Addition to Water-borne Fungal Spora of Western Ghat Streams,India

Conidial propagules encountered in foam samples of three lotic sources in Western Ghat forests of India are reported. Nine species can be assigned to known genera of water-borne hyphomycetes. Five kinds of conidia could not be assigned to known genera. Some of the conidia resemble spore types reported from Africa, Thailand and Malaysia.     

Host searching behavior and potential of an aquatic ichneumonid pupal parasitoid of rice caseworm (Parapoynx stagnalis) in an upland rice paddy agro-ecosystem of the Western Ghats,India

Parapoynx stagnalis (Zeller) (=Nymphula depunctalis (Guenée), is a sporadic rice paddy pest of south and southeast Asian rice paddy fields, and widely known as rice caseworm. A recent outbreak of the pest was observed in the upland rice paddy agro-ecosystem of the central Western Ghats, India. No potential natural enemies of this pest have so far been reported, mainly due to the semi-aquatic behavior of the larvae and pupae. However, an undescribed aquatic ichneumonid wasp species (belonging to a genus near Litochila) is reported as a potentially useful early stage pupal parasitoid of this pest in our study. The host searching behavior and potential of the parasitoid wasp was studied in detail using both field and laboratory experiments. The adult female wasps usually dive into the water in search of the host pupae, remaining under water for a maximum of 90.2s, while searching for rice caseworm pupae. In field and laboratory experiments, we found 73% of the parasitized pupae of P. stagnalis kept under water yielded adult parasitic wasps. However, no parasitoids emerged from parasitized host pupae maintained in dry terrariums. Sex ratio was 2.8:1. The present discovery of the semi-aquatic parasitoid wasp could aid in better management of the rice caseworm population in rice paddy fields.     

Colonization pattern of aquatic hyphomycetes on leaf packs in subtropical stream

Steralized leaf pieces of eight plants (Eucalyptus rostrata, Phoenix dactylifera, Phragmites australis, Musa nana, Salix subserrata, Cyperus alopecuroides, Ricinus communis and Eichhornia crassipes) were submerged in the Nile stream. Thirty-nine species of aquatic hyphomycetes were colonized on the plant leaves. Eucalyptus was the best substratum (30 species) for colonization by aquatic hyphomycetes. Phoenix (14 species), Phragmites (11 species), Salix (9 species), Musa (8 species), Ricinus and Cyperus (6 species) were also good substrata for aquatic hyphomycetes colonization. Echhornia (aquatic plant) was not suitable for aquatic hyphomycetes colonization. Alatospora acuminata, Triscelophorus monosporus and Tetracladium marchalianum were found to be the major colonizers on all leaf materials. Temperature and dissolved oxygen were the highest physico-chemical parameters affecting the aquatic hyphomycetes colonization. These results indicate that aquatic hyphomycetes have been shown to be successful colonizers on plants leaf in river Nile in Egypt as subtropical region. This revised version was published online in June 2006 with corrections to the Cover Date.     

Raised water temperature lowers diversity of hyporheic aquatic hyphomycetes

1. The hyporheic zone of a permanent first‐order stream was divided into a treatment and a control section using a 1 m deep sheet‐metal barrier. During a 4‐month pre‐treatment period, water temperatures in two transects of the two sections were not different. Upon heating, the water temperature in the treatment transect increased by an average of 4.3 °C over values in the control transect. 2. Eleven bimonthly core samples were taken from a treatment and a control transect, and recovered CPOM was classified as twigs, wood, grass, roots, cedar and deciduous leaves. 3. In both transects, twigs were the most common and deciduous leaves the least common substrates. The number of leaf fragments declined significantly in the heat‐treated transect. 4. Diversity and frequencies of occurrence of aquatic hyphomycetes were highest on leaves and lowest on grass and wood. On leaves, their frequency of occurrence was higher in control than in treatment samples. 5. Preliminary results with amplified and cloned 18S DNA sequences revealed many fungal taxa with high affinities to Basidiomycota, particularly to Limnoperdon incarnatum. 6. By itself, higher water temperature due to global warming is likely to lower the availability of substrates for, and therefore the occurrence of, aquatic hyphomycetes.     

