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Northeastern Atlantic and Arctic faunal provinces based on the distribution of Recent ostracod genera

(Institute of Earth Studies, University of Wales, Aberystwyth, Dyfed, SY23 3DB, UK)

R.C. Whatley

(Institute of Earth Studies, University of Wales, Aberystwyth, Dyfed, SY23 3DB, UK)

The benthonic ostracod communities of 93 Recent northeast Atlantic shallow marine sites have been studied. The ostracod assemblages from 76 of these sites were previously undescribed while an additional 17 sites, predominantly from British stations, were assessed from the available literature. Excluding mesohaline genera a total of 102 podocopid ostracod genera were recognized on the northeast Atlantic shelf between the Niger Delta and the Barents Sea. Using both semi-quantitative (most northerly and southerly occurrences of genera) and quantitative (Q-mode analysis, site-site) methods it becomes apparent that ocean currents and water-mass temperature exact a considerable control on the spatial (latitudinal) distribution of benthonic Ostracoda, at the generic level. It has been demonstrated that the majority of northeast Atlantic shelf Ostracoda are restricted to one or several zoogeographical regions or provinces: Nigerian (most southerly), Liberian, Sierra Leonian, Guinean, Mauritanian, Moroccan, Lusitanian, Celtic, Norwegian and Arctic. These provinces are themselves contained within two larger zoogeographical domains, the African and European realms. Each of the 10 provinces are distinguished, not only by the variations in the generic structure of the ostracod assemblages but also in their water-mass characteristics. Ostracod provincial boundaries, in essence, trace zones of intense vertical circulation (Arctic Polar Front and the southern edge of the Guinea Dome) or areas of current divergence (bifurcation of the North Atlantic Drift at Cape Finisterre). Differences also exist in the zoogeographical limits of northeastern and northwestern Atlantic ostracod provinces. The 'concertina' effect on the latitudinal bounds of northwest Atlantic ostracod shelf provinces appears to be intrinsically linked to the presence of a steep thermal gradient associated with the pervasive, southward flowing, Labrador Current. Diametrically, the ameliorating effect of the Gulf Stream has led to the augmentation of provinces within the European realm and assist in the development of broad ecotones, notably in the mid-latitudes. The development of this large modern database and the verification of ostracod provincialism greatly enhances their use, as proxy data, in palaeotemperature and palaeoenvironmental reconstruction of late Cainozoic successions.

Key Words: Ostracoda • Recent • northeast Atlantic • shallow marine • database • faunal provinces.

The Holocene, Vol. 4, No. 2, 174-191 (1994)
DOI: 10.1177/095968369400400207


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