Application of the non-invasive Aquatic Eddy Co-variance on complex cold-water benthic habitats

• Main Authors: Rovelli, Lorenzo, Attard, Karl M., Glud, Ronnie N.
• Format: Conference Object
• Language: English
• Published: 2018
• Subjects: Rockall Bank; Davis Strait
• Online Access: https://zenodo.org/record/1254504; https://doi.org/10.5281/zenodo.1254504

ATLAS work package 2 presentation at ATLAS 3rd General Assembly There is increasing evidence that cold-water coral (CWC) communities are regions of intensified carbon cycling, but direct measurements of community respiration rates have been limited by the lack of appropriate flux measuring techniques. In fact, in hard substrates habitats traditional approaches, e.g., benthic chambers and microprofiling, are often compromised. The non-invasive Aquatic Eddy Co-variance (AEC) technique can integrate the contribution from complex, mixed communities on both soft and hard substrates. Previous proof-of-concept measurements on CWC habitats have shown that the AEC technique is a valuable tool for investigating local carbon turnover by CWC communities, provided that particular attention is given to the AEC deployment strategy, instrumental setup and data evaluation. Within ATLAS, we expanded the knowledge base of earlier work to fine-tune our AEC systems for optimal operation in complex cold-water benthic habitats, with specific emphasis on the targeted deep-sea communities at the WP2 study sites: Rockall Bank, Davis Strait, and Condor Seamount (Azores). In particular, we have implemented dissolved oxygen (O2) optodes sensors, which offer improved handling and robustness over traditional Clark-type electrodes. To date, the ATLAS-optimized AEC system has been deployed in a variety of complex coastal and communities such as mussel reefs and sponge beds on submerged rocky outcrops, where benthic habitat complexities comparable to the WP2 sites occurred at shallower, less challenging, depths. This enabled us to fine-tune the deployment setup and AEC data processing to develop a strategy for subsequent deployments at the deeper ATLAS CWC sites. During the R/V Pelagia 420 cruise AEC activities at the Rockall site focused on the Haas mound (536 m depth) and the smaller Oreo mound (745 m depth). The summit of Haas mound was characterized by dead CWC. Average O2 uptake rates ranged from 12  4 to 25  6 mmol m-2 d-1, reflecting ...