S. Raghukumar et al., THRAUSTOCHYTRID AND FUNGAL COMPONENT OF MARINE DETRITUS .4. LABORATORY STUDIES ON DECOMPOSITION OF LEAVES OF THE MANGROVE RHIZOPHORA-APICULATA BLUME, Journal of experimental marine biology and ecology, 183(1), 1994, pp. 113-131
The role of thraustochytrid protists and fungi in detrital dynamics of
leaves of the mangrove Rhizophora apiculata was investigated in the l
aboratory. Field detritus of different ages (0, 4, 7, 14, 21, 28, 46,
53 and 60 days) obtained from litter-bag experiments were inoculated i
ndividually with five fungi, Cladosporium herbarum, Fusarium monilifor
me, Cirrenalia basiminuta, ''Hyphomycete XVII'' and Halophytophthora v
esicula and one thraustochytrid, Schizochytrium mangrovei. Biochemical
changes occurring after 1 wk in 8 ages of detritus were examined. The
results suggested two phases of fungal dynamics, the first correspond
ing to decompositional stages of 0-21 and the second to 28-60 days. De
trital material of the first phase supported better growth of the fung
i Cladosporium herbarum, Fusarium moniliforme, Cirrenalia basiminuta a
nd Halophytophthora vesicula. Cellulase production by all the test spe
cies, in general, was greatest on such detritus. Detritus of the secon
d phase proved to be better for the growth of the fungus ''Hyphomycete
XVII'' and production of xylanase by all test species. Pectic enzymes
, amylase and protease were produced more or less uniformly in all age
s of detritus. The thraustochytrid Schizochytrium mangrovei grew well
on both phases of detritus. The test species utilised a wide variety o
f substrates as sole carbon sources but differed significantly in thei
r capabilities to elaborate the various degradative enzymes in detritu
s. Fusarium moniliforme and Halophytophthora vesicula caused marked in
creases in detrital protein, while all the test species enhanced amino
acid levels. Schizochytrium mangrovei enhanced carbohydrate and reduc
ing sugar contents, while Fusarium moniliforme and Halophytophthora ve
sicula substantially decreased the levels of the former. Growth of Hal
ophytophthora vesicula in detritus caused a decline of total phenolics
. The net biochemical status of detritus seems to depend upon interact
ions between the biochemical state of detritus, the colonising species
and their biomass, and the enzymatic activities of the concerned micr
oorganisms.