AN ABSTRACT OF THE THESIS OF Robert Spencer Carney for the degree of Doctor of Philosophy in Oceanography presented on September 14, 1976 Title: PATTERNS OF ABUNDANCE AND RELATIVE ABUNDANCE OF BENTHIC HOLO- THURIANS (ECHINODERMATA:HOLOTHURIOIDEA) ON CASCADIA BASIN AND TUFT'S ABYSSAL PLAIN IN THE NORTHEAST PACIFIC OCEAN Abstract approved: Redacted for Privacy Dr. And r4 G. Jr. Cascadia Basin and the deeper Tuft's Abyssal Plain are inhabited by a common set of holothuroid species but differ markedly in propor- tional composition and apparent abundance. Seventy-six trawl samples were collected in a grid on Cascadia Basin. Depth appeared to be the major factor affecting the proportional composition of the dominant species. The fauna became progressively more uniform as the depth gra- dient decreased. The region adjacent to the base of the slope was distinct in its low diversity and low proportions of small specimens of the most common holothuroid species. These features might be due to in- creased competition and predation in that region. Sixteen trawl samples were examined from Tuft's Plain. Again the fauna appeared to be affected primarily by depth. While the abundance of holothuroids remained uniform across the flat Cascadia Basin, it appeared to decrease exponentially with depth across Tuft's Plain. The uniformity of proportional composition and abundance of the holothurian fauna across the floor of Cascadia Basin is in marked contrast with previously reported patterns of infaunal organisms. It is suggested that the differences reflect basic differences in the ecologies of the infauna and the motile epifauna, and that the size distribution of food material from overlying water may be of importance in determining the benthic fauna composition. A geometric representation of the analyses used is given0 Concepts of deep-sea benthic ecology are reviewed, and current diversity hypotheses are reviewed relative to the findings of the study. The Patterns of Abundance and Relative Abundance of Benthic Holothurians (Ecl-iinodermata :Holothurioidea) on Cascadia Basin and Tuft's Abyssal Plain in the Northeast Pacific Ocean. by Robert Spencer Carney A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Doctor of Philosophy June 1977 APPROVED: Redacted for Privacy Associate Prossor ofbeanography in charge of major Redacted for Privacy ActingeanL.óf the School of Oceanography Redacted for Privacy Dean of the Graduate School Date thesis is presented September 14, 1976 Typed by Rebecca Rakish for Robert Spencer Carney ACKNOWLEDGEMENTS The research reported in this thesis was undertaken because of an interest in marine life that began twenty years ago on Sanibel Island off the west coast of Florida. Since that beginning I have been most fortunate to have had several people make a contribution to the process by which a childhood fascination turns into directed scientific inquiry. Through their encouragement, teaching, and direction, each has directly contributed to the completion of this thesis. I am indebted to Dr. Andrew Carey for serving as my major profes- sor and freeing me from worries about funding andfacilities. By intro- ducing me to the fascinating aspects of quantitative ecology, Dr. Scott Overton significantly improved my ability to recognize, phrase, and answer ecological questions. T)r. Charles Miller provided excellent company during my varied attempts to both learn and to teachnumerical techniques. In addition, the thoughtful criticism he provided on very short notice greatly improved this thesis. Dr. William Pearcy and Dr. Vern Kuim both helped me to see the importance of my study in a larger ecological context. Although not serving on my graduate committee, several persons contributed to the thinking behind this thesis by sharing their own ideas and being tolerant of mine. In chronological order these include: Mrs. Francis Wild, Dr. D.A.Livingstone, Dr. Gilbert Rowe, Dr. Willis Pequegnat, Dr. David Pawson, Miss Maureen Downey, Dr. Peter Dawson, Dr. John Wiens, Dr. Author Boucot, and Dr. Jorn Theide. The production of this thesis wasgreatly facilitated by the help editorial and advice of many people.Pat Tester frequently provided assistance, and Rebecca Rakish wasquite tolerant of my many revisions. providing a I would especially like tothank Dr. Charles Shluts for needed bit of peace of mind, and theOregon State Sea Grant Program Computer use (grant number 4-5-158-2) forpartial financial support. Computer was funded through a grantfrom the Oregon State University Center. Of all the thanks that I owe,that due to my family is the rreatest. They have continued to be my greatestsource of encourageme1L..since beaches of the days of gallon jaraquaria and ghost crabs on the warm Sanibel Island. TABLE OF CONTENTS Page I, INTRODUCTION 1 General Considerations 1 General Approach 2 Evaluation of the Importance of Depth and Distance 3 II. REVIEW OF CONCEPTS 5 III. BIOLOGY OF THE HOLOTHURIOIDEA 16 IV