Phosphate excretion rate ofSalpa fusiformis Cuvier (Tunicata : Thaliacea)

The rate of phosphate excretion bySalpa fusiformis was measured for animals of various weights at temperatures of 12.5 to 25 °C. Blastozooids excreted only small, often undetectable quantities of phosphate, in contrast to oozooids, in which the effects of individual weight and temperature were mainly studied. Excretion rate and specific excretion rates were independent of body weight (as total protein). The specific excretion rate increased exponentially with temperature, giving a Q10 of 4.54 (3.17 to 6.43) over the whole temperature range. Using the measurements of Andersen & Nival (1986) on the ammonia excretion rate ofS. fusiformis, we calculated the atomic N/P ratio, which appeared, for oozooids, similar to N/P ratios reported for other zooplanktonic species.