Paper No. 6
Presentation Time: 9:15 AM


BUZAS, Martin A., Department of Paleobiology, Smithsonian Institution, Washington, DC 20024, HAYEK, Lee-Ann C., Chief Mathematical Statistician, Smithsonian Institution, National Museum of Natural History, MRC-121, Washington, DC 20560-0121, CULVER, Stephen J., Department of Geological Sciences, East Carolina University, Greenville, NC 27858, HAYWARD, Bruce W., Geomarine Research, 49 Swainston Rd, Auckland, New Zealand and OSTERMAN, Lisa E., St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey, 600 Fourth St. South, St. Petersburg, FL 33701,

Biodiversity stasis exists when stations along a traverse exhibit no change in diversity. For stasis, If N, the number of individuals, is constant at each station , then, S, species richness and H, the information function, will also be constant. Because rare species appear at only one or a few stations, as N and S are accumulated by station, the accumulated total number of species in a traverse will exceed the number at each station. The Log series distribution serves as a null model for this situation. For a Log series S increases with accumulating N at a semi-log rate, but H remains constant. The regression H = β0H + β1HlnN expresses the relationship of H with accumulating N where β0H is a constant and β1H is the regression coefficient expressing the rate of change between-station (habitat) diversity. At stasis β1H = 0 and there is no biodiversity gradient. When β1H is positive S accumulates at a higher rate than for a Log series and there is a positive gradient. Consequently, although two areas may contain the same number of species per station, the area with higher between-station diversity will contain more overall species. We divided the deep-sea into two categories: 200 – 1500 m and > 1500 m. The β1H coefficient was examined for benthic foraminifera between 333 stations within 49 communities from New Zealand, the South Atlantic Ocean, Gulf of Mexico, Norwegian Sea and the Arctic Ocean. Β1H-diversity exhibits no evidence of regional differences. Instead, higher values at shallower depths are observed world-wide. At depths > 1500 m the average β1H is zero, indicating stasis or no biodiversity gradient. This difference in β1H-diversity explains why, despite species richness often being greater per station at deeper depths, the total number of species is greater at shallower depths. The greater number of communities and higher rate of evolution resulting in shorter species durations at shallower depths is also consistent with higher β1H values.