Final Report: Restoring and Sustaining the Salton Sea: Supporting Science and Environmental Data Collection and Analysis

EPA Grant Number: R826552
Title: Restoring and Sustaining the Salton Sea: Supporting Science and Environmental Data Collection and Analysis
Investigators: Kirk, Tom
Institution: Salton Sea Authority
EPA Project Officer: Packard, Benjamin H
Project Period: September 30, 1998 through September 30, 2003
Project Amount: $4,875,000
RFA: Water and Watersheds (1998) RFA Text |  Recipients Lists
Research Category: Water , Water and Watersheds

Objective:

The overall goal of this research project was to satisfy and sustain several major values and uses of the Salton Sea. Sound judgments are required to assure that all of these needs are retained in a manner consistent with the values of the local community and society in general. The primary values to be served by the scientific and other activities undertaken in this project are listed below.

Provide a Safe, Productive Environment for Resident and Migratory Birds and Endangered Species. Five endangered species are found in the Salton Sea. The Salton Sea also is a critical component of the Pacific Flyway, serving as a winter habitat for millions of waterbirds and as a breeding area for several species. This role of the Sea has increased in importance during the past quarter century because of a loss of wetland habitat within the Flyway and specifically within California, but has become compromised by avian mortality events and perhaps other impacts on avian health.

Maintenance of a Viable Fishery. The fishery of the Sea has been of significant recreational and economic value. Salt tolerant species such as sargo, orangemouth corvina, and tilapia (Oreochromis mossambicus) have provided a sport fishery of great interest within Southern California. Little was known of the reproductive biology and population dynamics of these species within the Sea prior to work funded under this project. Unchecked levels of salinity are expected to impact reproduction of these species, and it is generally accepted that the Sea is reaching a level at which some species will be adversely affected.

Restoration of Recreation. Water-based recreation has been a major use of the Sea in the past. Although it is uncertain what has made the Sea undesirable as a recreational destination, it is probable that nuisance factors, such as odor, dead fish, dead birds, and algal blooms are major reasons. Research has been conducted to better understand the reasons why water-based recreation has declined and the factors that need to be addressed in the restoration effort of the Sea.

Agricultural Drainage Reservoir. Agriculture constitutes the major economic base in Imperial County and a significant economy in Riverside County. Because of the importance of drainage to maintenance of the agricultural economy and the lack of an alternative disposal site, the Sea has served as the repository for agricultural drainage. Agriculture in its present form relies on the ability to discharge drainage into the Salton Sea, and the Sea is dependent on this drainage as a buffer against accelerated rates of increased salinity and drying up because of the hot desert environment. Agricultural drainage has sustained the Sea for 90 years. This water drainage includes nutrients and other constituents that affect water quality within the Sea. Studies supported by this project have helped to define the limnology of the Sea and the factors influencing the ecological relations involved.

Economic Development. Economic activity surrounding the Sea has been in a depressed state for several years. Because many of the businesses depend on revenue from visitors to the area, the decline in visitation has had a direct impact on business success. Activities to clean up the Sea and restimulate economic growth require a sound scientific basis to avoid undesirable environmental impacts.

Although "saving the Sea" is the ultimate objective, the specific objectives of this project were to: (1) provide resources to undertake syntheses and evaluations of existing scientific information; and (2) initiate and conduct the highest priority research needed to inform the selection and evaluation processes associated with developing sustainable environmental conditions at the Salton Sea that support the values identified above.

The information synthesis, evaluations, and research funded by this project were to provide scientific assessments and recommendations required to inform the entire planning/environmental compliance process toward sound conclusions regarding management alternatives for the Sea. The research activities funded were to help determine and fill information gaps.

Summary/Accomplishments (Outputs/Outcomes):

Following receipt of this assistance grant, requests for proposals (RFPs) to conduct reconnaissance investigations of the Salton Sea were issued to solicit potential contractors. Studies of the Sea's fishery, biological limnology, algal toxins, microbial pathogens, chemical and physical limnology, sediments, and birds were funded during 1998-1999. These reconnaissance investigations were completed during the 2000-2001 reporting period, and final reports have been received from all of these studies. Additional studies were funded through solicitations for proposals prepared by the Science Subcommittee in late 1999, and later by the Science Office. These projects are completed or are still in the process of being completed (project completion date is September 2003). Progress and/or final reports have been received.

The following subprojects were initiated in early 1999 as 1-year reconnaissance subprojects. They were completed by early 2000. All of these subproject teams have submitted their final reports.

Salton Sea Fishery

Dr. Barry Costa-Pierce, a world-renowned expert on tilapia from the University of Southern Mississippi Institute of Marine Science, studied the Salton Sea fishery. His group sampled the Sea's fish population at stations in the middle of the Sea, at the mouths of the Alamo and New Rivers, and along the shoreline. The findings from this subproject include:

• The population of fish with highest biomass was that of tilapia, followed by the gulf croaker (Bardiella icistia), orangemouth corvina, and sargo.

