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C. M. Tate

Publications and source records attributed to C. M. Tate.

10 recordsLinked to original sources
USGS2007

Reactivation of a cryptobiotic stream ecosystem in the McMurdo Dry Valleys, Antarctica: A long-term geomorphological experiment

The McMurdo Dry Valleys of Antarctica contain many glacial meltwater streams that flow for 6 to 12??weeks during the austral summer and link the glaciers to the lakes on the valley floors. Dry valley streams gain solutes longitudinally through weathering reactions and microbial processes occurring in the hyporheic zone. Some streams have thriving cyanobacterial mats. In streams with regular summer flow, the mats are freeze-dried through the winter and begin photosynthesizing with the onset of flow. To evaluate the longer term persistence of cyanobacterial mats, we diverted flow to an abandoned channel, which had not received substantial flow for approximately two decades. Monitoring of specific conductance showed that for the first 3??years after the diversion, the solute concentrations were greater in the reactivated channel than in most other dry valley streams. We observed that cyanobacterial mats became abundant in the reactivated channel within a week, indicating that the mats had been preserved in a cryptobiotic state in the channel. Over the next several years, these mats had high rates of productivity and nitrogen fixation compared to mats from other streams. Experiments in which mats from the reactivated channel and another stream were incubated in water from both of the streams indicated that the greater solute concentrations in the reactivated channel stimulated net primary productivity of mats from both streams. These stream-scale experimental results indicate that the cryptobiotic preservation of cyanobacterial mats in abandoned channels in the dry valleys allows for rapid response of these stream ecosystems to climatic and geomorphological change, similar to other arid zone stream ecosystems. ?? 2006 Elsevier B.V. All rights reserved.

Geomorphology↗
USGS2005

Use of an urban intensity index to assess urban effects on streams in three contrasting environmental settings

To assess the effects of urbanization on assemblages (fish, invertebrate, and algal), physical habitat, and water chemistry, we investigated the relations among varying intensities of basin urbanization and stream ecology in three metropolitan areas: the humid northeastern United States around Boston, Massachusetts; the humid southeastern United States around Birmingham, Alabama; and the semiarid western United States around Salt Lake City, Utah. A consistent process was used to develop a multimetric urban intensity index (UII) based on locally important variables (land-use/land-cover, infrastructure, and socioeconomic variables) in each study area and a common urban intensity index (CUII) based on a subset of five variables common to all study areas. The UII was used to characterize 30 basins along an urban gradient in each metropolitan area. Study basins were located within a single ecoregion in each of the metropolitan areas. The UII, ecoregions, and site characteristics provided a method for limiting the variability of natural landscape characteristics while assessing the magnitude of urban effects. Conditions in Salt Lake City (semiarid climate and water diversions) and Birmingham (topography) required nesting sites within the same basin. The UII and CUII facilitated comparisons of aquatic assemblages response to urbanization across different environmental settings. ?? 2005 by the American Fisheries Society.

American Fisheries Society Symposium↗
USGS2004

Inorganic N and P dynamics of Antarctic glacial meltwater streams as controlled by hyporheic exchange and benthic autotrophic communities

The McMurdo Dry Valleys of South Victoria Land, Antarctica, contain numerous glacial meltwater streams that drain into lakes on the valley floors. Many of the streams have abundant perennial mats of filamentous cyanobacteria. The algal mats grow during streamflow in the austral summer and are in a dormant freeze-dried state during the rest of the year. NO 3 and soluble reactive P (SRP) concentrations were lower in streams with abundant algal mats than in streams with sparse algal mats. NO 3 and SRP concentrations were higher in the hyporheic zone of a stream with abundant algal mats than in the stream itself. An experimental injection of LiCl, NaNO 3 , and K 3 PO 4 was conducted in Green Creek, which has abundant algal mats. Substantial hyporheic exchange occurred. The NO 3 and PO 4 concentrations at 50 m below the injection were 55 μM and 18 μM, respectively, during the experiment. NO 3 and PO 4 concentrations were below the detection limit of 1 to 2 μM at a site 497 m below the injection during the Cl tracer arrival, indicating a high capacity for nutrient uptake by algal communities. NO 2 and NH 4 were present at sites 226 and 327 m below the injection, indicating that, in addition to denitrification and algal uptake, dissimilatory NO 3 reduction to NO 2 and NH 4 may be a NO 3 sink during transport. Transport modelling with nutrient uptake represented as a 1 st -order process yielded reach-scale parameters of 4.3 × 10 −5 to 3.9 × 10 −4 /s and 1.4 × 10 −4 to 3.8 × 10 −4 /s for uptake of NO 3 and PO 4 , respectively. The best match with the observed data was a model in which PO 4 uptake occurred only in the main channel and NO 3 uptake occurred in the main channel and in the hyporheic zone. Hyporheic NO 3 uptake was 7 to 16% of the total uptake for the different stream reaches. These results demonstrate that nutrient flux to the lakes is controlled by hyporheic exchange and nutrient uptake by algal mats in dry valley streams. Streams without algal mats contribute more nutrients to the lakes than streams with algal mats.

