SINKING RATE OF LORICAE OF SOME COMMON TINTINNID CILIATES

Sinking rate of empty loricae of seven tintinnid species was measured in settling chambers. The sinking rates normalized for 3% NaCl solutio n at 20 degrees C are 0.25-2.08 m day(-1) for five hyaline loricae and 1.90 and 15.9 m day(-1) for two agglutinated loricae. Positive relati onships between sinking rate and size of hyaline loricae such as volum e, surface area and nominal diameter were established, which favour th e practical estimation of sinking rate of empty loricae discarded by n atural tintinnid populations by measuring size composition. The slower sinking rate of hyaline loricae, compared with that of diatoms, indic ates their availability as indicators of particular water masses in th e ocean. Loricae incorporated into faecal pellets of zooplankton and m arine snow also indicate the origin of these sinking particles.