• Data on the age structure showed that the population of tilapia mostly consisted of the 1995 year class. Gulf croaker and corvina years 0-4 were well represented, and years 0-2 sargo were present.

• No significant instances of fish deformities were observed, lending supporting evidence that the Sea’s fish community was healthy.

• The near shore and river mouth habitats were the preferred location for fish feeding and reproduction. Those habitats were especially important during the summer as refugia from low oxygen and high temperature.

• Salton Sea tilapia growth was the fastest among conspecifics from other locations. The gulf croaker and orangemouth corvina appeared to be in better condition now than decades ago. There also is some evidence that sargos grow at a faster rate along the Pacific Coast of southern California.

San Diego State University Biological Limnology

This subproject explored the Sea's biological components and their interactions, and it complements the Bureau of Reclamation's chemical and physical study of the Sea. This subproject built on San Diego State University's (SDSU) independent investigations at the Sea, conducted under the direction of Dr. Stuart Hurlbert, Director of the Center of Inland Waters. These studies have demonstrated a more complex and dynamic biological component of the Sea's ecosystem than previously recognized. The findings of this subproject include:

• Limnology of the Salton Sea was surveyed during 1997-1999.

• The biotic inventory revealed about 300 species previously unreported for the Salton Sea and many species that appear to be new to science.

• The metazoan community is not diverse, but new species were found.

• The pileworm (Neanthes succinea) was the most dominant macroinvertebrate on the bottom at depths of 2-12 meters. There is evidence of a decline in pileworm abundance over the last several decades.

• The rocky shoreline had the highest numbers of benthic invertebrates per unit area.

• Dinoflagellates, diatoms, and raphidophytes dominated the phytoplankton. Species composition has changed since the 1950s.

• Zooplankton abundance was highest in the summer following late winter/early spring phytoplankton blooms.

• The surveys show that large changes have taken place in the ecology of the Salton Sea since the 1950s and 1960s.

U.S. Bureau of Reclamation Chemical and Physical Limnology of the Sea

Scientists from the Ecological Research and Investigations Group investigated the chemical and physical conditions of the Sea by gathering information on chemical and physical profiles, light penetration, and nutrients. Samples were taken monthly from January to March and October to December, and biweekly from April to September of 1999. Samples were collected at three sites on the Sea and from sampling points slightly upstream of the inflows of the New, Alamo, and Whitewater Rivers—the Sea's three main tributaries. Sampling on the Sea included measurements at various depths from surface to bottom to investigate the extent and nature of vertical stratification. In addition, concentrations of major ions were measured in February, May, August, October, and December, and trace metals and organic compounds (semivolatile organic compounds [SVOCS] and chlorinated pesticides) were measured in March and October of 1999.

Dissolved oxygen (DO) levels in the Salton Sea are characteristic of a highly eutrophic system. Surface oxygen levels often were greater than 200 percent of saturation, and some oxygen depletion was observed in the bottom waters of the Salton Sea throughout the year. Hypolimnetic DO concentrations often were severely depleted, with observed concentrations at the lake bottom usually less than 2 mg/L from April through November. DO levels in the rivers also exhibited oxygen depletion, with DO concentrations averaging 77.3, 66.2, and 73.2 percent of saturation in the Alamo, New, and Whitewater Rivers, respectively.

Nutrient ratios indicate that algal growth in the Sea should be phosphorus limited. As a result, management efforts to control eutrophication should focus on phosphorus removal.

Ammonia levels in the Salton Sea exceed water quality standards. It is possible that relatively high concentrations of unionized ammonia represent another stress to fish in the Salton Sea, in addition to the high temperature and low DO associated with algal blooms, and may be contributing to the observed fishkills.

Concentrations of nearly all major ions are higher in the Sea than in the rivers. The most soluble ions, sodium, potassium, and chloride, are enriched in the Sea by factors of 25 to 30 more than river concentrations. Magnesium concentrations are about 17 times as high in the Sea compared to the rivers, and sulfate concentrations are 14 times as high. Trace metal concentrations were all low and were lower in the Sea than in the rivers. This is not surprising because of the high concentrations of sulfide in the Salton Sea and the low solubility of most heavy metal sulfides. The findings from this subproject include:

• DO levels in the Salton Sea are characteristic of a highly eutrophic system.

• DO levels in the rivers also exhibited oxygen depletion.

• Nutrient ratios indicate that algal growth in the Sea should be phosphorus limited.

• Ammonia levels in the Salton Sea exceed water quality standards, thus representing another stress to fish in the Salton Sea.

• Concentrations of nearly all major ions are higher in the Sea than in the rivers.

• All trace metal concentrations were low, and they were lower in the Sea than in the rivers.

