2000 Progress Report: Multi-level Indicators of Ecosystem Integrity in Alpine Lakes of the Sierra NevadaEPA Grant Number: R827643
Title: Multi-level Indicators of Ecosystem Integrity in Alpine Lakes of the Sierra Nevada
Investigators: Oris, James T. , Bailer, A. John , Guttman, Sheldon I. , Miller, Glenn C. , Reuter, John E.
Institution: Miami University , University of California - Davis , University of Nevada - Reno
EPA Project Officer: Hahn, Intaek
Project Period: September 13, 1999 through September 12, 2002 (Extended to September 12, 2003)
Project Period Covered by this Report: September 13, 1999 through September 12, 2000
Project Amount: $894,627
RFA: Ecological Indicators (1999) RFA Text | Recipients Lists
Research Category: Ecosystems , Ecological Indicators/Assessment/Restoration
The overall objective of the proposed research is to develop protocols for environmental assessments of alpine lakes in the Sierra Nevada with a range of human impacts. These assessments will be conducted over the range of levels of biological organization (molecular to ecosystem) utilizing currently available assessment techniques and with the addition of two new ecological indicators. The use of population genetics analysis as a response indicator and the use of molecular biomarkers of exposure to contaminants as a diagnostic indicator are proposed for incorporation into monitoring and assessment programs for surface waters. These indicators will provide critical information concerning the status of population diversity and stability and concerning the exposure to non-persistent, non-bioaccumulative contaminants. This is information that is missing from current monitoring and assessment protocols.
Over the three year project period, we will conduct standard environmental assessments of a select group of alpine lakes with a defined range of human impacts. There will be a total of 16 assessment sites. Those selected for assessment include four minimally impacted areas (Castle Lake, Eagle Lake, Marlette Lake, and Upper Angora Lake), eight areas with a range of moderate impacts (Fallen Leaf Lake, Gold Lake, Lake Tahoe at Sand Harbor, Prosser Reservoir, Spaulding Reservoir, Stampede Reservoir, Topaz Lake, and Twin Lakes), and four highly impacted areas (Boca Reservoir, Donner Lake, Lake Tahoe at Tahoe City, and Lake Tahoe at Tahoe Keys).
In addition to the standard assessment, we will conduct population genetic assessments in fish and invertebrates at these same sites. Allozyme electrophoretic analysis and Randomly-Amplified Polymorphic DNA (RAPD) analyses will be conducted on two organisms common to the lakes of the region (fish: Lahontan redside; invertebrate: Signal crayfish). We also will conduct contaminant exposure assessments in fish using molecular biomarkers of exposure in the gills of fish. Five markers indicative of exposure to a wide variety of chemical contaminants (persistent and non-persistent) and that can account for interactions among complex mixtures of contaminants will be measured over time in the assessment areas using caged rainbow trout.
We then will apply these additional techniques to current assessment protocols. Because we will be examining a group of lakes with defined levels of human impacts, we will be able to analyze the discriminatory ability of the assessment techniques using the current protocols compared to the protocols with the two new indicators added. We hypothesize that since current protocols do not account for genetic diversity or non-persistent contaminants, the addition of these new indicators will greatly enhance monitoring and assessment programs for surface waters.
General Overview. From the initiation of the project through May 2000, we purchased all budgeted equipment and organized the project. Techniques for sampling and measurement of genetic and molecular biomarkers were refined. A meeting of all PI's was conducted in April 2000, at the UC Davis Tahoe Research Group Laboratory in Tahoe City, CA. Most of the assessment sites were visited by the PIs during this trip. During this meeting, the sampling schedule for sites was determined. In addition, it was decided that it would be appropriate to choose two lakes for annual repeat samplings. These sites were determined to be one minimal impact site (Marlette Lake) and one high impact site (Donner Lake). In early May 2000, project staff conducted a trial assessment at a local lake (Acton Lake, Butler Co., OH). Staff and students moved to the Tahoe region in early June 2000, and assessments began in June 2000. As planned, full assessments and sampling were conducted at eight sites during the period June through August 2000, with one assessment site completed each week of an eight week sampling period. The following sites were sampled: Minimal Impact: Marlette Lake and Eagle Lake; Moderate Impact: Gold Lake, Stampede Reservoir, Prosser Creek Reservoir, and Lake Spaulding; High Impact: Donner Lake and Tahoe Keys (Lake Tahoe). The original assessment plan called to conduct sampling at Ski Run Marina in South Lake Tahoe. However, because of logistical considerations and sampling requirements, we changed that site to nearby Tahoe Keys. The Tahoe Keys was originally a marsh at the south end of Lake Tahoe. It was developed during the 1970s into a canal community of homes, with private docks and a large and active marina. In addition to the full assessments conducted at eight sites, seven of the eight remaining sites were initially sampled for amphipods to conduct genetic diversity measurements. After the sampling season was complete, sample processing took place from the period of August 2000, through the present time. At this time, all chemical analyses are complete, most of the biological samples have been processed, approximately one half of the biomarker samples have been processed, and approximately one half of the genetics samples have been processed. We will continue to process samples and do preliminary analysis prior to initiating the next field sampling season.
