Open Access. Powered by Scholars. Published by Universities.®

Digital Commons Network™

Open Access. Powered by Scholars. Published by Universities.®

Environmental Sciences

Institution
Keyword
Publication Year
Publication
Publication Type
File Type

Articles 17461 - 17490 of 22692

Full-Text Articles in Entire DC Network

Evaluation Of Chemical Repellents For Reducing Crop Damage By Dickcissels In Venezuela, M. L. Avery, E. A. Tillman, C.C. Lauker Oct 2001

Evaluation Of Chemical Repellents For Reducing Crop Damage By Dickcissels In Venezuela, M. L. Avery, E. A. Tillman, C.C. Lauker

United States Department of Agriculture Wildlife Services: Staff Publications

In Venezuela, lethal control of wintering Dickcissels (Spiza americana) is considered a threat to the species survival. To help farmers protect their rice and sorghum crops from depredations by Dickcissels and to minimize the killing of large numbers of these birds, alternative non-lethal crop protection measures are needed. To that end, the responses of captive Dickcissels to three bird-repellent chemicals applied to rice seed were evaluated. In one-cup feeding trials, treatments of methiocarb (0.05% g g-1, applied as Mesurol® 75% wettable powder) and anthraquinone (0.5%, applied as Flight Control® ) reduced consumption of rice by 70% …


Guidelines For The Establishment Of A Fish Habitat Protection Area., Fisheries Western Australia Oct 2001

Guidelines For The Establishment Of A Fish Habitat Protection Area., Fisheries Western Australia

Fisheries Management Papers

These guidelines are designed to guide the Department of Fisheries staff and community groups (the proponent) on the process for developing a proposal for a Fish Habitat Protection Area (FHPA). The guidelines: 1. Describe the role and function of Fish Habitat Protection Areas; 2. Guide proponents in selecting a suitable site for an FHPA; 3. Describe the process to be used to develop a proposal for an FHPA; 4. Describe the methodology to be used to develop a management plan for an FHPA; 5. Ensure consistency between applications.


Movements And Population Structure Of Humpback Whales In The North Pacific, John Calambokidis, Gretchehn Steiger, Janice Straley, Louis Herman, Salvatore Cerchio, Dan Salden, Jorge Urban R., Jeff Jacobsen, Olga Von Ziegesar, Kenneth Balcomb, Christine Gabriele, Marilyn Dahlheim, Senzo Uchida, Graeme Ellis, Yukifumi Miyamura, Paloma Ladron De Guevara P., Manami Yamaguchi, Fumihiko Sato, Sally Mizroch, Lisa Schlender, Jay Barlow, Terrance Quinn Ii Oct 2001

Movements And Population Structure Of Humpback Whales In The North Pacific, John Calambokidis, Gretchehn Steiger, Janice Straley, Louis Herman, Salvatore Cerchio, Dan Salden, Jorge Urban R., Jeff Jacobsen, Olga Von Ziegesar, Kenneth Balcomb, Christine Gabriele, Marilyn Dahlheim, Senzo Uchida, Graeme Ellis, Yukifumi Miyamura, Paloma Ladron De Guevara P., Manami Yamaguchi, Fumihiko Sato, Sally Mizroch, Lisa Schlender, Jay Barlow, Terrance Quinn Ii

United States Department of Commerce: Staff Publications

Despite the extensive use of photographic identification methods to investigate humpback whales in the North Pacific, few quantitative analyses have been conducted. We report on a comprehensive analysis of interchange in the North Pacific among three wintering regions (Mexico, Hawaii, and Japan) each with two to three subareas, and feeding areas that extended from southern California to the Aleutian Islands. Of the 6,413 identification photographs of humpback whales obtained by 16 independent research groups between 1990 and 1993 and examined for this study, 3,650 photographs were determined to be of suitable quality. A total of 1,241 matches was found by …


Scwds Briefs: Volume 17, Number 3 (October 2001) Oct 2001

Scwds Briefs: Volume 17, Number 3 (October 2001)

