Terrestrial and Aquatic Ecology Commons^™

Lake Mead Nutrient Enhancement Project, Peter D. Vaux, Larry J. Paulson, Nevada Department Of Wildlife, National Oceanic And Atmospheric Administration

Publications (WR)

The Lake Mead Fertilization Project is a research program designed to investigate the potential for using large-scale artificial fertilization to enhance the game fisheries of this reservoir through an increase in the population of threadfin shad, the system's primary forage species. A substantial decline in the population of largemouth bass, together with poor condition of adult striped bass, are the two major issues affecting the Lake Mead game fisheries. Both issues have been hypothesized to be a result of an inadequate amount of forage in the reservoir. Previous studies have in turn suggested that a major factor limiting the shad …

Enhancement And Monitoring Of The Procambarus Clarkii Population In Lake Mead, Mikell Beth Hager

Publications (WR)

Procambarus clarkii are found in extremely low numbers throughout Lake Mead, AZ-NV. The crayfish are an important dietary component for game fish. Enhancement of the crayfish population would broaden the fishery forage base. Crayfish were stocked and monitored in a study cove on Saddle Island to determine if the Procambarus clarkii population could be enhanced. A trapping survey of the area after the following reproductive season yielded low numbers of crayfish. A comparison of pre-stocking and post-stocking catch per trap day (CPTD) values revealed no significant increase in the population. Procambarus clarkii growth is limited by environmental factors in Lake …

Effects Of Ambient Lake Mohave Temperatures On Development, Oxygen Consumption, And Hatching Success Of The Razorback Sucker, Michael A. Bozek, Larry J. Paulson, Gene R. Wilde

Publications (WR)

Spawning of razorback suckers, Xyrauchen texanus, in Lake Mohave occurred from 10-22° C and larvae were collected at water temperatures from 10-15° C in 1982 and 1983. In the laboratory, hatching success was similar from 12-20° C, but reduced hatching success was found at 10° C while none hatched at 8°C. Development rate and oxygen consumption were positively related to incubation temperature. Direct effects of ambient Lake Mohave water temperatures on hatching success of razorback sucker embryos are considered minimal. Historical spawning temperatures for the species are hypothesized based upon successful incubation temperatures and comparison to the white sucker, …

Temporal And Spatial Patterns Of Abundance Of Age 0 Threadfin Shad (Dorosoma Petenense) In Overton Arm, Lake Mead, William Lee Pelle

Publications (WR)

Temporal and spatial patterns of age 0 threadfin shad (Dorosoma petenense) abundance and growth, in the Overton Arm of Lake Mead, were examined to evaluate the effects of resource availability on the young fish. This was part of a larger, game fishery enhancement study (Lake Mead Fertilization Project), designed to assess feasability of increasing survivorship of larval/juvenile shad by boosting phosphate levels, thereby increasing algal and zooplankton biomass, during the shad spawning period. Shad are the primary forage base for the striped bass (Morone saxatilis) and black bass (Macropterus salmoides) fisheries. Weekly samples were …

Limnological Monitoring Data For Lake Mead During 1988, Suzanne E. Leavitt, Larry J. Paulson, State Of Nevada: Division Of Environmental Protection

Publications (WR)

Limnological monitoring was conducted in Las Vegas Bay and Boulder Basin from April to December of 1988. The purpose of the monitoring was to (i) document possible changes in water quality resulting from decreased phosphorus loading and increased ammonia in Las Vegas Wash, and (ii) establish a data base for evaluating the adequacy of water quality standards.

Red Swamp Crayfish Ecology In Lake Mead, Suzanne E. Leavitt, Jennifer Stephens Haley, Mikell Hager, Donald H. Baepler, Nevada Department Of Wildlife

Publications (WR)

Red swamp crayfish (Procambarus clarkii) were trapped in Flamingo Wash, an urban wash of Las Vegas, during four periods of 1988. Life history and reproductive success were determined. The trapped crayfish were marked and released into a study cove in Lake Mead as part of an experimental stocking program. Retrap data from the study cove were used to determine life history, habitat preferences, and movement patterns of the stocked crayfish. In addition, a literature search was done on red swamp crayfish ecology, including food preferences, life history, habitat preferences and fish predation.

