AN ABSTRACT OF THE THESIS OF David Randall Strehiow for the degree of Master of Science in the School of Oceanography presentedon 3 May 1982 Title: The Relation of.Tidal Height and Sediment Type to the Inter- tidal Distributi Redacted for privacy Abstract approved: .J. Gonor The taxonomy of intertidal oligochaetès, and the relationships between oligochaete species distributions, tidal height, and sediment type, were studied in detail for a sand and mud flat in lower Coos Bay, Oregon. Eighteen species, representing four families, were identified. Three species of Enchytraeidae (Marionina vaucheriae, Marionina callianassae, and Marionina gpnori) and one species of Tubificidae (Aktedrilus oregpnensis) are new to science. A preliminary description of a new family, Psamotheriidae, based on Psarrrnotheriuni hastatus n.g. n.sp. is given. Other species present were Marionina vancouverensis, M. sjaelandica, N. subterranea, and N. achaeta (Enchytraeidae); Aktedrilus locyi, Li.mnodriloides monothecus, L. victoriensis, L. vérrucosus, Tubificoides coatesae, and T. pseudogaster (Tubificidae); and Paranais litoralis (Naididae). Individuals of Enchytraeus sp. and Lumbricillus spp. (Enchytraeidae) were found but were not fully mature, and therefore could not be identified to species. Nine of the eighteen species are known oniy from the northeast Pacific littoral zone, indicating the existence of a distinct regthnal oligochaete fauna. Earlier studies of the Enchytraeidae (Coates and Ellis 1981) and Tubificidae (Brinkhurst and Baker 1979) support this conclusion. Distinct oligochaete species assemblages were closely associated with physical habitat types defined by tidal exposure and sediment type. The distributions of species were not correlated with each other or with physical habitat types, however. Tide levels at which large changes in maximum continuous tidal exposure or submergence occur (critical tide levels) are strongly associated with. the intertidal zonation of species. Sediment type is an important determinant of species composition, but is not closely associated with intertidal zonation. The Relation of Tidal Heilght and Sediment Type to the Intertidal Distributi:on of Marine Oligochaetes in Coos Bay, Oregon by David Randall Strehiow A THESIS submitted to Oregon State University in partial fulfillment of the requirements for the degree of Master of Science Completed May 3, 1982 Commencement June 1982 APPROVED: Redacted for privacy Redacted for privacy anograp Redacted for privacy Date thesis is presented May 3, 1982 Typed by Karen Dykes for David Randall Strehiow Acknowl edgements I thank my major professor Dr. J.J. Gonor for support and guidance during my research. My minor professor Dr. W. Scott Overton provided much useful advice on the proper use of statistics. I also thank committee members Dr. George Boehlert and Dr. Robert Olson for their advice and encouragement. Ors. W.E. Hogue, C. Marsh, and J. Siebenaller provided useful criticism on early drafts of this thesis, Marilyn Gum provided me with invaluable assistance in obtaining hard-to-get taxonomic references. I thank Dr. R.O. Brinkhurst, Dr.C. Ers.6us, Mr. H.R. Baker, and Ms. K.A. Coates for much useful discussion concerning oligochaete taxonomy. Karen Dykes worked above and beyond the call of duty to type my thesis on short notice. My stay in Newport was made possible through the support and friendship of Dan, Dan, Dena, Jim, Mary, and Sic. Above allI thank my parents for their continued support through what must have seemd an interminably long period of time. TABLE OF CONTENTS I. General Introduction..................... 1 II. The Systematics of Marine Intertidal Oligochaetes from Coos Bay, Oregon, with a Summary of the Zoogeography of West Coast Species...................... 4 Introduction....................... 5 Methods.......................... 5 Taxonomy of Species ................... 6 Discussion........................23 III. Aktedrilus locyi Ersus, 1980 and Aktedrilus oregonensis n. sp. (Oligochaeta, Tubificidae) from Coos Bay, Oregon, with Notes on Distribution with Tidal Height and Sediment Type............................. 27 Introduction.......................23 Methods .........................28 Taxonomy of Aktedrilus..................28 Distribution Relative to Physical Factors ........ 35 IV. The Relation of Tidal Height and Sediment Typeto the Intertidal Distribution of Marine Oligochaetesin Coos Bay, Oregon .........................39 Introduction .......................40 Study Site Description ..................41 Methods .........................45 Sampling Procedures .................45 Data Analysis ....................46 Results .........................49 Environmental Variables ...............49 Sediment Analysis ..................49 Tidal Exposure and Submergence ............52 The Fauna ......................53 Similarity Classifications of Samples ........59 Recurrent Species Groups ...............64 Faunal Classifications versus PhysicalHabitat Classifications ...................64 Sediment Type and Critical Tide Levels........67 Discussion ........................68 Physical Habitat Types ................68 Classifications of Samples by SpeciesComposition . 