Southeastern Cooperative Wildlife Disease Study: Publications


• Biosecurity Alert
• The United Kingdom appears to be near success in eradicating foot-and-mouth disease (FMD).
• USDA declares chronic wasting disease CWD emergency in captive elk.
• CWD Calamity in Colorado: Approximately 1,300 animals in seven Colorado captive elk herds currently are under quarantine because chronic wasting disease (CWD) has been diagnosed in or traced to the herds.
• Further Spread of West Nile virus (WNV)
• Eastern Equine Encephalitis (EEE) virus was isolated from the brain of a wild white-tailed deer from Houston County, Georgia. Togaviridae, Culiseta melanura
• Equine protozoal myeloencephalitis (EPM) is a severe neurological …


Water Current, Volume 33, No. 5. October 2001 Oct 2001

Water Current, Volume 33, No. 5. October 2001

Water Current Newsletter

• Research Indicates Sprinkler Irrigation Use Could Reduce Groundwater Nitrate Levels by Steve Ress

• From the Director

• Meet the Faculty

• Time for Change on the Missouri River by Chad Smith

• Four States Irrigation Council Tour Visits Western Kansas in July by Steve Ress

• Pumpkin Creek Surface-Ground Water Dispute by J. David Aiken

• Water Issues in 2001 by Tim Anderson

• Water News Briefs


The Standardized Fish Bioassay Procedure For Detecting And Culturing Actively Toxic Pfiesteria, Used By Two Reference Laboratories For Atlantic And Gulf Coast States, Joann M. Burkholder, Harold G. Marshall, David W. Seaborn, Nora J. Deamer-Melia Oct 2001

The Standardized Fish Bioassay Procedure For Detecting And Culturing Actively Toxic Pfiesteria, Used By Two Reference Laboratories For Atlantic And Gulf Coast States, Joann M. Burkholder, Harold G. Marshall, David W. Seaborn, Nora J. Deamer-Melia

Biological Sciences Faculty Publications

In the absence of purified standards of toxins from Pfiesteria species, appropriately conducted fish bioassays are the "gold standard" that must be used to detect toxic strains of Pfiesteria slop. from natural estuarine water or sediment samples and to culture actively toxic Pfiesteria. In this article, we describe the standardized steps of our fish bioassay as an abbreviated term for a procedure that includes two sets of trials with fish, following the Henle-Koch postulates modified for toxic rather than infectious agents. This procedure was developed in 1991, and has been refined over more than 12 years of experience in …


Effects Of Trapping And Subsequent Short-Term Confinement Stress On Plasma Corticosterone In The Brown Treesnake (Boiga Irregularis) On Guam, Tom Mathies, Todd A. Felix, Valentine A. Lance Oct 2001

Effects Of Trapping And Subsequent Short-Term Confinement Stress On Plasma Corticosterone In The Brown Treesnake (Boiga Irregularis) On Guam, Tom Mathies, Todd A. Felix, Valentine A. Lance

United States Department of Agriculture Wildlife Services: Staff Publications

The effects of capture in a live trap and subsequent handling stress on plasma concentrations of corticosterone and other sex steroids were examined in wild male and female brown treesnakes (Boiga irregularis), an introduced species on Guam that has been implicated in the extirpation or decline of many of that island's vertebrate species. Males and females that spent 1 night in a trap had plasma levels of corticosterone about four and two times higher, respectively, than those of the respective free-ranging controls. Mean plasma levels of corticosterone of snakes that had spent 3 nights in a trap were …


Porcine Zona Pellucida Immunocontraception: Long-Term Health Effects On White-Tailed Deer, Lowell A. Miller, Ken Crane, Stan Gaddis, Gary J. Killian Oct 2001

Porcine Zona Pellucida Immunocontraception: Long-Term Health Effects On White-Tailed Deer, Lowell A. Miller, Ken Crane, Stan Gaddis, Gary J. Killian

United States Department of Agriculture Wildlife Services: Staff Publications

As part of a 9-year study on the contraceptive effects of Porcine Zona Pellucida (PZP) on white-tailed deer (Odocoileus virginianus), we analyzed serum chemistry panels during the first 4 years. This included the first 2 years when does were being actively immunized, and 2 years post-immunization. The chemistry panel was designed to detect pathologies that might result from the immunization of the deer. Blood chemistry results did not suggest any pathological changes resulting from the immunization. Seasonal differences in serum cholesterol were similar in both the control and PZP-treated groups. Seasonal changes in the mean body weights of …


Decline Of The Red-Winged Blackbird Population In Ohio Correlated To Changes In Agriculture (1965-1996), Bradley F. Blackwell, Richard A. Dolbeer Oct 2001

