-Delta, or because their status prompted a federal judge to halt the pumps that transfer water south via the California Aqueduct. Delta smelt are fascinating because they have survived into this century, despite losing the habitat and foods they adapted to over 8,000 years ago. They managed to persist despite being picked off by introduced predators, such as striped bass and the hungry pumps that can reverse river flow and siphon fish into their waterworks from miles away. In spite of all the introduced threats, the elusive smelt can still be found in the Delta’s open water, seeking the salty margins between estuary tides and fresh rivers of Sierra snowmelt. In the few semi-salty regions that remain, a few juveniles are beating the odds for the 150-200 days they need to mature.

Most Delta smelt live about a year, which provides them with advantages and disadvantages for survival. Each new generation presented another opportunity for the smelt to adapt a bit more to its changing environment. On the other hand, a short life means that an abbreviated spawning seasons or peaks in mortality can have a devastating effect on the ability of spawning adults to rebound in subsequent years. The few smelt that survive two years may be part of an evolutionary insurance policy to keep the species viable.

Bill Bennett, Ph.D., researcher at the Center for Watershed Sciences, John Muir Institute of the Environment, found that many of the smelt characteristics were preferrable for studies of pelagic fish in the Delta.  Pelagic fish, which prefer open water, often suffer from drought-related food losses. Bennett came to UC Davis from Boston to complete his doctorate with renowned fish expert Peter Moyle. He investigated the nutritional fitness of striped bass, a pelagic species with a lifespan of twenty years that survives in a wide range of habitats. Compared to bass, smelt have more specific temperature and salinity requirements and a smaller "habitat volume.” Unlike terrestrial species that occupy two dimensional habitats (acres or square miles), fish habitats are expressed in three dimensions, defined by preferred depths. Food is essential to growth, so having more frequent, short-lived generations presents more opportunities to collect study data on the process that fish scientists refer to as “recruitment,” the growth of fish from spawning to maturity.

“In the dynamic ecosystems of the Delta, recruitment during drought conditions presents different challenges than during flood conditions, and each year brings a new scenario in which to observe the smelt adapting to the extensively managed Delta conditions. Since 1999, the most consistent finding is that the smelt decline a bit more each year, in drought years and in flood years.” explained Bennett. “I want to explain why this happens, so future water resource policies can prevent fish extinction while continuing to supply water. If we can keep the smelt healthy, we can apply the lessons learned to keep striped bass and salmon healthy as well.”

When Bennett began his research the early 1990s, the San Francisco Estuary was already in serious trouble. Drought conditions reduced the primary productivity--the growth of plankton that feeds the entire food web. Water exports in drought years reduced fresh water flows to the San Francisco Bay, decreasing nutrients carried by these flows. Lower flows of fresh runoff failed to “flush” pollutants discharged from cities and farms out of the Delta waters. Major declines in phytoplankton (including algae) were attributed to grazing by the overbite clam, first reported in the Delta in 1986. The invasive Asian freshwater clam entered the Delta’s inland waters about the same time. New species of zooplankton (tiny animals called copepods) predominated in Suisun Bay, replacing the established copepods that served as prey for young fish during summers in the Suisun Marsh. The new species of copepods were not easy prey, nor were they thought to be nutritionally equivalent to the smelt’s former diet. These changes and the introduction of invasive plants, such as Brazilian waterweed, that clogged the open waters that pelagic fish require were suspected of contributing to the long-term decline of three of the Delta's pelagic fish: Delta smelt, longfin smelt and striped bass.

The role of the export pumps during low water conditions has been a concern for decades. Drifting embryos, larval fish, and the two to three inch adult smelt, are not protected from pumps by the fish screens. Fish salvage facilities use the screens to entrap and redirect fish away from pumps. They are counted and transported by tanker truck to safer regions in the San Francisco Bay Estuary. But it is unclear how many smelt survive the journey--Bennett suspects that few do.

While scientists were grappling with the ecological mysteries of the transitory food web, salinity variations, increases in waterborne toxins, loss of habitat, and fish salvage stress, Bennett was systematically collecting smelt samples to freeze. After publishing on starvation in striped bass, Bennett and his collaborator Swee Teh, School of Veterinary Medicine, began to apply their methods to Delta smelt. They developed precise methods for using particles from fish ears called otoliths, which is translated as “ear-stones.” Smelt accumulate layers of calcium carbonate on their otoliths that resemble tree rings, one for each day of life. The depth of that layer is a measure of their recruitment.

Bennett suspected that the truth was more complicated than just losses from pumping. Like his colleagues, he didn’t believe that the decline of the once abundant Delta smelt was due to a single cause. He compares his investigation of the physiology and anatomy of Delta smelt to the work of a forensic scientist studying a crime scene, gaining clues and insights into how smelt adapt to change and whether trends in water management will help or hasten their disappearance.

In 2006, Bennett presented a new theory to colleagues in California’s Department of Water Resources Interagency Ecological Program. His hypothesis incorporated a research concept called the “Big Momma theory,” a term coined by Kenny Rose, Louisiana State University. As the name implies, the theory proposes that large females are the most fit, with more eggs of better quality. These females are first to spawn, and may even spawn twice in a season. Bennett speculated that as the pumps pulled higher flows in the winter and pumped less in the spring to protect the smelt during spawning, the smelt’s big mommas were “fished out” by the pumps, selecting for the smaller females that spawn later. This unintended selection mechanism could account for two observed changes in the survivors, a later spawning season and a 20 percent reduction in average length. Bennett’s data from smelt sampled a decade ago support the theory that larvae from large females was more robust.