Levine-Fricke-Recon Sediment Subproject

This project was the first reconnaissance subproject completed, and it was managed by Douglas Lipton, Ph.D., and Richard Vogl. Samples taken from the Sea were analyzed for metals, volatile organic compounds (VOCs), SVOCs, and agricultural chemicals and their residues. The distribution of these compounds within the Sea was mapped, along with such characteristics as the distribution of silt, sand, and clay, based on sediment size. Polychlorinated biphenyls, pesticides, herbicides, and other SVOCs in Sea sediment were less than the analytical detection levels. A limited number of VOCs were detected at the Sea, mostly in the northern areas. Also, the elevated concentrations of metals and selenium are primarily localized in the northern half of the Sea. The findings of this subproject include:

• Only a limited number of VOCs were detected at the Sea, mostly in the northern areas.

• Elevated concentrations of metals and selenium are primarily localized in the northern half of the Sea.

Point Reyes Bird Observatory Bird Subproject at the Salton Sea

This subproject documented population sizes, seasonal abundance, and habitat associations for the key groups of birds in the Salton Sea area. A suite of surveys, each tailored to a group of bird species, documented such groups as shorebirds, waterfowl, and passerines. Studies focused on all bird species, including species that were listed as threatened or endangered or of management concern by the state and federal governments, as well as species that have been heavily affected by recent dieoffs. The importance of different habitats for birds was measured by evaluating species richness, distribution, and abundance. The Salton Sea hosts hundreds of thousands, and at times low millions, of migratory, wintering, and breeding birds. Birds found at the Salton Sea come from many different areas in North America, including many postbreeding waterbirds from Mexico. Salton Sea populations of a number of species are of regional, continental, or worldwide importance. The findings of this subproject include:

• The Salton Sea hosts hundreds of thousands, and at times low millions, of migratory, wintering, and breeding birds.

• Birds found at the Salton Sea come from many different areas in North America, including many postbreeding waterbirds from Mexico.

U.S. Geological Survey (USGS) National Wildlife Health Center—Survey of Selected Microbial Pathogens

Drs. Tonie Rocke and Mark Wolcott, along with staff in Madison, WI, looked for avian botulism toxin production within the Sea, along with some common human and wildlife pathogens, including Salmonella. Samples were taken from both water and sediment, and the analyses included both routine microbiological culture and advanced molecular biology techniques. Botulinium toxin activity was detected in abiotic samples, and geographic locations for those samples were entered into the database. No significant human pathogens were detected among the bacteria isolated from water and sediment samples. Microcystin hepatotoxins can be produced by two genera of blue-green algae—filamentous Oscillatoria and unicellular Synechocystis—that have been found to be common in the Salton Sea. Certain Oscillatoria species also are known to produce neurotoxins.

Scripps Institution of Oceanography—Survey of Algal Toxins in the Salton Sea

Dr. John Faulkner of the Scripps Institution of Oceanography investigated whether or not toxins from algae were in water and in benthic invertebrates at the Salton Sea. Samples for algal toxins were collected and analyzed. Analytical results have disclosed the presence of toxins, which have been further analyzed and evaluated for their toxicity to fish and birds in a follow-up project.

The objective of this subproject was to determine if and when algal toxins are present in the water and benthic invertebrates at the Salton Sea. The work supported studies on the causes of eared grebe mortality. The findings of this subproject include:

• Samples of water and pileworms were analyzed for toxic algae.

• Water samples showed considerable variation, but some contained toxic algae.

• No exceptional toxic algal blooms occurred during the time samples taken.

• Some samples of pileworms showed moderate toxicity.

• Results did not support the hypothesis that algal toxins were contributing to the mortality of eared grebes.

Additional Studies

These studies were initiated in 1999 by the Science Subcommittee and later by the Science Office to provide information not covered by the initial set of reconnaissance projects. These were scheduled for completion in approximately 1 to 3 years from the date of initial funding.

U.S. Bureau of Reclamation Desert Pupfish Subproject at the Salton Sea

This subproject, coordinated by Dr. Ron Sutton, documented analysis of spatial and temporal movements, habitat information, feeding, and spawning. The desert pupfish (Cyprinodon macularius) is a federally listed endangered species. It is the only fish species endemic to the Salton Sea. Recently, extreme variability in catch numbers suggests that desert pupfish move among habitats, possibly using the Salton Sea as a corridor to allow mixing of the gene pool. Movement behavior of desert pupfish was evaluated among these various habitat types. Irrigation drains, shoreline pools, and Salt Creek were sampled six times during the summer of 1999. Collected pupfish were marked using fluorescent elastomer implants. Unique markings were used for each site. Tilapia dominated the catches in all habitats except Salt Creek, where desert pupfish were most abundant. Desert pupfish were found in 10 of the 12 sites sampled. The marking technique was successful, and it showed promise for future mark and recapture studies of desert pupfish, including population estimates. Of the 3,239 pupfish captured during the subproject, 278 were recaptures, including 27 recaptures at areas different from where they were initially marked. The best evidence of desert pupfish movements was in the southwestern area of the Salton Sea between an irrigation drain and a connected shoreline pool. Because the shoreline pool was always open to the Salton Sea, there was a good probability that some pupfish moved into other habitats via the Salton Sea. Movements also were detected between Salt Creek and a connected shoreline pool. The findings of this subproject include:

• The marking technique utilized in this study was successful, and it showed promise for future mark and recapture studies of desert pupfish, including population estimates.

