Sipuncula of the western North Atlantic. Bulletin of the AMNH

• Main Author: Cutler, Edward Bayler.
• Format: Text
• Language: English
• Published: New York : [American Museum of Natural History] 1973
• Subjects: Sipuncula > Atlantic Coast (U.S.); Sipuncula > North Atlantic Ocean; Cape Kennedy; North Atlantic
• Online Access: http://hdl.handle.net/2246/601

p. 105-204 : ill., maps 27 cm. Includes bibliographical references (p. 199-204). "More than 8300 sipunculans from more than 500 stations of the east coast of the United States are identified and described. The area under investigation extends from Nova Scotia to cape Kennedy, Florida, in depths from 10 to 5400 meters. Several abiotic factors of the environment (topography, currents, temperature, and sediments) are described. Each species is characterized morphologically and also in terms of depth, latitude, sediment, and temperature. A key is given for the identification of all the 26 species collected. Distribution maps for the species are presented, as well as figures showing their morphology. In the description of each species, particular attention is paid to variation in morphology due to ontogeny. Several combinations of existing species names are suggested. Based on abiotic niche features, the species are grouped into four major ecological units: southern, shallow, warm water; northern, shallow, cold water; slope; and abyssal. Competitive exclusion operates within each of these groups except the abyssal fauna; this group has more sympatric species than the shallower groups and their morphology is less distinctive. One possible explanation is the limited magnitude of the significant environmental differences, which may be too small to be effective. Another is that the relatively low density greatly reduces the likelihood of two worms coming into contact and competing for given resources. The continental slope may not be an ecotone, but ecotones may exist along its upper and lower boundaries. The existence of a shallow-water, zoogeographical barrier at Cape Hatteras is reaffirmed, but the role of currents on larval dispersal may be as important as temperature in maintaining this barrier. A barrier on the slope, maintained by the effect of the bottom currents on larval dispersion just south of Cape Hatteras (latitude 34°20'-34°30'N), is proposed. Three of the four ecological groupings of species fit into pre-existing zoogeographical provinces (Carolinian, Nova Scotian, and Abyssal Atlantic subarea), but a new province (Atlantic Transitional) is proposed for the slope. Sipunculans in the Virginian Province are extremely rare. Two pieces of evidence support the concept that abyssal, cold-water fauna is ancestral to the warmer, shallow-water fauna"--P. 107.