Laccase activity of lignicolous aquatic hyphomycetes isolated from the River Nile in Egypt

Eleven species of aquatic hyphomycetes were isolated from 92 samples of different lignin sources (unidentified wood segments, skeleton and neck of leaves, bark). The most common species were Pyramidospora casuarina (on 3.7% of samples), Triscelophorus monosporus (3.2%) and Flagellospora curvula (3%). Varying levels of laccase activity were present in most of the fungi included in this study. The laccase plate assay was found to be much less reliable than the spectrophotometric assay. Several factors including type of growth medium, the media pH and assay pH had marked effects on laccase activity. A few species produced high levels of laccase in both malt extract (ME) medium and low N medium; however, a majority of the species produced laccase in low nitrogen (N) medium (pH 4.5) but not in the ME medium. When the tested species were grown in low N medium at pH 4.5, six species showed acidic laccase (pH 4.5) activity; of these, four also showed alkaline laccase (pH 8.2) activity. Alatospora acuminata and Tetracladium marchalianum exhibited laccase activity only when grown in the low N medium at pH 8.2. These results indicate that aquatic hyphomycetes may play a role in the decomposition of lignin materials in freshwater environments. This revised version was published online in June 2006 with corrections to the Cover Date.     

Diversity and distribution of herbaceous vascular epiphytes in a tropical evergreen forest at Varagalaiar, Western Ghats, India

Herbaceous vascular epiphytes were screened in a total sample of 13 445 trees (in 153 species) and 348 lianas (in 30 species) 30 cm girth at breast height in a 30 ha plot of tropical evergreen forest at Varagalaiar, Indian Western Ghats. Of these, 4.3% of trees and 3.7% of lianas were infested with epiphytes. Epiphyte diversity totaled 26 species in 19 genera and 10 families. Sixteen species were angiosperms in three families (Orchidaceae 54%; Piperaceae and Araceae 8%) and 10 species (38%) were pteridophytes in seven families. The orchid, Pholidota pallida was most abundant and occurred on 178 (29.6%) stems. Asplenium nidus occurred on the maximum of 62 host species. The species richness estimators employed for species accumulation curves after 100 times randomization of sample order have stabilized the curve at 18th and 19th hectares respectively for Incidence-based Coverage Estimator and Chao2. A total of 588 trees and 13 liana stems lodged epiphytes, 74% of which were evergreen species and 26% deciduous. Epiphyte density was greater (56%) in deciduous species (Bischofia javanica 30% and Vitex altissima 8%). A significant positive relationship was found between trunk size and epiphyte association. Larger epiphyte species occurred mostly on middle and larger stems and smaller epiphyte species occurred on smaller stems. The majority of epiphytes (92%) were of autochorous dispersal type, bearing capsule or dust diaspores, while the remaining species with berries and nutlets are dispersed by small vertebrates.     

Patterns of species discovery in the Western Ghats,a megadiversity hot spot in India

Even since Linnaeus, naturalists and taxonomists have been systematically describing species new to science. Besides indicating gaps in taxonomic effort, understanding the temporal patterns of species discovery could help in identifying drivers that determine discovery. In this study we report the patterns of discovery of eight taxa — birds, butterflies, frogs, tiger beetles, grasses, asters, ferns and orchids — in the Western Ghats, a megadiversity centre in India. Our results indicate that the discovery curves for birds and butterflies have been saturated while those for frogs and grasses continue to increase. Within each taxon, the major drivers of discovery were commonness of the species and their size. The average years taken for discovery across taxa were directly related to the per cent endemicity and species richness of the taxa. We discuss the trajectories of discovery with respect to rarity or endemicity of the species and life history features, and the implications these might have for strategizing the discovery process in India.     

