Accumulation of heavy metals by some solitary tunicates

Abstract

The vanadium contents of eight species of solitary ascidians for which quantitative data are lacking are reported. It is observed that the occurrence of the metal within the class does not conform to taxonomic groups, but instead occurs sporadically throughout. For example, the phlebobranch Chelyosoma productum was observed to contain 800 ppm vanadium, whereas in a second member of the same family. Corella willmeriana, the metal could not be detected. Corella willmeriana contained a substantial iron concentration. The stolidobranch Boltenia villosa was found to contain vanadium at a level previously observed only among the phlebobranchs.The vanadium content of Ciona intestinalis shows a linear dependence upon the dry weight of the animal, and can be estimated from a concentration value of ~ 90 μg vanadium per gram dry weight, independent of the size class of the animal. No significant seasonal variation in the vanadium concentration of C. intestinalis was observed.