Stalder Claudio, ElKateb Akram, Spangenberg Jorge E, Terhzaz Loubna, Vertino Agostina, Spezzaferri Silvia
Department of Geosciences, University of Fribourg, Chemin du Musée 6, CH-1700 Fribourg, Switzerland.
Institute of Earth Surface Dynamics, University of Lausanne, Building Géopolis, CH-1015 Lausanne, Switzerland.
Heliyon. 2021 Aug 27;7(9):e07880. doi: 10.1016/j.heliyon.2021.e07880. eCollection 2021 Sep.
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 C 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 N of the organic fraction suggests that important atmospheric N-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.
底栖有孔虫（具有生物矿化测试的原生生物）与地球化学代理相结合，首次被用于描述地中海西部阿尔沃兰海东部（海百合脊和卡布利耶丘）冷水珊瑚生态系统（CWC）中当前的海洋学状况。在“马里昂·迪富尔内”号研究船上进行的MD194航次期间，从5个箱式岩芯中获取的关于活体（染色）底栖有孔虫的定量数据表明，在有珊瑚存在的地方，这些生物的多样性更高，那里的生态位比相邻的远洋沉积物中更多。这些数据证实，冷水珊瑚生态系统对于底栖有孔虫来说也可被视为“多样性热点”。地球化学特征表明，这些沉积物含有相对新鲜（不稳定）的有机物，但也有经过再加工的难熔成分。特别是，总有机碳和碳值表明，与温带浮游植物的典型值相比，一些有机物可能是海洋和再加工颗粒有机物的混合物。有机部分的氮表明该地区发生了重要的大气固氮和降解过程。最后，我们的结果表明，从表层水新输出的颗粒有机物在丘顶的平流比在丘底或丘外更有效，这使得该地区一些珊瑚群体能够在丘顶存活。覆盖在珊瑚碎石残骸上的泥层可能表明，海百合脊目前面临淤积，阻止了丘底或丘外珊瑚的生长。
