Ecosystem engineering creates a direct nutritional link between 600-m deep cold-water coral mounds and surface productivity.

Karline Soetaert,Christian Mohn,Anna Rengstorf,Anthony Grehan,Dick Van Oevelen

doi:10.1038/srep35057

Abstract

Cold-water corals (CWCs) form large mounds on the seafloor that are hotspots of biodiversity in the deep sea, but it remains enigmatic how CWCs can thrive in this food-limited environment. Here, we infer from model simulations that the interaction between tidal currents and CWC-formed mounds induces downwelling events of surface water that brings organic matter to 600-m deep CWCs. This positive feedback between CWC growth on carbonate mounds and enhanced food supply is essential for their sustenance in the deep sea and represents an example of ecosystem engineering of unparalleled magnitude. This ’topographically-enhanced carbon pump’ leaks organic matter that settles at greater depths. The ubiquitous presence of biogenic and geological topographies along ocean margins suggests that carbon sequestration through this pump is of global importance. These results indicate that enhanced stratification and lower surface productivity, both expected consequences of climate change, may negatively impact the energy balance of CWCs.

Highlights

Cold-water corals (CWC) are ecosystem engineers building extensive reefs that are habitat for a diverse fauna, such as sponges, crinoids and fish, making them hotspots of biodiversity[1] and significant sinks of organic matter[2,3] in the deep sea
Is there a positive feedback between CWC growth on carbonate mounds and food supply from the surface ocean? And, what are the implications for organic matter sequestration to the deep ocean?
We identify pathways of organic matter supply to 600-m deep CWCs along Rockall Bank (NE Atlantic) and provide evidence for a positive feedback between organic matter supply and CWC growth

Summary

OPEN Ecosystem engineering creates a direct nutritional link between

Karline Soetaert[1], Christian Mohn[2], Anna Rengstorf[3], Anthony Grehan3 & Dick van Oevelen[1]. The ubiquitous presence of biogenic and geological topographies along ocean margins suggests that carbon sequestration through this pump is of global importance These results indicate that enhanced stratification and lower surface productivity, both expected consequences of climate change, may negatively impact the energy balance of CWCs. Cold-water corals (CWC) are ecosystem engineers building extensive reefs that are habitat for a diverse fauna, such as sponges, crinoids and fish, making them hotspots of biodiversity[1] and significant sinks of organic matter[2,3] in the deep sea. Food limitation exerts a well-known control on biological activity in the deep sea, as the organic matter is produced in the sunlit surface ocean and rapidly degrades during the 100 s to 1,000 s of meters transit to the seafloor[4] It is paradigmatic how diverse and productive CWCs can thrive in this resource-limited environment. The results of our modelling approach will be presented first, followed by the implications of our findings

Results and Discussion

Methods

Additional Information