Open-File Report 02-012
Physical Data and Biological Data for Algae, Aquatic Invertebrates, and Fish from Selected Reaches on the Carson and Truckee Rivers, Nevada and California, 1993-97
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In 1991, the U.S. Geological Survey (USGS) began a nationwide study of water quality in 20 areas across the United States. The National Water-Quality Assessment Program (NAWQA), is designed to assess the status of, and trends in, the Nation's water quality, and to develop an understanding of the major factors that affect water quality (Gilliom and others, 1995; Hirsch and others, 1988; Leahy and others, 1990). To accomplish these goals, NAWQA will assess 51 study areas on a staggered time scale (20 started in 1991, 16 in 1994, 13 in 1997, and 2 in 1999) by collecting physical, chemical, and biological data from large river basins affected by natural and human-created processes. By integrating the physical, chemical, and biological data, a comprehensive determination of aquatic ecosystem health in these river basins may be made.
The Nevada Basin and Range Study unit (NVBR) was among the first 20 areas to begin the NAWQA study in 1991 (Bevans and Kilroy, 1991). Physical data for sites in the NVBR are compiled in Lawrence and Pennington (1998), trace element data for bed sediment and crayfish samples are compiled in Lawrence (1998), and surface water-quality data are compiled in Emett and others (1994), Clary and others (1995); and Bauer and others (1996).
Biological data-collection activities within NVBR consisted of sample collection, identification, and enumeration of algae, aquatic invertebrate, and fish populations at select sites in the Carson and Truckee River Basins. The sampling protocols developed were designed to identify species distribution and community structure in algae (Porter and others, 1993), aquatic invertebrate (Cuffney and others, 1993a), and fish populations (Meador and others, 1993). The distribution of species, in particular, community structure, provides the only means for directly identifying ecosystem health that is sensitive to both toxicological influence and habitat degradation (Cuffney and others, 1993a).
This report presents a compilation of physical and biological data collected from 20 sites that were sampled principally between 1993 and 1996 in the Carson and Truckee Rivers, Nevada and California. Biological data also are included for one site on the Truckee River where additional samples were collected in 1997. The physical data describe the stream habitat and the biological data describe the algal, aquatic invertebrate, and fish populations in the streams. The biological data for algae and small aquatic invertebrates were derived from 103 semi-quantitative and 55 qualitative samples for algae and 49 semi-quantitative samples for aquatic invertebrates. Fish and crayfish populations were sampled 29 times using electroshocking and seining.
The only chemical data presented are concentrations of chlorophyll a and b in algae. Chemical data for asiatic clams (Corbicula sp.), caddisfly larva (Hydropsyche sp.), and crayfish (Pacifastacus leniusculus) were published by Bonner and others (1998, p. 558-560). The relation between trace element concentrations in bottom sediment and crayfish tissue was interpreted by Lawrence (1998).
The study area consists of the Carson and Truckee River Basins in Nevada and California and the Upper Truckee River Basin upstream from South Lake Tahoe, Calif. (fig. 1). The Upper Truckee River at South Lake Tahoe, Calif., was the only site sampled within the Lake Tahoe Basin. The environmental setting is described in detail by Covay and others (1996) and detailed physical and geomorphological measurements in selected reaches of the Carson and Truckee Rivers are given by Lawrence and Pennington (1998).
NAWQA data-collection sites are classified as basic-fixed sites and as synoptic sites. Basic-fixed sites are sites where a broad suite of chemicals are analyzed in water, bed sediment, and aquatic biota, where continuous discharge measurements are made; and where ecological surveys are completed (Porter and others, 1993). Basic-fixed sites form the backbone of NAWQA's long-term trend and transport evaluations, and the integrated physical, chemical, and biological studies within and among assessment cycles within NAWQA. Synoptic sites are those sites where limited chemical, physical, and biological data samples are collected only once in a NAWQA cycle (Porter and others, 1993).
A total of seven basic-fixed sites (three on the Carson River and four on the Truckee River) were sampled between 1993 and 1996 (fig. 1). Thirteen additional synoptic sites (seven on the Carson and six on the Truckee River) were sampled in 1994 and 1995. Additional data were collected at one basic-fixed site on the Truckee River in 1997. Selected physical data also were collected at all sites used for biological sampling in the Carson and Truckee River Basins.
