Biometry of late Quaternary coccoliths from the Southern Cadiz region

The Cadiz region lies between the Iberian borderland and Morocco, west of the Strait of Gibraltar and the Western Mediterranean. Core GeoB9064-1 (35°24,91’N 6°50,72’W) is located in the southwest at a depth of 702 m, close to the Al Arraich mud volcano field 30 km off the Moroccan margin„ and has a length of 544 cm. Like most coastal regions, the southern Cadiz region is characterised by a coccolith assemblage dominated by the placoliths Emiliania huxleyi and Gephyrocapsa muellerae.Late Quaternary fluctuations are pronounced in this core, as shown by geochemical (TOC and CaC03) and XRF analysis (K, Mg, Fe, etc.), but also in abundances of coccoliths and more particularly Emiliania huxleyi. These can be related to upwelling and/or bottom currents.Colmenero-Hidalgo (2002) has split up Emiliania huxleyi in a larger coldwater and smaller warmwater variety based on a 4 µm cut-off value. Colmenero-Hid algo (2004) identified a deglacial decrease in the larger coldwater variety.In this study, 100 Emiliania huxleyi and 100 Gephyrocapsa muellerae lengths were measured in 30 samples. Comparison of the biometry of Emiliania huxleyi and Gephyrocapsa muellerae shows that these both species have similar fluctuations and both become smaller during the Holocene, revealing the splitting of Emiliania huxleyi in two morphotypes, to be more complex. A new method to tackle this problem is proposed

Atlantic water inflow to Labrador Sea and its interaction with ice sheet dynamics during the Holocene

The hydrodynamics of the Labrador Sea, controlled by the complex interplay of oceanographic, atmospheric and ice-sheet processes, play a crucial role for the Atlantic Meridional Overturning Circulation (AMOC). An improved understanding of the hydrodynamics and its forcing in the past could therefore hold a key to understanding its future behaviour. At present, there is a remarkable temporal mismatch, in that the largely microfossil-based reconstructions of Holocene Atlantic-water inflow/influence in the Labrador Sea and Baffin Bay appear to lag grain size-based current strength reconstructions from the adjacent North Atlantic by > 2ka. Here, we present the first current strength record from the West Greenland shelf off Nuuk to reconstruct Atlantic Water (AW)-inflow to the Labrador Sea via the West Greenland Current. Our data show that the Holocene AW-inflow into Labrador Sea is well aligned with the Holocene Speed Maximum documented in the North Atlantic (McCave and Andrews, 2019; Quat. Sci. Rev. 223), suggesting a close coupling with the AMOC. The observed lag between the microfossil-based records and the Holocene Speed Maximum can be explained when considering the presence of an extended meltwater lens that prevented the shoaling of the inflowing Atlantic waters. Once the meltwater discharge waned after the cessation of large-scale melting of the surrounding ice sheets, the AW could influence the surface waters, independently of the strength of its inflow. Only then was an effective ocean-atmosphere heat transfer enabled, triggering the comparably late onset of the regional Holocene Thermal Maximum. Furthermore, sediment geochemical analyses show that short term cooling events, such as the 8.2 ka event related to the final drainage of glacial Lake Agassiz, lead to glacier advances of the Greenland Ice Sheet. Since the grain size data show that these events had no influence on the AW-inflow to the north eastern Labrador Sea, these advances must have been caused by atmospheric cooling. Consequently, we argue that (i) in this region, surface water-based proxies register AW influence rather than inflow (ii) the AW inflow into the Labrador Sea is controlled by the AMOC, but (iii) its impact on an effective ocean-atmosphere heat transfer was hindered by a prevailing meltwater lens in the early Holocene, i.e. until the cessation of large-scale melting of the surrounding ice sheets

The White Coral Community in the Central Mediterranean Sea Revealed by ROV Surveys

White coral communities consist of scleractinian corals that thrive in the ocean’s bathyal depths (~ 200–4000 m). In the Atlantic Ocean, white corals are known to form complex, three-dimensional structures on the seabed that attract vast amounts of other organisms, accumulate suspended detritus, and influence the local hydrodynamic flow field. These attributes coincide with what we generally describe as a coral reef. With time, environmental change causes decline of the framework-constructing corals; this is followed by erosion of the reef sequence or its draping with noncoral-related deposits. After several such sequences, the structures are known as coral carbonate mounds, which can grow as high as 350 m. Both bathyal white coral reefs and mounds are widely distributed in the Atlantic Ocean and adjacent marginal seas, such as the Gulf of Mexico. The Mediterranean Sea, however, known for its richness of fossil white coral communities exposed in land outcrops, harbors very few extant coral communities. The HERMES project extended its study sites deep into the Mediterranean with state-of-the-art mapping and visualization technology. By doing so, many previously unknown coral sites were discovered during inspections of Mediterranean narrow shelves, canyon walls, escarpments, and seamounts by remotely operated vehicles. Such shelf and continental margin settings are characteristic of the dynamic margins of the Mediterranean Sea and contrast significantly with the much broader shelves of the Atlantic Ocean. This paper reports on a HERMES cruise that was dedicated to exploring these rough submarine topographies in search of white coral communities in the central Mediterranean, and re-evaluates the general perception of the assumed paucity of white corals in this sea

Environmental forcing of the Campeche cold-water coral province, southern Gulf of Mexico

