New Publication on cold-water coral growth and its link to African Hydroclimate

Thomas Krengel on RV Maria S Merian 2014

Claudia Wienberg, Thomas Krengel and co-workers present up to 70 m long drill cores bearing cold-water corals from mounds in the western Mediterranean Sea. Based on 200 Th/U ages collected during the PhD of Thomas Krengel the evolution of Mediterranean coral mounds was reconstructed. One mound base was penetrated and dated to the Mid-Pleistocene (~390 ka). We also found that mound initiation was non-synchronous as larger mounds possibly initiated already during the Mid-Pleistocene Transition. During the last 480 kyr, mound development occurred in short and intense pulses (duration: ~10 to 30 kyr; with aggradation rates: 20 - 275 cm/kyr1). Those can be assigned to ice age-paced oscillations, but showed a remarkably coherent pattern with precession-driven changes in African hydroclimate. Increased dust supply, related to a desertification of the Sahara and northern Africa, appears to have boosted mound development by enhancing productivity conditions (to promote coral growth) and sediment supply (to promote mound aggradation). In addition, mound development is closely linked to the well-ventilated and nutrient-rich Levantine Intermediate Water and internal wave activity today associated to this water mass that provided turbulent conditions and enhanced the lateral delivery of food and sediments. During African humid periods, increased freshwater input into the Mediterranean impaired the formation of Levantine Intermediate Water, which most likely resulted in low-energy and oxygen-depleted living conditions for Mediterranean coral communities. For more information see the new publication in Quaternary Science Reviews