Search

The oceans and coastal seas provide mankind with many benefits including food for around a third of the global population, the air that we breathe and our climate system which enables habitation of much of the planet. However, the converse is that generation of natural events (such as hurricanes, severe storms and tsunamis) can have devastating impacts on coastal populations, while pollution of the seas by pathogens and toxic waste can cause illness and death in humans and animals. Harmful effects from biogenic toxins produced by algal blooms (HABs) and from the pathogens associated with microbial pollution are also a health hazard in seafood and from direct contact with water. The overall global burden of human disease caused by sewage pollution of coastal waters has been estimated at 4 million lost person-years annually. Finally, the impacts of all of these issues will be exacerbated by climate change. A holistic systems approach is needed. It must consider whole ecosystems, and their sustainability, such as integrated coastal zone management, is necessary to address the highly interconnected scientific challenges of increased human population pressure, pollution and over-exploitation of food (and other) resources as drivers of adverse ecological, social and economic impacts. There is also an urgent and critical requirement for effective and integrated public health solutions to be developed through the formulation of politically and environmentally meaningful policies. The research community required to address “Oceans & Human Health” in Europe is currently very fragmented, and recognition by policy makers of some of the problems, outlined in the list of challenges above, is limited. Nevertheless, relevant key policy issues for governments worldwide include the reduction of the burden of disease (including the early detection of emerging pathogens and other threats) and improving the quality of the global environment. Failure to effectively address these issues will impact adversely on efforts to alleviate poverty, sustain the availability of environmental goods and services and improve health and social and economic stability; and thus, will impinge on many policy decisions, both nationally and internationally. Knowledge exchange (KE) will be a key element of any ensuing research. KE will facilitate the integration of biological, medical, epidemiological, social and economic disciplines, as well as the emergence of synergies between seemingly unconnected areas of science and socio-economic issues, and will help to leverage knowledge transfer across the European Union (EU) and beyond. An integrated interdisciplinary systems approach is an effective way to bring together the appropriate groups of scientists, social scientists, economists, industry and other stakeholders with the policy formulators in order to address the complexities of interfacial problems in the area of environment and human health. The Marine Board of the European Science Foundation Working Group on “Oceans and Human Health” has been charged with developing a position paper on this topic with a view to identifying the scientific, social and economic challenges and making recommendations to the EU on policy-relevant research and development activities in this arena. This paper includes the background to health-related issues linked to the coastal environment and highlights the main arguments for an ecosystem-based whole systems approach.

International audience

Cold-water corals are widely distributed along the Moroccan margin in the Northeast Atlantic Ocean. Within the Gulf of Cadiz mud volcanoes, submarine ridges and steep fault escarpments occur, which favour the settlement of scleractinians and build up coral mounds. One of these sites is the Pen Duick Escarpment, situated in the El Arraiche mud volcano field, 35 km offshore the city of Larache. Pen Duick Escarpment is a 6 km long, SSE-NNW oriented, 80 to 125 m high wall with a southwest-facing slope of 8 to 12°. Up to now, 15 coral mounds were recognized on top of the escarpment with an average estimated elevation of 15 m. Although cold-water corals are a common feature on the adjacent cliffs, mud volcanoes and seafloor, no actual living coral has been observed.This study is based upon three on-mound gravity cores (Alpha, Beta and Gamma mound) acquired by R/V Marion Dufresne in 2008 (MD169). Each mound was cored at least twice to recover both a core for biogeochemical and microbial studies, and another core for sedimentological purposes, in order to link both processes. The sedimentological cores were analysed using different techniques (medical CT scanning, XRF, U/Th dating, stable isotopes, grain-size analysis) in order to obtain a holistic view on the build-up of a mound. The coring, together with present-day seabed observations, revealed the architectural importance of open coral rubble plates in the role of mound building. These graveyards act not only as sediment trap but also as microhabitat for a wide range of benthic organisms.