Riparian Plant Water Relations Along The North Fork Of The Kings River, California, J. L. Nachlinger, S. D. Smith, R. J. Risser

Life Sciences Faculty Research

Plant water relations of five obligate ripar-ian species were studied along California's North Fork Kings River. Diurnal stomatal conductance, transpi-ration, and xylem pressure potentials were measured throughout the 1986 growing season and in mid-season in 1987. Patterns were similar for all species although absolute values varied considerably. Maximum stomatal conductance occurred early in the day and season during favorable environmental conditions and decreased as air temperature and the vapor pressure difference between the leaf and air increased. Maximum transpiration rates occurred in mid-morning and mid-summer resulting in estimated daily water losses per unit sunlit leaf area of 163-328 mol H2O …

An Isotopic Analysis Of The Hydrology And Riparian Vegetation Water Sources On Bishop Creek, M. L. Space, J. W. Hess, S. D. Smith

Life Sciences Faculty Research

Five power generation plants along an eleven kilometer stretch divert Bishop Creek water for hydro-electric power. Stream diversion may be adversely affecting the riparian vegetation. Stable isotopic analysis is employed to determine surface water/ground-water interactions along the creek. surface water originates primarily from three headwater lakes. Discharge into Bishop Creek below the headwaters is primarily derived from ground water. The average δD and δ18O values are significantly different for surface water and ground water that an isotopic analysis can delineate between these two components of flow. Therefore isotopic shifts along the creek can determine gaining reaches. In addition, by knowing …

Temporal And Spatial Variation In Pelagic Fish Abundance In Lake Mead Determined From Echograms, Gene R. Wilde, Larry J. Paulson

Publications (WR)

Echograms have been used extensively to locate and estimate the relative abundance of marine fish stocks (Cushing 1973). In freshwater, echograms have been used to describe vertical (Netsch et al. 1971; Eggers 1978; O'Brien et al. 1984; Matthews et al. 1985), spatial (O'Brien et al. 1984; Wanjala et al. 1986) and temporal (Baker and Paulson 1983) patterns in fish abundance. Although most uses of echograms have been qualitative, Mullan and Applegate (1969) and Matthews et al. (1985) obtained relative estimates of fish abundance by counting targets (fish) on echograms. However, neither Mullan and Applegate (1969) nor Matthews et al. (1985) …

Characterization Of The Aquatic Environment In Lake Mead Near The Proposed Spring Canyon Pumped-Storage Project, And Assessment Of Potential Aquatic Impacts, Charles R. Liston, Stephen J. Grabowski, Bureau Of Reclamation

Publications (WR)

A pumped storage system consists of an upper reservoir and lower reservoir separated by an elevation difference. During low demand energy periods such as nights and weekends water is pumped from the lower to the upper reservoir using available energy from conventional steam electric power plants. During high energy demand periods, such as mornings and afternoons of weekdays, upper reservoir water is allowed to drop back down through the same system of water conduits and turbines, generating electricity to conveniently meet abrupt electrical energy requirements. The same water turbines thus act both as pumps and as conventional hydroelectric turbines. Because …

Environmental Assessment Of Las Vegas Wash And Lake Mead Artificial Wetlands Demonstration Project, John R. Baker, R. M. Gersberg, U.S. Environmental Protection Agency

Publications (WR)

The effective use of artificial wetlands for treatment of municipal wastewater is well documented; however, design and economic data for artificial wetlands development are limited (Gersberg et al., 1984a). This is due partly to regional differences in climate, soils, and vegetation and partly to the desired waste treatment. As a result, specific treatment levels and cost benefits relative to the use of an artificial wetlands for a particular site cannot be evaluated adequately without a pilot demonstration project. Las Vegas Wash receives sewage effluent from the Las Vegas metropolitan area and has been designated as a wetlands community park. Las …

Limnological Monitoring Data For Lake Mead During 1987: Technical Report No. 20, Larry J. Paulson

Publications (WR)

Limnological monitoring was conducted in Las Vegas Bay and Boulder Basin from April to December of 1987. The purpose of the monitoring was to (i) document possible changes in water quality resulting from decreased phosphorus loading in Las Vegas Wash, and (ii) establish a data base for evaluating the adequacy of water quality standards.