Studies on the aquatic hyphomycetes of a sulfur spring in the Western Ghats, India

Studies on the occurrence of aquatic hyphomycetes were carried out in Panekal sulfur spring in the Western Ghats, India by incubation of leaf litter and analysis of natural foam and of induced foam. Sampling was done once every three months over a period of two years from September 1989 to June 1991. The temperature, pH, dissolved oxygen, and sulfide content of water were also measured. No fungi were observed within the spring, whereas 16 species belonging to 13 genera were isolated from two outflow sites of the stream. The percent frequency of Triscelophorus monosporus was high (24.0%). The temperature of water in the spring ranged between 30.0 and 38.5°C and the sulfide content between 3.2 and 4.3 mg 1^–1. Studies showed that sulfide water (4.0 mg 1^–1). from the spring inhibited the growth of the colonies of Dactylella aquatica, Phalangispora constricta, Tetracladium setigerum, Vermispora cauveriana, and Wiesneriomyces laurinus. When the leaves colonized by aquatic hyphomycetes were incubated at different temperatures in sulfur-spring water and stream water separately, sporulation was not observed in any of the fungi at and above 35°C except Phalangispora constricta, which could sporulate at 35°C. At lower temperatures (15–30°C) relatively fewer species were found to sporulate in sulfur-spring water than in stream water. Correspondence to: K.M. Kaveriappa     

The shrubs of the Western Ghats (South India): floristics and status

Abstract. This study examines the understorey shrub community in a wet evergreen forest of South India. The shrub community in the evergreen forests of the Western Ghats, Eastern Ghats, Sri Lanka, South-east Asia, Neotropics, Africa and Madagascar are compared. The shrub community is richer in the Old World Tropics as compared to the Neotropics. The common families in the Old World Tropics are: Rubiaceae, Acanthaceae, Euphorbiaceae, Myrsinaceae and Annonaceae. The number of families constituting the understorey shrub community falls from forty-six (Western Ghats) to thirteen (Central Amazon). The study concludes that the evergreen forests in the Western Ghats probably have the richest understorey shrub community.
Résumé. L'étude concerne la communauté d'arbustes de sous-bois d'une forêt sempervirente du Sud de l'lnde. Les communautés d'arbustes dans les forèts sempervirentes des Ghâts Occidentaux, des Ghâts Orientaux, du Sri Lanka, du Sud-Est Asie, des Néotropiques, de l'Afrique et de Madagascar sont comparées. La communauté d'arbustes est plus riche dans le Vieux Monde Tropical que dans les Néotropiques. Les families communes dans le Vieux Monde Tropical sont; Rubiaceae, Acanthaceae, Euphorbiaceae, Myrsinaceae et Annonaceae. Le nombre de families constituant la communauté d'arbustes de sous-bois varie de 46 (Ghâts Occidentaux) à 13 (Amazonie Centrale). L'étude conclue que les forêts sempervierentes des Ghàts Occidentaux ont probablement la plus riche communauté d'arbustes de sois-bois.
Mots clés. Communauté d'arbustes de sous-bois, forêts sempervirentes, Ghâts Occidentaux, endémisme, Inde.     

Effects of temperature and light on growth and sporulation of aquatic hyphomycetes

Nine isolates of the aquatic hyphomycetes Dactylella aquatica, Flagellospora penicillioides, Flagellospora saccata, Helicomyces sp., Lunulospora curvula, Phalangispora constricta, Tetracladium setigerum, Vermispora cauveriana and Wiesneriomyces laurinus were incubated at different temperatures (5–35 °C) to study their growth on MEA medium. Maximum growth was observed between 20 and 30 °C. Growth rate was highest in Vermispora cauveriana and lowest in Tetracladium setigerum. Colonies on submerged leaves showed maximum spore production at 25 °C. Light was confirmed as a stimulus to sporulation.     

