Actus de Monaco (in French; video)

L’aspect financier, sous différentes formes, a dominé la semaine, une secousse sismique sans gravité s’est fait ressentir nous rappelant combien cette belle région est fragile…

L’acidification des océans est toujours au programme

Du 17 au 19 janvier dernier s’est tenue à Okinawa, dans l’archipel japonais des Ryūkyū, une réunion “sur les impacts de l’acidification des Océans sur la biologie et les écosystèmes marins”, organisée par le GIEC, Groupe intergouvernemental d’experts sur l’évolution du climat, en collaboration avec le Département des Relations extérieures de la Principauté de Monaco. Y participaient quatre-vingt scientifiques et experts internationaux, et parmi eux le professeur Denis Allemand, directeur du Centre scientifique de Monaco, CSM. Ils ont débattu des effets biologiques et économiques de l’acidification des océans, secteur dans lequel les chercheurs monégasques ont acquis une certaine expérience. Les participants ont commencé la préparation d’un bilan critique des connaissances de ce domaine en pleine évolution pour permettre au GIEC de rédiger le cinquième rapport, “Changements climatiques 2014″, qui devrait paraître en mai 2014. La participation du CSM à cet Atelier tenu à Okinawa consacre les actions de recherches de la Principauté en ce qui concerne l’acidification des océans. Dès novembre 2010, cette institution avait organisé en collaboration avec l’Agence Internationale de l’Energie Atomique, AIEA, une réunion “Economics of Ocean Acidification” qui avait bénéficié de financements de la Fondation Prince Albert II, du ministère français de l’Ecologie et du Gouvernement Princier. Elle suivait la Déclaration de Monaco sur l’acidification des océans, document de référence adopté en octobre 2008 lors du symposium sur “les Océans dans un monde avec un taux élevé de CO2″ tenu sous l’égide de la Commission océanographique intergouvernementale COI, de l’UNESCO.

Ocean warming and acidification; implications for the Arctic brittlestar Ophiocten sericeum

The Arctic Ocean currently has the highest global average pH. However, due to increasing atmospheric CO2 levels, it will become a region with one of the lowest global pH levels. In addition, Arctic waters will also increase in temperature as a result of global warming. These environmental changes can pose a significant threat for marine species, and in particular true Arctic species that are adapted to the historically cold and relatively stable abiotic conditions of the region. Consequently, we investigated some key physiological responses of brittlestar Ophiocten sericeum, a polar endemic which can dominate benthic infauna, to a temperature increase of 3.5°C (ambient, 5–8.5°C) and CO2 induced reduction in pH of 0.6 units (pH 7.7) and 1 unit (pH 7.3) below ambient (pH 8.3). Metabolism was upregulated at low pH. Faster arm regeneration stimulated by increased temperature was counteracted by low pH; at pH 7.3 in the high-temperature treatment, the maintenance of calcium carbonate structures in undersaturated conditions resulted in reduction in the rate of arm regeneration, possibly due to accelerated the use of energy reserves. If so, this could result in an energy deficit at times of increased energetic costs associated with responding to the combined factors of high temperature and low pH.

Synergistic effects of elevated CO2 and temperature on the metabolic scope and activity in a shallow-water coastal decapod (Metapenaeus joyneri; Crustacea: Penaeidae)

The physical drivers of climate change (increased CO₂; hypercapnia and temperature) are causing increasing warming of the earth’s oceans, elevating oceanic CO₂ concentrations, and acidity. Elucidating possible climate change impacts on marine biota is of paramount importance, because generally, invertebrates are more sensitive to hypercapnia than fish. This study addresses impacts of synergistic factors; hypercapnia and temperature on osmoregulation, acid–base balance, and resting and active metabolism (assessed as oxygen consumption rates) and behavioural performance in a model nektonic crustacean. Metapenaeus joyneri exposed to both hypercapnia (1 kPa) at two temperatures (15 and 20°C) demonstrated significant physiological effects, i.e. new regulatory set points (lower haemolymph osmolality and higher pH, i.e. alkalosis) and reduced metabolic scope (MS), compared with control individuals (normocapnia, 0.04 kPa). Behavioural effects included a significant 30% reduction in swimming ability and may be the result of reduced MS (i.e. difference between active and routine metabolism). Synergistic factors may cause organisms to shift energy utilization towards up-regulation of maintenance functions (i.e. osmoregulatory ability) resulting in a decrease in both aerobic scope and energy-demanding activities. Laboratory-derived evidence elucidating the impacts in key model groups is of paramount importance, if we are to improve our knowledge of physiological effects of synergistic climate change factors.

Ocean acidification saturation and pH

Description:
Ocean acidification is a consequence of humankind’s release of carbon dioxide emissions to the atmosphere. Excess carbon dioxide enters the ocean, reacts with water, decreases ocean pH (i.e., makes seawater less basic), and lowers carbonate ion concentration. Organisms such as corals, clams, and some plankton use carbonate ions to create their shells and skeletons. Decreases in carbonate ion concentration will make it difficult for these creatures to form hard structures. Ocean acidification may cause some organisms to die, reproduce less successfully, or leave an area. Other organisms such as seagrass and some plankton species may do better in oceans affected by ocean acidification. Ocean ecosystem diversity and ecosystem services may therefore change dramatically from ocean acidification.