Decline Of The Red-Winged Blackbird Population In Ohio Correlated To Changes In Agriculture (1965-1996), Bradley F. Blackwell, Richard A. Dolbeer

United States Department of Agriculture Wildlife Services: Staff Publications

Based on North American Breeding Bird Survey (BBS) data since 1966, Ohio has traditionally hosted 1 of the highest breeding season densities of red-winged blackbirds (Agelaius phoeniceus) of any U.S. state or Canadian province. However, from 1966 through 1996, breeding populations of red-winged blackbirds in Ohio showed a marked decline (x̅ % change/yr in birds per route = -3.9), with breeding population indices decreasing by over 53%. Because the red-winged blackbird successfully adapted to habitats created by agricultural expansion over the last century and became a recognized pest of crops such as corn (Zea mays), …


Weed Plan For Western Australia, State Weed Plan Steering Group, Department Of Agriculture And Food, Western Australia Oct 2001

Weed Plan For Western Australia, State Weed Plan Steering Group, Department Of Agriculture And Food, Western Australia

Bulletins 4000 -

One of the most significant environmental challenges facing Western Australia is the minimisation of the impact of weeds. In the relatively short history of this State since European settlement, some 1155 exotic plant species have established as weeds in our diverse and generally fragile ecosystems. While development for agriculture, mining, transport and housing must by its nature result in some change to the State’s flora, the introduction of weedy plant species has caused serious impacts which cause great concern.

Weeds now pose a serious threat to many of the State’s ecosystems, and impose high annual costs on agricultural industries. Weeds …


Inside Unlv, Andy Grossman, Mark Wallington, Dave Phillips Oct 2001

Inside Unlv, Andy Grossman, Mark Wallington, Dave Phillips

Inside UNLV

No abstract provided.


Water Resources Review - Fall 2001 Vol 14 No 2, Annis Water Resources Institute Oct 2001

Water Resources Review - Fall 2001 Vol 14 No 2, Annis Water Resources Institute

AWRI Reviews

No abstract provided.


The Role Of Predation In Wildlife Population Dynamics, Eric M. Gese, Frederick F. Knowlton Sep 2001

The Role Of Predation In Wildlife Population Dynamics, Eric M. Gese, Frederick F. Knowlton

United States Department of Agriculture Wildlife Services: Staff Publications

The role predation plays in the dynamics of prey populations is controversial. Our understandings of predator-prey relationships is complicated by a multitude of factors in the environment and a general lack of knowledge of most ecological systems. Various other factors, besides predation, may regulate or limit prey populations, and various factors influence the degree to which predation affects prey populations. Furthermore, some factors may create time lags, or even cause generational effects, that go unnoticed. Herein, we review the role of predation in wildlife population dynamics, some of the factors influencing predator-prey interactions, and attempt to indicate where the professional …


Journalists' Views Of The Environment: Issues And Challenges, Bernadette West, Jane Lewis, Michael Greenberg Sep 2001

Journalists' Views Of The Environment: Issues And Challenges, Bernadette West, Jane Lewis, Michael Greenberg

RISK: Health, Safety & Environment (1990-2002)

In advocating the use of an environmental handbook for journalists, the authors report on a survey of reporters and editors regarding salient environmental issues in different regions of the United States and e emphasis placed on environmental reporting in newsrooms.


The Prairie Naturalist Volume 33, No.3 September 2001 Sep 2001

The Prairie Naturalist Volume 33, No.3 September 2001

The Prairie Naturalist

SEASONAL REPRODUCTION IN SIGMODON HISPIDUS INHABITING TALLGRASS PRAIRIES OF OKLAHOMA ▪ J. A. Wilson and R. L. Lochmiller

USE OF THE INDEX OF BIOLOGICAL INTEGRITY IN EASTERN SOUTH DAKOtA RIVERS ▪ C. L. Milewski, C. R. Berry, and D. Dieterman

SEED USE BY VERTEBRATES AND INVERTEBRATES IN TALLGRASS PRAIRIE ▪ A. W. Reed, G. A. Kaufman, J. E. Boyer, Jr., and D. W. Kaufman

