Deep-sea benthic foraminifera at a bauxite industrial waste site in the Cassidaigne Canyon (NW Mediterranean): Ten months after the cessation of red mud dumping

During an environmental survey performed in autumn 2016, living (stained) benthic foraminiferal faunas were investigated at 16 stations sampled within the Cassidaigne Canyon (NW Mediterranean Sea) and surrounding area and located between 265–2500 m water depth. For many decades, industrial bauxite residues of red mud have drained into the canyon via a submarine pipe, causing physical disturbance and chemical contamination. In January 2016, solid waste disposal ceased and was replaced with the dumping of a low-density liquid effluent. Our ecological observations at the 725 m-depth station closest to the Cassidaigne Canyon submarine pipe show the highest concentration of the opportunistic species, and a strongly altered benthic diversity. At the other fifteen stations, foraminiferal standing stocks and simple diversity decrease with decreasing food input to the seafloor and increasing water depth. There, foraminiferal composition with a minor contribution of stress-tolerant species echoes the overall meso-oligotrophic patterns of a relatively stable ecosystem

Deep-sea benthic foraminifera at a bauxite industrial waste site in the Cassidaigne Canyon (NW Mediterranean): Ten months after the cessation of red mud dumping

During an environmental survey performed in autumn 2016, living (stained) benthic foraminiferal faunas were investigated at 16 stations sampled within the Cassidaigne Canyon (NW Mediterranean Sea) and surrounding area and located between 265–2500 m water depth. For many decades, industrial bauxite residues of red mud have drained into the canyon via a submarine pipe, causing physical disturbance and chemical contamination. In January 2016, solid waste disposal ceased and was replaced with the dumping of a low-density liquid effluent. Our ecological observations at the 725 m-depth station closest to the Cassidaigne Canyon submarine pipe show the highest concentration of the opportunistic species, and a strongly altered benthic diversity. At the other fifteen stations, foraminiferal standing stocks and simple diversity decrease with decreasing food input to the seafloor and increasing water depth. There, foraminiferal composition with a minor contribution of stress-tolerant species echoes the overall meso-oligotrophic patterns of a relatively stable ecosystem

Deltaic and Coastal Sediments as Recorders of Mediterranean Regional Climate and Human Impact Over the Past Three Millennia

International audienc

Unexpected biotic resilience on the Japanese seafloor caused by the 2011 Tōhoku-Oki tsunami

On March 11th, 2011 the Mw 9.0 2011 Tōhoku-Oki earthquake resulted in a tsunami which caused major devastation in coastal areas. Along the Japanese NE coast, tsunami waves reached maximum run-ups of 40 m, and travelled kilometers inland. Whereas devastation was clearly visible on land, underwater impact is much more difficult to assess. Here, we report unexpected results obtained during a research cruise targeting the seafloor off Shimokita (NE Japan), shortly (five months) after the disaster. The geography of the studied area is characterized by smooth coastline and a gradually descending shelf slope. Although high-energy tsunami waves caused major sediment reworking in shallow-water environments, investigated shelf ecosystems were characterized by surprisingly high benthic diversity and showed no evidence of mass mortality. Conversely, just beyond the shelf break, the benthic ecosystem was dominated by a low-diversity, opportunistic fauna indicating ongoing colonization of massive sand-bed deposits.Peer reviewe

Tsunami sediments and their foraminiferal assemblages

Tsunami hazard assessment begins with a compilation of past events that have affected a specific location. Given the inherent limitations of historical archives, the geological record has the potential to provide an independent dataset useful for establishing a richer, chronologically deeper time series of past events. Recent geological studies of tsunami are helping to improve our understanding of the nature and character of tsunami sediments. Wherever possible, geologists should be working to improve the research 'tool kit' available to identify past tsunami events. Marine foraminifera (single celled heterotrophic protists) have often been reported as present within tsunami-deposited sediments but in reality, little information about environmental conditions, and by analogy, the tsunami that deposited them, has been reported even though foraminifera have an enormous capacity to provide meaningful palaeo-environmental data. Here, we review what foraminifera are, describe their basic form and significance, summarise where they have been reported in tsunami sediments and identify what can be learnt from them. We review the gaps in our understanding and make recommendations to assist researchers who examine foraminiferal assemblages in order to enhance their use within tsunami geology.16 page(s

Deep sea benthic foraminifera as proxies for palaeoclimatic fluctuations in the New Caledonia Basin, over the last 140,000years

The New Caledonia Basin (NCB), SW Pacific, a deep bathyal to abyssal basin bordered by the Lord Howe Rise to the west and the Norfolk Ridge to the east, has received little scrutiny with regard to the taxonomic diversity of benthic organisms in its Quaternary to Recent deep sea sediments. In 2001, Gravity Core 4 (GC4) was extracted from the NCB and the uppermost 141. cm, representing approximately the last 140,000. years, was investigated for chemical isotopic, carbonate, non-carbonate and trace element signatures. In this study, subsamples of the same uppermost 141. cm of GC4 were picked and sorted for all foraminiferal taxa. At selected intervals in GC4, all benthic species were identified and counted for measures of relative abundance. A total of 161 species of benthic foraminifera were obtained from the core and 46 species occurred in sufficient numbers to investigate changing patterns and trends in biodiversity and relative abundance. Changes found within the foraminiferal distribution down the core can be related to some oceanic and palaeoclimatic fluctuations during the last ~ 140,000. years. Within GC4, two distinct foraminiferal assemblages were detected using Bray-Curtis cluster analysis and Multidimensional Scaling (MDS) analysis. Foraminiferal Assemblage 1 occurs in lower bathyal to abyssal depths and was largely influenced by high oxygen levels at the sediment-water interface throughout Marine Isotopic Stage (MIS) 6-3 (approximately 128-25. ka). Foraminiferal Assemblage 2 dominated the upper bathyal shelf during MIS 2 (approximately 25-10. ka), with surface waters characterised by high sea surface productivity (SSP) and eutrophic conditions. During the time covered by GC4, there are instances where the relative abundance of the dominant taxon Epistominella exigua (Brady) and other key taxa decreases and opportunistic species of Uvigerina, adapted to lower oxygen levels, increase in relative abundance, indicating a shift of conditions at the sediment-water interface. Factors that influence the foraminiferal assemblages include environmental setting, SSP, oxygen levels at the sediment-water interface and transportation by oceanic current systems operating within the region.13 page(s

Effects of cyclone-generated disturbance on a tropical reef foraminifera assemblage

The sedimentary record, and associated micropalaeontological proxies, is one tool that has been employed to quantify a region’s tropical cyclone history. Doing so has largely relied on the identification of allochthonous deposits (sediments and microfossils), sourced from deeper water and entrained by tropical cyclone waves and currents, in a shallow-water or terrestrial setting. In this study, we examine microfossil assemblages before and after a known tropical cyclone event (Cyclone Hamish) with the aim to better resolve the characteristics of this known signal. Our results identify no allochthonous material associated with Cyclone Hamish. Instead, using a swathe of statistical tools typical of ecological studies but rarely employed in the geosciences, we identify new, previously unidentified, signal types. These signals include a homogenising effect, with the level of differentiation between sample sites greatly reduced immediately following Cyclone Hamish, and discernible shifts in assemblage diversity. In the subsequent years following Hamish, the surface assemblage returns to its pre-cyclone form, but results imply that it is unlikely the community ever reaches steady state.12 page(s

The highest southern latitude record of a living Tridacna gigas

5 page(s

The Australian Tsunami Warning System and lessons from the 2 April 2007 Solomon islands tsunami alert in Australia

2 page(s