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- Title
Maintenance of coelomic fluid pH in sea urchins exposed to elevated CO: the role of body cavity epithelia and stereom dissolution.
- Authors
Holtmann, Wiebke; Stumpp, Meike; Gutowska, Magdalena; Syré, Stephanie; Himmerkus, Nina; Melzner, Frank; Bleich, Markus
- Abstract
Experimental ocean acidification leads to a shift in resource allocation and to an increased [HCO] within the perivisceral coelomic fluid (PCF) in the Baltic green sea urchin Strongylocentrotus droebachiensis. We investigated putative mechanisms of this pH compensation reaction by evaluating epithelial barrier function and the magnitude of skeleton (stereom) dissolution. In addition, we measured ossicle growth and skeletal stability. Ussing chamber measurements revealed that the intestine formed a barrier for HCO and was selective for cation diffusion. In contrast, the peritoneal epithelium was leaky and only formed a barrier for macromolecules. The ossicles of 6 week high CO-acclimatised sea urchins revealed minor carbonate dissolution, reduced growth but unchanged stability. On the other hand, spines dissolved more severely and were more fragile following acclimatisation to high CO. Our results indicate that epithelia lining the PCF space contribute to its acid-base regulation. The intestine prevents HCO diffusion and thus buffer leakage. In contrast, the leaky peritoneal epithelium allows buffer generation via carbonate dissolution from the surrounding skeletal ossicles. Long-term extracellular acid-base balance must be mediated by active processes, as sea urchins can maintain relatively high extracellular [HCO]. The intestinal epithelia are good candidate tissues for this active net import of HCO into the PCF. Spines appear to be more vulnerable to ocean acidification which might significantly impact resistance to predation pressure and thus influence fitness of this keystone species.
- Subjects
OCEAN acidification; GREEN sea urchin; MACROMOLECULES; EPITHELIUM; DISSOLUTION (Chemistry); BODY cavities
- Publication
Marine Biology, 2013, Vol 160, Issue 10, p2631
- ISSN
0025-3162
- Publication type
Article
- DOI
10.1007/s00227-013-2257-x