Fish Aid: The Lake Mead Fertilization Project, Richard Axler, Larry Paulson, Peter Vaux, Patrick Sollberger, Donald H. Baepler

Publications (WR)

Sport fishing at Lake Mead in Nevada and Arizona is a resource valued at nearly $100 million per year to southern Nevada. During the past two decades, salmonids, mostly trout, have disappeared entirely, the largemouth bass catch has drastically declined despite greater fishing pressure, and the condition factors for striped bass have steadily deteriorated. It appears that a major reduction in phosphorus loading caused by the upstream impoundment of the Colorado River to form Lake Powell in 1963 and advanced wastewater treatment removal of phosphorus from domestic wastewater inflows in 1981 are the principal factors responsible for decreased production at …

Lake Mead Prefertilization Study: Preliminary Nutrient Enhancement Studies In Lake Mead, Richard P. Axler, Larry J. Paulson, Patrick J. Sollberger, Donald H. Baepler, U.S. Bureau Of Reclamation

Publications (WR)

Studies conducted by the University of Nevada-Las Vegas (UNLV), the Nevada Department of Wildlife (NDOW), the Arizona Game and Fish Department (AGFD), The Nevada Division of Environmental Protection (NDEP), and the United States Bureau of Reclamation (USBR) have identified decreased algal production as a major factor involved in the decline of the Lake Mead sport fishery. Phosphorus-laden silt particles in the Colorado River have been sedimenting out in Lake Powell since the completion of Glen Canyon Dam 286 miles upstream in 1963. This sharp decrease in phosphorus loading to Lake Mead (>5000 tons per year) has resulted in decreased …

Thermal Tolerances And Preferences Of Fishes Of The Virgin River System (Utah, Arizona, Nevada), James E. Deacon, Paul B. Schumann, Edward L. Stuenkel

Publications (WR)

Critical thermal maxima (CTM) and thermal preferenda of the common fishes of the Virgin River were examined. Differences in final temperature preferenda and CTM for species with low thermal lability (speckled dace, spinedace, roundtail chub) correspond well with differences in their distribution and abundance in the river. These species shifted their acute thermal preferences relatively little as acclimation temperature increased. For thermally labile species (woundfin, red shiner, desert sucker, and fiannehnouth sucker), the final preferendum is a less precise indicator of probable distribution. The woundfin, an endangered fish, has a high CTM (39.5 C at 25 C acclimation) and a …

Benthic Invertebrates And Crayfish Of Lake Mead, Susan K. Peck, William L. Pratt, James E. Pollard, Larry J. Paulson, Donald H. Baepler

Publications (WR)

The objectives of this study were to:

1. Establish baseline densities of benthic invertebrates and relative abundance of crayfish in Lake Mead.

2. Evaluate the distributions of benthic organisms and crayfish in relation to existing habitat conditions and 1imnological characteristics of Lake Mead.

3. Measure seasonal changes in abundances of benthic organisms and crayfish in Lake Mead.

4. Compare observations of Procambarus clarkii life history in Lake Mead to reports from other aquatic systems.

5. Evaluate the importance of benthic organisms and crayfish as food sources for game fish in Lake Mead.

Las Vegas Wash And Lake Mead Proposed Water Quality Standards: Revisions And Rationale, State Of Nevada: Division Of Environmental Protection

Publications (WR)

Rationale of review and for proposed changes to the Nevada Pollution Control Regulations (NAC 445.1354, 445.1355, 445.1356, 455.1367, 445.1352, 445.1353, 445.1350, 445.1351) before the State Environmental Commission on June 23 and 24, 1987.

Comparison Of Littoral And Limnetic Zooplankton Communities Of Lake Mead, Patrick Joseph Sollberger

Publications (WR)

Microfaunal communities were studied in littoral (inshore) and limnetic (offshore) areas of the lower basin in Lake Mead to compare species composition and abundance between the two zones. Planktonic forms (zooplankton) dominated inshore and offshore habitats and the occurrence of littoral species was low. Therefore, high similarity in zooplankton species composition was found among all sampling stations. This was perhaps due to two main factors: (i) the physical and chemical environment among the stations were very similar and (ii) the lack of aquatic vegetation in the littoral zone reduced the occurrence of littoral species.

