Cephalopods of the Benguela Upwelling off Namibia
During three cruises of the USSR research vessels Professor Shtokman and Flamingo (April to June, 1985) and Akademik Kurchatov (January, 1986) extensive collections, primarily of pelagic cephalopods, were taken in the area off Namibia, southeastern Atlantic, 17°30′ to 27°S (in all 128 trawls). Thirty-eight cephalopod species were found, many new for this area. The Namibian cephalopod fauna is comparatively poor in species number but characterized by a high abundance of pelagic-oceanic and nerito-oceanic species. The benthic and nektobenthic species, particularly those species inhabiting the middle and outer shelf, are extremely impoverished in the comparison with analogical faunas off Angola and South Africa. The nerito-oceanic ommastrephids, Todarodes angolensis and Todaropsis eblanae, were caught in near-bottom layers seaward of 115 to 125 m depths. Most pelagic species occur only seaward of the 300 m isobath. Many tropical and tropical-subtropical species, common and widely distributed in the open South Atlantic, are either absent off Namibia or occur only in the most northern part of the area (17°30′ to 20°S) or farther than 200–250 nm off the coast. The boundaries of their distributions vary seasonally and/or interannually. The boundary between the impoverished periphery of the tropical zoogeographic zone and the southern subtropical zone lies at 21–23°S. Some nerito-oceanic and distant-neritic (pseudo-oceanic: N.A. Voss, 1985:40) species, e.g., Alloposus mollis, are frequent. During the austral summer 1986, the average biomass of cephalopods in the catches of IKMT trawls was 2.5 times lower but the average abundance was 2.3 times higher than during the austral autumn 1985. Pelagic cephalopods are most abundant, by number and biomass, in the 0 to 200 m layer in the northern part of the area (17°30′ to 20°S), over the upper slope (bottom depths 300 to 1,500 m), i.e., at the northern and seaward periphery of the main upwelling area located in nearshore waters at 25–29°S.
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Document Type: Research Article
Publication date: 01 September 1991
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