• There was significant evidence of desert pupfish movements between an irrigation drain and a connected shoreline pool, and between Salt Creek and a connected shoreline pool.

• There is a good probability that some pupfish moved into other habitats via the Salton Sea.

University of California at Riverside (UCR), Nutrient Cycling in the Salton Sea

This subproject (Principal Investigators: Michael Anderson and Chris Amrhein) was initiated in April 2000 to provide additional information about nutrient cycling and internal loading from the sediments. The Salton Sea has been plagued by increasing salinity, algal blooms, low DO concentrations, odors, and frequent fishkills. Restoration of the Salton Sea requires both salinity and nutrient control. The findings of this subproject include:

• Peepers placed in the sediments demonstrated substantial differences in the sediment porewater chemistry as compared with the overlying water column.

• Alkalinity, NH4-N (ammonium), soluble reactive phosphorus, and sulfide concentrations all increased markedly over the 5-15 cm depth interval within the sediments. Alkalinity and sulfide concentrations reached about 30 meq/L and 3 mM, respectively, while sulfate concentrations decreased by about 50 percent. These changes in porewater chemistry are attributed to biological sulfate reduction reactions within the sediments. The gradient in concentration between the porewater and water column provides the driving force for diffusive flux of nutrients and other constituents across the sediment-water interface.

• Using the internal loading and sediment trap results, combined with estimates of external loading of nutrients based on stream flow and nutrient concentrations and atmospheric deposition, nitrogen and phosphorus budgets for 2000-2001 were developed. The rate of nitrogen and phosphorus released from the sediments via mineralization and other reactions normalized against their rate of deposition demonstrated that phosphorus is sequestered in the sediments more effectively than nitrogen.

• Laboratory studies confirmed that coprecipitation of phosphorus with calcium carbonate (calcite) is the major mechanism of phosphorus sequestration within the Sea. Calcite formation within the sediments is a biogeochemical process that is accelerated within the sediments because of sulfate reduction reactions.

• Sedimentation was the primary removal process for nitrogen from the water column, accounting for 69 percent of the loss. Approximately 30 percent of the total nitrogen lost from the Sea was via ammonia volatilization. Denitrification appears to be relatively less important in the Sea when compared with other freshwater and estuarine environments.

• Reductions in external nutrient loading will lead to improved water quality in the Sea, although internal loading will continue to maintain relatively high levels of productivity until biogeochemical sequestration of phosphorus adequately lowers internal loading rates.

University of Southern Mississippi Tilapia Feeding

This subproject (Principal Investigator: Barry Costa-Pierce) was initiated to examine tilapia food habits to assess linkages among tilapia, avian botulism, and pelican mortality.

Tilapia gastrointestinal material was sampled at five stations to assess feeding preferences. Stomachs were significantly more acidic during mid-afternoon, indicating more active feeding during the day. Eleven animal taxa were identified from stomach contents. Rotifers were dominant during the spring and summer; copepods were dominant during the fall; and barnacle larvae were dominant during the winter. Pileworms were present throughout the year, and were likely the most important food item for tilapia. Proportions of plant material in stomachs were different through time; a lower proportion of macrophyte plant material was found during the evening and night. The proportion of macrophyte plant material in fish stomachs was higher at the river mouth areas. Diatoms dominated the phytoplankton in the stomach and overall plankton component. There was no evidence of a diel pattern in feeding activity, intestinal color and stomach acidity, or feeding selectivity. Tilapia foraging location in the water column was investigated to assess feeding behavior. Foraging location was a function of DO. Fish foraged at the surface during the summer when DO was low, and spent most time at the bottom during the other seasons. The findings of this subproject include:

• Feeding is less active in the summer, when DO is low.

• During the summer, the oxygen-rich rivers act as refugia by also providing extra food from macrophytes.

• Pileworms are the major food item for tilapia.

U.S. Geological Survey, Avian Botulism

This subproject (Principal Investigator: Tonie Rocke) continues until September 2003. It investigated the ecology and management of avian botulism, including: (1) a determination of the links between fish-eating birds and environmental factors; (2) an evaluation of the potential risk of type E botulism; (3) an evaluation of the risk of botulism in birds other than pelicans and in fresh water areas near the Sea; and (4) the development and testing of potential methods for controlling botulism at the Sea.

