Great Basin Naturalist Volume 52 Number 2 Article 3 9-22-1992 Diatom flora of Beaver Dam Creek, Washington County, Utah, USA Kurtis H. Yearsley Brigham Young University Samuel R. Rushforth Brigham Young University Jeffrey R. Johansen John Carroll University, University Heights, Ohio Follow this and additional works at: https://scholarsarchive.byu.edu/gbn Recommended Citation Yearsley, Kurtis H.; Rushforth, Samuel R.; and Johansen, Jeffrey R. (1992) "Diatom flora of Beaver Dam Creek, Washington County, Utah, USA," Great Basin Naturalist: Vol. 52 : No. 2 , Article 3. Available at: https://scholarsarchive.byu.edu/gbn/vol52/iss2/3 This Article is brought to you for free and open access by the Western North American Naturalist Publications at BYU ScholarsArchive. It has been accepted for inclusion in Great Basin Naturalist by an authorized editor of BYU ScholarsArchive. For more information, please contact [email protected], [email protected]. Great Basin Naturalist 52(2), pp 131-138 DIATOM FLORA OF BEAVER DAM CREEK, WASHINGTON COUNTY, UTAH, USA Kurtis H. Yearslel, Samuel R. Rushforth1, and Jeffrey R. Johansen! ABSTRACT.-The diatom flora ofBeaver Dam Creek, Washington County, Utah, was studied. The study area is in awarm MOjave Desert environment at an elevation between 810 and 850 m. A total of 99 taxa were identified from composite samples taken in the fall, winter, spring, and summer seasons. These taxa are all broadly distributed and no endemic species were encountered. Three new records for the state of Utah were identifted: Gomp!umeis eriense Sky. & Mayer, Navicula clginensis var.lata (M. Perag.) Paa., and Nitzschia-calida Grun. The most important taxa throughout the studyas determined by multiplying percent presence by average relative density (Important Species Index) were Cymbella affinM Katz., Epithemia sorex Katz., Navicula veneta Katz .. Nitzschia paleo. (Klitz.) W. Sm., and Nitzschia microcephala Grun. K£y words, Bea"",' Dam Creek, diatoms, desert streams. The algal flora ofthe IntermountainWest of tional areas with slower flows, and (3) epiphytiC North America is not well known despite the habitats on the stems and leaves ofaquatic vas­ fact that numerous studies dealing with algal cular plant vegetation. systems ofwaters in this region have been com­ pleted in recent years. These studies have exam­ SITE DESCRIPTION ined streams, fresh water lakes, saline lakes, thermal springs, and terrestrial habitats (Sommerfeld et al. 1975, Stewart and Blinn Beaver Dam Creek at Lytle Ranch Preserve 1976, Czarnecki and Blinn 1977, 1978, Blinn et is located 37'10' North latitude and 114' West longitude in Wasbington County, Utah (Fig. I). al. 1980, Bush and Fisher 1981; for bibliogra­ The stream occurs in our study area at an eleva­ pbies see Rushforth and Merkley 1988, Melting tion ofabout 850 m at Lytle Ranch dropping to 1991). 810 m at Terry's Ranch. Our study sites are Algal floras ofwarm desert systems are espe­ located along the wash near the ranch house at cially poorly known. The present study was ini­ Lytle Ranch Preserve and near a smaller out­ tiated to provide additional information on the building at Terry's Ranch. diatom flora ofa desert stream located in west­ Beaver Dam Creek is a vigorous, braided em North America. We examined the diatom perennial desert stream. It is important to the communities ofBeaver Dam Creek, a tributary entire biota ofthe area since it is the main source of the Virgin River in southwestern Utah. This of l?erennial water. The stream through the paper is intended as a baseline floristic and study area has formed a broadgravel flood plain community study of the diatom communities due to frequent flooding. The stream occurs in present in this Mojave Desert stream. bajada and alluvial fan materials derived from We had three objectives in this study: (1) to the Bull Valley, Pine Valley, and Santa Clara identifY all species ofdiatoms present in Beaver mountains (Welsh et al. 1987). Dam Creek, (2) to document seasonal variation Beaver Dam Creek is fed by seeps, springs, in the diatom communities of this stream, and and snowmelt primarily from the Pine Valley (3) to compare diatom populations according to Mountains. This area is also characterized by habitat type. Our study reports all diatom taxa flash floods caused hy severe periodic tbunder­ present in this stream across fouT seasons of storms in the summer and fall seasons. For 1987-88. We studied populations in (1) rime instance, prior to the April 1988 collection, areas with erosional flow velocities, (2) deposi- Beaver Dam Wash received 11 days of rain 1DepRrtroent of Bott.ny and ~~, 8righam Young Uni"e1'Jity, ProYo, Uab 84602. s.Depwtrneot ofBiology, Jdm Carroll Univenity. University ~~b;, Obio ~1l8. 131 132 GREAT BASIN NATImALIST [Volume 52 3100-, g '"'" c LvtleAanc? ,,} 3\00 ~ Canyon ~ <'6'Q V 3100 3200 .c: ~'" UTAH t ...........Iol-"'-_.........l......._ ....__..............