Suchergebnisse

9 páginas, 3 tablas, 1 figura ; Effects of coastal ocean acidification, other than calcification, were tested on juvenile clams Ruditapes decussatus during a controlled CO2 perturbation experiment. The carbonate chemistry of natural (control) seawater was manipulated by injecting CO2 to attain 2 reduced pH levels (–0.4 and –0.7 pH units) as compared with the control seawater. After 87 d of exposure, we found that the acidification conditions tested in this experiment significantly reduced the clearance, ingestion and respiration rates, and increased the ammonia excretion rate of R. decussatus seeds. Reduced ingestion combined with increased excretion is generally associated with a reduced energy input, which will likely contribute to a slower growth of the clams in a future high CO2 coastal ocean. These results emphasize the need for management policies to mitigate the adverse effects of global change on aquaculture, which is an economically relevant activity in most coastal areas worldwide. ; This is a contribution to the ACIDBIV project, which is part of the CIRCLE Med projects, funded by the Regional Ministry of Innovation and Industry of the Galician Government (08MDS018402PR), the Italian Ministry for Environment, Land and Sea, and the Foundation for Science and Technology of Portugal (ERA-CIRCLE/0004/ 2007), in the framework of the Circle ERA Net project (which is funded by the European Commission 6th Framework Programme). ; Peer reviewed

10 páginas, 3 tablas, 1 figura ; Coastal ocean acidification is expected to interfere with the physiology of marine bivalves. In this work, the effects of acidification on the physiology of juvenile mussels Mytilus galloprovincialis were tested by means of controlled CO2 perturbation experiments. The carbonate chemistry of natural (control) seawater was manipulated by injecting CO2 to attain 2 reduced pH levels: −0.3 and −0.6 pH units as compared with the control seawater. After 78 d of exposure, we found that the absorption efficiency and ammonium excretion rate of juveniles were inversely related to pH. Significant differences among treatments were not observed in clearance, ingestion and respiration rates. Coherently, the maximal scope for growth and tissue dry weight were observed in mussels exposed to the pH reduction ΔpH = −0.6, suggesting that M. galloprovincialis could be tolerant to CO2 acidification, at least in the highly alkaline coastal waters of Ria Formosa (SW Portugal). ; This is a contribution to the 'The integrated impacts of marine acidification, temperature and precipitation changes on bivalve coastal biodiversity and fisheries: how to adapt?' project, which is part of the CIRCLE Med projects, funded by the Regional Ministry of Innovation and Industry of the Galician Government (08MDS 018402PR), the Italian Ministry for Environment, Land and Sea, and the Foundation for Science and Technology of Portugal (ERA-CIRCLE/0004/2007), in the framework of the Circle ERA Net project (which is funded by the European Commission 6th Framework Programme). ; Peer reviewed

7 pages, 4 figures.-- Printed version published in Oct 2008. ; The extension and intensity of the upwelling season in the NW Iberian Peninsula (42°N–43°N) have decreased by 30 and 45% over the last 40 years, respectively. Accordingly, the renewal time (τ) of the Rías Baixas, four large coastal inlets where 15% of the World extraction of blue mussels occurs, has increased by 240%. We indirectly demonstrate here that the growing τ has caused the increasing occurrence of harmful microalgae in these embayments, dramatically affecting mussel raft cultivation. The equation D = 365(1 − exp(−τ/c1)) explains 80% of the variability of the number of days per year that mussels cannot be extracted from the hanging ropes because of the occurrence of harmful microalgae (D). The coefficient c1 = 37 ± 2 days indicates that an average τ over the upwelling season of >25 ± 1 or 50 ± 3 days reduce mussel extraction to only 50 or 25% of the year, respectively. ; This study was supported by the contract-project PROINSA Mussel Farm, Code CSIC 20061089, Xunta de Galicia PGIDIT06RMA018E. Additional support came from the Ministry of the Environment and Sustainable Development of the Galician Government funds to study the evidences and impact of climate change in Galicia (program CLIGAL). This is a contribution to the GEOHAB Core Research Project—HABs in upwelling systems. ; Peer reviewed