UNIVERSITY OF TORONTO STUDIES BIOLOGICAL SERIES, No. 56 AN ECOLOGICAL INVESTIGATION OF STREAM INSECTS IN ALGONQUIN PARK, ONTARIO By Wm. M. SPRULES (From the Department of Zoology, University of Toronto) PUBLICATIONS OF THE ONTARIO FISHERIES RESEARCH LABORATORY, No. 69 TORONTO UNIVERSITY OF TORONTO PRESS 1947 1 it CONTENTS PAGE Abstract • ......1 Introduction ...................................................................................... 2 Historical Review ............................................................................. 3 Acknowledgments ............................................................................. 4 Description of Drainage Area, Streams and Station Sites ........... 5 Physico-Chemical Conditions ......................................................... 10 Apparatus and Methods ............................................................. 11 Oxygen .......................................................................................... 12 Hydrogen Ion Concentration ..................................................... 13 Type of Bottom ........................................................................... 13 Flow ................................................................................................ 13 Depth ............................................................................................. 14 Colour ............................................................................................ 14 Temperature ................................................................................. 14 Biological Conditions ........................................................................ 16 Apparatus and Methods ............................................................. 16 Sources of Error ....................................................................... 17 The Diurnal Emergence of Insects from a Rapids ................... 21 The Effect of a Freshet on the Insect Fauna of a Stream ....... 24 The Effect of Intermittent Flow on the Insect Fauna of a Rapids ................................................................................... 27 Quantitative Results ................................................................. 27 Qualitative Results 30 Discussion ................................................................................. 30 The Effect of Flooding by a Beaver Dam on the Insect Fauna of a Rapids ............................................................................ 34 The Insect Distribution on Different Types of Bottom ........... 37 Quantitative Results ............................................................... 38 Qualitative Results ................................................................... 40 (a) General Differences ..................................................... 40 Sand ............................................................................ 41 Muck ............................................................................ 41 Gravel .......................................................................... 41 Rubble .......................................................................... 41 (b) Species Differences ....................................................... 42 Plecoptera .................................................................... 42 Ephemeroptera ........................................................... 43 Trichoptera .................................................................. 45 PAGE Biological Conditions—(continued) Discussion ................................................................................. 47 The Distribution of Insects in Rocky Riffles at Various Dis- tances from the Source ....................................................... 52 Quantitative Results ................................................................. 53 Qualitative Results ................................................................... 55 Plecoptera ............................................................................. 55 Ephemeroptera ..................................................................... 60 Trichoptera ........................................................................... 64 Discussion ................................................................................. 67 Summary ............................................................................................ 71 List of Species ................................................................................... 73 Literature Cited ............................................................................... 79 TABLES PAGE 1. Average physical and chemical conditions at the stations in the summer of 1938 ............................................................................................ 10 2. Periods during which collections were made at stations in 1938, 1939, 1940, and 1941 .................................................................................. 12 3. Number of insects that emerged at stations 5, 6, and 7 from June 6 to August 31, 1939 and 1940 .................................................................. 25 4. Analysis of the total insect emergence at station 1 from June 1 to September 11 in 1938 and 1939 .......................................................... 29 5. Analysis of the total insect emergence from different types of bottom in 1938, 1939, and 1940 39 6. Average per cent composition of the insect emergence from rubble (rapid), gravel, muck, and sand bottoms, for 1938, 1939, and 1940 . ... 40 7. Total number of species of Plecoptera, Ephemeroptera, and Trichoptera that emerged from different types of bottom during the investigation. 42 8. Distribution of Plecoptera and relative abundance of each species on different types of bottom 43 9. Distribution of Ephemeroptera and relative abundance of each species on different types of bottom 44 10. Distribution of Trichoptera and relative abundance of each species on different types of bottom 46 11. Quantitative analysis of the total insect emergence from June 1 to August 31 at station 2 in 1939, station 3a in 1940, station 3 in 1938 and station 4 in 1939 ................................................................................ 53 12. Distribution of Plecoptera at stations 2, 3a, 3, and 4 showing the relative abundance of each species 55 13. Relative importance of the families of Plecoptera at the stations 57 14. Distribution of Ephemeroptera at stations 2, 3a, 3, and 4, showing the relative abundance of each species 61 15. Distribution of Trichoptera at stations 2, 3a, 3, and 4, showing the relative abundance of each species 65 FIGURES PAGE FIG. 1. Map of Mud Creek drainage system 6 FIG. 2. Illustrations of stations in Mud creek facing 8 FIG. 3. Illustration of station in the Madawaska river facing 9 FIG. 4. Cage-trap in position in the stream facing 9 FIG. 5. The total insect emergence for twenty-four-hour periods at sta- tions 4a and 4b from July 3rd to 13th inclusive, 1941, showing the results of collecting the cages once a day, every hour and at four-hour intervals. 19 FIG. 6. The total hourly emergence of insects and water temperature in degrees Fahrenheit at stations 4a and 4b from July 3rd to 7th, 1941, beginning at noon. 22 FIG. 7. Emergence polygons of representative species at station 1 in 1938 and 1939, showing the effect of the drying up of the stream on July 17th, 1938, on the insect emergence 31 FIG. 8. Relationship of numbers of species of insects and temperature of the water. 56 FIG. 9. Seasonal distribution of the emergence of representative Plecop- tera at station 4 in 1939 and 1940. 59 FIG. 10. Seasonal distribution of the emergence of representative Ephe- meroptera at station 2 in 1939. 62 FIG. 11. Seasonal distribution of the emergence of representative species of Trichoptera at Station 4 in 1938 and 1939. 66 AN ECOLOGICAL INVESTIGATION OF STREAM INSECTS IN ALGONQUIN PARK, ONTARIO ABSTRACT The effect of several ecological factors on the qualitative and quantitative dis- tribution of stream insects in Algonquin Park, Ontario, was determined from data obtained by use of the cage-trap method of sampling the emergence of in- sects from unit areas in streams, at regular daily intervals. Incidents that induced significant alterations in the physical nature of the streams were accompanied by marked reductions in the total insect population and a change in the faunal composition of the affected areas. Such incidents included a severe freshet, cessation of flow and subsequent desiccation of the stream bed, and transformation of a shallow rocky riffle into a deep sedimented pool by construction of a beaver dam. A correlation .was found between the total number of species in rocky riffle areas at different distances from the source, and the average water temperatures. The linear distribution of species was delimited by the water temperatures ob- taining in different sections of the stream and this was correlated with the thermal tolerance of the immature stages. Within the limits set by tempera:ture the distribution of species was affected by other factors including rate of flow and nature of the bottom, two factors which are closely interrelated and fundamentally inseparable. The diversity of the fauna decreased from rubble, through gravel, and muck, to sand as the variety of util- izable microhabitats decreased. The observed distribution on different types of bottom was related to habitat preference and associated morphological adaptations in the species. The seasonal emergence periods of