Ursula Witte | University of Aberdeen (original) (raw)

Address: Aberdeen, Scotland, United Kingdom

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Papers by Ursula Witte

In order to evaluate bioturbation in abyssal Arabian-Sea sediments of the Indus fan profiles of 2... more In order to evaluate bioturbation in abyssal Arabian-Sea sediments of the Indus fan profiles of 210Pb (half-life: 22.3 yr) and 234Th (half-life: 24.1 d) were measured in cores collected during September and October 1995 and April 1997, respectively. The density and composition of epibenthic megafauna and lebensspuren were determined in vertical seafloor photographs during April 1997. Mean eddy-diffusive mixing coefficients according to the distribution of excess 210Pb ( 210Pb-DB) were 0.072±0.028, 0.068±0.055, 0.373±0.119, 0.037±0.009 and 0.079±0.119 cm**2 yr**-1 in the northern, western, central, eastern and southern abyssal Arabian sea, respectively. Mean eddy-diffusive mixing coefficients according to the distribution of excess 234Th (234Th-DB) were 0.53, 1.64 and 0.47 cm**2 yr**-1 in the northern, western and central abyssal Arabian Sea, respectively. Mobile epibenthic megafauna at the western, northern, central and southern study sites were dominated by ophiuroids, holothurians...

Limnology and Oceanography, May 1, 2005

Frontiers in Earth Science, Jun 8, 2016

Frontiers in Marine Science, May 17, 2018

During the large-scale deep-sea programme BIGSET in situ measurements of sediment community oxyge... more During the large-scale deep-sea programme BIGSET in situ measurements of sediment community oxygen consumption (SCOC) were carried out during three cruises between 1995-1998 at five abyssal sites (3190-4450 m water depth) in the deep Arabian Sea in order to elucidate the regional and temporal variation of benthic carbon remineralisation. SCOC ranged from 0.9-6.3 mmol O2 m**-2 d**-1, with highest values in the western and northern Arabian Sea and lowest values in the southern Arabian Sea. For the central Arabian Sea intermediate oxygen uptake rates were detected. This regional pattern mirrors the overall regional pattern of primary productivity in surface waters and vertical particulate organic carbon (POC) flux at 1000 mab. Primary productivity in Arabian Sea surface waters and particulate flux into the deep-sea are controlled by the monsoon system and the flux maxima during the SW and NE monsoon are among the highest particle fluxes recorded in the deep open ocean. Highest flux rat...

With this challenge as its main focus, in May 2012 the Changing Oceans Expedition set sail from G... more With this challenge as its main focus, in May 2012 the Changing Oceans Expedition set sail from Govan, Scotland, on the RRV James Cook (cruise JC 073; Figure 1(a)) for a 5-week expedition to the outermost limits of the UK’s 200 nautical mile exclusive economic zone, and into the high seas beyond national jurisdiction, to study some of Earth’s most remote deepsea ecosystems. The cross-disciplinary international team of researchers used the Irish Marine Institute’s Holland 1 Remotely Operated Vehicle (ROV) and a full suite of the latest oceanographic and acoustic in situ instrumentation to measure fine-scale hydrography and map deep-sea habitats. This approach delivered a full programme of research, allowing detailed investigations of the often complex relationships that deep-sea species have with their changing environments.