Contribution of the thraustochytrid <i>Corallochytrium limacisporum</i> Raghukumar to microbial biomass in coral reef lagoons

Abstract

ATP and organic carbon (OC) contents of cells of 5 isolates of thraustochytrids, including one of <i>C. limacisporum</i> were estimated from cultures. OC:ATP ratio in these isolates averaged 99. Based on these and the data collected on the number of <i>C. limacisporum</i>, total viable bacteria (saprophyte numbers), chlorophyll a content and total ATP in the lagoon waters, the contribution of <i>C. limacisporum</i> to the microbial biomass in coral reef lagoons of the Lakshadweep islands was calculated. The thraustochytrid contributed 2.88 to 213.57% ATP and 1.15 to 85.43% OC relative to total viable bacteria and 0.024 to 3.09% ATP and 0.002 to 1.24% OC to total microbial biomass. <i>C. limacisporum</i> and total viable bacteria together contributed only 0.844 to 6.02% ATP and 0.822 to 4.97% OC to the biomass. About 90% of the microbial biomass in the lagoons appeared to be from organisms other than the thraustochytrid, total viable bacteria and phytoplankton.