TY  - JOUR
A1  - Raddatz, Jacek
A1  - Liebetrau, Volker
A1  - Rüggeberg, Andres
A1  - Foubert, Anneleen
A1  - Flögel, Sascha
A1  - Nürnberg, Dirk
A1  - Hissmann, Karen
A1  - Musiol, Johannes
A1  - Goepfert, Tyler Jay
A1  - Eisenhauer, Anton
A1  - Dullo, Wolf-Christian
T1  - Living on the edge: environmental variability of a shallow late Holocene cold-water coral mound
T2  - Coral reefs
N2  - Similar to their tropical counterparts, cold-water corals (CWCs) are able to build large three-dimensional reef structures. These unique ecosystems are at risk due to ongoing climate change. In particular, ocean warming, ocean acidification and changes in the hydrological cycle may jeopardize the existence of CWCs. In order to predict how CWCs and their reefs or mounds will develop in the near future one important strategy is to study past fossil CWC mounds and especially shallow CWC ecosystems as they experience a greater environmental variability compared to other deep-water CWC ecosystems. We present results from a CWC mound off southern Norway. A sediment core drilled from this relatively shallow (~ 100 m) CWC mound exposes in full detail hydrographical changes during the late Holocene, which were crucial for mound build-up. We applied computed tomography, 230Th/U dating, and foraminiferal geochemical proxy reconstructions of bottom-water-temperature (Mg/Ca-based BWT), δ18O for seawater density, and the combination of both to infer salinity changes. Our results demonstrate that the CWC mound formed in the late Holocene between 4 kiloannum (ka) and 1.5 ka with an average aggradation rate of 104 cm/kiloyears (kyr), which is significantly lower than other Holocene Norwegian mounds. The reconstructed BWTMg/Ca and seawater density exhibit large variations throughout the entire period of mound formation, but are strikingly similar to modern in situ observations in the nearby Tisler Reef. We argue that BWT does not exert a primary control on CWC mound formation. Instead, strong salinity and seawater density variation throughout the entire mound sequence appears to be controlled by the interplay between the Atlantic Water (AW) inflow and the overlying, outflowing Baltic-Sea water. CWC growth and mound formation in the NE Skagerrak was supported by strong current flow, oxygen replenishment, the presence of a strong boundary layer and larval dispersal through the AW, but possibly inhibited by the influence of fresh Baltic Water during the late Holocene. Our study therefore highlights that modern shallow Norwegian CWC reefs may be particularly endangered due to changes in water-column stratification associated with increasing net precipitation caused by climate change.
KW  - Desmophyllum pertusum
KW  - Deep-sea ecosystems
KW  - Mg/Ca
KW  - Lobatula lobatula
KW  - Computed tomography
KW  - Th/U dating
KW  - Seawater density
KW  - Oxygen isotopes
Y1  - 2022
UR  - http://publikationen.ub.uni-frankfurt.de/frontdoor/index/index/docId/69590
UR  - https://nbn-resolving.org/urn:nbn:de:hebis:30:3-695908
SN  - 1432-0975
N1  - Open Access funding enabled and organized by Projekt DEAL.
N1  - Research Cruise POS391 was realized through DFG Project RI 598/4-1.
VL  - 41
IS  - 4
SP  - 1255
EP  - 1271
PB  - Springer
CY  - Berlin ; Heidelberg
ER  -