Cold-water coral ecosystems have been identified as vulnerable, but quantitative data on their conservation status is very limited. The Marine Strategy Framework Directive (MSFD) is the tool implemented by the European Union's Integrated Maritime Policy to achieve Good Environmental Status (GES) of marine waters by 2020. In this context, the aim of this study was to evaluate the Ecological Status of benthic habitats in Cassidaigne canyon, focusing in particular on cold-water coral habitats dominated by Madrepora oculata. Data were collected during the Videocor1 cruise (2017). Videos and photos collected during eight dives of the H-ROV Ariane were used to reconstruct, in 3-dimensions, the areas where cnidarians have settled in the canyon. A total of 33 3D models were built, which allowed measuring the spatial and vertical distribution, surface, density and size structure of cnidarian populations at four different sites. When 3D reconstructions were not possible, GIS tools were used. The seven cnidarian species considered were the scleractinian M. oculata; three antipatharians: Leiopathes glaberrima, Antipathella subpinnata, Antipathes dichotoma; and three aclyonaceans: the precious red coral Corallium rubrum and the gorgonians Callogorgia verticllata and Viminella flagellum. Using photogrammetry, we were able to reveal the size structure of the dense population of M. oculata in the canyon, as well as to obtain knowledge on a complex site (Cassis-200) composed of 15 knolls, and to quantify the surface occupied by M. oculata at a separate site (Cassis-500) influenced by industrial discharges. At the southern flank of the canyon we found a highly diverse site (SW Flank) dominated by antipatharians and gorgonians composing large forests, and finally a reservoir of M. oculata was identified under overhangs at a site called the Wall. The diversity of accompanying species is also reported and marine litter quantified. Images collected before 2017 were compared to the 3D models to precisely locate them on the sites, and assess temporal changes in M. oculata colony sizes at Cassis-200 site. We also report on the ground-truthing of predicted habitat maps produced previously, and confirm their good representation of the distribution of cold-water coral habitats. Finally, we quantified the criteria defined by the MSFD, aimed at evaluating the GES of benthic habitats for M. oculata ecosystems, at the scale of the Please note that this is an author-produced PDF of an article accepted for publication following peer review. The definitive publisher-authenticated version is available on the publisher Web site. Cassidaigne canyon. Measurements showed that the extent of loss of the observed M. oculata habitat reached 56% according to the MFSD definition. Highlights ► Cold-water corals distribution, density and size structure are reported. ► Size measurements were performed using 3D-models. ► A diverse site dominated by antipatharians and gorgonians forests was found. ► The extent of loss of the observed M. oculata habitat reached 56...
Temperature and conductivity fluctuations caused by the hydrothermal emissions released during the degasification stage of the Tagoro submarine volcano (Canary Islands, Spain) have been analysed as a robust proxy for characterising and forecasting the activity of the system. A total of 21 conductivity-temperature-depth time series were gathered on a regular high-resolution grid over the main crater of Tagoro volcano. Temperature and conductivity time series, as manifestations of stochastic events, were investigated in terms of variance and analysed by the Generalised Moments Method (GMM). GMM provides the statistical moments, the structure functions of a process whose shape is an indicator of the underlying stochastic mechanisms and the state of activity of the submarine volcano. Our findings confirm an active hydrothermal process in the submarine volcano with a sub-normal behaviour resulting from anti-persistent fluctuations in time. Its hydrothermal emissions are classified as multifractal processes whose structure functions present a crossover between two time scales. In the shorter time scale, findings point to the multiplicative action of two random processes, hydrothermal vents, which carries those fluctuations driving the circulation over the crater, and the overlying aquatic environment. Given that both temperature and conductivity fluctuations are nonstationary, Tagoro submarine volcano can be characterised as an open system exchanging energy to its surroundings.
Sailing on scientific expeditions as an early career researcher (ECR) offers the beneficial opportunity to gain field experience and training. However, the number of available berths to achieve the scientific goals of an expedition limits the number of onboard participants. Telepresence and remote learning can be utilized to increase the number of active participants, broadening the reach of capacity development. The 2021 iMirabilis2 expedition on board the Spanish Research Vessel Sarmiento de Gamboa used telepresence to virtually involve ECRs from several countries in deep-sea science. One year post-expedition, a survey of onshore participants was conducted to assess and quantify the effectiveness of the peer-to-peer ECR ship-to-shore scheme. During the expedition, live, interactive training via WhatsApp and Zoom was utilized by onshore ECRs more than traditional static, unidirectional methods of blog posts and pre-recorded videos. All respondents either agreed or strongly agreed that the scheme provided an inclusive and accessible platform to share deep-sea science. These results suggest similar schemes could be used to supplement shorter-duration at-sea-training, used prior to a seagoing experience to better prepare ECRs, or to allow members of the science community unable to join an expedition in person to actively participate remotely, increasing inclusivity.
<p>The Guinea Dome, located in the eastern tropical North Atlantic, is produced by cyclonic circulation associated with the eastward North Equatorial Countercurrent, the northward Mauritanian Current and the westward North Equatorial Current, which causes the uplift of the isotherms in the Guinea Dome. This oceanographic feature is important for the regional atmosphere-ocean dynamics, and its variability was suggested to be linked with precipitation changes in North Africa, at least at a decadal scale. Characterizing the development of the dome through the Holocene will contribute to understand the prominent environmental changes that occurred regionally during this period, as evidenced by the green-to-desert Sahara transition at the end of the African Humid Period (ca. 6,000 years ago).</p> <p>A 35cm sediment multicore, extracted southwest off Cabo Verde during the iMirabilis2 scientific cruise, at a water depth of 4,394 m, is being investigated. We present planktonic foraminifera counts and X-ray fluorescence (XRF) scanning data to reconstruct palaeoceanographic and sediment input changes during the Holocene. An age-depth model for the sediment core was established with three samples dated by the radiocarbon method, indicating that the sediment was deposited from 11,180 to 1,257 calibrated years before present (cal. BP).</p> <p>Planktonic foraminifera results show a gradual but important change in the assemblages throughout the core, where the abundance of species preferring warmer waters increase by 44% towards the top of the core. These results are interpreted as warming of the surface water masses during the Holocene, as a result of reduced influence of the Guinea Dome due to its change of location to a more southern position and/or as a consequence of a weakening of the dome. X-ray fluorescence scan variations along the core show that the faunal shift is encompassed by differences in the terrigenous sediment supply, indicating changes in the inland climate regime. For instance, changes in the Ti/Fe, Ti/Al and Al/Ca ratios are proxies for the fluvial/aeolian sedimentary input and the hinterland climate variability. An increase of the high river discharge indicators is displayed between 10 and 6 kyr BP, probably as a consequence of the increased precipitation that took place during the African Humid Period.</p> <p>Further ongoing geochemical analyses of foraminifera shells will provide information regarding the temperature, salinity and productivity of both, the mixed layer and the sub-thermocline, which will improve the characterization of the variability that the Guinea Dome experienced during the Holocene.</p>
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