The epizootiology of avian botulism in fish-eating birds at the Salton Sea is very unique, and appears to be closely tied to tilapia, an introduced fish species exotic to North America. Other fish, such as Gulf croakers, also may be peripherally involved. Using novel molecular assays that we developed for this subproject, we have determined that live fish routinely harbor type C toxin-producing cells in their gastrointestinal tracts, and the prevalence of the bacteria in fish varies between years. During the years of our subproject (1999-2001), live fish were as likely to harbor toxin-producing cells as sick or freshly dead fish. Also, prevalence in fish reflected the levels of disease occurrence in pelicans during these years.

We have found evidence that type E toxin-producing cells are present in both the sediments of the Salton Sea and in tilapia. Although their distribution around the Sea was similar to type C, their seasonal prevalence in 1999 was very different, peaking several months later. Although only a single bird has been diagnosed with type E botulism at the Sea in the past, we believe the disease may have occurred more frequently, and may have been missed. Because humans are susceptible to type E toxin, the presence of type E toxin-producing cells in Salton Sea sediments and fish should be noted by public health officials. The findings of this subproject include:

• The epizootiology of avian botulism in fish-eating birds at the Salton Sea is very unique, and appears to be closely tied to tilapia (O. mossambicus), an introduced fish species exotic to North America.

• Live fish routinely harbor type C toxin-producing cells in their gastrointestinal tracts, and the prevalence of the bacteria in fish varies between years.

• There is evidence that type E toxin-producing cells are present in both the sediments of the Salton Sea and in tilapia.

• Although only a single bird has been diagnosed with type E botulism at the Sea in the past, it is believed that the disease may have occurred more frequently, and may have been missed.

USGS National Wildlife Health Center, Identification and Ecology of Disease-Causing Agents for Eared Grebes (Podiceps Nigricollis) at the Salton Sea.

This subproject (Principal Investigator: Christian Franson) continues until September 2003. In this subproject, researchers worked to identify the cause(s) and ecology of eared grebe mortality. Areas for investigation included: (1) agents causing disruption of feather arrangement; (2) the role of avian cholera; and (3) the role of biotoxins. The subproject identified natural toxins at the Sea by isolating such toxins from phytoplankton, invertebrates, surface slicks, and sediments. The chemical structures of natural toxins were determined, along with their movement through the food chain. The findings of this subproject include:

• Significant mortality of eared grebes has occurred at the Salton Sea, which is a major wintering area for this species.

• No single responsible agent has been identified as the cause of the mortality events.

• Trace elements, organochlorine contaminants, salt toxicosis, and botulism were ruled out. Avian cholera was detected in some grebes.

• Algal biotoxins have been suggested as potential contributory causes of mortality, but microcystin analysis has been difficult to evaluate because of a lack of interpretive information.

• Hypotheses for the dieoffs are interactive effects of contaminants, immunosuppression, a yet unidentified biotoxin or pathogen, impairment of feather waterproofing leading to hypothermia, or a unique manifestation of avian cholera that evades laboratory detection.

Wright State University, Dayton, OH, Avian Disease Related to Algal Toxins

This subproject (Principal Investigator: Wayne Carmichael) investigated the role of cyanobacteria (blue-green algae) toxins (cyanotoxins) as a causative agent in eared grebe mortalities at the Salton Sea. Cyanobacteria-producing microcystins were cultured and speciated. Tissues from grebes found dead at the Sea also were evaluated for the presence of cyanotoxins. The findings of this subproject include:

• Water sample collections started in November 1999, and ended in April 2001. Sampling dates varied, but samples were received from every month except May, June, and July. Twenty shipments were received over this 18-month period. Fifteen of the shipments contained water and phytoplankton samples, while six contained grebe tissue samples (one shipment contained both water and tissue samples).

• Water samples containing cyanobacteria at numbers giving a visible color to the water samples (~ 105 to 107 cells/mL) were lyophilized and analyzed for microcystins by enzyme-linked immunosorbent assay (ELISA). Approximately 85 percent of 247 samples were positive for microcystins.

• Concentrations of microcystins were typically less than 100 µg/gdw. This concentration is generally less than needed to cause acute lethal toxicity from ingestion of bloom samples by mammals.

• The majority of water samples were dominated by the filamentous genus, Oscillatoria, and the picoplanktic genus, Synechococcus, throughout the sampling period.

• Isolation, culture, and ELISA testing for microcystin of 50 strain isolates found that microcystins were produced by all strains, although at low levels (< 1 µg/gdw)

• Genera producing measurable levels of microcystin included mainly Synechococcus and Oscillatoria. Other positive microcystin genera include Gloeocapsa, Phormidium, Aphanothece, and Lyngbya.

• 16S rRNA analyses confirmed that the Synechococcus strains grown isolated and cultured are more similar to marine species than to freshwater species.

• These marine species of Synechococcus were shown by ELISA and liquid chromatography/mass spectrometry to produce the microcystins-MCYST-LR and MCYST-YR.

• Microcystins were detected by ELISA in the majority of liver and intestine samples from grebes collected because of morbidity or mortality. The concentrations of microcystins were not always high enough to account for acute lethal toxicity (< 50 ng/g), but a significant number of liver samples contained microcystin levels high enough to account for acute lethal toxicities (> 50 ng/g).