Physical Water Quality Measurements. At each of the eight lakes sampled during the 2000 field season, a temperature and dissolved oxygen (DO) profile of the water column was measured using a YSI multi-parameter Water Quality Monitor (610DM and 600XL sonde). The profiles were conducted at the index location in the deepest portion of the lake. Data was recorded from the surface to the bottom of the water body. Due to the physical differences between lakes, there was a large variation in profile depth ranging from the Tahoe Keys (6m) to Stampede Reservoir (45m). The temperature and dissolved oxygen profiles were used to determine the limnetic zones of each lake (epilimnion, metalimnion, and hypolimnion). These measurements formed the framework for determining the depth of various biological sampling techniques.
Water Sample Collections. Water samples were collected from two depths at the index station in each of the lakes. A shallow sample was collected from 1-1.5 m below the surface and a deep sample was taken from 1m above the bottom. The shallow sample was collected by hand while the deep sample was retrieved using a Van Dorn sampler. Water samples were retained in separate sealed containers and transported on ice to the appropriate laboratory for analysis. Water to be analyzed for nutrients and chlorophyll "a" were returned to the TRG laboratory in Tahoe City. Samples to be analyzed for dissolved organic carbon, mercury, metals, anions, cations, chloronated hydrocarbons, ortho-phosphates, and polycyclic aromatic hydrocarbons were delivered to the University of Nevada Reno for analysis. Nutrient samples were analyzed for total phosphorus (TP), soluble reactive phosphorus (SRP), nitrate (NO3), and ammonia (NH4) using standard colorimetric techniques. The water samples collected for chlorophyll "a" analysis, were kept on ice in opaque bottles during transport. A 100ml sub-sample was filtered on the day of collection through a 0.45 µm, GF/C filter. Filters were stored frozen for later analysis. Both, chlorophyll and the degradation product, pheophyton, were extracted in methanol and determined by fluorescence on a Turner III fluorometer.
Benthic Sample Collections. Benthic grab samples were collected using a Ponar grab sampler at a depth equal to the top of the metalimnion, offshore of each habitat assessment station. When an adequate sample could not be obtained from a particular site, the site was abandoned and the next habitat assessment station was used. Due to varied substrate types (soft silt to granite bedrock), the total number of benthic samples collected differed from lake to lake. Five or more samples were collected at five of the lakes while only two or three were possible at the remaining three lakes. Sorting of benthic invertebrates from the collected samples is ongoing at the TRG laboratory.
Sediment Core Collection. The collection of sediment cores was hampered during the summer of 2000 due to equipment problems. However by the end of September, half of the lakes had been successfully cored. Plans have been made to return to the remaining lakes during the late spring of 2001, prior to the second year of sampling.
Collected cores averaged 50cm in length, which is believed to be sufficient to attain pre-urbanization sediment history conditions for the natural lakes in the area. All cores were returned to the TRG laboratory where their entire length was sectioned into 1cm fractions. The top and bottom sections of the cores will be analyzed for diatom assemblage during the winter months.
Zooplankton Collections. Zooplankton species were collected from each of the study lakes using an 80 µm mesh net with a 30 cm opening and a length of 1 m. Net tows were started one meter above the bottom and brought to the surface. Zooplankton were condensed in the net and preserved in accordance with EPA Lake Assessment protocols. These samples are currently being stored. An additional net with a 202 µm mesh has been purchased. Each lake will be sampled with both nets during the 2001 season in order to obtain a complete set of matched samples. These will be preserved and stored for winter counting at the TRG facilities. Any duplicate samples resulting from repeat sampling will be maintained for archive purposes.