At some of the data-collection sites the length of the river where samples were collected was uniform with regard to depth, slope, and bottom. At other sites the length of the river sampled was not uniform and at those sites the river was broken into segments or "reaches" that were uniform. Descriptions of the reaches are given by Lawrence and Pennington (1998).
Physical data such as water depth, velocity, dominant and subdominant substrate type, substrate embeddedness, water temperature, and mean daily discharge were collected to provide information describing the habitat where the organisms were collected. Water-quality parameters such as dissolved oxygen, pH, and specific conductance were not measured during collection of biological material; however, they were measured at many of the data collection sites between 1993 and 1997 (Emett and others, 1994; Clary and others, 1995; Bauer and others, 1996; Bostic and others, 1997; and Bonner and others, 1998).
Physical measurements, except water temperature and mean daily discharge, were taken at the location where an algae and aquatic invertebrate sample was collected. Water depth was measured using the USGS top-setting wading rod and stream velocity was measured with a rated pygmy meter attached to the wading rod (Rantz and others, 1982a and b). Dominant and subdominant substrate type and embeddedness were determined visually. Water temperature was measured continuously at the nearest USGS gaging station using a USGS minimonitor and datalogger. Mean daily discharge was derived from stream discharge records from the nearest USGS gaging station.
Semi-quantitative samples for algae and aquatic invertebrate were collected from a richest-targeted habitat (RTH), usually cobble or gravel riffles. Algae and aquatic-invertebrate samples also were collected from a depositional-targeted habitat (DTH), usually pools. In the DTH, however, only the algae samples were analyzed. Because sand and silt were the predominant substrates at two sites in the study area, submerged woody snags were considered the RTH at those sites. In each of the habitats, subsamples were collected at locations that were representative of the entire habitat within the reach. The surface area of the subsample was known or calculated from the sampling equipment. Three to five subsamples were collected from each habitat and composited in the field. Stream depth and velocity were measured at the location of each subsample, and substrate type and embeddedness were determined. Additional details about the semi-quantitative sample collection methods used are given in Porter and others (1993) and Cuffney and others (1993a and b).
For some algal samples collected at the depositional-targeted habitats, not all data required for calculating dilutions were collected. For these samples, the density of the populations in cells, per square centimeter, of habitat could not be calculated. The density of algal populations for these samples is given as a percent of the cells counted during the algal identification and enumeration.
Qualitative multihabitat (QMH) samples for algae and aquatic invertebrate were collected at basic-fixed sites and at synoptic sites. Qualitative sampling involved sampling all available habitats without regard to a known areal dimension: riffles both mid-channel and along the edges, pool environments, macrophyte and macroalgae beds, and woody debris and snags. Details for the qualitative sample collection methods used are given in Porter and others (1993) and Cuffney and others (1993a).
Algae were semi-quantitatively sampled in the cobble-riffle habitat by selecting one or two representative stones from each RTH subsample location. For those sites where only three subsamples were collected, a minimum of six stones was selected. A small area on the surface of each stone was isolated by a periphyton sampler and periphyton removed within that area with a stiff-bristled brush. An "O" ring gasket on the sampler/stone interface isolated an area of the stone and allowed the sampler to hold stream water. Water was added to the sampler to aid in scraping and produce an algal slurry that was transferred to a container for compositing of each subsample.
Depositional-targeted habitats were sampled using a 47-mm plastic, disposable microbiological petri dish pushed into the surface layer of sediment. The petri dish defined a circular sample area of 17.35 cm2 and a depth of 3 mm. While the petri dish with its trapped sediment remained in the stream bottom, a flat, plastic spatula was slid into the stream bottom and under the petri dish and both the dish and sediment were removed. Five subsamples were collected at different locations within the depositional habitat and composited into a wide-mouth, polyethylene bottle. A solution of 5-percent buffered formalin was used as a preservative. Samples were then shipped to the Biological Unit at the USGS National Water-Quality Laboratory (NWQL).
After algae scrapings from each stone were composited, a 15-mL aliquot of sample material was transferred to a 20-mL polyethylene vial. Eight to ten drops of formaldehyde were added to the vial to produce a 5 percent formalin solution for preservation of algal cells. Samples were then shipped to the Biological Unit at the USGS-NWQL and from there to the Philadelphia Academy of Sciences in Philadelphia, Penn., for algae identification and enumeration.