• Concentration of microcystins in the water and cells of cyanobacteria were not high enough to induce acute lethal toxicity, but levels accumulated—by an unknown vector—in grebe tissues to levels that could be lethal.

The following recommendations resulted from this subproject:

• The cyanotoxin group microcystins should be considered as a contributing cause of grebe morbidities and mortalities in the Salton Sea, and efforts to remediate the Salton Sea water quality should consider this.

• Further research should confirm microcystin acute toxicity to grebes (and by extension, other Salton Sea waterfowl) through an oral exposure subproject.

• Further research on cyanotoxin-induced toxicities in the Salton Sea should look at the vectors by which acute and acute lethal levels of microcystins accumulate in birds and possibly in other Salton Sea organisms.

• Efforts to reduce salinity and to improve water quality in the Salton Sea should consider that the genera of cyanobacteria currently in the sea are not high producers of microcystins. Salinity levels currently present are likely a significant factor in selecting for the low microcystin producers. If salinities are lowered without managing levels of key nutrients such as nitrogen and phosphorus, other genera of cyanobacteria that produce higher levels (acute lethal) of microcystins may be selected. These genera could include Microcystis and Anabaena. Waterblooms of these genera are typically much more intense, and would present a higher risk from cyanotoxin (microcystins, anatoxins, cylindrospermopsin, and saxitoxins) exposures.

Agrarian Research and Management Company, Characterization of Shallow Subsurface Sediments in the Salton Sea, California

The proposed transfer of Colorado River water from the farmlands of the Imperial Irrigation District to the urban areas of coastal California will almost certainly result in declining levels of the Salton Sea. As the Sea level retreats, subsurface sediments will become exposed, potentially causing wind erosion and dust emission that would threaten health and trigger violations of air quality standards. This subproject (Principal Investigator: Carla Scheidlinger) is designed to identify and describe the nature of the material that would be exposed by declining Sea levels. These data will provide a critical tool for the future evaluation of the potential for dust emissions from the exposed playa surface. The findings of this subproject include:

• The Salton Sea is an energetic system, and the current sediment mosaic reflects the distribution of that energy.

• Nine morphosedimentary districts—including open shore, transitional, and deltaic districts—were recognized in the Salton Sea, covering an area of 68,304 acres.

• These sediments bear some resemblance to the exposed sediments at the Owens Lake playas, which have been a source of severe PM10 emissions.

• Falling water levels are expected to result in a reworking of lower shore sediments in open shore and transitional districts.

• Deltaic sequences with muddy sediments are less subject to wave attack, and are less likely to be reworked as water levels fall.

• Barnacle beds blanketing surface sediments were a significant feature across many parts of the lake bed, possibly protecting covered sediments from erosion as lake levels fall.


