The physiology of the blue mussel (Mytilus edulis) in relation to ocean acidification

• Main Author: Saphoerster, Julia
• Format: Thesis
• Language: English
• Published: 2008
• Subjects: Ocean acidification
• Online Access: https://oceanrep.geomar.de/id/eprint/3352/; https://oceanrep.geomar.de/id/eprint/3352/1/469_Saphoerster_2008_ThePhysiologyOfTheBlue_Hschri_pubid11278.pdf

Anthropogenic CO2 emissions have already altered ocean chemistry, leading to lower carbonate saturation states, elevated seawater pCO2 and decreased pH. This scenario will even be enhanced in the future due to rising atmospheric CO2 levels. Recent studies suggested drastic impacts of increased seawater pCO2 values especially on the ecophysiological performance of calcifying organisms. In this study, whole-animal performance of the blue mussel, Mytilus edulis, from the Baltic Sea was related to rising pCO2 levels in order to predict physiological changes on the organism level in a future high CO2 world. Thus, cardiac performance and activity patterns were observed in adult specimens exposed to different pCO2 values (380 ppm [39 Pa; pH 8.0], 560 ppm [57 Pa; pH 7.9], 840 ppm [85 Pa; pH 7.8], 1120 ppm [114 Pa; pH 7.7], 1400 ppm [142 Pa; pH 7.6] and 4000 ppm [405 Pa; pH 7.1]) for two weeks. The results revealed that heart rates and heart rate variability, as well as activity patterns were not significantly affected by CO2 levels applied in this study. The mean instantaneous heart rate (IHR) was determined using infrared light sensors (plethysmographs). Throughout the experiment, IHR fluctuated around a mean value of 12 beats per minute (BPM). There was also no change in the distribution of beat-to-beat intervals (heart rate variability, HRV). This study examined changes in the HRV by comparing different parameters, including parameters so far only used in humans, composed of mean, median, mode, range, skewness, kurtosis, coefficient of variation (CV), standard deviation of beat-to-beat intervals (SDNN), standard deviation of differences between adjacent beat-to-beat intervals (SDdeltaNN) and root mean square successive differences (RMSSD). Valve and siphon activity was investigated using time lapse images recorded with a set of webcams. The valve and siphon diameter in percentage of their maximum opening per mussel varied around 57 % (Valve) and 46 % (Siphon). On average valve and siphon were open about 50 % of the ...