Aliquots of the preserved material were diluted and examined under the microscope. Cells were identified to species where possible, but often cells could only be identified to a higher level taxa. In these cases the cells may represent plants new to science, or the cells may belong to known species but could not be identified for various reasons. Such unidentifiable cells could have been lacking necessary diagnostic characteristic because they were immature. Cells were enumerated by diluting the aliquots and counting under the microscope the number and types of cells in known volumes.
Two 25- to 50-mL aliquots of sample material were filtered through glass-fiber filters at the collection site to collect algae cells for ash-free dry weight and chlorophyll a and b measurements. Each filter was folded into fourths, wrapped in aluminum foil, placed in a labeled, 20-mL polyethylene vial, frozen, and shipped to the USGS-NWQL for analysis. USGS analytical methods used for ash-free dry weight and chlorophyll a and b determinations were those published in Britton and Greeson (1988).
Detailed discussion about all aspects of aquatic invertebrate sampling in the NAWQA program are given by Cuffney and others (1993a). Aquatic invertebrate RTH samples were collected in the same general habitat area that algae RTH samples were collected. Precise sample locations were different, however, to ensure sampling activities for algae had not disturbed the invertebrate community.
In cobble riffles, a rectangular dip net, 30 cm in depth and 51 cm in width, was used to collect an RTH subsample. The net bag was nylon with a mesh of 425 µm. The open end of the net was placed facing upstream and a 45-cm area of the riffle upstream from the net was disturbed to a depth of about 8 cm. Submerged woody snags were sampled by placing the net downstream from the snag and brushing invertebrates off the wood with a small, nylon brush. Burrowing invertebrates visually detected in the substrate were removed using forceps.
Qualitative multihabitat samples were collected from all wadeable habitats using a D-frame net with a net-bag mesh of 210µm. Dimensions of the area sampled were not measured. Sample processing was similar to RTH sample processing.
For both RTH and QMH samples, the contents of the net at each subsample location were composited in a 9.5-liter bucket. These composite samples were processed on the stream bank using an elutriation method whereby the bucket, with streamwater, is vigorously swirled to wash invertebrates out of the accumulated sand, algae, and detritus (elutriation). After swirling, water with suspended invertebrates was poured through a 425-µm mesh nylon sieve (RTH sample) or a 210-µm mesh brass sieve (QMH sample). This processing allowed three subsets of the sample to be identified and preserved separately. One subset contained large and rare invertebrates, another contained the main body or bulk of the sample, and the third subset contained the sands and gravels remaining after elutriation. These three subsets facilitated identification and enumeration by separating out large and rare invertebrates that might be missed when the main body of the sample was split and subsampled in the laboratory. The sands and gravels were further processed in the USGS Nevada District laboratory to ensure that clams, snails, cased caddisfly larvae, or other "heavy" invertebrates were not missed.
After sieving and removing large and rare invertebrates, the remaining contents on the sieve were placed in a sample bottle and labeled as the main body. Aquatic insect samples were preserved at the stream site by adding Kahle's solution to each bottle. Kahle's solution is a mixture of glacial acetic acid, formaldehyde, ethanol, and water (Pennak, 1989, p. 608). After several weeks in Kahle's solution samples were placed in 80 percent ethanol. Clams and snails were preserved at the stream site with 80 percent ethanol because the acetic acid in Kahle's solution can dissolve the shell. All samples were shipped to the Biological Unit at the USGS NWQL for analysis. Methods used by the USGS NWQL for processing aquatic invertebrate samples are given in Cuffney and others, 1993b).
The invertebrates were identified to species where possible but often only could be identified to a higher level taxa. In these cases the invertebrates may represent organisms new to science or may belong to a known species but could not be identified for various reasons. For example, such unidentifiable organisms could have been lacking necessary diagnostic characteristics because they were immature or were damaged during sample collection.
Crayfish were collected using the electroshocking procedure described in the following section ("Fish Sampling Methods") and by "minnow-type" traps (Hubert, 1983), built by study unit personnel. These traps were 25 x 51 x 91 cm in size and constructed of 1.25-cm hardware cloth. Traps were open at both ends and the openings were tapered inward with hardware cloth from the 25 x 51 cm original opening to a 5 x 7.5 cm opening which prevented the crayfish from escaping. All traps were baited with beef heart and left in the stream overnight. Crayfish collected in the traps were processed in the same manner as those collected by electroshocking.