Journal of the North American Benthological Societ↗
USGS1999

Dry Valley streams in Antarctica: Ecosystems waiting for water

An axiom of ecology is: 'Where there is water, there is life.' In dry valley ecosystems of Antarctica, this axiom can be extended to: 'Where there has been and will be water, there is life.' Stream communities in the dry valleys can withstand desiccation on an annual basis and also for longer periods - as much as decades or even centuries. These intact ecosystems, consisting primarily of cyanobacteria and eukaryotic algae, spring back to life with the return of water. Soil organisms in the dry valleys also have remarkable survival capabilities (Virginia and Wall 1999), emerging from dormancy with the arrival of water. Streams in the dry valleys carry meltwater from a glacier or ice-field source to the lakes on the valley floors and generally flow for 4-10 weeks during the summer, depending on climatic conditions. Many of these streams contain abundant algal mats that are perennial in the sense that they are in a freeze-dried state during the winter and begin growing again within minutes of becoming wetted by the first flow of the season. The algal species present in the streams are mainly filamentous cyanobacteria (approximately 20 species of the genera Phormidium, Oscillatoria, and Nostoc), two green algal species of the genus Prasiola, and numerous diatom taxa that are characteristic of soil habitats and polar regions. Algal abundances are greatest in those streams in which periglacial processes, acting over periods of perhaps a century, have produced a stable stone pavement in the streambed. This habitat results in a less turbulent flow regime and limits sediment scour from the streambed. Because dry valley glaciers advance and retreat over periods of centuries and millennia and stream networks in the dry valleys evolve through sediment deposition and transport, some of the currently inactive stream channels may receive flow again in the future. Insights- into the process of algal persistence and reactivation will come from long-term experiments that study the effects of reintroducing water flow to channels in which flow has not occurred for decades or centuries. The present work of the McMurdo Dry Valleys LTER has led us to conclude that the legacy of past conditions constitutes a dominant influence on present-day ecosystem structure and function in the dry valleys (Moorhead et al. 1999). For example, Virginia-and Wall (1999) have found that soil nematodes are partly sustained by relict organic carbon from algae that grew during the high lake stands of 8000-10,000 years ago. Similarly, the growth of current algal populations in the lakes of the dry valleys is supported by diffusion of nutrients from relict nutrient pools in the deep bottom waters (Priscu et al. 1999). For the stream ecosystems, abundant algal mats are present in channels that have stable stone pavements, which formed through freeze-thaw cycles occurring over long periods, possibly hundreds of years. We hypothesize that these stone pavements are an important ecological legacy permitting the successful 'waiting for water' strategy. Similarly, the biodiversity of algal species that can survive the harsh conditions in the streams of the dry valleys may be stable for centuries or more, representing a second important ecological legacy.

BioScience↗
USGS1997

Concentration, distribution, and comparison of selected trace elements in bed sediment and fish tissue in the South Platte River Basin, USA, 1992- 1993

During August–November 1992 and August 1993, bed sediment and fish liver were sampled in the South Platte River Basin and analyzed for 45 elements in bed sediment and 19 elements in fish liver. The results for aluminum, arsenic, cadmium, chromium, copper, iron, lead, manganese, selenium, silver, uranium, and zinc are presented here. All 12 trace elements were detected in bed sediment, but not all were detected in fish liver or in all species of fish. A background concentration of trace elements in bed sediment was calculated using the cumulative frequency curves of trace element concentrations at all sites. Arsenic, cadmium, copper, lead, manganese, silver, uranium, and zinc concentrations were greater than background concentrations at sites in mining areas or at sites that have natural sources of these elements. Trace element concentrations in fish liver generally did not follow the same patterns as concentrations in bed sediment, although concentrations of aluminum and cadmium were higher in fish liver collected at mountain sites that had been disturbed by mining. Concentrations of aluminum, arsenic, cadmium, chromium, copper, iron, lead, silver, and zinc increased in bed sediments in urban areas. Iron, silver, and zinc concentrations in fish liver also increased in urban areas. Concentrations of cadmium, copper, silver, and zinc in fish liver increased in the agricultural areas of the basin. Downstream changes in trace element concentrations may be the result of geological changes in addition to changes in land use along the river.

