Human activities are responsible for the increment in CO2 atmospheric concentration, resulting in global warming and increasing acidification of oceans. In order to compare effects of acidification on physiological responses of juveniles of two bivalves species, Mytilus galloprovincialis and Chamelea gallina, an experimental outdoor flow-through plant was set up, fed with sea water from the lagoon of Venice. Six tanks (3 for control and 3 for treatment conditions) were used. 400 mussel and 600 clam juveniles per tank were exposed to two pH levels (lagoon water pH as control, and 7.4 pH as treatment) from October 2009 to April 2010. Environmental parameters were monitored daily, while bivalve growth (length and weight) and mortality were evaluated monthly. At the end of the experiment, physiological parameters (respiration, clearance and excretion rates) and condition index were measured. In mussels, byssal thread formation was also evaluated. In both species, mortality was very low during winter periods, but significantly increased during the last month of the experiment. Length, weight and condition index significantly decreased in C. gallina, whereas no difference between treated and control mussels was highlighted. The results show that physiological responses were affected by low pH. In particular, clearance rate decreased significantly in both species, whereas excretion rate increased, although significantly in C. gallina only. Respiration rate did not show any significant variation. The mean number of byssal threads also decreased significantly in treated mussels. Our results suggest that C. gallina is less tolerant than M. galloprovincialis to the stress conditions considered, and its populations may be more threatened in future climate change scenarios.

Long-term effects of sea water acidification on physiological responses of juvenile bivalves Mytilus galloprovincialis and Chamelea gallina

M. Munari;MATOZZO, VALERIO;BRESSAN, MONICA;MARIN, MARIA
2011

Abstract

Human activities are responsible for the increment in CO2 atmospheric concentration, resulting in global warming and increasing acidification of oceans. In order to compare effects of acidification on physiological responses of juveniles of two bivalves species, Mytilus galloprovincialis and Chamelea gallina, an experimental outdoor flow-through plant was set up, fed with sea water from the lagoon of Venice. Six tanks (3 for control and 3 for treatment conditions) were used. 400 mussel and 600 clam juveniles per tank were exposed to two pH levels (lagoon water pH as control, and 7.4 pH as treatment) from October 2009 to April 2010. Environmental parameters were monitored daily, while bivalve growth (length and weight) and mortality were evaluated monthly. At the end of the experiment, physiological parameters (respiration, clearance and excretion rates) and condition index were measured. In mussels, byssal thread formation was also evaluated. In both species, mortality was very low during winter periods, but significantly increased during the last month of the experiment. Length, weight and condition index significantly decreased in C. gallina, whereas no difference between treated and control mussels was highlighted. The results show that physiological responses were affected by low pH. In particular, clearance rate decreased significantly in both species, whereas excretion rate increased, although significantly in C. gallina only. Respiration rate did not show any significant variation. The mean number of byssal threads also decreased significantly in treated mussels. Our results suggest that C. gallina is less tolerant than M. galloprovincialis to the stress conditions considered, and its populations may be more threatened in future climate change scenarios.
2011
AEHMS 10 International Conference
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11577/2484953
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