With an extension of >40 km2 the recently discovered Campeche cold-water coral province located at the northeastern rim of the Campeche Bank in the southern Gulf of Mexico belongs to the largest coherent cold-water coral areas discovered so far. The Campeche province consists of numerous 20 to 40 m high coral ridges that are developed in intermediate water depths of 500 to 600 m. The ridges are colonized by a vivid cold-water coral ecosystem that covers the upper flanks and summits. The rich coral community is dominated by the framework-building scleractinia Enallopsammia profunda and Lophelia pertusa while the associated benthic megafauna shows a rather scarce occurrence. The recent environmental setting is characterized by a high surface water production caused by a local upwelling center and a dynamic bottom water regime comprising vigorous bottom currents, internal waves and strong density contrasts, which all together provide optimal conditions for the growth of cold-water corals. The strong hydrodynamics – potentially supported by the diel vertical migration of zooplankton in the Campeche area – drive the delivering of food particles to the corals. The Campeche cold-water coral province is, thus, an excellent example highlighting the importance of the hydrographic setting in securing the food supply for the development of large and vivid cold-water coral ecosystems

La construcción simbólica del futuro en los discursos científico-tecnológicos de las industrias culturales: EPCOT como caso de estudio

Imaginar cómo podemos mejorar nuestra calidad de vida a partir de las innovaciones científicas y tecnológicas ha sido uno de los temas principales de diversas instituciones e industrias culturales como la cinematografía y los museos. A diferencia de las palabras modernización o desarrollo, el concepto de progreso denota cambios de más de un tipo y representa una identidad cultural influenciada por el ethos de cada época. El problema de esta investigación radica en el esfuerzo, por parte de diversos organismos y corporaciones de mantener una ideología del progreso al proponer discursivamente sus percepciones del tema y legitimarlos por medio de mensajes científico-tecnológicos expuestos especialmente a través de las industrias culturales, consideradas medios masivos que ayudan a perpetuar discursos dominantes sobre diversos temas. Lo anterior se aborda desde la teoría de comunicación del sociólogo estadounidense John B. Thompson (1997) y la hermenéutica profunda. El caso de estudio se centra en el parque temático EPCOT. Entre los resultados se encuentra que la construcción de la noción del progreso se ve fuertemente influenciada por los intereses comerciales de los patrocinadores. Por otro lado, el futuro se presenta como uno utópico y extremadamente optimista sin cuestionamiento o disrupción alguna, esta percepción permeó el desarrollo de Estados Unidos durante el siglo XX y luchó por permanecer vigente durante el siglo XXI a pesar de las guerras y las crisis

Cold-Water Coral Ecosystem Functioning through Time in the Deep Sea: The example of cold-water coral carbonate mounds in the northeast Atlantic (from IODP307 to EuroMARC - CARBONATE)

Along the European Atlantic continental margin, recent to young (late Quaternary) fossil carbonate mounds and build-ups by cold-water corals (predominantly the framework forming ahermatypic corals Lophelia pertusa and Madrepora oculata) occur from northern Norway to the Gulf of Cadiz with an emerging global distribution pattern showing a European concentration (see Roberts et al., 2006). These have been the focus of multi-disciplinary European investigations that has moved from the discovery phase (where and what are they) to a more applied stage (how do they function and what do we need to know). One key question is how do these ecosystems function through time and how do they respond to environmental forcing.Investigations so far reveal that all mounds possess different growth histories depending on the environmental setting and the involved faunal associations. Unfortunately, existing cores only penetrated the upper few meters of the mounds thus limiting mound research to the very late stage of mound development. Access to the longer sequences preserved in giant carbonate mounds was overcome in May 2005 when the IODP Expedition 307 (Porcupine Mound Drilling) recovered complete sedimentary records from the 155 m high “Challenger Mound” in the Porcupine Seabight west off Ireland, including the underlying strata and the enigmatic mound base. Shipboard and preliminary shore based investigations of the recovered sediments exposed complex internal mound sedimentary structures and sedimentary fabrics. Coral occurrences throughout the core stressed the biological influence on mound development and construction. The common occurrence of hardgrounds is indicative of harsh environmental controls on mound formation and development with diagenetic effects playing a progressive role in internal mound geochemical environment influencing cementation, dissolution, porosity and permeability.Up to now the carbonate stored in carbonate mounds has not been considered in any global carbonate budget or linked to any global carbon budget involving greenhouse gases. A major challenge exists to quantify the amount and flux of carbon stored by these newly discovered areas of enhanced carbonate accumulation in intermediate water depth (e.g. carbonate mounds). The only existing integrative cold-water coral carbonate budget that has been performed is on short, post-glacial cores relevant to the Norwegian shelf only, which suggests that these small cold-water coral carbonate mounds alone may account for an additional 1% of total marine carbonate production (Lindberg et al., 2005).IODP has delivered one complete record from base to top of one carbonate mound in the Belgica Mound Province, Porcupine Seabight, NE Atlantic. EU FP projects have revealed late stage history of giant mounds in different settings showing that different mounds respond in different ways to environmental forcing factors with no one mound being typical of all. EuroMARC – CARBONATE hopes to study sequences through various mounds in different environmental settings. By understanding how biogeochemical processes control the development of these carbonate mounds and their response to climate change, we will make an important step in quantifying their role as mid-latitude carbonate sinks. In the end, a better understanding of the processes involved in mound formation and development may also result in new views on fossil analogues many of which are less accessible hydrocarbon reservoirs