Riffle Insect Community Structure in Eight Northern California Streams
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RIFFLE INSECT COMMUNITY STRUCTURE IN EIGHT NORTHERN CALIFORNIA STREAMS by Jonathan J. Lee A Thesis Presented to The Faculty of Humboldt State University In Partial Fulfillment of the Requirements for the Degree Master of Arts May, 1990 RIFFLE INSECT COMMUNITY STRUCTURE IN EIGHT NORTHERN CALIFORNIA STREAMS by Jonathan Lee We certify that we have read this study and that it conforms to acceptable standards of scholarly presentation and is fully acceptable, in scope and quality, as a thesis for the degree of Master of Arts. Major Professor Approved by the Graduate Dean ACKNOWLEDGEMENTS I gratefully thank Dr. David Lauck for his help in the field, in the laboratory and fοr having a bit of patience. I also thank Dr. Richard Hurley (Humboldt State University) and Dr. Ole Saether (University of Bergen) fοr their help in reviewing some of the taxonomic determinations. Also, thanks to my committee members; Drs. Kenneth Lang, David Lauck, Mike Messler and Terry Roelofs for their critical review and constructive suggestions leading towards the completion of this thesis. iii ABSTRACT Riffle sections of eight streams in Northern California were sampled for aquatic insects using a kick net. Eleven chemical and physical stream parameters were measured at each riffle sampled. Biological data was analyzed using Simpsons diversity index and Chandlers Biotic Score index. Calculated values were plotted against measured chemical/physical parameters. The resulting scattergrams were examined for relationships between chemical/physical data and the indices values. No relationships were observed. Biological samples were inspected for trends not apparent in the scattergrams. Insect community structure varied among streams and seasonally within streams. The ten most abundant taxa from each sample were plotted by percent abundance and their cumulative percentage was totaled for each sample. The resultant graphs carry more information on community structure than the diversity or biotic indices. A qualified community structure and a diversity component can be observed. Streams are separated into "headwater" and middle order streams based primarily on degrees slope and annual temperature range. Notes are made on insect taxa typical of these streams types. Recommendations are made for regional expansion of Chandlers Biotic Score table and further taxonomic and life history research, particularly within the dipteran family Chironomidae. iv TABLE OF CONTENTS List of Tables vi List of Figures vii Introduction 1 Study Area 5 Materials and Methods 14 Results 20 Notes on taxa within each order 31 Plecoptera 31 Ephemeroptera 34 Trichoptera 37 Coleoptera. 42 Diptera 45 Odonata 51 Lepidoptera 52 Hemiptera 52 Discussion 126 Conclusion 141 Literature Cited 144 Personal Communication 154 Appendix A. Taxonomic literature used 155 Appendix B. List of insect taxa collected 160 Appendix C. Insect diversity and biotic indices values vs. chemical and physical stream parameters 168 V LIST OF TABLES Table Page 1. Chandlers Biotic Score Index 19 2. Water chemistry values at date of sample. 22 3. Stream physical values at time of sampling 24 4. Simpson diversity values, Chandler Biotic Score values, and number of taxa in each sample 28 5. Insect taxa collected (Hatchet Creek) 54 Insect taxa collected (Little Cow Creek) 60 Insect taxa collected (Clear Creek) 65 Insect taxa collected (Weaver Creek) 70 Insect taxa collected (Canyon Creek) 76 Insect taxa collected (Bidden Creek) 80 Insect taxa collected (East Fork Willow Creek) 84 Insect taxa collected (North Fork Mad River) 89 vi LIST OF FIGURES Figure page 1. Study area 6 2. Percent substrate composition 27 3(a) - 10(g) Percentage of ten most abundant taxa 3. Hatchet Creek 94 4. Little Cow Creek 98 5. Clear Creek 102 6. Weaver Creek 106 7. Canyon Creek 110 8. Bidden Creek 114 9. East Fork Willow Creek 118 10. North Fork Mad River 122 11. Comparison of samples with similar diversity values but dissimilar community structure 132 12(a-b) Seasonal community structure (a) Hatchet Creek 135 (b) Little Cow Creek 135 13(a) Diversity values vs. alkalinity values 168 (b) Diversity values vs. total hardness values 168 (c) Diversity values vs. conductivity values 169 (d) Diversity values vs. pH values 169 (e)Mean diversity vs. mean slope 170 (f)Mean diversity vs. mean substrate composition 170 vii LIST OF FIGURES (cont.) Figure Page 13(g) Diversity values vs. surface velocity values. ...171 (h) Diversity values vs. temperature values 171 (i) Diversity values vs. turbidity values 172 14(a) Biotic Score values vs. alkalinity values 173 (b) Biotic Score values vs. total hardness values 173 (c) Biotic Score values vs. conductivity values 174 (d) Biotic Score values vs. pH values 174 (e) Mean Biotic Score vs. stream slope 175 (f) Mean Biotic Score vs. mean substrate composition 175 (g) Biotic Score values vs. surface velocity values 176 (h) Biotic Score values vs. temperature values 176 (i) Biotic Score values vs. turbidity values 177 viii INTRODUCTION Aquatic insects have long been used in attempts to evaluate the relative health of stream ecosystems. Factors contributing to the suitability of insects for stream evaluation include abundance in most lotic systems, a general lack of mobility and uni- or bi-voltinism. Recent stream perturbations of short duration should be indicated by the insect fauna even after physical or chemical stream characteristics have returned to pre-perturbed conditions. An unperturbed stream community would typically have relatively few common species and many species represented by relatively few individuals (Wilhm 1971). Empirical indices based upon the concept of community diversity have become popular in the assessment of environmental stress (Helliwell 1978). Diversity indices attempt to condense data on species abundance within a community into a single number (Washington 1984). Community structure would be reflected by the calculated value. Diversity indices analyses in stream studies have traditionally investigated the effect of organic waste on the community structure, however, no assumptions are made regarding the nature of the stress (Helliwell 1986). Biotic indices are also used in assessing stream water quality (Helliwell 1986). Biotic indices are based on the concept of "indicator organisms", organisms sensitive to or 1 2 tolerant of various environmental conditions. Like diversity indices, values are expressed as numerical units. Unlike diversity indices, community structure is not necessarily represented in biotic indices. Values calculated are usually based on organism tolerance to organic enrichment although values may reflect physical factors such as elevated water temperatures (Helliwell 1986). Biotic indices, however, should be a reliable tool in ranking a streams health using regional indices (Hilsenhoff 1977). An alternate approach to investigating the interaction of environmental conditions and stream community structure is to graphically illustrate the ten most abundant taxa in a benthic invertebrate sample by relative percentage. The data express an evenness component of diversity and an "indicator" community (Wilhm 1970). The resultant graph does not "neatly package" a benthic sample but expresses more information than a single value would and is not as cumbersome as a list of the entire benthos from the sample. Insect community diversity is influenced by a number of physical habitat and/or nutritional resource factors. Important physical factors controlling distribution and abundance include substrate (Cummins and Lauff 1969; Hynes 1970; Kimble and Wesche 1975; Minshall and Minshall 1977; Tolkamp 1980; Reice 1983), temperature (Armitage 1961; Hynes 1970; Vannote 1973; Vannote and Sweeney 1980; Ward and Stanford 1982; Townsend et al. 1987) and current velocity 3 (Hynes 1970; Kimble and Wesche 1975; Minshall and Minshall 1977). Nutritional research has included studies dealing with trophic relationships (Cummins 1973), nutritional ecosystem dynamics (Vannote et al. 1980; Knight and Bottorff 1984) and species and community nutrition, food resources and growth (Anderson and Cummins 1979; Naiman and Sedell 1980; Hawkins 1982; Hawkins et al. 1982; Hawkins 1986; Behmer and Hawkins 1986). Dissolved substances in running waters are also considered to be important factors controlling stream benthos distribution (Hynes 1970). International Hydrological Decade- World Health Organization (1978) includes dissolved minerals, pH and anion-cation concentrations as baseline data for "water quality" surveys. Townsend et al. (1983,1987) found pH strongly influenced community structure in British streams. Winget and Mangum (1979) used alkalinity and sulfate concentrations as limiting chemical parameters when calculating tolerance quotients for stream invertebrates. Krueger and Waters (1983) found a positive correlation between alkalinity and macroinvertebrate production values in three Minnesota streams. United States Environmental Protection Agency documents have reviewed the literature and compiled checklists for certain chemical and physical parameters at which Chironomidae (Diptera) (Beck 1977), Ephemeroptera (Hubbard and Peters 1978), Plecoptera (Surdick and Gaufin 1978) and Trichoptera (Harris and Lawrence 1978) 4 larvae have been found. In general, there is a paucity of published literature comparing benthic invertebrate community structure and physicochemical parameters of several streams using similar methodologies. Ideally, results would indicate