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We provide records of relative sea level since A.D. 1500 from two salt marshes in North Carolina to complement existing tide-gauge records and to determine when recent rates of accelerated sea-level rise commenced. Reconstructions were developed using foraminiferabased transfer functions and composite chronologies, which were validated against regional twentieth century tide-gauge records. The measured rate of relative sea-level rise in North Carolina during the twentieth century was 3.0-3.3 mm/a, consisting of a background rate of ~1 mm/a, plus an abrupt increase of 2.2 mm/a, which began between A.D. 1879 and 1915. This acceleration is broadly synchronous with other studies from the Atlantic coast. The magnitude of the acceleration at both sites is larger than at sites farther north along the U.S. and Canadian Atlantic coast and may be indicative of a latitudinal trend.

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The distribution and abundance of live (rose Bengal stained) and dead, shallow infaunal (0-1 cm depth) and deep infaunal (Ͼ1 cm depth) benthic foraminifera have been documented at three locations representing different salinity settings on the fringing marshes along the Pamlico Sound and Currituck Sound coasts of North Carolina's Outer Banks. Two cores taken at each site represent the lower and higher marsh.Twenty-two taxa were recorded as live. Of these, eight taxa were found only at shallow infaunal depths; the other 14 taxa occur at deep infaunal depths in one or more cores. Only Jadammina macrescens and Tiphotrocha comprimata were recorded as living in all six cores. The distributions of the other taxa were restricted by combinations of infaunal depth, salinity regime and location on the marsh.The tests of infaunal foraminifera were generally more likely to be preserved in the lower marsh than the higher marsh at low-and intermediate-salinity sites. The opposite pattern was evident at the high-salinity site but this may be due to the low numbers of deep infaunal specimens recovered. Arenoparrella mexicana, Haplophragmoides wilberti, Jadammina macrescens and Trochammina inflata are the most resistant taxa, whereas Miliammina fusca is the species whose tests are most likely to be lost to post-mortem degradation. In five of the six cores, foraminiferal assemblages and populations do not differ significantly with depth which suggests that the foraminifera of the 0-1 cm depth interval provide an adequate model upon which paleoenvironmental (including former sea level) reconstructions can be based.

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Tropical diversity has generally exceeded temperate diversity in the present and at points in the past, but whether measured differences have remained relatively constant through time has been unknown. Here we examine tropical vs. temperate diversities from the Neogene to Recent using the within-habitat diversity measure Fisher's alpha of Cenozoic benthic foraminifera from the temperate Central Atlantic Coastal Plain and the tropical Central American Isthmus. During the Neogene, the mean value of alpha at temperate latitudes increased 1.4 times or 40%, whereas in the tropics it increased 2.1 times or 106%. Thus, while both areas exhibit an increase of diversity with time, past differences in the rate of increase have generated a more pronounced gradient today (164%) than existed in the Miocene (80%). These data disagree with the suggestion that the world reached an equilibrium number of species during the Paleozoic and demonstrate the need to consider both temperate and tropical components in global diversity assessments.

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