69 Species Assemblages versus Physical HabitatTypes . 69 Critical Tide Levels .................70 Effect of Sediment Type and Vegetation........73 V. General Sumary and Conclusions ...............75 VI. Bibliography ......................... LIST OF FIGURES Figure Page 1. Marionina vaucheriae 10 2. Marionina callianassae 13 3. Marionina gpnori 16 4. Aktedrilus oregonensis. Lateral view of genital organs 32 5. Aktedrilus oregonensis. Lateral view of sperniatheca 36 of a British CoFumbia specimen showing the narrow-lumen of thespermathecal duct 6. Topography of the study site and locations of sampling 42 areas 7. Sampling areas mapped using three sets of attributes: 54 physical habitat type, oligochaete species composition, and non-oligochaete species composition 8. Frequency histogram of the similarity coefficients of 65 spatial distributions for all oligochaete and non- oligochaete species pairs LIST OF TABLES Table Page 1. Marine oligochaete species known from the Pacific 25 coast of North America, with known geographical ranges indicated 2. Aktedrilus locyi. A comparison of Coos Bay specimens 30 with the original description of California material 3. Sediment composition of sampling areas at the study 50 site 4. Sediment correlation matrix 51 5. Description of physical habitat types mapped 56 in Figure 7 6. Oligochaete species found in this study 57 7. Average number of oligochaete specimens per sample 58 (177 cm2) for strata 8. Numerically dominant species in sample groups clustered 60 by oligochaete species composition as mapped in Figure 7 9. Numerically dominant non-oligochaete species used in 61 this study and their habits 10. Average number of non-oligochaete specimens per sample 62 (177 cm2) for strata 11. Numerically dominant species in sample groups clustered 63 by non-oligochaete species composition as mapped in Figure 7 According to the International Code of Zoological Nomenclature, articles 8 and 9, this manuscript does not constitutéapublication and species names cited herein may not be cited in any form. The Relation of Tidal Height and Sediment Type to the Intertidal Distribution of Marine Oligochaetes in Coos Bay, Oregon General Introduction The Oligochaeta are hermaphroditic, burrowing annelid worms found in almost all soils and aquatic sediments worldwide. More than 5700 species belonging to 24 families are known (Reynolds and Cook 1976), but only the Tubificidae and the Enchytraeidae are abundant in the marine environment. There are about 200 marine species in these two families together. Most Enchytraeidae are terrestrial, but some species are aquatic. Three of the 21 enchytraeid genera, Lumbricillus, Marionina, and Crania are well represented in the marine environment, but Crania is the only strictly marine genus. Almost all marine species in this family are limited to the intertidal zone, with only Grania and some Lumbricillus species found subtidally. The Tubificidae are primarily freshwater, but most marine oliqochaete genera and species are included in this family, which is distinctly divided at generic and subfamilial levels into marine and freshwater forms. Tubificid genera as presently defined (see Holmquist 1978, 1979; Brinkhurst and Baker 1979; Baker and Brinkhurst 1981) gen- erally contain either freshwater or marine species, but not both, and most marine species belong to one subfamily, the Phallodrilinae. Tubificids have been found in all marine benthic substrates from the intertidal to the abyssal zone (Ersus 1980b). Knowledge of the geographical distribution and biology of marine oligochaetes has advanced considerably in recent years. Recent work by Brinkhurst and Jamieson (1971), Giere (1975), Brinkhurst and Cook (1980), and Ersus (198Gb) indicates that marine oligochaetes are a diverse, widespread group in the marine environment, and may be numerically very abundant, particularly in the littoral arid sublittoral zones. The population biology of marine oligochaetes is poorly known, but the studies of Pfannkuche (1979, 1980) indicate that some tubificid species mature and reproduce only once, after their second year, and then die. Reproduction was found to occur mainly in the spring. In- formation from taxonomic studies (e.g. Nielsen and Christensen 1959, personal observations) indicates that fecundity is low with only one or a few mature eggs