DISTRIBUTION AND ABUNDANCE OF BENTHIC INVERTEBRATES IN A SONORAN DESERT ...

98 Pages·2012·1.69 MB·English

DISTRIBUTION AND ABUNDANCE OF BENTHIC INVERTEBRATES
IN A SONORAN DESERT STREAM
by
Dale Anthony Robert Bruns
A Thesis Presented in Partial Fulfillment
of the Requirements for the Degree
Master of Science
ARIZONA STATE UNIVERSITY
August 1977
ABSTRACT
Seasonal and longitudinal distribution and abund-
ance of dominant benthic invertebrates in a Sonoran
Desert stream were investigated relative to selected
environmental factors. Occurrence and abundance of
algae were most important to invertebrate standing
crops and densities during periods of modal flow.
General life history phenomena of invertebrates are
examined in regard to this factor and its possible role
in the trophic structure of the stream. Flash flooding,
a principal feature in the seasonal cycle of the
ecosystem, is considered relative to its impact upon
invertebrates and other components of the lotic
\
environment. Pathways and inputs of allochthonous
organic matter are enumerated and discussed, particularly
those unique to the system with regard to discharge
activity.
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ACKNOWLEDGEMENTS
Completion of this research project was made possible
through the help of many individuals to whom I wish to
express my sincere appreciation. Dr. Mont A. Cazier, my
committee chairman, gave support throughout my graduate
program. Dr. Wendell L. Minckley offered advice and
assistance during all phases of the study, and I am
particularly grateful for his many ideas and discussions
concerning desert stream ecology. Dr. Gordon B. Castle
contributed ideas in the formative stages of the project,
and Dr. Stuart G. Fisher read the manuscript and provided
useful suggestions. Donald C. Schreiber helped in the
collection of field samples, M. Steven Thompson aided in
the sorting of specimens in the laboratory, G. Dan Overman
furnished advice and assistance regarding computer
utilization, and Steven F. Burton provided the photo-
graph depicted in Figure 2. Residents along the stream
provided helpful cooperation, especially Fred Woods of
the Panorama Ranch. Drs. Richard K. Allen (California
State University) and William E. Ricker (Pacific Biological
Station, B.C.) identified ephemeropterans and plecopterans,
respectively. Costs of printing were defrayed by a grant
to Dr. Wendell L. Minckley from the U. S. Bureau of
Land Management.
IV
TABLE OF CONTENTS
INTRODUCTION .......................................... 1
DESCRIPTION OF THE STUDY SITE ........................ 3
Topography and Geology ........................... 3
Climate ........................................... 4
Vegetation ........................................ 4
Description of Sampling Stations ................. 5
MATERIALS AND METHODS ................................ 14
RESULTS ...............................................16
Physical Factors ................................. 16
Temperature ...................................16
Discharge .................................... 17
Chemical Factors ................................. 26
Hydrogen ion ................................. 26
Dissolved Oxygen ............................. 29
Macro-nutrients .............................. 30
Biological Factors ............................... 31
Fishes ........................................31
Macrophytes ...................................32
Benthic algae .................................33
Detritus ......................................34
Benthic Invertebrates ............................ 35
Ephemeroptera ................................ 39
VI
Plecoptera ................................... 44
Trichoptera .................................. 45
Diptera ...................................... 47
Hemiptera .................................... 48
Coleoptera ................................... 50
Odonata ...................................... 51
Megaloptera .................................. 52
Lepidoptera .................................. 52
Oligochaeta .................................. 52
Acarina ...................................... 53
Nematoda ..................................... 53
Ostracoda .................................... 53
Miscellaneous ................................ 53
