Our Common Future Under Climate Change

International Scientific Conference 7-10 JULY 2015 Paris, France

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Wednesday 8 July - 15:00-16:30 UPMC Jussieu - Amphi Astier

2208 - Deep-sea ecosystems and climate-change: new perspectives to address knowledge gaps in impact assessment

Parallel Session

Lead Convener(s): N. Le Bris (Sorbonne Universités UPMC Univ Paris 06 - CNRS LECOB, Banyuls-sur-mer, France)

15:00

Climate Change Challenges Ecological Functions of the Deep Half of the Planet

L. Levin (Scripps Institution of Oceanography, UC San Diego, La Jolla, United States of America)

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Climate Change Challenges Ecological Functions of the Deep Half of the Planet

L. Levin (1)
(1) Scripps Institution of Oceanography, UC San Diego, Integrative Oceanography Division and Center for Marine Biodiversity and Conservation, La Jolla, United States of America

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Half of the planet’s surface, and over 90% of its volume is covered by deep ocean below 200 m. We now know this realm hosts a wealth of different species and ecosystems that provide services critical to the health of the planet. Nutrient recycling, carbon sequestration, habitat and food web support of biodiversity occur on vast scales.  The deep sea also contains fish, shellfish, hydrocarbons, mineral and genetic resources subject to growing demand from human society.  The deep ocean is highly connected to the surface ocean and accordingly experiences both natural and anthropogenically induced climate variation. Ocean warming, ocean acidification, ocean deoxygenation and altered organic matter fluxes to the seabed are among the major deep-water manifestations of rising CO2 in the atmosphere. We are just beginning to document these changes and understand the implications for ecological function and resilience in the traditionally stable deep sea.  Deep waters have absorbed significant heat from the atmosphere, with potential effects on species metabolic rates, distributions, and interactions.  Warming margins will experience gas hydrate dissociation, releasing methane, a potent greenhouse gas. Increasing CO2 and carbonate undersaturation threatens the process of calcification and the resilience of deep-water coral reefs in the face of disturbance, particularly in the North Atlantic.  Ocean deoxygenation and expanding oxygen minimum zones at upper bathyal depths can lead to biodiversity loss, habitat compression, and changes in food webs – all of which affect fisheries and livelihoods. Interactions among stressors are likely. Warming will interact with oxygen and the carbonate system (pH, carbonate saturation) to cross tipping points and shift ecological functions. Changing ocean conditions will alter fluxes of particulate organic carbon to the deep sea, influencing energy budgets and organism abilities to cope with climate stressors. Insights into potential future changes can be drawn from the study of deep-sea faunal responses to environmental gradients in space and to changes over time.  By combining information from the paleo record and from patterns in the modern ocean, and by conducting experiments we can begin to assess how climate change might be manifested in the future deep sea. There remains an urgent need however, for a network that measures essential climate-change variables in the deep ocean over time and documents biological responses from the molecular and genetic to the population and ecosystem level.  The influence of climate change on the function, resilience and recovery of deep-sea ecosystems and on the services they provide takes on added significance as societal exploitation of the deep sea introduces novel forms of disturbance and stress.

15:20

Evidence of change in deep-sea ecosystems: a societal concern?

A. Glover (Natural History Museum, London, United Kingdom)

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Evidence of change in deep-sea ecosystems: a societal concern?

A. Glover (1)
(1) Natural History Museum, Life Sciences Department, London, United Kingdom

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Concerns over the potential impacts of recent global change have prompted renewed interest in the long-term ecological monitoring of large ecosystems. The deep sea is the largest ecosystem on the planet, the least accessible, and perhaps the least understood. Nevertheless, deep-sea data collected over the last few decades are now being synthesised with a view to both measuring global change and predicting the future impacts of further rises in atmospheric carbon dioxide concentrations. For many years, it was assumed by many that the deep sea is a stable habitat, buffered from short-term changes in the atmosphere or upper ocean. However, recent studies suggest that deep-seafloor ecosystems may respond relatively quickly to seasonal, inter-annual and decadal-scale shifts in upper-ocean variables. At some deep-sea sites, progressive changes can be detected that could be linked to recent climatic change. 

 

Why should society be concerned about changes in the deep sea when it is so apparently remote from most humans economic, social, cultural, aesthetic and ethical world? One answer is that it is one of our last great wilderness regions, filled with an astonishing reservoir of mostly undocumented biodiversity. Where it is documented, we have found examples of remarkable evolutionary and ecological novelty that have challenged the notions of where life may exist, or have existed, in elsewhere in the solar system and beyond.  The deep-sea, less constrained by time, has become a vast evolutionary experiment across one of the great ecological gradients on the planet, that of depth. Knowledge of this diversity, how it has formed and what role it plays in the global ecosystem should not be a hobby for enthusiasts, but a key tranche of the scientific and public understanding of our planet and how we attempt to manage it.

