A Comparison of Aquatic Invertebrate Assemblages Collected from the Green River in Dinosaur National Monument in 1962 and 2001 Final Report for United States Department of the Interior National Park Service Dinosaur National Monument 4545 East Highway 40 Dinosaur, Colorado 81610-9724 Report Prepared by: Dr. Mark Vinson, Ph.D. & Ms. Erin Thompson National Aquatic Monitoring Center Department o f Fisheries and Wildlife Utah State University Logan, Utah 84322-5210 www.usu.edu/buglab 22 January 2002 i Foreword The work described in this report was conducted by personnel of the National Aquatic Monitoring Center, Utah State University, Logan, Utah. Mr. J. Matt Tagg aided in the identification of the aquatic invertebrates. Ms. Leslie Ogden provided computer assistance. Several people at Dinosaur National Monument helped us immensely with various project details. Steve Petersburg, Dana Dilsaver, and Dennis Ditmanson provided us with our research permit. Ann Elder helped with sample archiving. Christy Wright scheduled our trip and provided us with our river permit. We thank them all for all their help and good spirit. We also thank Mr. Walter Kittams (National Park Service, Regional Office, Omaha Nebraska) and Mr. Earl M. Semingsen (Superintendent, Dinosaur National Monument) for funding the study and the members of the 1962 University of Utah expedition: Dr. Angus M. Woodbury, Dr. Stephen Durrant, Mr. Delbert Argyle, Mr. Douglas Anderson, and Dr. Seville Flowers for their foresight to conduct the original study nearly 40 years ago. The concept and value of long-term ecological data is often bantered about, but its value is never more apparent then when we conduct studies like that presented here. Additional copies of this report are available on the internet at: http://www.usu.edu/buglab/ cover photographs: Top left - Green River in Lodore Canyon, bottom - sunset near Big Island, top right - Homoeoneuria alleni [Ephemeroptera: Oligoneuriidae] adult and nymph. Scenery pictures by E. Thompson. Insect photograph by M. Vinson. 1 Summary of 1962 study Flaming Gorge Dam is located approximately 45 miles upstream from Dinosaur National Monument. The dam was completed in December 1962. Prior to the closure of Flaming Gorge Dam, the National Park Service initiated a study (National Park Contract No. 14-10-0232-685) to assess and survey the Green River and its surrounding environment. This study is described in detail by Woodbury (1963). This study was led by Dr. Stephen Durrant from the University of Utah. The expedition party sampled locations along the Green River from the Gates of Lodore downstream to Split Mountain from 20 July to 6 August 1962. Samples were also collected on the Yampa River near Deer Lodge and Echo Park. Data were collected on aquatic plants, aquatic invertebrates, fishes, as well as riparian and plants and animals. The objective of their aquatic invertebrate sampling was to determine the species present in the Green River prior to the closure of Flaming Gorge Dam. A synopsis of their sampling methods from Woodbury (1963) is as follows: At each site, samples were collected from all habitat types present. Samples were collected using a hand screen and a ¼ inch minnow seine. Abundance data is presented in the report, but this data should be evaluated cautiously, as the samples were qualitative in nature. It seemed that the invertebrates were likely removed from the debris in the field and identified back at the University of Utah. Drs. George Edmunds, Jr. and Arden Gaufin of the University of Utah consulted in the collection and identification of the aquatic invertebrates. We transcribed the aquatic invertebrate data in Woodbury s (1963) into our computer system. Where taxonomic changes had occurred since 1963, we changed their classification (invertebrate genus or species names) to those currently valid. Study design Our objective was to replicate the 1962 expedition as closely as possible. We collected samples at the same locations (Table 1), at the same time of the year (Table 2), using similar methods as the 1962 study. 