Ergosterol content of living and submerged, decaying leaves and twigs of red mangrove

Ergosterol was measured in red-mangrove (Rhizophora mangle) materials as an index of eumycotic fungal mass. Living green and senescent leaves and living twigs contained no detectable ergosterol (< 1μg∙g organic mass −1). After falling into the water and reaching the red–brown stage of decomposition (mass loss of about 30%), leaves exhibited ergosterol contents ranging from undetectable to 19 μg∙g−1. At the black submerged stage (mass loss of about 40–60%), ergosterol contents of leaves ranged from undetectable to 85 μg∙g−1. Submerged, decaying twigs and dead twigs on the tree had similar ranges of ergosterol content (9–79 μg∙g−1). The maximum value for standing crop of eumycotic fungal mass in submerged, decaying mangrove materials, calculated on the basis of the present ergosterol analyses, was 1.7% organic fungal mass of organic leaf mass. It may be that marine oomycotes (species of Halophytophthora), which do not contain ergosterol, are more important than ergosterol-containing fungi in decay of submer...