15:40

Marine cabled observatories as a new technology for the highly integrated environmental and biological monitoring

J. Aguzzi (Instituto de Ciencías del Mar (ICM-CSIC) (www.icm.csic.es), Barcelona, Spain), A. Purser (Jacobs University, Bremen, Germany), L. Thomsen (Jacobs University, Bremen, Germany), J. B. Company (CSIC, Barcelona, Spain)

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Marine cabled observatories as a new technology for the highly integrated environmental and biological monitoring

J. Aguzzi (1) ; A. Purser (2) ; L. Thomsen (2) ; JB. Company (3)
(1) Instituto de Ciencías del Mar (ICM-CSIC) (www.icm.csic.es), Recursos marinos Renovables, Barcelona, Spain; (2) Jacobs University, Ocean lab. earth and space sciences, Bremen, Germany; (3) CSIC, Institut de ciències del mar, Barcelona, Spain

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Marine depths below 1000 m represent approximately the 65% of the planet surface, making of the deep-sea the largest biome on Earth. Presently, there is a lack of capability in fostering high-frequency sampling in deep-sea areas, which is limiting our understanding of oceanographic processes and their influence on continental margin and deep-sea life. Additionally, this constraint is hindering development of the marine ecological framework. In this context, marine species show rhythmic and massive population movements synchronous with geophysical cycles (light intensity, hydrodynamic tidal and inertial variations), over timescales not comparable with the frequencies of trawling surveys. As a result, significant errors in population/stock and biodiversity assessments occur over 24-h and seasons as a result of use of this “classic” sampling method. Also for more advanced ROV surveys a time-consuming and costly vessel support can be required, limiting the sampling repetition. A new technology should therefore be implemented in order to establish reliable: i. Faunal lists, key in deep-water ecosystems exploration; ii. Cause-effect principles, which link animal behavior to environmental changes; and finally, iii. Population assessments, with sampling stations coordinated into geographic networks. Cabled seafloor observatories allow the continuous and real-time video-counting of animals, and allow these counts to be related to the oceanographic, chemical, and geologic multiparameters, as measured by sensor systems mounted alongside the imaging equipment. Video cameras may be the first true “intelligent” ecological sensors operating at high level of ecological complexity (i.e. ecosystems fauna), as these can capture species rhythms and resulting overall community dynamism in an automated fashion. Automation may transform cameras into sensors delivering numeric outputs (i.e. visual count time series for the different species). Presently, networks of fixed monitoring stations, which include cabled seafloor and water column observatories, are being deployed to provide scientists and generic users with relevant data for the environmental research and sustainable management of marine ecosystems at all depths, considering the geosphere, hydrosphere, and biosphere as integrated components. These observatories are “historicizing” data acquisition, delivering multiannual time series (i.e. into decades) of physical, chemical, and geological parameters. International networks include the European Multidisciplinary Seafloor and water-column Observatory (EMSO; www.emso-eu.org) as a Research Infrastructure of the European Strategy Forum on Research Infrastructures (ESFRI; ec.europa.eu/research/esfri/). At this stage of technological development, cabled observatories may be used forreliable ecosystem monitoring at discreet locations, i.e. the sensor platforms. In order to expand their field of coverage, crawlers (Univ. of Bremen; http://www.jacobs-university.de/ses/research/oceanlab/crawler; L. Thomsen IP) are a promising tool for extending the reach of the observatory to the surrounding area. Crawlers connected to benthic observatory nodes by umbilical, are movable multiparametric and multisensor expandable platforms. They can monitor the marine environment around the node with nested transect procedures which may be modified according to required changes in sampling strategies. Presently, crawler technology is in use at the largest infrastructural observatory network in the planet, the Ocean Network Canada (ONC; http://www.oceannetworks.ca/). A unit (named Wally) has been in operation for 5 years in Barkley Canyon (~890 m depth), video-surveying fauna in a geomorphologically active, hydrocarbon cold seep region of Pacific margin. In the future, crawlers could be standard equipment deployed with benthic platforms. Current developments are underway to automate crawler movements, with umbilical cables being superseded by submarine wifi communications, wireless power transfer and automated docking procedures similar to those developed for Space robotics (ROBEX; http://www.robex-allianz.de/en/).

16:00

Poster presentations

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16:15

Panel discussion

N. Le Bris (Sorbonne Universités UPMC Univ Paris 06 - CNRS LECOB, Banyuls-sur-mer, France), L. Levin (Scripps Institution of Oceanography, UC San Diego, La Jolla, United States of America), A. Glover (Natural History Museum, London, United Kingdom), J. Aguzzi (Instituto de Ciencías del Mar (ICM-CSIC) (www.icm.csic.es), Barcelona, Spain)

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