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Size-dependent pH effect on calcification in post-larval hard clam Mercenaria spp.
| Content Provider | Semantic Scholar |
|---|---|
| Author | Waldbusser, George G. Bergschneider, Heather Green, Mark A. |
| Copyright Year | 2010 |
| Abstract | Increasing atmospheric carbon dioxide threatens to decrease pH in the world's oceans. Coastal and estuarine calcifying organisms of significant ecological and economical importance are at risk; however, several biogeochemical processes drive pH in these habitats. In particular, coastal and estuarine sediments are frequently undersaturated with respect to calcium carbonate due to high rates of organic matter remineralization, even when overlying waters are saturated. As a result, the post-larval stages of infaunal marine bivalves must be able to deposit new shell material in conditions that are corrosive to shell. We measured calcification rates on the hard clam, Mercenaria spp., in 5 post-larval size classes (0.39, 0.56, 0.78, 0.98, and 2.90 mm shell height) using the alkalinity anomaly method. Acidity of experimental water was controlled by bubbling with air-CO2 blends to obtain pH values of 8.02, 7.64, and 7.41, corresponding to pCO2 values of 424, 1120, and 1950 µatm. These pH values are typical of those found in many near-shore terrigenous marine sediments. Our results show that calcification rate decreased with lower pH in all 5 size classes measured. We also found a signif- icant effect of size on calcification rate, with the smaller post-larval sizes unable to overcome dissolu- tion pressure. Increased calcification rate with size allowed the larger sizes to overcome dissolution pressure and deposit new shell material under corrosive conditions. Size dependency of pH effects on calcification is likely due to organogenesis and developmental shifts in shell mineralogy occurring through the post-larval stage. Furthermore, we found significantly different calcification rates between the 2 sources of hard clams we used for these experiments, most likely due to genotypic dif- ferences. Our findings confirm the susceptibility of the early life stages of this important bivalve to decreasing pH and reveal mechanisms behind the increased mortality in post-larval juvenile hard clams related to dissolution pressure, that has been found in previous studies. |
| Starting Page | 171 |
| Ending Page | 182 |
| Page Count | 12 |
| File Format | PDF HTM / HTML |
| DOI | 10.3354/meps08809 |
| Volume Number | 417 |
| Alternate Webpage(s) | https://www.int-res.com/articles/meps2010/417/m417p171.pdf |
| Alternate Webpage(s) | https://doi.org/10.3354/meps08809 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