Journal Articles on this Report : 36 Displayed | Download in RIS Format

Other project views: All 59 publications 37 publications in selected types All 33 journal articles
Type Citation Project Document Sources
Book Chapter Costa-Pierce BA, Riedel R. Fisheries ecology of the tilapias in subtropical lakes in the United States. In: Costa-Pierce B, Rakocy J, eds. Tilapia Aquaculture in the Americas. Baton Rouge, LA: World Aquaculture Society, 2000, Volume 2, pp. 1-20. R826552 (Final)
  • Other: World Aquaculture Society
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  • Book Chapter Rocke TE, Friend M. Wildlife disease in the Colorado Delta as an indicator of ecosystem health. In: Rapport DJ, Lasley WL, Rolston DE, Nielsen NO, Qualset CO, Damania AB, eds. Managing for Healthy Ecosystems. Boca Raton, FL: Lewis Publishers/CRC Press, 2003, Section III.1, Chapter 110, pp. 1111-1124. R826552 (Final)
  • Other: Google Books-Book URL
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  • Book Chapter Rocke TE, Nol P, Pelizza C, Sturm KK. Type C botulism in pelicans and other fish-eating birds at the Salton Sea, California, 1994-2003. In: Shuford WD, Molina KC, eds. Ecology and Conservation of Birds of the Salton Sink: An Endangered Ecosystem. Studies in Avian Biology No. 27. Camarillo, CA: Cooper Ornithological Society, 2004, pp. 136-140. R826552 (Final)
  • Other: Book Review
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  • Journal Article Barlow SB, Kugrens P. Cryptomonads from the Salton Sea, California. Hydrobiologia 2002;473(1-3):129-137. R826552 (Final)
  • Abstract: Springerlink
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  • Journal Article Buckles JE, Kashiwase K, Krantz T. Reconstruction of prehistoric Lake Cahuilla in the Salton Sea Basin using GIS and GPS. Hydrobiologia 2002;473(1-3):55-57. R826552 (Final)
  • Abstract: Springerlink
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  • Journal Article Cook CB, Orlob GT, Huston DW. Simulation of wind-driven circulation in the Salton Sea: implications for indigenous ecosystems. Hydrobiologia 2002;473(1-3):59-75. R826552 (Final)
  • Abstract: SpringerLink
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  • Journal Article Detwiler PM, Coe MF, Dexter DM. The benthic invertebrates of the Salton Sea: distribution and seasonal dynamics. Hydrobiologia 2002;473(1-3):139-160. R826552 (Final)
  • Abstract: SpringerLink
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  • Journal Article Friend M. Avian disease at the Salton Sea. Hydrobiologia 2002;473(1-3):293-306. R826552 (Final)
  • Abstract: SpringerLink
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  • Journal Article Hauer G, Rogerson A, Anderson OR. Platyamoeba pseudovannellida n. sp., a naked amoeba with wide salt tolerance isolated from the Salton Sea, California. Journal of Eukaryotic Microbiology 2001;48(6):663-669. R826552 (Final)
  • Abstract from PubMed
  • Abstract: Wiley
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  • Journal Article Holdren GC, Montano A. Chemical and physical characteristics of the Salton Sea, California. Hydrobiologia 2002;473(1-3):1-21. R826552 (Final)
  • Abstract: SpringerLink
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  • Journal Article Jehl JR, McKernan RL. Biology and migration of eared grebes at the Salton Sea. Hydrobiologia 2002;473(1-3):245-253. R826552 (Final)
  • Abstract: SpringerLink
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  • Journal Article Kuperman BI, Matey VE. Massive infestation by Amyloodinium ocellatum (Dinoflagellida) of fish in a highly saline lake, Salton Sea, California, USA. Diseases of Aquatic Organisms 1999;39(1):65-73. R826552 (Final)
  • Abstract from PubMed
  • Full-text: Disease of Aquatic Organisms PDF
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  • Abstract: Disease of Aquatic Organisms
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  • Journal Article Kuperman BI, Matey VE, Hurlbert SH. Parasites of fish from the Salton Sea, California, U.S.A. Hydrobiologia 2001;466(1-3):195-208. R826552 (Final)
  • Abstract: SpringerLink
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  • Journal Article Kuperman BI, Matey VE, Barlow SB. Flagellate Cryptobia branchialis (Bodonida: Kinetoplastida), ectoparasite of tilapia from the Salton Sea. Hydrobiologia 2002;473(1-3):93-102. R826552 (Final)
  • Abstract: SpringerLink
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  • Journal Article Kuperman BI, Matey VE, Dexter DM, Tiffany MA. Invertebrates of the Salton Sea: a scanning electron microscopy portfolio. Hydrobiologia 2002;473(1-3):203-216. R826552 (Final)
  • Abstract: SpringerLink
    Exit
  • Journal Article Lange CB, Tiffany MA. The diatom flora of the Salton Sea, California. Hydrobiologia 2002;473(1-3):179-201. R826552 (Final)
  • Abstract: SpringerLink
    Exit
  • Journal Article Nol P, Brannian RE, Berlowski BM, Wolcott MJ, Rocke TE. New host record of avian tuberculosis in an American White Pelican (Pelecanus erythrorhynchus). California Fish and Game 2003;89(3):152-154. R826552 (Final)
    not available
    Journal Article Nol P, Rocke TE, Gross K, Yuill TM. Prevalence of neurotoxic Clostridium botulinum type C in the gastrointestinal tracts of tilapia (Oreochromis mosambicus) in the Salton Sea. Journal of Wildlife Diseases 2004;40(3):414-419. R826552 (Final)
  • Full-text:
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  • Abstract:
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  • Other:
    Exit
  • Journal Article Nol P, Williamson JL, Rocke TE, Yuill TM. Detection of Clostridium botulinum type C cells in the gastrointestinal tracts of Mozambique tilapia (Oreochromis mosambicus) by polymerase chain reaction. Journal of Wildlife Diseases 2004;40(4):749-753. R826552 (Final)