RANGE EXPANSION OF THE PILEATED WOODPECKER IN NORTH DAKOTA ▪ J. A. Dechant 163

LAB FATTENING AND NON-INVASIVE ESTIMATES OF BODY COMPOSITION IN DEER MICE ▪ E. T. Unangst, Jr., M. J. Blair, M. W. Granger, …


Designing A Terminal Area Bird Detection And Monitoring System Based On Asr-9 Data, Seth Troxel, Mark Isaminger, Beth Karl, Mark Weber, Arthur Levy Aug 2001

Designing A Terminal Area Bird Detection And Monitoring System Based On Asr-9 Data, Seth Troxel, Mark Isaminger, Beth Karl, Mark Weber, Arthur Levy

Bird Strike Committee-USA/Canada Joint Annual Meeting: 3rd (2001)

Conflicts between birds and commercial aircraft are a noteworthy problem at both large and small airports [Cleary, 1999]. The risk factor for United States airports continues to increase due to the steady rise in take-off/landings and bird populations. There is a significant bird strike problem in the terminal area as shown by the incidents reported in the National Bird Strike Database [Cleary and Dolbeer, 1999]. The focus of bird strike mitigation in the past has centered primarily on wildlife management techniques. Recently, an Avian Hazard Advisory System (AHAS) has been developed to reduce the risks of bird strikes to military …


Development Of A Bird Aircraft Strike Hazard Program At Langley Afb, Virginia., Ted Sprague (Maj.), Stephen Kendrot Aug 2001

Development Of A Bird Aircraft Strike Hazard Program At Langley Afb, Virginia., Ted Sprague (Maj.), Stephen Kendrot

Bird Strike Committee-USA/Canada Joint Annual Meeting: 3rd (2001)

Bird and other wildlife collisions with aircraft are frequently expensive and sometimes tragic. Each year, the US Air Force (USAF) reports an average of 2772 aircraft/bird strikes costing over 35 million dollars annually. Since 1985, 17 USAF planes have been destroyed and 32 airmen have lost their lives. Accordingly, the USAF invests heavily in preventing bird strikes and requires all Air Force bases to create a Bird Aircraft Strike Hazard (BASH) plan. The BASH plan is tailored to each base and identifies key wildlife hazards, tasks required to mitigate hazards and personnel to oversee and implement the plan. The installation’s …


Bird Strike Risk Forecasting: A Modelling Approach, Wilhelm Ruhe Aug 2001

Bird Strike Risk Forecasting: A Modelling Approach, Wilhelm Ruhe

Bird Strike Committee-USA/Canada Joint Annual Meeting: 3rd (2001)

The German Military Geophysical Office (GMGO) issues BIRDTAM (Bird Warning to Airman) on the basis of current bird observations in order to reduce bird strike danger during low-level military missions. BIRDTAM force pilots to avoid or leave airspaces with high bird densities at the specific time period, therefore reducing bird strike danger significantly. However, BIRDTAM are depending on the actual observation of bird movements, are issued often unexpectedly, disturb the flight missions and can only display the risk situation with a validity of about 2 or 4 hours in advance. In order to be aware of possible bird related restrictions …


Elmendorf Afb Bash Program, Robert J. Hahn , Capt, Usaf Aug 2001

Elmendorf Afb Bash Program, Robert J. Hahn , Capt, Usaf

Bird Strike Committee-USA/Canada Joint Annual Meeting: 3rd (2001)

Elmendorf AFB, located in Anchorage, Alaska, is home to over 60 aircraft to include F-15s, C-130’s, E- 3’s, C-12s, and Army Citations. In addition, it’s a major hub for both military and contract strategic airlift enroute to the Pacific. The large airspace training areas make Alaska an ideal environment suitable for large scale flying exercises. The result is several different types of aircraft from military sister services and foreign countries based out of Elmendorf throughout the year. Overlay the tremendous volume of air traffic on the huge numbers of birds in a confined area and your bound to have collision …


The Need For A Radar-Based, Operational Bird Warning System For Civil Aviation, Hans Blokpoel, B. Mackinnon Aug 2001

The Need For A Radar-Based, Operational Bird Warning System For Civil Aviation, Hans Blokpoel, B. Mackinnon

Bird Strike Committee-USA/Canada Joint Annual Meeting: 3rd (2001)