__.:::.._" • Study Site Fig. 1. Map ofBeuver Dam Wash showing the location ofcollt:d:ing localities at Terry's Hunch and Lytle Ranch Preserve. Due to the meandering and changing nature of Beaver Dam Creek, the stream itself is not shown on this map. 1992] DIATOMS OF BEAVER DAM CREEK 133 producing moderate to severe flooding along METHODS the stream channel. This scoured the stream channel) removing large amounts of aquatic Water chemistry was sampled at the collec­ vegetation and causing channel relocation in tion sites for February, April, and July 1988 some areas. using a portable Hach field water chemistry lab. The gravel bar in Beaver Dam Creek is gen­ Air temperature and water temperature, dis­ erally higher in the center than at the margins, solved oxygen, hardness, alkalinity, and pHwere causing the stream to meander over a wide area measured. with frequent changes ofchannel during flood­ Diatom collections were taken on 21 ing (Welsh et al. 1987). The fall in elevation November 1987, 20 Fehruary 1988, 30 April downstream is not constant. Gravel tends to pile 1988, and 6 July 1988 to document seasonal up in steps that vary in length and height. This variations in diatom populations. Composite uneven granular substrate causes the stream to samples were collected from three habitat types. First, riffle areas with erosional flow rates meander along the gravel bar and eventually to were sampled by scraping algae from large sink underground approximately four miles stones in the creek bed. Second, slow water below the southernmost collection site (Welsh areas in the stream were sampled by obtaining et al. 1987). The perennial stream reappears sediments, rock scrapings, and visible attached infrequently as seeps and springs lower' in algae. Finally, submerged sedge stems and Beaver Dam Wash until mergingwith the Virgin leaves were scraped or collected at selected River. iocalities to study epiphytiC assemblages. Climate in the study area varies consider­ Due to seasonal changes, it WdS not always ably, not only diurnally and seasonally, but over possible to sample all three substrate types at longer periods of time. Winters are generally both locations. A total of 19 samples were ana­ cool and dry, summers hot and dry. Maximum lyzed during the course of the study. Samples summertime temperatures have been recorded were stored at air temperature and returned to at 45.6 C. Rainfall averages less than 15 cm a the labordtory at Brigham Young University for year, although this is variable due to intense analysis. storms (Welsh et al. 1987). Diatoms were cleared hy boiling in nitric acid and potassium dichromate (St. Clair and The biota of our study area is exceptionally Rushforth 1977). After rinsing, cleared frustules diverse. Mammals, birds, reptiles, amphibians, were suspended in distilled water and allowed invertebrates, and a great variety ofplants occur to air dry on cover slips. Strewn mounts were in Beaver Dam Wash (Welsh et aI. 1987). The prepared using Naphrax high-resolution resin. stream supports a diverse riparian habitat con­ Representative slides were examined with Zeiss sisting of Fremont cottonwood (Popmus RA microscopes equipped with Nomarski fremontii Wats.), Arizona ash (Fraxinus velutina optics and bright field illumination. An Olym­ Torr.), black willow (Salix gooddingii Ball), seep pus AD photomicrographic system was used to willow (Baccharis emoryi GrayinTorr.), numer­ record each taxon. Strewn mounts have been ous forbes, grasses, andgrasslike species (Welsh placed in the collections at Brigham Young Uni­ et al. 1987). Silty terraces occur immediately versity. adjacent to the wash and have been historically A minimum of 500 valves was counted for used for cultivation. These areas-are dominated each sample, and a percent relative density was by catclaw acacia (Acacia greggii Gray), panicu­ calculated for each taxon (Kaczmarska and late rabbitbrush (Chrysothamnus paniculatus Rushforth 1983). An Important Species Index (lSI) for taxa present was calculated by multi­ [Gray] Greene), Ambrosia species, and numer­ plying the percent frequency ofoccurrence ofa ous others (Welsh et al. 1987). Adjacent uplands taxon in the samples by its overall average per­ support Joshua tree forests (Yucca bremjolia cent relative density in all samples (Ross and Engelm.), creosote bush (Larrea trioontata Rushforth 1980, Kaczmarska and Rushforth [DC.] Cov.), prickly pear cactus (Opuntia 1983). This method is useful since it considers engelmonnii Engelm.), cholla cactus (Opuntia both abundance and seasonal distribution of a basilaris Engelm. and Bigel.), and numerous taxon (Warner and Harper1972). Species diver­ other xerophytic species (Welsh et aI. 1987). sity for each sample was calculated using the 134 GREAT BASIN NATURALIST [Volume 52 TABLE 1. Mean values for air tempernture and water chemical parameters tnken from collecting localities in Beaver Dam Creek, Washington County, Utah. February April July Lytle Terris L)11e Teny's 4't1e Terry's Air temp. (C) 16.3 17.3 2ll.5 2ll.5 33.0 26.0 Water temp. (e) 14.5 17.5 16.8 16.8 24.3 22.3 Dissolved 02 (mgll) 9.5 10.0 9.0 9.0 7.7 7.0 Hardness (mgll) 247.3 276.1 707.5 707.5 281.9 362.4 Alkalinit)' (mgt1 195.6 207.1 201.3 224.3 pH 7.3 7.1 6.9 7.0 8.I 7.7 TARU; 2.