Longitudinal Patterns of the Benthofauna ......... 54
Seasonal Patterns ................................ 60
'DISCUSSION ........................................... 72
SUMMARY .............................................. 82
BIBLIOGRAPHY ......................................... 85
LIST OF TABLES
TABLE Page
1. Taxonomic list of all invertebrates
found in the Aravaipa Creek basin,
Graham and Pinal counties, Arizona,
from April 1975 to April 1976 ..... 36
2. Annual mean dqnsities of invertebrate
taxa (no./m4) at eight stations on
Aravaipa Creek, Graham and Pinal
counties, Arizona ........................ 40
3. Seasonal mean densities of invertebrate
taxa (no./m2) in riffles of Aravaipa
Creek, Graham and Pinal counties ......... 61
4. Comparison of invertebrate density and
biomass in Aravaipa Creek, Graham
and Pinal counties, Arizona, with
those of other streams ................... 79
VIII
LIST OF ILLUSTRATIONS
FIGURE Page
1. Aravaipa Creek, Graham and Pinal
counties, Arizona: braided channel
of sand and fine gravel common
throughout the stream .................... 7
2. Aravaipa Creek, Graham and Pinal counties,
Arizona: undercut pool along large
boulders between Stations V and VI
on 27 April 1975 ......................... 10
3. Aravaipa Creek, Graham and Pinal counties,
Arizona .................................. 12
4. Daily mean discharge of Aravaipa Creek,
Graham and Pinal counties, Arizona,
from January 1975 to April 1976 .......... 19
5. Aravaipa Creek, Graham and Pinal counties,
Arizona: Station VII looking upstream
before a flash flood on 25 July 1975 ..... 23
6. Aravaipa Creek, Graham and Pinal counties,
Arizona: Station VII looking downstream
during a flash flood on 25 July 1975 ..... 25
7. Diel patterns of change in pH (a), and
concentration of dissolved oxygen
expressed in mg/1 (b) and percentage
of saturation (c) at four stations on
Aravaipa Creek, Graham and Pinal
counties, Arizona ........................ 28
8. Annual mean densities (a) and biomass(b)
of all invertebrates at eight stations
on Aravaipa Creek, Graham and Pinal
counties, Arizona, based upon nine
sampling dates from April 1975 to
April 1976 ............................... 56
Ix
FIGURE Page
9. Annual mean densities (a) and
biomass (b) at three general areas
of Aravaipa Creek, Graham and Pinal
counties, Arizona, generally
corresponding to sites above (A),
within (B), and below (C) the canyon ..... 58
10. Seasonal changes in population density of
selected taxa of invertebrates in
riffles of Aravaipa Creek, Graham
and Pinal counties, Arizona .............. 65
11. Seasonal changes in density (a) and
biomass (b) of all invertebrates
in Aravaipa Creek, Graham and Pinal
counties, Arizona ........................ 69
INTRODUCTION
As evidenced by recent reviews of Cummins (1966),
Hynes (1970a, 1970b) and Macan (1974), the majority of
studies on benthic invertebrates of streams have been
conducted in temperate zones. To date, no published
data are available on invertebrates of streams of the
Sonoran Desert, a situation becoming critical in light
of perturbations of lotic environments resulting from
increasing human demands on water. Disruption of natural
stream habitats by man in the arid Southwest has been
documented by Miller (1961), Minckley and Deacon (1968)
and Deacon and Minckley (1974) with regard to extirpation
of native fishes.
Aravaipa Creek, Graham and Pinal counties, Arizona, is
one of the rare low desert streams to have so far escaped
the ecological hazards of channelization, impoundment and
the introduction of exotic species. The stream serves as
a refuge for seven native fishes, many of which are depen-
dant upon benthic invertebrates as food (Minckley 1973,
Deacon and Minckley 1974). Effects of human activity
presently appear minimal.
Examination of the seasonal and longitudinal dis-
tribution and abundance of dominant benthic invertebrates
in Aravaipa Creek was made as a step toward understanding
desert aquatic ecosystems. Although obvious taxonomic
difficulties frustrated detailed analysis of community
2
dynamics, a general assessment of invertebrate densities
and standing crops relative to selected environmental
factors will serve as a basis for future research and
management of aquatic ecosystems and their native
biotas.