Although species composition did not vary …

Benthic Diatom Community Dynamics In The Colorado River: Interactive Effects Of Periodic Dessication And Current Regime, Christopher Gerard Peterson

Publications (WR)

The response to periodic desiccation of periphyton communities developed in eddy environments or in areas exposed to variable, direct current was examined. Algal communities were incubated on clay tiles for between 2 and 12 weeks in the Colorado River, directly below Hoover Dam from October, 1983 - January, 1984. Mean daily discharge from the dam decreased over this period. To assess the influence of these discharge changes on community dynamics, samples collected over the first 12 weeks of the investigation were compared to samples of the same age collected over the final 8 weeks.

The small diatom taxon Achnahthes spp …

A Proposal To Fertilize The Overton Arm And Gregg Basin Areas Of Lake Mead, Larry J. Paulson

Publications (WR)

Several limnological studies have been conducted in Lake Mead during the past decade. The recent studies clearly show that most of Lake Mead is deficient in nutrients, especially phosphorus, and very low in productivity. The reservoir-wide average total phosphorus concentration for 1981 - 1982 was only 9 mg/m³. This is below levels found In most oligotrophic lakes and reservoirs. Algal biomass, as measured by chlorophyll-a, averaged only 1.5 mg/m³. That also places Lake Mead in the oligotrophic range. Transparency, as measured by a Secchi disc, averaged 9-5 m in Lake Mead during 1981-1982. That far exceeds …

Seasonal And Spatial Heterogeneity In The Limnetic Zooplankton Community Of Lake Mead, Gene Robert Wilde

Publications (WR)

Zooplankton samples collected from throughout Lake Mead, in 1981-1982, demonstrate the presence of a statistically significant seasonal and spatial heterogeneity in zooplankton densities. Seasonally, the major zooplankton groups were most abundant in the spring and fall, coincident with maxima in chlorophyll-a concentrations. Successions among the various rotifers, cladocerans and copepods present in the reservoir were influenced by food availability, diapause, predation by planktivorous fish and, possibly, water temperatures. Spatial heterogeneity in zooplankton densities was unrelated to water temperature, pH, conductivity and dissolved oxygen concentrations, but was related to the abundance of phytoplankton (chlorophyll-a concentrations) and fish. Statistical analyses indicate that …

The Role Of Nannoplankton In The Phytoplankton Dynamics Of Four Colorado River Reservoirs (Lakes Powell, Mead, Mohave, And Havasu), Jeffrey John Janik

Publications (WR)

Phytoplankton species composition and community size structure were studied in four warm-monomictic Colorado River reservoirs; lakes Powell, Mead, Mohave, and Havasu from March 1981 to February 1982. Sampling was done at approximately monthly intervals from several stations in each reservoir. The Utermohl technique was used to enumerate phytoplankton. The phytoplankton assemblage was divided into the following six size classes using microscopic techniques; netplankton (>64 um), and nannoplankton (>5, 5-11, 12-21, 22-44, and 45-64 um).

Total phytoplankton biomass and community size structure were different among these four reservoirs with considerable spatial and temporal variation present. Average reservoir-wide areal weighted …

Las Vegas Wash Multispectral Scanner Survey, T. H. Mace, M. V. Olsen, Environmental Protection Agency

Publications (WR)

At the request of the U.S. Bureau of Reclamation, Boulder City, Nevada, the U.S. Environmental Protection Agency's Environmental Monitoring Systems Laboratory at Las Vegas collected multispectral scanner imagery of Las Vegas Wash on October 1, 1982. A combined maximum likelihood classification and editing procedure was used to classify the multispectral scanner imagery into 12 categories of land cover. The classification identified four categories of marsh vegetation, one category of riparian, two categories of mixed scrub, and two desert categories. Turbid water and cultivated land formed an "other" category. Area tabulations were formed by georeferencing the classification to the Universal Transverse …

Factors Affecting Reproductive Success Of Bonytail Chubs And Razorback Suckers In Lake Mohave, Michael A. Bozek, Larry J. Paulson, James E. Deacon, U.S. Department Of Interior, Fish And Wildlife Service

Publications (WR)

Razorback suckers (Xyrauchen texanus) and bonytail chubs (Gila elegans) were once widespread throughout the Colorado River system. The ranges and populations of these native species and others have declined in the past 50 years. Bonytail chubs appear to be extremely rare and possibly nearing extinction in the Upper Colorado River Basin. The razorback sucker is widely distributed in the upper river but is considered rare throughout most of that range and is also rare in the Grand Canyon. Razorback suckers are abundant only in a few habitats in the upper river. They congregate and spawn over …

