Biodiversity and ecology of benthic foraminiferans from the Antarctic deep sea

• Main Author: Cornelius, Nils
• Format: Thesis
• Language: English
• Published: University of Southampton 2005
• Subjects: Antarctic; The Antarctic; Antarctic Peninsula; Antarc*
• Online Access: https://eprints.soton.ac.uk/465581/

Live foraminferal assemblages (i.e. including soft-walled species) and the metazoan fauna were analysed using replicate multicorer subcores (3.45 cm 2 surface area, 0-1 cm layer; >63 μm fraction for meiofaunal forms) and boxcorer subcores (100 cm 2 surface area, 0-5 cm layer; >300 μm fraction for macrofaunal forms) from stations along a transect (1100 - 4975 m water depth) east of the Antarctic Peninsula and a station in the S. Sandwich Trench (6,300 m water depth). Wet-sorting revealed abundant and diverse meio- and macrofaunal assemblages. Foraminiferans usually accounted for 43-83% of all meiofaunal and 65-96% of macrofaunal organisms. Many faunal trends were related to water depth and distance from land, representing a decrease in organic carbon inputs. Foraminiferan and metazoan densities were broadly coherent across the depth range sampled. Abundance generally decreased with water depth, as did the proportion of calcareous individuals, although there was considerable variability between replicate multicorer subcores at some stations. The location of the Carbonate Compensation Depth at about 3000 m did not seem to limit the bathymetric distribution of live individuals of certain calcareous species. Macrofaunal foraminiferans were concentrated in the surface 1 cm of sediment and sediment penetration increased with water depth. A total of 205 live foraminiferal species were recognized, of which only 93 belonged to described taxa. The species diversity of both meio- and macrofaunal assemblages exhibited a unimodal pattern with depth and was highest on the lower slope. Monothalamous taxa increased and calcareous taxa decreased in relative abundance with increasing depth, especially in the meiofaunal fraction. A large proportion (2.5 - 73.3%) of the meiofaunal assemblages were hidden within phytodetrital aggregates; species such as Epistominella exigua, Alabaminella weddellensis and Tinogullmia riemanni were concentrated within these microhabitats. The phytodetrital assemblages are strikingly similar to ...