AN ABSTRACT OF THE THESIS OF Jose D. Nunez Dupre for the degree of Master of Science in Oceanography presented on December 15, 1978 Title: Numerical Classification Analysis of Infaunal Composition and Distribution on Two Oreqon Coast Beaches Redacted for Privacy Abstract approved: Jefferson J. Gonor This investigation examined the community structure of two inter- tidal sedimentary environments on the Oregon coast in terms of species composition and vertical distribution. A coring device was used to obtain samples from two levels above MLLW in each beach on four occasions. Of the 54 taxa found, 46.2% were crustaceans, 35.2% polychaetes, 11.1% molluscs and 7.6% were of other phyla. The, group average sorting strategy was used to produce a dendro- gram after a Bray-Curtis dissimilarity matrix was made up for each survey. Two way coincidence tables were used to compare normal and inverse classifications and to determine the species which characterized each faunistic group. A basic pattern of six station groups and five to seven species groups were found in the study areas by classification analysis. Station groups were described by dominant species, frequency and mean density. Species groups were described by the dominance of constituent species restricted to site groups. The assemblages defined by numerical analysis represented the different beaches and tide levels sampled, thus at Lost Creek Eohastorius estuarius, E. brevicuspis, Dogielinotus loquax, Cirolanaharfordi, Nephtys californiensis and Euzoriumucronata typified the upper intertidal and Archaeomysis grebnitzkii, Eteone lcna and Eohastoriuwashingtonianus characterized the lower intertidal while at Yaquina Bay Eohastorius estuarius, Paraphoxus obtusiciens, LeDtocheiia dubia and Macoma sp. typified the upper level and Spio filicornLs, Mediomastus californiensis Odostomia sp., Neoarnphitrite sp., Phoronis oallida, Owenia collaris, Modiolus sp., Macoma balthica, Transenella tantilla and Clinocardium nutalli were lower level species. During all sampling periods the community inhabiting the Lost Creek beach was numerically dominated by haustoriid arnphipods with densities up to 8,908 individuals per square meter (Eohastorius brevicuspis) while at Yaquina Bay beach Leptochelia dubia, Pygospio sp. and Paraphoxus obtusidens were the dominant species with densities up to 8r738' 3,971, and 1,562 individuals per square meter respectively. With the exception of Euzonus mucronata which presented an evident patchy distribution at Lost Creek, the infauna showed a homogenous horizontal distribution at all levels at both types of environments. Temporal variation in community structure was minimal in both type of beaches during the sampling periods considered in this study. APPROVED: Redacted for Privacy Professor of Oceanography As'iate Professor in charge of majo/// Redacted for Privacy Dean of the School of Oceanography Redacted for Privacy Dean of the Graduate School Date thesis is presented December 15, 1978 'ped by Rebecca Rakish for Jose D. Nunez Dupre Numerical Classification Analysis of infaunal composition and distribution on two Oregon coast beaches by Jose D. Nunez Dupre A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Completed December 15, 1978 Commencement June 1979 to my wife, Teresa ACKNOWLEDGMENTS I wish to express my appreciation to Dr. Jefferson J. Gonor whose advice and guidance prompted this thesis. I am indebted to Drs. William G. Pearcy and David 1'Intyre for their comments and advice. Special thanks go to Jim Keniston whose friendly help was appreciated in the computer work. I am deeply indebted to my wife, Teresa, for her patience during these years of study. Her love, continued encouragement and inspiration has been instrumental in seeing this work completed. I am indebted to Julie Arana who typed my first draft and to Becky Rakish who professionally typed the final copy of this thesis. Finally, I wish to thank my sponsor, the Latinoamerican Scholarship Program of american Universities who made my studies possible. TABLE OF CONTENTS I. INTRODUCTION 1 II. DESCRIPTION OF THE STUDY AREA 8 1. General characteristics 8 2. Lost Creek beach 8 3. Yaquina Bay beach 10 III. METHODS AND MATERIALS 12 1. Sampling strategy 12 2. Processing of samples 13 IV. DATA ANALYSIS 15 V. OBSERVATIONS AND RESULTS 18 1. General 18 2. April 1976 sampling period 20 2.1 Benthic assemblages (site classification) 20 2.1.1 Sandy beach site groups 20 2.1.2Muddy beach site groups 23 2.2 Species groups (species classification) 25 2.2.1 Predominantly sandy beach species groups 25 2.2.2 Predominantly muddy beach species groups 27 2.3 Comparison of site and species classifications 29 2.4 Density 32 3. April 1977 sampling period 34 3.1 Benthic assemblages (site classification) 34 3.1.1 Sandy beach site groups 34 3.1.2 Muddy beach site groups 37 3.2 Species groups (species classification) 37 