  • Full-text: Journal of Wildlife Diseases
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  • Abstract: Journal of Wildlife Diseases
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  • Other: Journal of Wildlife Diseases PDF
    Exit
  • Journal Article Reifel KM, McCoy MP, Tiffany MA, Rocke TE, Trees CC, Barlow SB, Faulkner DJ, Hurlbert SH. Pleurochrysis pseudoroscoffensis (Prymnesiophyceae) blooms on the surface of the Salton Sea, California. Hydrobiologia 2001;466(1-3):177-185. R826552 (Final)
  • Abstract: SpringerLink
    Exit
  • Journal Article Reifel KM, McCoy MP, Rocke TE, Tiffany MA, Hurlbert SH, Faulkner DJ. Possible importance of algal toxins in the Salton Sea, California. Hydrobiologia 2002;473(1-3):275-292. R826552 (Final)
  • Abstract: SpringerLink
    Exit
  • Journal Article Riedel R, Caskey L, Costa-Pierce BA. Fish biology and fisheries ecology of the Salton Sea, California. Hydrobiologia 2002;473(1-3):229-244. R826552 (Final)
  • Abstract: SpringerLink
    Exit
  • Journal Article Riedel R, Costa-Pierce BA. Review of the fisheries of the Salton Sea, California, USA: past, present, and future. Reviews in Fisheries Science 2002;10(1):77-112. R826552 (Final)
  • Abstract: IngentaConnect
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  • Journal Article Riedel R, Schlenk D, Frank D, Costa-Pierce B. Analyses of organic and inorganic contaminants in Salton Sea fish. Marine Pollution Bulletin 2002;44(5):403-411. R826552 (Final)
  • Full-text: Science Direct
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  • Abstract: Science Direct
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  • Other: Science Direct PDF
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  • Journal Article Rocke T, Converse K, Meteyer C, McLean B. The impact of disease in the American White Pelican in North America. Waterbirds 2005;28(Sp Iss 1):87-94. R826552 (Final)
  • Full-text: University of Nebraska-Lincoln PDF
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  • Abstract: University of Nebraska-Lincoln
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  • Journal Article Rogerson A, Hauer G. Naked amoebae (protozoa) of the Salton Sea, California. Hydrobiologia 2002;473(1-3):161-177. R826552 (Final)
  • Abstract: SpringerLink
    Exit
  • Journal Article Schroeder RA, Orem WH, Kharaka YK. Chemical evolution of the Salton Sea, California: nutrient and selenium dynamics. Hydrobiologia 2002;473(1-3):23-45. R826552 (Final)
  • Abstract: SpringerLink
    Exit
  • Journal Article Shuford WD, Warnock N, Molina KC, Sturm KK. The Salton Sea as critical habitat to migratory and resident waterbirds. Hydrobiologia 2002;473(1-3):255-274. R826552 (Final)
  • Abstract: SpringerLink
    Exit
  • Journal Article Sutton RJ. Summer movements of desert pupfish among habitats at the Salton Sea. Hydrobiologia 2002;473(1-3):223-228. R826552 (Final)
  • Abstract: Springerlink
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  • Journal Article Tiffany MA, Barlow SB, Matey VE, Hurlbert SH. Chattonella marina (Raphidophyceae), a potentially toxic alga in the Salton Sea, California. Hydrobiologia 2001;466(1-3):187-194. R826552 (Final)
  • Abstract: Springerlink
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  • Journal Article Tiffany MA, Swan BK, Watts JM, Hurlbert SH. Metazooplankton dynamics in the Salton Sea, California, 1997-1999. Hydrobiologia 2002;473(1-3):103-120. R826552 (Final)
  • Abstract: Springerlink.
    Exit
  • Journal Article Tiffany MA. Skeletal development in Hermesinum adriaticum Zacharias, a flagellate from the Salton Sea, California. Hydrobiologia 2002;473(1-3):217-221. R826552 (Final)
  • Abstract: Springerlink.
    Exit
  • Journal Article Vogl RA, Henry RN. Characteristics and contaminants of the Salton Sea sediments. Hydrobiologia 2002;473(1-3):47-54. R826552 (Final)
  • Abstract: Springerlink
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  • Journal Article Warwick RM, Dexter DM, Kuperman B. Freeliving nematodes from the Salton Sea. Hydrobiologia 2002;473(1-3):121-128. R826552 (Final)
  • Abstract: Springerlink
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  • Journal Article Watts JM, Swan BK, Tiffany MA, Hurlbert SH. Thermal, mixing, and oxygen regimes of the Salton Sea, California, 1997-1999. Hydrobiologia 2001;466(1-3):159-176. R826552 (Final)
  • Abstract: Springerlink
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  • Journal Article Wood AM, Miller SR, Li WKW, Castenholz RW. Preliminary studies of cyanobacteria, picoplankton, and virioplankton in the Salton Sea with special attention to phylogenetic diversity among eight strains of filamentous cyanobacteria. Hydrobiologia 2002;473(1-3):77-92. R826552 (Final)
  • Abstract: Springerlink
    Exit
  • Supplemental Keywords:

    Salton Sea, southern California, California, CA, Mexico, Colorado River, data collection, resident birds, migratory birds, endangered species, fishery, recreation, agricultural drainage, economic development, limnology, chemical limnology, physical limnology, sediment, microbial pathogens, botulism, algal toxins., Scientific Discipline, ENVIRONMENTAL MANAGEMENT, Water, Ecosystem Protection/Environmental Exposure & Risk, Restoration, Resources Management, Ecology and Ecosystems, Aquatic Ecosystem Restoration, human use, biodiversity, fish habitat, agricultural ecosystems, conservation, restoration strategies, Salton Sea, acuatic ecosystems, aquatic ecosystems, environmental rehabilitation, water quality, recreation

    Progress and Final Reports:

    Original Abstract
  • 1999
  • 2000
  • 2001
  • 2002