Sub-recent cold-water carbonate mounds localized in deeper slope settings on the Atlantic continental margins cannot be any longer neglected in the study of carbonate systems. They clearly play a major role in the dynamics of mixed siliciclastic-carbonate and/or carbonate-dominated continental slopes. Carbonate accumulation rates of cold-water carbonate mounds are about 4 to 12 % of the carbonate accumulation rates of tropical shallow-water reefs but exceed the carbonate accumulation rates of their slope settings by a factor of 4 to 12 (Titschack et al.,2009). These findings emphasize the importance of these carbonate factories as carbonate niches on the continental margins. The primary environmental architecture of such carbonate bodies is well-characterized. However, despite proven evidences of early diagenesis overprinting the primary environmental record (e.g. aragonite dissolution) (Foubert & Henriet, 2009), the extent of early diagenetic and biogeochemical processes shaping the petrophysical nature of mounds is until now not yet fully understood.Understanding (1) the functioning of a carbonate mound as biogeochemical reactor triggering early diagenetic processes and (2) the impact of early diagenesis on the petrophysical behaviour of a carbonate mound in space and through time are necessary (vital) for the reliable prediction of potential late diagenetic processes. Approaching the fossil carbonate mound record, through a profound study of recent carbonate bodies is innovative and will help to better understand processes observed in the fossil mound world (such as cementation, brecciation, fracturing, etc. . . ).In this study, the 155-m high Challenger mound (Porcupine Seabight, SW of Ireland), drilled during IODP Expedition 307 aboard the R/V Joides Resolution (Foubert & Henriet, 2009), and mounds from the Gulf of Cadiz (Moroccan margin) will be discussed in terms of early diagenetic processes and petrophysical behaviour. Early differential diagenesis overprints the primary environmental signals in Challenger mound, with extensive coral dissolution and the genesis of small-scaled semi-lithified layers in the Ca-rich intervals. The low cementation rates compared to the extensive dissolution patterns can be explained by an open-system diagenetic model. Moreover, Pirlet et al. (2009) emphasizes the occurrence of gypsum and dolomite in another mound system (Mound Perseverance) in Porcupine Seabight, which might be also related with fluid oxidation events in a semi-open diagenetic system. Along the Moroccan margins, fluid seepage and fluxes in pore water transport affect the development of mound structures, enhancing extensive cold-water coral dissolution and precipitation of diagenetic minerals such as dolomite, calcite, pyrite, etc. (Foubert et al., 2008). Recent carbonate mounds provide indeed an excellent opportunity to study early diagenetic processes in carbonate systems without the complications of burial and/or later meteoric diagenesis.

During the R/V Marion Dufresne 169 ‘MiCROSYSTEMS’ cruise (July 2008) to the El Arraiche mud volcano field in the Gulf of Cadiz cold-water coral mounds were targeted. Four on-mound gravity cores, with a total length of 17.5 m, were obtained for sedimentological and palaeoceanographic analyses in order to unveil the history of the uppermost meters of these cold-water coral build-ups. In parallel, four on-mound cores were taken on approximately the same location for microbiological and biogeochemical analyses. By comparing and correlating both results, more information can be revealed about the processes acting in the dead coral rubble fields which cover these mounds.Computed X-ray tomography (CT) was used for the identification and quantification of the corals inside the gravity cores. Furthermore, this technique is also useful for the investigation of sedimentological features, i.e. bioturbation, porosity, laminations... In this study, cores were scanned using a medical CT scanner on a relative high resolution which allows the three-dimensional visualization of the corals and sedimentological features. Slices were taken every 3 mm with an overlap of 1 mm.Based on these data it was possible to delineate different “CT” facies within the cores. On one hand there are intervals with a high amount of corals and on the other hand zones with a very low amount of corals or even no corals at all. In the first case two different facies can be distinguished: one facies with clearly recognizable, well preserved corals, and the second facies with crushed coral fragments. In both facies the corals are embedded in a homogenous matrix. Different facies could also be defined in the intervals containing little or no corals. For example, a homogenous facies with bioturbations and/or cracks. Also an important observation is the resence of pyrite which appears in all cores at a certain depth. Sometimes the pyrite could be observed in bioturbations or inside the corals.Besides that also the percentage of corals in these gravity cores were quantified using the “Morpho+” software, which was developed at the UGCT (Centre for X-ray Tomography, Ghent University, Belgium). Based on these results, a clear difference can be noticed between the four mounds. On Conger cliff, corals were only observed in the upper 34 cm while in the other locations corals can be found throughout the entire core with significant variations in the amount of corals.Finally, it was possible to identify different species of cold-water corals, namely Lophelia pertusa, Madrepora oculata, Desmophyllum cristagalli and Dendrophyllia. In conjunction with dating and palaeoenvironmental analyses of the corals and the sediment matrix, this can yield valuable information about the build-up of these cold-water coral mounds in the El Arraiche mud volcano field and the palaeoenvironmental characteristics at the time the corals were living.

