AME 09:117-125 (1995)  -  DOI: https://doi.org/10.3354/ame009117

Thraustochytrid and fungal component of marine detritus. III. Field studies on decomposition of leaves of the mangrove Rhizophora apiculata

Raghukumar S, Sathe-Pathak V, Sharma S, Raghukumar C

The sequence of colonisation, densities and biomass of fungi, thraustochytrid protists and bacteria during decomposition of leaves of the mangrove Rhizophora apiculata Blume, as well as the accompanying biochemical changes of the detritus, were studied in 2 litterbag experiments at Goa, India. Three phases were observed. (1) Thraustochytrids and the fungi Cladosporium herbarum and Halophytophthora vesicula colonised detritus during the first week, characterised by a rapid loss of detrital dry weight and a reduction in proteins, carbohydrates, reducing sugars, phenolics and cellulose. (2) Decline of most of the organic constituents 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 weight of 21 and 35 d detritus respectively. Protein values never increased with decomposition and microbial biomass buildup, although C:N values declined. (3) Total fungal and bacterial biomass decreased after 3 and 5 wk, respectively. However, thraustochytrids and marine fungal species such as Cirrenalia basiminuta and 'Hyphomycete XVII' attained high densities by 56 to 60 d. Most of the species present initially in the detritus were observed even in the last stages of decomposition examined (56 to 60 d). Thraustochytrids and fungi were isolated both from surface-sterilized and untreated detritus, suggesting epi- and endobiontic modes of life. Distinct sequences of fungal and thraustochytrid colonisation, presence of high fungal biomass relative to bacterial biomass, the high densities of thraustochytrids and accompanying biochemical changes indicate the importance of these organisms in the mangrove detrital processes.


Thraustochytrids . Fungi . Mangrove detritus


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