3.2.1 Sandy beach species groups 40 3.2.2 Sandy-Muddy species groups 40 3.2.3 Muddy beach species groups 40 3.3 Comparison of site and species classifications 41 3.4 Density 44 4. December 1977 sampling period 46 4.1 Benthic assemblages (site classification) 46 4.1.1 Sandy beach site groups 46 4.1.2 Muddy beach site groups 4.2 Species groups (species classification) 51 4.2.1 Sandy beach species groups 51 4.2.2 Muddy beach species groups 51 4.3 Comparison of site and species classifications 53 4.4 Density 55 5. March 1978 sampling period 58 5.1 Benthic assemblages (site classification) 58 5.1.1 Sandy beach site groups 58 5.1.2 Muddy beach site groups 61 5.2Species (speciesclassification) 61 5.2.1 Sandy beachspeciesgroups 64 5.2.2 Sandy-Muddyspeciesgroups 64 5.2.3 Muddy beach species groups 64 5.3 Comparisonof siteand species classifications 65 5.4 Density 65 vi. DISCtJSSION 70 VII. SUMMARY AND CONCLUSIONS 79 VIII. BIBLIOGRAPHY 81 IX. APPENDICES AppendixI 85 Appendix II 87 Appendix III 89 Appendix IV 93 LIST OF ILLUSTRATIONS Figure Page 1 Lost Creek beach, Lincoln County, Oregon showing 9 location of sampling area 2 a. Yaquina Bay, Newport, Oregon 11 b. Inset from Fig. 2a showing transect locations 3 Dendrogram of site groups based on group-average 21 sorting of Bray-Curtis dissimilarity values between all possible pair of stations. April 1976 4 Dendrograrn of species groups based on group average 26 sorting of Bray-Curtis dissimilarity values between all possible pair of species. April 1976 5 Mean density of individuals(N/rn2) per assemblage 33 of species considered in the numerical analysis in April 1976. 6 Dendrogram of site groups based on group average 35 sorting of Bray-Curtis dissimilarity values between all possible pair of stations, April 1977. 7 Dendrogram of species groups based on group-average 39 sorting of Bray-Curtis dissimilarity values between all possible pair of species, April 1977. 8 Mean density of individuals (N/rn2) per assemblage of 45 species considered in the numerical analysis in April 1977 47 9 Dendrogram of site groups based on group average sorting of Bray-Curtis dissimilarity values between all possible pair of stations, December 1977. 10 Dendrogram of species groups based on group-average 52 sorting of Bray-Curtis dissimilarity values between all possible pair of species. December 1977. 11 Mean density of individuals (N/ui2) per assemblage of 57 species considered in the numerical analysis in December 1977. 12 Dendrogram of site groups based on group average 59 sorting of Bray-Curtis dissimilarity values between all possible pair of stations, March 1978. Figure Page 13 Dendrogram of species groups based on group-average 63 sorting of Bray-Curtis dissimilarity values between all possible pair of species, March 1978. 14 Mean density of individuals (N/rn2) per assemblage of 68 species considered in the numerical analysis in March 1978. LIST OF TABLES Table Page I Percentages of species in the predominant taxonomic 19 groups at the different beaches and sampling periods II Total number of individuals (N), percentage of 22 occurrence(%),frequency (f), and mean density (N/rn2) of species in the sandy beach assemblages, for April 1976. III Total number of individuals (N), percentage of 24 occurrence(%),frequency (f), and mean density (N/rn2) of species in the muddy beach assemblages for April 1976 IV Percentage of abundance of species groups per 30 assemblage based on stations-species classification for April 1976. Very high (VH) 75%; High (H) 50-74%; Moderate (M) 25-49%; Low (L) 10-24%; Very Low (VL) 9%. V Percentage of abundance of each species groups per 31 assemblage based on station-species classification for April 1976. Very high (VH) 75%; High (H) 50-74%; Moderate CM) 25-49%; Low CL) 10-24%; Very Low (VL) 9%. VI Total number of individuals (N), percentage of occui- 36 rence (%) frequency (f) and mean density (N/rn2) of species in the sandy beach assemblages for April 1977. VII Total number of individuals (N), percentage of 38 occurrence (%),frequency (f),and mean density (N/rn2) of species in the muddy beach assemblages for April 1977. VIII Percentage of abundance of species groups per 42 assemblage based on station-species classification for April 1917. Very high (VH) 75%; High (H) 50-74%; Moderate (N) 25-49%; Low CL) 10-24%; Very Low (VL) <9%. IX Percentage of abundance of each species group per 43 assemblage based on station-species ciassification for April 1977. Very High (VT-i) >75%; High (H) 5074%; Moderate (N), 25-49%; Low CL) 10-24%; Very Low (VL) 9%. Table Page X Total number of indtidua' s'N) percentage of 48 occurrance (%), frequency (f), and mean density (N/rn2) of species in the sandy beach assemblage for December 1977. XI Total number of individuals (N) percentage of 50 occurrence (%), frequency (f), and mean density (N/rn2) of species in the muddy hach assemblage for December 1977.