During IODP Expedition 307, the first complete sequence through a cold-water coral carbonate mound (a bio-geological seafloor feature created through successive stages of cold-water coral mediated sediment accumulation) was successfully acquired. The recovery of the Challenger Mound record, one of the large (ca. 155 m high) cold-water coral carbonate mounds along the NE Atlantic continental margin (Belgica Mounds,eastern Porcupine Seabight), finally facilitates the study of an entire coral carbonate mound’s development process and allows the identification of the environmental conditions driving and maintaining the build-up of these remarkable seafloor habitats. Furthermore, due to its location along the NE Atlantic continental margin, the Challenger Mound sequence contains a potential record of continent-ocean climatic evolution during the Plio-Pleistocene [1,2]. In this study, the different sediment contributors to the Challenger Mound are identified and assessed throughout its entire sedimentary sequence. High resolution siliciclastic particle-size end-member modelling and its ground-truthing (XRD, quartz-sand surface microtextures) indicate the dominant influence of a climatically-steered contour-current system. Iceberg rafting is identified as important depositional mechanism throughout the whole mound development. Furthermore, new evidence (Nd-Sr isotopes of ice-rafted grains) for locally-derived icebergs reaching the eastern Porcupine Seabight continental margin, even in the early stages of Northern Hemisphere glacial expansion, is preserved in the mound sequence. The Challenger Mound reveals a two-phase development, separated by a significant hiatus (from 1.7 to 1 Ma [1,2]). The lower mound-phase indicates a (semi-)continuous, fast accumulating current-controlled depositional environment, while the condensed upper mound-phase bears witness of the distinct shift to a more glacially-influenced, more varying global environment since the mid-Pleistocene climate transition. The density of the cold-water coral cover at the site of deposition plays an essential role in sediment deposition and preservation on Challenger Mound. Moreover, the sediment stabilising capacities of a dense coral cover facilitated sediment accumulation on Challenger Mound in the general erosive/non-depositional Pliocene environment present along the NE Atlantic continental margin. A unique, higher resolution record is hence preserved in the lower mound sequence. Overall, the potential of coldwater coral carbonate mounds as intermediate water depth, continental margin, Plio-Pleistocene palaeo-archives is showcased.

Heinrich Layers are found in the North Atlantic Ocean as well-constrained markers of catastrophic iceberg surges from the Pan-Atlantic ice sheets during the last glacial cycle. Their physical and geochemical characteristics allow for relatively fast diagnostics using the state-of-the-art core scanners such as a Multi-Sensor Core Logger and an XRF core scanner. The nature of these characteristics are predominantly due to the source sediments of the ice-rafted debris (IRD) on the one hand (magnetic susceptibility, color, carbonate content) and the response of the palaeo-environment on the other hand (carbonate content, foraminiferal assemblage). However, changes in (gamma) bulk density of the sediment within a Heinrich Layer cannot solely be explained due to the higher content of IRD. Sediment cores in the Porcupine Seabight (West off Ireland) have shown the presence of Heinrich Events without the diagnostic changes in magnetic susceptibility (MS), suggesting a more drastic change in oceanography which could cause widespread diagenesis on the seabed during Heinrich Events. In order to better understand the physical behavior of a Heinrich Layer, 2 cores were studied taken from the northern Porcupine Seabight by R/V Marion Dufresne campaign MD123 in September 2001. More specifically HL2 was studied since it carries the most typical HL signature. The main anatomical information, with a resolution of 0.5 mm, was obtained by means of medical computed tomography of half-core sections of 50 cm length from the Ghent University Hospital. This information was used for detailed sampling for mineralogy, grainsize measurements and palaeoenvironmental analyses. On one core section, XRF core scanning was performed at a 0.5 cm interval. Higher-resolution information was obtained from five 8 cc subsamples which underwent µCT scanning and cold-cathode luminescence microscopy. The results of this unique approach show a rather surprising 3D view of a Heinrich Layer. As expected, the concentration of ice-rafted debris (commonly referred to as the fraction > 150 µm) increases towards the culmination of HL2, marked by an increase in MS, XRF Ca and the percentage of N. pachyderma s. However, the zone where the density increases is marked by a cloud of fine and highly dense particles surrounding the IRD. It seems as if the fine clayey “background” matrix throughout the core consolidates near the centre of HL2. The same feature has been observed within the µCT samples, where the cold-cathode luminescence microscopy has indicated the presence of zoned dolomites. These dolomites might be the result of a diagenetic process that might explain the elevated density. Moreover, the mineralogical analyses show for a predominant volcanic source for the magnetic susceptibility. Contrastingly, both XRF Fe and Ti show significant decreases near the HL culmination, which calls again for diagenetic alteration of the sediment during or just after the Heinrich Event. At this stage of the research, the mechanisms of these diagenetic processes remain unclear. Nevertheless, these results call for a wider view on the depositional processes of Heinrich Layers and their impact upon the seabed geochemistry.

