ECOLOGY AND TAXONOMY OF Halimeda 



267 



- • Rhodophyceae 

 o Chlorophyceae 



0.0 1 1 I II I I I I I 



U I L 



001 0.1 



Mean calcium accretion rate in light (% increment ti~ ) 



Fig. 87. Linear relationship of calcium uptake within members of a taxon. The Chloro- 

 phyta are represented by 18 taxa, the Rhodophyta by 16. The overall linear relation- 

 ship between the two functions is somewhat different in the two divisions of algae, 

 as shown by the slopes of the regression lines. The curves were fitted by the least 

 squares method. As the carbon accretion is related to tissue growth and the calcium 

 accretion to skeletal growth, the slopes of the lines indicate that tissue growth rates 

 in the Chlorophyta are proportional to the 0-3 power of the skeletal growth rate, 

 whereas in the Rhodophyta the tissue growth rate is proportional to the 0-5 power 

 of skeletogenesis. (From Goreau, 1963.) 



It is probably unwise to attempt to convert Goreau's figures into 

 carbonate productivities per segment, thallus or unit area. The nitrogen 

 basis of the measurements is excellent for comparing rates of uptake at 

 the apex in vigorously growing specimens over short time intervals, but 

 it does not follow that estimates of nitrogen in whole plants will let 

 these data yield carbonate fluxes from senile plants. It is noted in 

 Table XXX that segments are at their heaviest at senescence. Calcium 

 uptake may not be a linear function of segment age. 



4. Bate of segment production and the accumulation at Glory Be reef 



The contribution of Halimeda populations to the carbonate mass of 

 a reef is a function of the rate at which segments are lost, the carbonate 

 content of the segments at loss and the destruction of carbonate 

 between loss from the Halimeda and incorporation into the sediment. 

 Losses of carbonate from shed segments are by such processes as 

 destruction by detritus-feeding animals (in which event the net car- 

 bonate accumulation may not be altered) and solution. These carbonate 