Water Quality Trends In The Las Vegas Wash Wetlands, F. A. Morris, L. J. Paulson

Publications (WR)

The Las Vegas Wash is a wetlands ecosystem that acts to buffer the effects of wastewater discharges on the receiving waters of Lake Mead. The wash is the terminus for the 4,144 km2 Las Vegas Valley drainage basin, emptying into Las Vegas Bay of Lake Mead (Colorado River). It is in the northern Mojave desert, which receives an average of only 10 cm of rainfall annually. The Las Vegas Wash is technically an artificial wetland supported almost entirely by the perennial flows from sewage treatment plants. These flows contribute an average of 3-7 t of nutrients (nitrogen and phosphorus) and …

Use Of Hydroelectric Dams To Control Evaporation And Salinity In The Colorado River System, Larry J. Paulson

Publications (WR)

The main stem reservoirs on the Colorado River comprise one of the largest and most heavily used freshwater bodies in the nation. These reservoirs (Lake Powell, Lake Mead, Lake Mohave and Lake Havasu) can store up to 53,590,400 acre-feet of water at their maximum capacities. Nonetheless, local water shortages still exist in some areas of the Colorado River Basin. There is also concern that salt concentrations are approaching levels that could severely affect municipal and agricultural uses. Water shortages will become even more acute as demands for water increase with continued urban and agricultural development in the basin. Water conservation …

The Influence Of Lake Powell On The Suspended Sediment-Phosphorus Dynamics Of The Colorado River Inflow To Lake Mead, T. D. Evans, Larry J. Paulson

Publications (WR)

The Colorado River has been successively modified by the construction of several reservoirs, beginning in 1935 with the formation of Lake Mead by Hoover Dam. These reservoirs are located in a chain, and each one has an influence on the nutrient dynamics and productivity of the river and downstream reservoir. Lake Mead derives 98% of its annual inflow from the Colorado River. Historically, the Colorado River inflow was unregulated into Lake Mead. Regulation occurred in 1963, when Lake Powell was impounded by the construction of Glen Canyon Dam, approximately 450 km upstream. The formation of Lake Powell drastically altered the …

Methods For Biological, Chemical, And Physical Analyses In Reservoirs, Penelope E. Kellar, Sherell A. Paulson, Larry J. Paulson

Publications (WR)

This manual contains detailed descriptions of biological, chemical and physical sampling and analytical procedures used at the Lake Mead Limnological Research Center. The manual was prepared in response to requests made by numerous individuals involved in the Las Vegas Valley Water Quality Program. This manual represents what we consider to be a reasonably complete compilation of methods useful in studying both general and specific limnological questions. While each section is sufficiently detailed to be of use to investigators with little experience in limnological methodology, the methods can be used on a wide variety of lakes and reservoirs, with relatively little …

Influence Of Las Vegas Wash Density Current On Nutrient Availability And Phytoplankton Growth In Lake Mead, John R. Baker, Larry J. Paulson

Publications (WR)

Density currents are commonly formed in reservoirs because of temperature or salinity induced density differences between inflowing and receiving waters. Anderson and Pritchard (1951) were among the first to demonstrate this in their investigations of density currents in Lake Mead. They found that the Colorado River formed an underflow in Lake Mead during the winter, an overflow in the spring and an interflow in the summer and fall. Wunderlich and Elder (1973) have since described the hydromechanics of these types of flow patterns, and density currents have been reported for several other large reservoirs (Carmack et al. 1979, Johnson and …

Nutrient Interactions Among Reservoirs On The Colorado River, Larry J. Paulson, John R. Baker

Publications (WR)

Interactions among physical, chemical and biological processes in reservoirs can significantly alter the characteristics of the discharge (Neel 1963, Wright 1967, Hannan 1979) that, in turn, can influence the ecology of the river downstream .(Ward and Stanford 1979). Investigations of the Colorado River, system reveal that reservoir-induced changes in the river can also affect downstream reservoirs. The formation of Lake Powell, in 1963 was accompanied by reductions in suspended sediment and nutrient loading and changes in the seasonal temperature and discharge cycles of the Colorado River. In this paper, we evaluate how these changes have influenced the nutrient and trophic …