Abstract
Benthic foraminifera (protists with biomineralized tests) coupled with geochemical proxies are used for the first time to characterize present oceanographic conditions occurring in cold-water coral ecosystems (CWC) in the eastern Alboran Sea (Brittlestar Ridge and Cablier Mound), western Mediterranean Sea. Quantitative data on living (stained) benthic foraminifera from 5 box cores retrieved during the MD194 cruise on the RV Marion Dufresne reveal that these organisms are more diverse in presence of corals, where more numerous ecological niches occur than they are in pelagic adjacent sediments. These data confirm that CWC can be considered as “diversity hotspots” also for benthic foraminifera.Geochemical characterization shows that these sediments contain relatively fresh (labile) organic matter but also a reworked refractory component. In particular, the total organic carbon and the δ13Corg values suggest that some of the organic matter may be a mixture of marine and reworked particulate organic matter, compared to typical values from temperate phytoplankton. The δ15N of the organic fraction suggests that important atmospheric N2-fixation and degradation processes occur in the region.Finally, our results show that a more effective advection of freshly exported particulate organic matter from the surface waters occur at the mound top rather than at the mound base or off-mound allowing some coral colonies to survive on the top of mounds in this region. The mud layer covering the coral rubble debris may suggest that the Brittlestar Ridge is today exposed to siltation preventing the growth of corals at the mound base or off-mound.
Highlights
Cold-water coral (CWC) ecosystems are “hotspots” of biodiversity offering diversified habitats to marine organisms (Freiwald et al, 2004; Mastrototaro et al, 2010; Henry and Roberts, 2017)
We investigated five box cores recovered during the Eurofleets Marion Dufresne 194 cruise in June 2013 in the eastern Alboran Sea at water depths ranging from 251 m to 474 m (Figs. 1A-B; Table S1)
Video survey of the Melilla Mound Field (MMF) showed that most of the elongated ridges occurring in this area (e.g., Comas et al, 2009), mostly consist of dead coral framework with abundant coral rubbles and that small living CWC colonies are presently restricted to their tops (Hebbeln et al, 2009)
Summary
Cold-water coral (CWC) ecosystems are “hotspots” of biodiversity offering diversified habitats to marine organisms (Freiwald et al, 2004; Mastrototaro et al, 2010; Henry and Roberts, 2017) These ecosystems preferentially occur on subvertical walls, overhangs and pre-existing topographic highs with sustained nutrient and food particle input and where intense bottom currents prevent corals to be smothered by sediment (e.g., White et al, 2005; Davies et al, 2008; Vertino et al, 2010). These ecosystems are presently a main concern for the scientific community for their sensitivity in changing environmental conditions They play an important role in the total carbonate budget and in the regulation of atmospheric CO2 on Earth (e.g., Lindberg and Mienert, 2005; Roberts et al, 2006; Movilla et al, 2014; Titschack et al, 2016)
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