His data was taken from a fish population that might be changing as fast as scientists can study it. Bennett is passionate about using knowledge gained from Delta smelt to improve the management of all threatened fish. He is encouraged by the increase in funding for science-based evidence, “We are closer than we have even been to understanding the Delta’s ecosystem. I think we are ready to answer some very hard questions. Without a better understanding of the outcomes of past management decisions, we can’t make sound investments in the future.” He plans to publish his findings next year while continuing his search for clues in the case of the missing pelagic fish everywhere.

The half day Delta Smelt "workshop" in Kemper Hall last week was a fascinating look at heroic efforts to save a "vanishing" species. If there are smelt remaining in the Sac-San Joaquin Delta, and a US Fish and Wildlife researcher assured me that there are, they are getting harder to locate. That poses a big problem for research, since you can't study what you can't find. Nonetheless, studies are in progress and waiting for smelt. The UC Davis staff in Byron, California is gearing up to provide larger quantities of smelt for research purposes only. Since UC Davis researchers Joan Lindberg and Bradd Baskerville have been nurturing their "refugial population," they estimate they have provided 70,000 fish for research so far. There are no plans to turn their facility into a smelt "hatchery" for restocking the Delta, they were quick to state that they don't want to be regulated as a hatchery, however as the Delta smelt become more elusive, there is a possibility that the smelt "refugia" might someday be the last and only home for this sensitive species. A "just-in-case" plan has already been spawned for captive breeding, mostly in terms of how the refugia can improve and expand the genetic breeding of this captive population.

Lessons learned about captive species were brought to this forum by Phil Hedrick from Arizona State University. Hedrick was involved in breeding winter run chinook in the Sacrmento River and topminnows from various Arizona springs. Endangered species are known to have frequent inbreeding and less genetic variation than what is desired for ensuring healthy populations in the wild. When fish hatcheries began studying their spawing populations, it was discovered that 41% of the product of one hatchery was from a single female ancestor. After developing a protocol for returning spawners, they were able to improve the genetics of their releases, which is important to keeping the population resistant to disease. By the mid-1990s, it was possible to trace the fish lineage using genetic markers called "microsatellites." The method uses DNA sequences to verify that the crosses made in the breeding program were successful.

Before a captive population can be reintroduced, it has to exhibit "genetic fitness." Since captive breeding often reduces fitness by encouraging captive adaptations, efforts must to be made to preserve the wild adaptions and minimize any new captive adaptions. This is done by starting with a large captive population, minimizing kinship during breeding, and keeping replicate populations as a safeguard. It also helps to breed in a simulated environment that is as close as possible to their natural habitat. The lower the number of generations that are bred in captivity, the less the population can adapt to captivity, and the higher the success of reintroduction. If a captive population is released while there is still a wild population to breed with, the captives might transfer undesireable traits to the wild fish, further weakening them. So as long there are smelt in the Delta, the captive population will be swimming only in circles (meaning in a tank). If the program breeds more fish than needed, they will be allowed to die a natural death, presumably from old age, which for a captive smelt is about two years.

If the worst case scenario for the smelt is realized, who is going to take action? It might be up to the Department of Water Resources, who is bringing in power, back up generators, and major improvements to the smelt breeding facility to shore up the breeding capacity. There are 44 multi-family groups of smelt capable of producing up to 7000 eggs. These will be transferred to the facility once the improvements are completed. A spawning pedigree is being developed for 2009 and more wild fish will be brought in to augment the genetic fitness if permits can be issued for taking these. (No mention of the cost of these extraordinary efforts.) The Bureau of Reclamation is partnering with US Fish and Wildlife to study how the export pump screens can be improved to exclude the smelt, which they hope will eliminate the pumps as one of many causes for the smelt's demise. The smelt might be done in by their preference for a species of zooplankton that no longer predominates, overtaken by an invasive species from the release of ship bilgewater.

If they release captive smelt, would they survive? With limited food due to changes in the Delta ecosystem, the smelt today are smaller than they used to be. You can't release them until they at least learn to feed, and will they know where to hide from predators when the trucks drop them off in Suisun Bay? Once released, it might be impossible to track them and determine their fate. A previous study of larger electronically-tagged fish released near Stockton last summer ended with the expensive fish dead on the river bottom, suspiciously near the waste treatment plant outlet.

If the smelt habitat could be restored, how long might that take? If it takes ten years for the export pumps to retrofit for the smelt,  will the smelt become another aquarium species waiting to get fed at the same time every day?

And what does this have to do with climate change?   If the smelt survive the loss of their favorite food and habitat, and manage to avoid getting sucked into the export pumps, it may be the heat that finally does them in for good after these investments have been made. They have been referred to the environmental community as an "indicator fish", the canary in the coal mine, a warning system for rapid change. One of the last questions asked in the smelt meeting was, "Could you breed a smelt that could survive higher temperatures?" Can you imagine asking, "Can you breed a canary that can live in poison gas in a coal mine?" The fish has already indicated, the sport fisherman have heard the warning and sued for action. Will breeding a more adaptive indicator satisfy the laws protecting this species? In the uncertain Delta, every solution is worth considering, for at least a moment.

Photo courtesy of US Bureau of Reclamation

 

 

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The John Muir Institute of the Environment has been hosting a Speaker Series entitled, Climate Change Solutions and Implementations since January. It is now wrapping up with a panel discussion, May 22, at UC Davis. We have summarized all the presentations into bulleted highlights that you can view on our web site: http://johnmuir.ucdavis.edu/events/climatesolutions.html

Our panel discussion is an attempt to create a "climate change commons" where solutions in common can be identified.

The posters provide the background on the series, and we welcome anyone to post here about these presentations and their relevance to the academic and cooperative extension community.

More later on the final outcomes of the panel.

If there is interest, I would like to add stories about people engaged in  climate change activities  at UC Davis.