Reference: Biol. Bull., 145: 180-199. (August, 1973) SALT AND WATER BALANCE IN LUGWORMS (POLYCHAETA: ARENICOLIDAE), WITH PARTICULAR REFERENCE TO ABARENICOLA PACIFIC A IN COOS BAY, OREGON LARRY C. OGLESBY Institute of Marine Biology, University of Oregon, Charleston, Oregon; and Zoology Department, Pomona College, Clarcmont, California 91711 Polychaetes of the family Arenicoliclae, commonly called lugworms, are im-portant members of the infauna of muddy-sand beaches throughout the world, both in estuaries and along the open coast where wave action is slight (Wells, 1963). On suitable beaches, lugworms may be so abundant that their burrowing and feeding activities markedly influence the composition and structure of the sub-strate (Clay, 1959; Klein, 1967), much as do certain other mudflat polychaetes studied quantitatively by Rhoads (1967). Lugworms are of great importance in processing organic detritus and debris in estuaries (Clay, 1959; Day, 1967; Long-bottom, 1970), and provide food for birds (Clay, 1959; Orton, 1925), and bottom-feeding fishes of both sport and commercial importance (Clay, 1959; Day, 1967). Lugworms are therefore a significant link in the detritus food web that is char-acteristic of estuaries (Darnell, 1967). Lugworms have been subjects of numerous studies on morphology, feeding and burrowing activities, respiratory physiology, reproduction, and other aspects of their ecology and physiology. Most of these studies have dealt with the common European lugworm, Arenicola marina (Linnaeus), while other species of the family have received little attention. These studies have been reviewed several times, initially by Ashworth (1904), and more recently by Wells (1945), Clay (1959), Green (1968) and Kriiger (1971). In view of their extensive distribution in estuaries, it is surprising that salt and water balance in lugworms has been so little studied. While there are many separate reports on various aspects of this topic (see Discussion), most of these provide ony fragmentary data which do not give a comprehensive picture of any species. Several species of Abarenicola are the common lugworms of estuaries and quiet coastal waters around the North Pacific Ocean from Japan to northern California (Healy and Wells, 1959). Ab. pacifica Healy and Wells is one of the most common polychaetes in Coos Bay, the largest estuary in Oregon. Because of the abundance and presumed ecological importance of Ab. pacifica, and because of the limited published information on salt and water balance in lugworms generally, the present study was conducted. MATERIALS AND METHODS The nomenclature for the Arenicolidae follows Wells (1959, 1963). The abbreviations A. will be used for the genus Arenicola, Ab. for Abarenicola, and Ad. for Arenicolides. 180
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