Breakdown of Ficusand Eucalyptusleaves in an organically polluted river in India: fungal diversity and ecological functions

Abstract

1. At two organically polluted sites in the River Nethravathi, banyan and eucalypt leaves were colonized by one or two species of aquatic hyphomycetes. A total of three or four species were identified at the two sites in samples of water and naturally occurring leaves. 2. Spore production from stream‐exposed leaves by aquatic hyphomycetes was lower by a factor of up to 1 million compared with an earlier study in geographically close but unpolluted streams. 3. Exponential decay rates and loss rates of phosphorus and calcium, were not statistically different from an earlier study in unpolluted streams. Nitrogen increased during decomposition more slowly in the current study. 4. The microbial community on both leaves released enzymes active against starch, pectin, cellulose and xylan. 5. Banyan leaves conditioned for 12 weeks were more palatable to the gastropod Notopala sp. than unconditioned leaves. 6. Together with earlier data from unpolluted streams, the study provides evidence that organic pollution severely restricts diversity of aquatic hyphomycetes and their reproductive output, but does not have an equally strong effect on ecological functions generally associated with this group.

Contribution of Fungi and Bacteria to Leaf Litter Decomposition in a Polluted River

“…The species richness of aquatic hyphomycetes associated with alder leaves at studied sites (20 to 25 species) was similar to that found in a nonpolluted stream from central Portugal (5) and slightly higher than that observed during the previous autumn in the Ave River (37). Although aquatic hyphomycetes have been associated with clean and well-aerated waters (4) and low diversity has been reported in an organically polluted stream (3 or 4 species [38]), they appear to be rather well represented in streams with either heavy-metal (13 or 14 species [42]) or organic and inorganic (18 to 23 species [37]) pollution. CA ordination of sampling sites and dates on the basis of aquatic hyphomycete assemblages on leaves separated reference (L1 and L2) from polluted (L6 and L7) sites, suggesting that shifts in the structure of fungal communities were associated with changes in the water chemistry.…”

Assessing impact of eucalyptus plantations on benthic macroinvertebrate communities by a litter exclusion experiment

“…Effects of changing autochthonous mixed oak forest litter by eucalyptus litter could be expected at the community level, since Raviraja et al (1998) and Yeates & Barmuta (1999) found that consumption and growth rates are reduced in eucalyptus-fed macroinvertebrates irrespective of the functional feeding group. Similarly, Abelho & Graça (1996) found less macroinvertebrates in reaches below eucalyptus plantations than in reaches under autochthonous deciduous forests.…”

Colonization and diversity of aquatic hyphomycetes in relation to decomposition of submerged leaf litter in River Kali (Western Ghats, India)

“…Usually species richness will be higher in mixed leaf litter (e.g. Sridhar & Kaveriappa 1988, Chandrashekar et al 1990Sridhar et al 1992) than immersed single leaf litter (Raviraja et al 1996(Raviraja et al , 1998b. However, there are some exceptions, for instance: banyan (Ficus benghalensis) leaves was a preferred substrate compared to other leaf litter (e.g.…”

“…A few studies are available on the leaf chemistry (Raviraja et al 1996(Raviraja et al , 1998b) and leaf enzymes (Raviraja et al 1998b) linked with the activities of aquatic hyphomycetes in the Western Ghats. As seen in earlier studies, the present study also reveals increase in leaf nitrogen (corroborates studies by Bärlocher 1985, Webster & Benfield 1986 and decrease in leaf phosphorus and leaf phenolics.…”

“…Decomposition of banyan and cashew leaves in Konaje (coastal) and Sampaje (Western Ghat) streams were in medium range (0.0068-0.009) (Raviraja et al 1996). So also the banyan leaves in polluted stretch of the River Nethravathi (k, 0.0066-0.0075) (Raviraja et al 1998b). It is evident that elevation of temperature generally increases the rate of leaf decomposition (Webster & Benfield 1986).…”