Detailed descriptions of fish sampling methods used in the NAWQA program are given in Meador and others (1993). Fish populations were sampled at each site using a combination of electroshocking methods and seining. A backpack-mounted electroshocker was used to collect fish within stream reaches where a seine could not be used because of rocks, debris, or water with high velocity. A sampled reach ranged from 91 to 365 m in length. Multiple passes were not attempted because of the length of the reaches and the stress incurred by fish inhabiting water with temperatures above 25°C. As fish were stunned by the pulsed direct current, they were collected with dip nets or a 3-m seine placed downstream from the electroshocker. Fish were placed in buckets and ice chests and kept alive by aerating the water with battery-operated pumps. If possible, up to 30 fish were measured for total length, standard length, weight, and observed for external anomalies such as lesions, tumors, parasites, fungus, fin erosion or other deformities, and disease. NAWQA protocols for measuring total and standard length and evaluating external anomalies on fish are described by Meader and others (1993). If more than 30 fish were collected, the remaining were counted. Most fish collected were returned alive to the river where they were collected. Fish were identified in the field by the senior author. Some specimens were retained in a preserved state to confirm the field identification. Confirmation of field identifications were made by Larry Brown (USGS, Sacramento, Calif., written commun., 1994 and 1995) or locally in the USGS Nevada District Laboratory by the senior author.
Data presented in this report are for the following: Physical characteristics of the richest-targeted habitat (table 1); a taxonomic list of the algae identified and the habitats in which they were found (table 2); algal abundance from the Carson River (tables 3, 4, 5, 6, 7, 8, 9, 10, 11, and 12) and the Truckee River (tables 13, 14, 15, 16, 17, 18, 19, 20, and 21) ; ash-free dry weight and chlorophyll concentration in algae samples from the Carson and Truckee Rivers (table 22); a taxonomic list of aquatic invertebrates identified in samples collected at the Carson and Truckee Rivers (table 23); abundance of aquatic invertebrates from the Carson River (tables 24, 25, and 26) and the Truckee River (tables 27, 28, and 29); a taxonomic list of fish identified (table 30); and data for fish and crayfish collected from the Carson River (tables 31, 32, and 33) and Truckee River (tables 34, 35, 36, 37,and 38).
For the invertebrates, a binomial listed with a name after the species name (for example, Pacifastus leniusculus Dana) shows the name of the first person to validly publish the species name as given. A binomial listed with a name in parentheses after the species name [for example, Hyallela azteca (Saussure)] shows the name of the first person to validly publish the species name, but under a different genus. For aquatic invertebrates and fish, the validity of a species name is determined by the International Committee on Zoological Nomenclature.
Values presented in tables 6-33 are rounded to only two significant figures. Sampling algae and benthic invertebrates directly from natural substrates presents special sampling challenges and the uncertainty in the numbers is an inherent limitation of the sampling process. Precisely determining the area sampled is difficult for rocks and submerged branches. Some samplers like those used in this study have precisely defined areas, however, irregularities in the surfaces of rock can cause leakage of sample material around the edges.
A total of 103 semi-quantitative and 55 qualitative algae samples were collected at sites on the Carson and Truckee Rivers between 1993 and 1996. These samples represent algae in cobble riffles, on submerged woody snags, and on sediment surfaces in depositional areas. In those 158 samples, 514 algal species, varieties, or forms were identified. Of the 8 algal phylum represented, the diatoms (Phylum Bacillariophyta) were the most abundant with 351 species, varieties, or forms. The green algae (Phylum Chlorophyta) were next in abundance with 108 species, varieties, or forms followed by the blue-green algae (Phylum Cyanophyta) with 41 species, varieties, or forms.
A total of 49 semi-quantitative aquatic invertebrate samples were collected at sites on the Carson and Truckee Rivers between 1993 and 1996. These samples represent invertebrates in cobble riffles and on submerged woody snags. In those 49 samples, members of 6 phyla were identified. Roundworms were identified only to phylum (Nematoda) and free-living flatworms and snails were identified only to class (Turbellaria and Gastroda). Organisms could be identified belonging to 19 invertebrate orders. Most of the invertebrates that could be identified to genus or species belonged in the orders Ephemeroptera, Plecoptera, and Trichoptera of the arthropod class Insecta.
Fish and crayfish populations in the Carson and Truckee Rivers were sampled 29 times between 1993 and 1997. These collections resulted in the identification of 18 fish species and one endemic crayfish species. Twelve of the 18 fish species identified are not native to the Carson and Truckee River Basins.
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