Effects of Water Velocity on Respiration, Calcification, and Ammonium Uptake of a Porites compressa Community

Abstract

Colonies of Porites compressa Dana were placed in a 10-m-long flume to form a community of coral. Ammonium uptake (N uptake) rate, respiration rate, and calcification rate were measured at different water velocities, ranging from 1 to 57 cm sec-1. N uptake was proportional to concentration from 20 to 0.15 uM N. The first-order rate constant for N uptake varied from 6.8 to 15.6 day-1, only an average of 2.1 times over a l0-fold change in water velocity. First-order rate constants for respiration were less than those for N uptake and ranged from 4.8 to 6.6 day-1. Respiration rate and calcification rate were not correlated with water velocity. The relative turnover of N compared with oxygen (O2) indicates that 94-98% of N flux must be retained within this coral community.