Macrozoobenthos diversity in an oxygen minimum zone off northern Namibia

• Published in: Marine biology Vol. 156; no. 9; pp. 1949 - 1961
• Main Authors: Zettler, Michael Lothar, Bochert, Ralf, Pollehne, Falk
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.08.2009; Springer; Springer Nature B.V
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Biological and medical sciences; Biomedical and Life Sciences; Community; Environmental conditions; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; Life Sciences; Marine; Marine & Freshwater Sciences; Marine biology; Microbiology; Oceanography; Original Paper; Sea water ecosystems; Studies; Synecology; Zoology; Namibia; Africa; Polychaete; Angola; Bottom Water; Shell Deposit; Oxygen Minimum Zone; Oxygen; Diversity
• ISSN: 0025-3162; 1432-1793
• DOI: 10.1007/s00227-009-1227-9

A benthological survey in the Benguela upwelling area off northern Namibia (located at 17.3°S and water depth ranging between 26 and 117 m) showed the concentration of dissolved oxygen and the accumulation of organic-rich sediments to control macrozoobenthic community patterns. In contrast to highly biodiverse nearshore areas with well-structured shell deposits of the brachiopod Discinisca tenuis (Sowerby 1847), the benthic community in the oxygen minimum zone (OMZ) decreased strongly in species numbers. Nevertheless, a well-established community ranging from 13 to 31 species persisted. Species densities (300–3,350 ind m −2 ) and biomass (4–109 g afdw/m 2 ) were surprisingly high for areas with near bottom oxygen concentrations from 0.06 to 0.88 ml l −1 . In contrast to OMZ’s of other upwelling areas, where the benthic macrofauna is generally dominated by small-bodied polychaetes, off Namibia larger key organisms like the bivalve Nuculana bicuspidata (Gould 1845) and the snail Nassarius vinctus (Marrett 1877) accounted for a large proportion of the macrozoobenthos >1 mm. This is supposed to have a distinct effect on the functional properties of the sediments.