Fish Assemblage Sampling. During the 2000 summer season, each lake was sampled with scientific fishing gear to determine the current resident fish assemblage. Gill net, minnow trap, and beach seine equipment was used in varying amounts of effort depending on the physical characteristics of the water body. All of the water bodies with the exception of the Tahoe Keys were thermally stratified. For this reason, gill nets and minnow traps were set both shallow and deep to capture species above and below the thermocline. Both bottom and mid-water nets were set in the evening and pulled the following morning. Monofillament gill nets with multiple mesh sizes proved to be the most successful method of fish capture. The greatest species diversity and abundance came from the gill net sampling. Fish captured in the gill nets were returned to the TRG laboratory. They were measured for length (fork length) and weight, and the gender and maturity of each fish was determined. Flesh samples of each species were frozen for later determination of mercury (Hg) contamination. Minnow traps were baited with dry dog food and allowed to fish overnight. The traps were successful in capturing benthic-oriented species, including crayfish, which do not exhibit the motility of limnetic species. For this reason the traps successfully represented the non-game fish species which are often the native component in lakes of Sierra Nevada mountain range. A sub-sample of each fish species captured in the minnow traps was measured for length prior to release to the water body. Beach seine hauls were conducted in shallow, near shore waters when visual observations detected fish populations that were not being sampled by the other gear types. This has proven to be a valuable method of capturing juvenile fish populations often underrepresented in offshore waters. A subsample of each fish species represented was measured for length frequency.
Contaminants Sampling. Water and fish samples from all sites were taken for contaminants analysis. All samples have been processed except mercury analysis in fish tissue. No contaminants (PCBs, PAHs, pesticides, herbicides) were measured above limits of detection for any of the samples.
Molecular Biomarkers. Biomarker analysis is incomplete at this time. However, we do have a comparison of data from a minimal impact lake (Eagle) and a high impact site (Tahoe Keys) for two of the biomarkers. Activin and MXR are both considered markers of general chemical stress. Both markers were significantly elevated in Tahoe Keys samples compared to Eagle Lake samples. These markers were elevated in spite of the fact that no chemical contaminants were measured at either assessment site. This result is extremely promising since standard assessment techniques (i.e., chemical measurements) would not have shown an impact due to contaminants at Tahoe Keys, yet the molecular biomarkers clearly showed that the fish experienced some chemical exposure. Because both markers are general indicators, we do not know which contaminants were present. However, an exposure was detected, and that result could be used in future assessments to direct further attention to suspected impact sites.
Amphipod Genetic Assessments. Sixteen sites were sampled in the Sierra Nevada for the freshwater amphipod, Hyalella azteca. We found ten sites (Marlette, Taylor Creek Marsh, Tahoe Keys, Stampede, Eagle Lake, Gold Lake, Topaz Lake, Truckee Marsh, Boca, and Emerald Bay) where amphipods occurred. Anywhere from 10-100 individuals were collected from each site (approximately 850 individuals were collected and are being stored in a Miami University -80 freezer). In the fall, cellulose acetate electrophoresis was performed using 13 enzyme systems (AAT, ACP, AO, G3PDH, GPI, LAP, LDH, MDH, ME, MPI, PEP, PGM, and TPI). All 13 systems showed Sierra individuals were genetically distinct from H. azteca. Additionally, the occurrence of two haplotypes (small and large) were described and also were found to be genetically distinct from one another. Thus, it seems we have found two new species of the genus Hyalella. Currently, we are in the process of comparing the genetic data to physical and chemical parameters (temperature, pH, dissolved oxygen, conductivity, watershed data, substrate type, etc) measured this past summer to determine the relationship between the population genetic structure of the amphipods to the level of anthropogenic influence at each site.
We will continue to analyze biological samples from the 2000 sampling season. During the summer of 2001, we will attempt to sample the remaining eight assessment sites. This will put us in position to analyze data from all 16 sites during the winter of 2002, and to determine if further sampling (other than the repeat sites?Donner Lake and Marlette Lake) is required.