THE ENVIRONMENT SAMPLED 20 V. SAMPLING 33 Evaluation of the Beam Trawl 37 Attempt to Determine Area Sampled 37 Sampling Efficiency 40 VI. ANALYSES 46 General Considerations 46 Vector Representation of a Sample 48 Vector Lengths-Distances 49 Angles Between Vectors - SIMI 51 Restraining Surfaces 54 AIDN Analysis of Variation on the Proportion-Surface 57 Computation Form of the AIDN Analysis of Variance 60 Reducing the Dimensionality of a SIMI matrix 62 Analysis of SLze Relationships 64 VII. RESULTS 66 Vertical Zonation 66 Holothurian Catch vs. Total Invertebrates 69 Abundance of Holothurians 71 Within Sample Relative Abundance 79 AIDN Analyses of Variance 79 Inter-area Similarities 88 CABFAC Vector Analysis 91 Diversity Patterns 97 Distribution of Species 104 Abundance vs. Occurrence 114 Body Sizes 119 Dependence of Small:Large Upon Region Sampled 123 Summary of Results 127 VIII. DISCUSSION 130 Depth Controlled Species Composition 130 Distribution of Size Classes 132 Page Holothuroid Size and Diversity Hypotheses 136 Infauna-Holothuroid Comparisons 139 Suggested Importance of Food GrainSize 145 150 IX.CONCLUSIONS 153 BIBLIOGRAPHY APPENDIX 1 162 Station data for beam trawlsamples. 166 APPENDIX II Faunal lists for beam trawl samples. LIST OF TABLES Page Table species off Oregon. 67 1 Vertical ranges of holothuroid minimum catch of Holothuroids 77 2 The average, maximum, and per trawl at eachsampling area. Cascadia Basin series of 85 3 AIDN analysis of variance for samples. for each offshore 86 4 Separate AIDN analyses of variance series. Tuft's Plain series of 87 5 AIDN analysis Qf variaiice for samples. similarity index. 89 6 Matrix of inter-area SIMI's, 92 7 Unrotated CABFAC factor scores. each sample area. 103 8 Three measures of diversity at pooled sample area. 105 9 Proportion of each species at each 124 10 Contingency tables for large andsma.l specimens of six species across the basinand plain. holothurians and for 141 11 Comparison of Slill matrices for infaunal polychaetes along theCP-E series of samples LIST OF FIGURES Page Figure 24 1 Major physiographic features off Oregon. sediments of 26 2 Gradation of percent clay in surface Astoria Fan and adjacent areasof Cascadia Basin. detrital grains in 27 3 Decrease in terestrial1y derived the surface sediments of CascadiaBasin. plant fragments in 28 4 Gradation of percent of terrigenous the coarse fraction of surfacesediments of Cascadia Basin. 29 5 Distribution of postg],acial claymineral fades. 34 6a Location of beam trawl samplestaken in Cascadia Basin and Tuft's Plain. 35 b Identifying codes for the sample grid. 39 7 Scatter plot of aumber ofholothurians collected per trawl versus areaof bottom sampled according to the odometers. 42 8 Effect of selection ogive upon thefauna sampled. histogram for 11,320 44 9 The cumulative size frequency specimen lengths taken from sevenspecies. 50 lOa Samples 1 and 2 modeled as two pointsin three dimensioned species space. 50 b Three distance, vector length, measures. separation 52 c Comparing twp samples by the angular of two vectors. separation 52 d Comparing two sample points by the angular between the two SD vectors the center-line of 53 e The angle Rho when looking from space towards the origin. 53 f Insertion of the proportion surface. the proportion 56 g Distance measures and the angle Rho on surface. 56 h The right tetrahedron of diversity,equitability, and similarity. surface. 63 i Insertion of the unit sphere restraining (factors) relative 63 j Position of new, orthogonal axes to the olçI axes and sample vectors. 70 11 Plot of the number of holothi.troidspecimens per trawl versus the number ofinvertebrates. Page Figure first and second most 72 12 The rank of abundance of the abundant holothuroids pertrawl when all inverte- brates are ranked. the depth 75 13 The number of ho1othuroidper trawl versus of collection. trawl versts position seaward.76 14 Plot of holothurians per four major species on 80 15 Change in abundance of the Tuft's Plain. major species at CP-1 81 16 Change in abundance of three with accompanying changes inSimpson's D squared. major species at CP-2 82 17 Change in abundance of three with accompanying changes inSimpson's D squared. major species at CP-3 83 18 Change in abundance of three with accompanying changes inSimpson's D squared. sample vector and the 94 19a Cosine of angle between each first reference axis. sample vector and the 95 b Cosine of angle between each second reference axis. sample vector and the 96 c Cosine of angle between each third reference axis, species per trawl against 99 20 The number of holothurian the log of both numberof holothurian specimens and total invertebrates on CascadiaBasin. species per trawl against 100 21 The nunber of holothuroid the log of both numberof holothurianspecimens and total invertebrates onTuft's Plain. 101 22 The rank-abundance diagramsfor the pooled samples of Tuft's Plain and CascadiaBasin showing the sLmilarity of form.