2 Sampling Locations Table 1. Location of aquatic invertebrate sampling sites. Sites DINO-01 to DINO-06 were sampled in 1962 and 2001. Sites DINO-07 and DINO-08 were sampled only in 2001. Site ID Location Latitude Longitude Elevation (m) DINO-01 Green River at Lodore Ranger Station 40.728 108.888 1618 DINO-02 Yampa River at confluence with Green River 40.529 108.983 1557 DINO-03 Green River upstream from the Yampa River 40.530 108.984 1553 DINO-04 Green River at Steamboat Rock 40.526 108.992 1558 DINO-05 Green River at Rainbow Park 40.497 109.171 1514 DINO-06 Green River at Split Mountain Campground 40.444 109.251 1453 DINO-07 Green River at Rippling Brook Campsite 40.586 108.983 1548 DINO-08 Green River at Big Island Campsite 40.512 109.126 1512 Methods used in 2001 Locations and physical habitat The latitude and longitude of each site was determined using hand held global positioning units. Elevation was determined using U.S. Geological Survey 7.5 min topographic maps. Water and air temperatures were determined at the time of sampling using thermometers. The conductivity of the water was determined using an Oakton TDS Testr 40 hand held meter and the pH was determined using an Oakton pH Testr 2. Aquatic invertebrates Qualitative samples The objective of qualitative invertebrate collections was to collect as many different kinds of invertebrates living at a site as possible. Qualitative collections of invertebrates were done at all sites. Samples were collected with a rectangular kicknet (457 x 229 mm) with a 500 micron mesh net and by hand picking invertebrates from woody debris and large boulders. All available habitat types (e.g., riffles, po ols, back waters) were sampled and all samples were composited to form a single sample from each site. 3 Quantitative samples The objective of quantitative invertebrate sampling was to collect invertebrates from a fixed sampling area and estimate their relative abundances. Quantitative samples were collected using a modified Surber sampler (0.093 m2) with a 500 micron mesh net. Samples were collected by disturbing the area immediately upstream of the net with our hands and scrubbing individual substrate particles within the sampling area and allowing the invertebrates and detritus to wash downstream into the net. Eight samples were collected throughout a sampling reach and composited to make a single sample of approximately 0.7 m2 (8 samples x 0.093 m2). Laboratory methods The general procedures followed for processing invertebrate samples were similar to those recommended by the United States Geological Survey (Cuffney et al. 1993) and are described in greater detail and rationalized in Vinson and Hawkins (1996). Both qualitat ive and quantitative samples were ident ified in t heir entirety, i.e., all of t he organisms collected were identified. Organisms were identified to the lowest taxonomic level possible based on organism maturity, except for Chironomidae and some non-insect groups, which were identified to sub-family or Class or Order. Insects were most frequently identified to genus or family for small, immature, or damaged specimens. Species level identifications were based on identification keys, distributions records, and the author s experience. The number of individual invertebrates collected and identified in each sample is shown in Table 2. All identified invertebrates in each sample were composited into a single museum-grade glass screw-top vial with a polypropylene lid and polypropylene liner. Sample labels were written with fade proof permanent black carbon ink on waterproof paper. Information on each label included the sampling location, sampling date and a unique catalog number. Vials were filled with 70% ethanol. All samples were retained in our collection and will be sent to Dinosaur National Monument upon request. These samples will also be made available to other researchers upon request and permission from the National Park Service. Data analysis and presentation The primary objective of this study was to compare the invertebrate assemblages collected in 1962 to those collected in 2001. Data are provided on the occurrence and relative abundance 4 of aquatic invertebrates collected at each site for qualitative (1962 and 2001) and quantitative (2001) samples as well as composite (quantitative and qualitative samples) samples (2001) and a composite of all invertebrates collected by each study for all sampling locations. We used the data collected in 1962 as the basis for all comparisons presented here. We feel that our sampling effort was as great or greater than that done in 1962. Thus, if we failed to find a taxon, we think this suggests that this taxon may be extirpated from this reach of the river. Comparisons of taxa collected at individual sites should be done by comparing their data to the data from our qualitative samples, as these were done using similar methods, and presumably similar sampling effort, as was done in 1962. Table 2. Sampling dates, habitats sampled, type of sample collected, and the number of invertebrates identified in each sample. Data from 1962 is from Woodbury (1963). Sample ID is the National Aquatic Monitoring Center s identification number. Sampling Habitat Sample Invertebrates Sample ID Station date sampled type Identified 115827 DINO-01 07/28/2001 Riffle Quantitative 58 116147 DINO-01 07/28/1962 All present Qualitative 125 115828 DINO-02 07/30/2001 All present Qualitative 73 115829 DINO-02 07/30/2001