Dynamics of calcification in the mediterranean red coral,Corallium rubrum (Linnaeus) (Cnidaria, Octocorallia)
✍ Scribed by Allemand, Denis; Bénazet-Tambutté, Sylvie
- Publisher
- John Wiley and Sons
- Year
- 1996
- Tongue
- English
- Weight
- 938 KB
- Volume
- 276
- Category
- Article
- ISSN
- 0022-104X
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✦ Synopsis
The spatial and temporal dynamics of calcification in whole colonies of Mediterranean red coral Corallium rubrum (Linnaeus) (Cnidaria, Octocorallia) was studied by incubating colonies with 45caloium (45Ca) or 14C-aspartic acid (14C-asp), and measuring the radioisotope uptake in sectioned fractions including tissue, isolated spicules and axial skeleton. The results show that the ectodermal structure of the coenenchyme was fully able to transport calcium and aspartic acid from base to tip at the same rate. Following short-term incubation, the rate of axial skeleton formation, as measured either with 45Ca or 14C-asp incorporation, was slightly higher at the base of the colony than <it the tip. While 14C-aspartic acid deposition in the spicule fraction was maximal at the base of the colony, the distribution of 45Ca in the same fraction showed a U-shape with a maximum at the tip. The total rate of calcification (spicules and axial skeleton) was about 1.6 times higher at the tip of the colonies. A 5-day kinetic experiment showed that the growth process of axial skeleton differed between base and tip. Indeed while the growth rate of axial skeleton was almost constant at the base, a biphasic pattern was observed at the tip suggesting that the apical growth rate of axial skeleton was the consequence of two different calcium supplies: the first one, directly supplied from seawater, and a second one, indirectly supplied via an other pool and significant after 3 days of incubation in labelled seawater. A l-week pulse chase experiment showed that, while no modification in the distribution of 45Ca occurred among the three compartments (tissue, spicules, axial skeleton) in the basal part of the colony, the skeletal fraction increased at the expense of both spicules and tissue at the apical part. All these results suggest, in accordance with previous studies