Serious multi-engine strikes on civil aviation aircraft continue to occur despite bird control efforts at and around airports. Radar-based bird warning systems currently used in military aviation are largely unsuitable for operational use in civil aviation because of the considerable constraints and inflexibility inherent in civil aviation operations. Pilots of civil aviation aircraft need to get timely, pertinent information on bird hazards, complete with options on how to minimize the associated risk. Recent advances in the design of radars and computers allow for the development of a real-time radar-based system to detect and warn of high-risk situations involving birds. High-risk …


Avian Foraging Behaviors And Habitat Manipulation At Portland International Airport, Janina M. Lamb Aug 2001

Avian Foraging Behaviors And Habitat Manipulation At Portland International Airport, Janina M. Lamb

Bird Strike Committee-USA/Canada Joint Annual Meeting: 3rd (2001)

Between January 1996 and May 2001 more than 300 bird strikes occurred at Portland International Airport. Records indicate that herons and raptors consistently make up nearly one-half of species struck. These species regularly use the airport grassland as a foraging ground, feeding on ground-dwelling rodents, including the graytailed vole (Microtus canicaudus) and vagrant shrew (Sorex vagrans). As part of a current study, various manipulations are being made to the grassland habitat and an assessment will be conducted of their effects on the airfield rodent and avian predator populations. This study will specifically correlate the presence and behaviors of predatory birds …


An Analysis Of Deer Strikes With Civil Aircraft, Usa, 1982-2000, Sandra E. Wright Aug 2001

An Analysis Of Deer Strikes With Civil Aircraft, Usa, 1982-2000, Sandra E. Wright

Bird Strike Committee-USA/Canada Joint Annual Meeting: 3rd (2001)

Wright et al. (1988) stated that although deer strikes comprise only about 2% of total reported wildlife strikes, 86% of those strikes damaged the aircraft. Dolbeer et al. (2000) ranked deer as the most hazardous species to aircraft based on damage and effect-on-flight. On January 14, 2001, a Learjet collided with two white-tailed deer (Odocoileus virginianus) on an airport in Troy, Alabama. Both pilots were critically injured and would have perished in the fire that destroyed the aircraft if rescuers had not arrived quickly. The above example of a damaging wildlife strike to an aircraft is not uncommon. Wildlife strikes …


Enhancements To The United States Bird Avoidance Model (Us Bam), Timothy Beermann, Matthew Bobo, Russell P. Defusco Aug 2001

Enhancements To The United States Bird Avoidance Model (Us Bam), Timothy Beermann, Matthew Bobo, Russell P. Defusco

Bird Strike Committee-USA/Canada Joint Annual Meeting: 3rd (2001)

The United States Bird Avoidance Model (US BAM) uses Geographic Information System (GIS) technology to analyze and correlate bird habitat, migration, and breeding characteristics with key environmental and human-made geospatial features. The application consists of raster grids covering the conterminous United States. The value for each grid pixel location is equivalent to the sum of the mean bird mass (in ounces) for all species present during one of four daily time periods (dawn, day, dusk, and night), for one of 26 two-week periods in a year. The US BAM is a desktop application that has an intuitive design and includes …


A Review Of Deer Control Devices Intended For Use On Airports, Thomas W. Seamans Aug 2001

A Review Of Deer Control Devices Intended For Use On Airports, Thomas W. Seamans

Bird Strike Committee-USA/Canada Joint Annual Meeting: 3rd (2001)

Deer living on airport habitats pose a direct threat to aircraft operations and to public safety. From 1990– 2000, about 520 collisions between civil aircraft and deer were reported in the USA with damage occurring in 86% of the collisions. Removal of individual deer by lethal or non-lethal means can reduce the potential for deer-aircraft collisions; however, such action is often controversial. Various items are marketed to keep deer away from airports, crops or residential areas. Some items have been tested while others have unsubstantiated claims of efficacy. This paper reviews the use of various fence designs, propane cannons, cattle …


The John Muir Newsletter, Fall 2001, The John Muir Center For Regional Studies Aug 2001

The John Muir Newsletter, Fall 2001, The John Muir Center For Regional Studies

Muir Center Newsletters (1981-2015)

