Poster Open Access

Biological and environmental drivers of deep-sea benthic ecosystem functioning in Canada's Laurentian Channel Area of Interest (AOI)

Miatta, Marta; Snelgrove, Paul

Poster presentation at ATLAS 3rd General Assembly.


Ongoing environmental changes and accelerating biodiversity loss, raise concern and interest about the role environmental factors and biodiversity plays in determining marine ecosystem functioning (defined as the biological and chemical processes that reflect the capacity of an ecosystem to exploit available energy to maximize its biomass and production). Past studies suggest that multiple abiotic and biotic factors influence functioning, and that benthic communities play an important role in organic matter remineralization. However, many findings are based on controlled laboratory experiments, which simplify complex natural processes. As a consequence, understanding the main drivers of functioning in marine natural systems remains a major challenge. At the same time, sea pens (soft corals order Pennatulacea) are believed to be keystone species able to increase oxygen penetration in the sediment through burrowing behaviour, consequently enhancing biochemical processes and infaunal biodiversity. However, this is yet to be assessed. This study aims to identify the main drivers of benthic ecosystem functioning in deep-sea sedimentary habitats in the Laurentian Channel Area of Interest (AOI), off the coast of Newfoundland (Canada), and to investigate the role of sea pens as potential keystone species in the area. Using the ROV ROPOS, we collected sediment cores and measured environmental variables from 6 stations inside the AOI (depths 348-445 m) in September 2017. Through 48-hours incubations and flux measurements (oxygen, inorganic nutrients), we estimated organic matter remineralization, a key benthic function. Preliminary analyses show no significant variation in fluxes among stations, despite significant differences in environmental and biological variables. However, the presence of Pennatulacea inside the cores was sometimes associated with enhanced remineralization, particularly nitrification. In addition, preliminary findings show a higher abundance and diversity of macrofauna and polychaetes in the stations characterized by the presence of Pennatulacea fields, suggesting the ability of these organisms to enhance infaunal biodiversity. Ongoing analyses will address sediment properties (e.g., organic matter quantity and quality, grain size), prokaryotic abundance, macrofaunal biodiversity to the lowest practical taxonomic level, its functional diversity and the relationships between ecosystem functioning and abiotic/biotic factors. Shedding new light on the primary drivers of ecosystem functioning and on the biodiversity of the area, this study will inform the monitoring strategies proposed for this Marine Protected Area (MPA) and offer new perspectives and tools for MPA design. For instance, the key role of Pennatulacea in the Laurentian Channel AOI highlights the importance to protect these organisms from impacting human activities (e.g., bottom trawling).


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