S. Raghukumar et al., THRAUSTOCHYTRID AND FUNGAL COMPONENT OF MARINE DETRITUS .3. FIELD STUDIES ON DECOMPOSITION OF LEAVES OF THE MANGROVE RHIZOPHORA-APICULATA, Aquatic microbial ecology, 9(2), 1995, pp. 117-125
The sequence of colonisation, densities and biomass of fungi, thrausto
chytrid protists and bacteria during decomposition of leaves of the ma
ngrove Rhizophora apiculata Blume, as well as the accompanying biochem
ical changes of the detritus, were studied in 2 litterbag experiments
at Goa, India. Three phases were observed. (1) Thraustochytrids and th
e fungi Cladosporium herbarum and Halophytophthora vesicula colonised
detritus during the first week, characterised by a rapid loss of detri
tal dry weight and a reduction in proteins, carbohydrates, reducing su
gars, phenolics and cellulose. (2) Decline of most of the organic cons
tituents in detritus to almost the lowest observed levels within 21 d
was accompanied by an increase in fungal and bacterial biomass. Fungi
and bacteria together contributed maxima of 0.052 and 0.065% to dry we
ight of 21 and 35 d detritus respectively. Protein values never increa
sed with decomposition and microbial biomass buildup, although C:N val
ues declined. (3) Total fungal and bacterial biomass decreased after 3
and 5 wk, respectively. However, thraustochytrids and marine fungal s
pecies such as Cirrenalia basiminuta and 'Hyphomycete XVII' attained h
igh densities by 56 to 60 d. Most of the species present initially in
the detritus were observed even in the last stages of decomposition ex
amined (56 to 60 d). Thraustochytrids and fungi were isolated both fro
m surface-sterilized and untreated detritus, suggesting epi- and endob
iontic modes of life. Distinct sequences of fungal and thraustochytrid
colonisation, presence of high fungal biomass relative to bacterial b
iomass, the high densities of thraustochytrids and accompanying bioche
mical changes indicate the importance of these organisms in the mangro
ve detrital processes.