Volume 11, Number 4 NEWSLETTER John Muir's Travels to South America and Africa By Michael P. Branch, University of Nevada, Reno ■; ;rt?Jxcerpted from Michael Branch's new book, John Muir's Last turney: South to the Amazon and East to Africa; Unpublished irnal and Selected Correspondence. Copyright © 2001 by fl§and Press. Published by Island Press/Shearwater Books, Wash- Bgton, D.C., and Covelo, California. All rights reserved. Hardcover $27.50. ISBN 1-55963-640-8. To order John Muir's Last Journey, please call Island Press at (800) 828-1302, or place your order at the Island Press website, www.islandpress.org. ve had a most glorious time on this …


A Five Year Management Strategy For Recreational Fishing In The Gascoyne Region Of Western Australia. Final Report Of The Gascoyne Recreational Fishing Working Group., Gascoyne Recreational Fishing Working Group. Aug 2001

A Five Year Management Strategy For Recreational Fishing In The Gascoyne Region Of Western Australia. Final Report Of The Gascoyne Recreational Fishing Working Group., Gascoyne Recreational Fishing Working Group.

Fisheries Management Papers

The recommendations contained within this paper were reached after careful consideration of the public submissions provided in response to the working group’s discussion paper A Quality Future for Recreational Fishing in the Gascoyne (Fisheries Management Paper 124). The working group would like to thank everyone who forwarded submissions on the discussion paper and attended public meetings to provide input. The wide variety of comments and views expressed reflect the diverse nature of the recreational fishing sector. I believe this range of views was also well represented by the various members of the working group.


Plan Management For The Cottesloe Reef Fish Habitat Protection Area., Fisheries Western Australia Aug 2001

Plan Management For The Cottesloe Reef Fish Habitat Protection Area., Fisheries Western Australia

Fisheries Management Papers

This document is the final Plan of Management for the Cottesloe Reef FHPA. The significant contribution made by the CMPG and members of the community in the preparation of this plan is acknowledged and appreciated by the Department of Fisheries. The overall objective of the Plan of Management is to promote and encourage protection of the Cottesloe Reef aquatic habitat and involve the community in its management. It is anticipated that the establishment of the Cottesloe Reef FHPA will provide a framework, through regulations and education, to manage human activities that have, or may have, a destructive impact on the …


Dye Tracing To Delineate Drainage Basins And Determine Groundwater Sensitivity, Mammoth Cave, Kentucky; With Special Reference To Potential Groundwater Contamination From Spills Along Interstate I-65, Arthur Capps Aug 2001

Dye Tracing To Delineate Drainage Basins And Determine Groundwater Sensitivity, Mammoth Cave, Kentucky; With Special Reference To Potential Groundwater Contamination From Spills Along Interstate I-65, Arthur Capps

Masters Theses & Specialist Projects

The Mammoth Cave System of south central Kentucky encompasses more than 560 km of surveyed cave passages. The largest groundwater basin (244 km2) found within this cave system emerges from the Turnhole Bend Spring on the Green River. During high flow conditions, water from this groundwater basin will spill over into the Echo River section of the cave. Previous research, including cave mapping and dye tracing (Quinlan and Ray, 1989; Currens and Ray, 1998; Coons, 1994), has delineated the boundaries of spring groundwater basins for numerous springs along the Green and Barren Rivers. These data showed that 60% of the …


Water Current, Volume 33, No. 4. August 2001 Aug 2001

Water Current, Volume 33, No. 4. August 2001

Water Current Newsletter

• About 50 Attend June’s Summer Tour of Urban Water and Natural Resources Challenge by Steve Ress

• From the Director

• Meet the Faculty

• Inventorying Nebraska’s Irrigation Acres

• Taking a Look at TMDLs in Nebraska by Patrick O’Brien

• Water News Briefs

• Water Quality Funding Measure Passes by Roy Frederick


The Distribution Of Macroinvertebrates Along The Impounded Middle Chattahoochee River, Page Jones Aug 2001

The Distribution Of Macroinvertebrates Along The Impounded Middle Chattahoochee River, Page Jones

Theses and Dissertations

This project was part of a series of investigations designed by the Columbus (Georgia) Water Works to evaluate composition of the macroinvertebrate fauna of the mainstem of the middle Chattahoochee River, as well as its tributaries. An additional objective of the survey was to characterize impacts of storm events on urban streams and the mainstem of the Chattahoochee River. This portion of the study was designed to assess composition of benthic communites of an urbanized river in which flow regime is altered by a series of impoundments. Nine dams currently regulate flow of the mainstem of the middle reach of …