Sediment grab samples from a series of depth transects were collected at 112 locations on the continental margin of Portugal. The benthic microfauna is rich and diverse; 248 species in 107 genera were observed. Distributions of the more frequent benthic species were further examined. Twenty-four species of planktonic foraminifera were identified. All the data have been treated by a descriptive multivariate analysis (correspondence analysis). The major oceanographic feature is seasonal upwelling, which decreases the planktonic-benthic ratio and permits the introduction of cold water species, both benthic and planktonic. The distribution of benthic and planktonic species depends on the depth and more exactly on factors related to it: temperature and its seasonal variations, salinity and sediment facies. Three benthic distributional patterns have been related to the grain size of the sediment. We can distinguish sand-dwellers, species tolerant towards muddy sediment, species tolerant towards muddy sand and species living indifferently in sand and mud. INTRODUCTION Two cruises were conducted on the Portuguese continental margin from Viana de Castello to the north to Faro to the south, by the Portugal Geological Survey. Along cross-shelf transects, 376 samples have been collected with Shipek and Van Veen grabs from 35 to 415m depth (text-fig. 1). Benthic foraminifera were counted in 112 samples and planktonic species in 105 samples. The benthic microfauna is rich and diverse both in species and in number of individuals; 248 species in 107 genera were observed. Distributions of 73 benthic species, which were present in more than 10 stations, were further examined. Twenty-four species of planktonic foraminifera were identified. Foraminifera of the Portuguese continental margin have been studied by only a few authors. Its seems that the first work on foraminifera of the Portuguese coast is by Nobre (1903-1904) in Lagos bay (Algarve). The publication of Galhano (1963) can be considered as the first on the systematics of foraminifera of Algarve shelf. He mentioned and described 178 species without clearly explaining their relation with the sediment facies. Thiede (1971, 1972, 1973) in several papers on the Atlantic, Spanish and Moroccan coasts, studied planktonic foraminifera of a few drillings off Sines and pointed out some faunal differences between the shelf, the slope and the abyssal plain. He also studied relationships between planktonic foraminifera, water temperature and carbonate dissolution-rate. Matos (1973-1974) studied benthic and planktonic foraminifera from the shelf and slope of the area between Cabos Raso and Espichel; he compared this fauna and the ones of the Atlantic and Mediterranean. Seiler (1975) studied the benthic foraminifera in two transects from the shelf to 1000m, north and south of Lisbon. He mainly observed the bathymetric distribution which allowed him to give a zonation. This zonation cannot be explained by factors such as temperature, salinity and oxygen. Ubaldo and Otero (1978) published a work on foraminifera of the southwester Portuguese coast (between Cabos Roca and Sao Vicente) which deals with systematics and depth-distribution of benthic foraminifera and ecology of planktonic foraminifera. They indicated a possible interpenetration of planktonic Atlantic and Mediterranean faunas and observed assemblages of benthic foraminifera at characteristic depths. Levy et al. (1984, 1985) wrote two short papers on the distribution of benthic foraminifera of the Portuguese shelf, one north, the other south of Rio Tejo. They gave the distribution of the most abundant species according to the depth. A few works dealing with Atlantic foraminifera involve some Iberian localities: MolinaCruz and Thiede (1978), Otero (1979), Pujol (1980) and Duprat (1983). micropaleontology, vol. 39, no. 1, pp. 75-87, text-figures 1-6, tables, 1-2, 1993 75 This content downloaded from 157.55.39.104 on Sun, 19 Jun 2016 06:51:45 UTC All use subject to http://about.jstor.org/terms A. Levy et al: Recent foraminifera from the continental margin of Portugal