Coral communities aren’t just beautiful - they are also home to multiple underwater species, making them an important hotspot of biodiversity in oceans around the world. Corals are under threat due to ocean acidification from climate change, pollution, bottom trawl fishing and the increasing presence of marine litter, and need urgent measures to protect and conserve them.
A new study of cold-water coral communities located in Barkley Canyon off the coast of southern Vancouver Island aims to better understand how they function and adapt to changing environmental conditions, to order to contribute to the management and conservation of these ecosystems.
From June until October 2022, Claudio Lo Iacono, ONC Researcher in Residence and senior scientist from the Marine Sciences Institute of the Spanish National Research Council (ICM-CSIC) in Barcelona will be working with ONC senior scientist Fabio De Leo. Their collaborative study is tackling several unknowns for Barkley Canyon.
Internal tide waves’ effect on coral
Internal tide waves are large and long-standing waves generated in the ocean interior and controlled by tidal cycles. Up to 200 m high, these waves are recorded daily by several NEPTUNE “nodes” around the area at a depth between 800 m and 1000 m, and their role as physical mechanisms responsible for cold-water corals’ functioning is currently unclear. In steep topographic terrains, such as near the walls of submarine canyons, the breaking of internal tides generates turbulence and mixing that brings sediments rich in nutrients essential for coral feeding.
This study will quantify the role of internal tide waves on the maintenance of coral assemblages observed on the “coral cliffs”, located within Barkley Canyon at the depth of around 900 m.
A 3d bathymetric model of Barkley Canyon showing the main coral cliff (transect 1) and smaller cliff locations (transects 2&3) where new coral fields have been identified in exploratory ONC dive video transects. Blue dots correspond to the locations of ONC instrument platforms.
Deoxygenation trends
This study also aims to better understand how cold-water coral populations adapt to oxygen depleted environments in order to make predictions of future climate change scenarios.
ONC Remotely Operated Vehicle (ROV) video transects near these coral cliffs show an unexpected high abundance of black corals, sponges and juvenile thornyhead rockfish, indicating a nursery zone.
ROV flyover footage of the coral cliffs of Barkley Canyon, at a depth of approximately 900 metres.
At these specific depths in Barkley Canyon, the ecosystem is bathed in waters with very low natural concentrations of dissolved oxygen (0.25 mL/L) at the core of a so-called Oxygen Minimum Zone (OMZ). For comparison, in most areas near the ocean surface the oxygen concentrations range between 4-8 mL/L. The OMZ in the NE Pacific is one of the marine areas experiencing a rapid loss of oxygen content as a likely consequence of climate change.
As the ocean surface warms, absorption of oxygen and other gases into the ocean slows. At the same time, the ocean becomes more stratified, which reduces vertical mixing, making it harder to bring deep cold, nutrient rich waters to the surface and reducing productivity.
Claudio Lo Iacono will be using time-series datasets recorded over the past decade by ONC’s cabled NEPTUNE observatory, in particular in Barkley Canyon, and available through the Oceans 3.0 portal, focusing on the hydrography, current dynamics and oxygen variability.
“The opportunity to monitor submarine canyon processes across multiple spatial scales and at high temporal resolution using ONC’s seafloor sensors is unique if compared with any of the few similar infrastructures of the world. We will be able to shed light on the long-term role of oceanography on the maintenance of cold-water coral assemblages, but also better understand how deep-sea mega-benthic (seafloor inhabiting) communities can cope with harsh environmental conditions provided by hypoxic water masses, and under fast paced changes.”
Findings from this collaborative study will be used in numerical models able to predict cold-water coral distribution in Barkley Canyon and contribute to the management of its associated biodiversity and fisheries resources.
ONC Researcher in Residence, Claudio Lo Iacono, holding a coral sample.
Claudio Lo Iacono and Fabio De Leo’s common research interests have recently consolidated through the European Union H2020 Marie Sklodowska Curie Project “HABISS”, and through the Expression of Interest (EOI) “PATTERN” submitted to ONC in 2020. These projects involve several marine scientists from European and Canadian Institutions and aim to better understand the dynamics of cold-water corals, and their adaptation to natural and human-induced stressors.
Biography of ONC Researcher in Residence, Claudio Lo Iacono
Claudio Lo Iacono is a marine scientist of ICM-CSIC in Spain and was previously based in the National Oceanography Centre of Southampton in the UK. His expertise builds on seafloor mapping and physical characterization of benthic habitats at nested scales, using geophysical methodologies and marine robotics (AUVs and ROVs). His research focuses on vulnerable benthic ecosystems, and their interaction with human impacts (marine litter, trawling activities). He is particularly interested on cold-water coral assemblages in submarine canyons, carbonate mounds and seamounts.
Lo Iacono has conducted research in NW Atlantic, Western and Central Mediterranean and he is involved in several European projects devoted to understanding the functioning of deep-sea reefs and assess levels of degradation by human activities, including the controls played by ocean currents on pollutant dispersal. Find out more on his multidisciplinary research on submarine canyons in the link of his last European cruise.