Cold-water coral ecosystems may constitute a geologically significant fraction (>1%) of global carbonate production (Lindberg and Mienert, 2005). Thriving cold-water coral reefs are also considered to be hot-spots of diversity and biomass production. Nevertheless, the impacts of these ecosystems on the adjacent sediment and associated geochemical processes including carbonate preservation are poorly understood.Here we present the first data quantifying the biogeochemical processes in modern (post-glacial) cold-water coral reef sediments. This work integrates organoclastic sulfate reduction rates, multi-element pore-water profiles and solid-phase analyses of gravity cores (8 sites at two reefs) retrieved during R/V Polarstern expedition ARKXXII/1a to the mid-Norwegian cold-water coral reefs in June 2007.The reef sediments are comprised of coral fragments embedded in loose silt or clay and biogenic debris (of 0,5 to 3,2 m thickness). The base of the coral-bearing reef sediments consists of highly compacted glacial clays. High carbonate contents (up to 75 %) and low organic carbon contents (~0,5 %) characterize the reef sediments. Porewater Ca2+, Mg2+ and Sr2+ profiles indicate that on-going carbonate precipitation dominates any carbonate dissolution. Overall microbial activity in these sediments is low; measured sulfate reduction rates are less than 1 nmol S cm-3 d-1. Pore-water analyses reveal elevated Fe2+ and Mn2+ concentrations suggesting that Fe and Mn reduction occurs. This may be the result of sulfide reacting with the available reactive iron pool to form Fe-sulfides indicated by the absence of sulfide in the pore water. Fe and Mn reduction may also be attributed to dissimilatory microbial metal reduction. Iron reduction linked to microbial sulfate reduction may enhance diagenetic carbonate precipitation and coral preservation in these sediments as suggested for the older coldwater coral mound systems drilled in IODP Expedition 307 (Ferdelman et al., 2006). Extremely low methane concentrations (

During the Geomound-cruise with the R/V Marion Dufresne in 2001 gravity cores were recovered on the top of Thérèse mound (MD01-2463G) and Challenger mound (MD01-2451G). Both mounds are built up by cold-water corals (Lophelia pertusa sp. and Madrepora oculata sp.). This was confirmed by the IODP drilling (expedition 307) where Challenger mound was drilled to its base and cold-water corals were observed over the entire length of the mound.The gravity core (MD01-2463G), taken on top of Thérèse mound, was described and analyzed for its foraminiferal content and grainsize. A combination of these data with the results from previous studies (P-wave velocity, gamma density, magnetic susceptibility, X-ray imagery, U/Th-dating of corals and foraminifera (Frank et al., 2005, Foubert et al., 2006)), made it possible to distinguish different units, enabling a reconstruction of the evolution of the top of Thérèse mound.In a next step, the different zones in the core on top of Thérèse mound could be correlated with the sections identified in the gravity core recovered on top of Challenger mound (MD01-2451G) (Foubert et al., 2006). The mounds unveiled a comparable recent history, implying that their growth was controlled by the same parameters. Both cores revealed at least one discontinuity in the record, corresponding with a time hiatus of more than 200 ka. This discontinuity corresponds most likely to a change in hydrodynamic environment which prohibited further coral growth but erosional processes cannot be ruled out. The hiatus is in both cases covered with a layer of fine laminated sediments and dropstones. The origin of this detritic material is still unclear and will be further investigated using the Nd isotopic signature of the sediment as a tracer.