Archives of Environmental Contamination and Toxico↗
USGS1996

Organochlorine compounds in bed sediment and fish tissue in the South Platte River Basin, USA, 1992-1993

Bed-sediment and fish-tissue samples were collected in the South Platte River Basin to determine the occurrence and distribution of organochlorine compounds in the basin. During August–November 1992 and August 1993, bed sediment (23 sites) and fish tissue (subset of 19 sites) were sampled and analyzed for 32 organochlorine compounds in bed sediment and 27 compounds in fish tissue. More types of organochlorine compounds were detected in fish tissue than in bed sediment. Total DDT, p,p ′-DDE, o,p ′-DDE, p,p ′-DDD, total PCB, Dacthal ® , dieldrin, cis -chlordane, cis -nonachlor, trans -nonachlor, and p,p ′-DDT were detected in fish tissue at >25% of the sites; p,p ′-DDE, total DDT, cis -chlordane, and trans -chlordane were detected in bed sediment at >25% of the sites. Organochlorine concentrations in bed sediment and fish tissue were related to land-use settings. Few organochlorine compounds were detected at minimally impacted sites located in rangeland, forest, and built-up land-use settings. Chlordane-related compounds and p,p ′-methoxychlor in bed sediment and fish tissue, endrin in fish tissue, and endosulfan I in bed sediment were associated with urban and mixed (urban and agricultural) sites. Dacthal ® in bed sediment and fish tissue was associated with agricultural sites. The compounds HCB, γ-HCH, PCA, and toxaphene were detected only at mixed land-use sites. Although DDT and DDT-metabolites, dieldrin, and total PCB were detected in urban, mixed, and agricultural land-use settings, highest mean concentrations were detected at mixed land-use sites. Mixed land-use sites had the greatest number of organochlorine compounds detected in fish tissue, whereas urban and mixed sites had the greatest number of organochlorine compounds detected in bed sediment. Measuring concentrations of organochlorine compounds in bed sediment and fish tissue at the same site offers a more complete picture of the persistence of organochlorine compounds in the environment and their relation to land-use settings.

Colorado, Nebraska, wyoming↗
USGS1996

Nitrogen transport from tallgrass prairie watersheds

Discharge and N content of surface water flowing from four Karat watersheds on Konza Prairie Research Natural Area, Kansas, managed with different burn frequencies, were monitored from 1986 to 1992. The goal was to establish the influence of natural processes (climate, fire, and bison grazing) on N transport and concentration in streams. Streams were characterized by variable flow, under conditions that included an extreme flood and a drought during which all channels were dry for over a year. The estimated groundwater/stream water discharge ratio varied between 0.15 to 6.41. Annual N transport by streams, averaged across all watersheds and years, was 0.16 kg N ha-1 yr-1. Annual N transport per unit area also increased as the watershed area increased and as precipitation increased. Total annual transport of N horn the prairie via streams ranged from 0.01 to 6.0% of the N input from precipitation. Nitrate and total N concentrations in surface water decreased (P < 0.001, r values ranged from 0.140.26) as length of time since last fire increased. Increased watershed area was correlated negatively (P < 0.0001) to stream water concentrations of NO3-N and total N (r values = -0.43 and -0.20, respectively). Low N concentration is typical of these streams, with NH4/+-N concentrations below 1.0 ??g L-1, NO3-N ranging from below 1.4 to 392 ??g L-1, and total N from 3.0 to 714 ??g L-1. These data provide an important baseline for evaluating N transport and stream water quality from unfertilized grasslands.

Conference Paper↗
USGS1995

Water-quality assessment of the South Platte River basin, Colorado, Nebraska, and Wyoming: Analysis of available nutrient, suspended-sediment, and pesticide data, water years 1980-92

Nutrient, suspended-sediment, and pesticide data from surface- and ground-water sites in the South Platte River Basin for water years 1980-92 were compiled, screened, and interpreted. This activity is part of the U.S. Geological Survey's National Water Quality Assessment (NAWQA) program. The analysis of existing water-quality data provides a perspective on recent water-quality conditions in the South Platte River Basin, evaluations of the strengths and weaknesses of available data, and implications for water-quality issues and future study priorities and design. Most data analyzed were collected by the U.S. Geological Survey. Additionally, data from three local agencies were used in the analysis. A total of 3,484 samples from 54 surface-water sites and 107 wells were used in the analysis. The areal distribution of nutrient samples collected from surface-water and ground-water sites were sufficient in number and areal distribution to describe current water- quality conditions throughout the basin, but data were not sufficient to analyze factors and processes affecting water quality. However, suspended- sediment and pesticide data were sparse in their distribution with respect to time, space, and flow regime, and were sufficient only to provide a preliminary description of conditions in the basin.

Colorado, Nebraska, Wyoming↗