Arbuscular mycorrhizas of plants growing in the Western Ghats region, Southern India

A survey of the arbuscular mycorrhizal (AM) status of plants growing in the Western Ghats region of Southern India was undertaken. Root and soil samples of plants growing in the four vegetation types forest, grassland, scrub, and cultivated land or plantation were examined. Of the 329 species (representing 61 families) examined, 174 were mycorrhizal. AM association was recorded in 81 species for the first time, including species from several families assumed to be non-mycorrhizal, e.g. Amaranthaceae, Capparaceae, Commelinaceae, Cyperaceae and Portulacaceae. AM fungal spores of 35 species belonging to Acaulospora, Gigaspora, Glomus, Sclerocystis and Scutellospora were recorded. AM fungal species richness was found to be highest in scrub and lowest in agricultural and plantation soils. Mean colonization levels were dependent on plant life-form, life-cycle pattern and vegetation type. Accepted: 26 October 1999     

Biodiversity inventory of trees in a large-scale permanent plot of tropical evergreen forest at Varagalaiar, Anamalais, Western Ghats, India

A permanent plot of 30 ha (600 × 500 m²) was established for long-term ecological research on biodiversity and forest functioning in a tropical evergreen forest at Varagalaiar, Anamalais, Western Ghats. This paper gives the results of the first census of trees in the 30 ha plot. All trees 30 cm gbh were permanently tagged with sequentially numbered aluminium tags and their girth measured. 148 tree species (in 120 genera and 49 families) were enumerated in a total sample of 13,393 individuals. Species diversity, density and dispersion patterns were determined. The mean species richness, density and basal area per hectare were 65 species, 446 stems and 36.26 m² respectively. The Sorensen similarity index for thirty 1-ha subplots varied from 0.7 to 0.9, indicating the homogeneity in species composition of the stand. The pronounced species hierarchy has resulted in the dominance of four species that occupy four different forest storeys: Drypetes longifolia (lower storey) Reinwardtiodendron anamallayanum (middle storey), Poeciloneuron indicum (upper storey) and Dipterocarpus indicus (emergent). The forest was dominated by Euphorbiaceae in terms of richness (18 species) and abundance of species (3788 stems), and Dipterocarpaceae based on the contribution to basal area (18.4%). Species richness and density decreased with increasing girth-class. Girth class frequency of the stand exhibited an expanding population of trees. Twenty-nine tree species, analysed for spatial dispersion at 1-ha scale, exhibited both clumped and uniform patterns, except Vateria indica which was randomly distributed in one hectare. Repeat census scheduled for subsequent years, will elucidate the behaviour of the individual species and the population dynamics of the tree flora and will be useful for forest conservation and management. It will also help to monitor human activity within this forest.     

Effects of cadmium,copper, and zinc on growth and thiol content of aquatic hyphomycetes

The effects of cadmium, copper, and zinc on the growth of ten strains ofaquatic hyphomycetes were investigated. On a solid medium, Cd and Cu reducedradial growth of most strains by 50% at concentrations between150–400 µM; in a liquid medium, the strains were more sensitive.The inhibitory effects of zinc were much less severe. Two isolates(Articulospora tetracladia and Tetracladium marchalianum) from a copper-minestream were more resistant against copper than conspecific strains from anon-polluted stream. Heliscus lugdunensis and Varicosporium elodeaeresponded to Cd exposure, but not to Cu or Zn exposure, by increasedsynthesis of SH-containing compounds. Glutathione levels showed a unimodalresponse to increasing Cd and Zn exposure. With copper, glutathionedecreased at intermediate levels of contamination. In the presence of Cd, H. lugdunensis synthesized several unknown sulfur-rich substances that wereabsent or produced at reduced rates in control cultures.     

Sandfly species diversity in association with human activities in the Kani tribe settlements of the Western Ghats,Thiruvananthapuram, Kerala, India

Sandfly prevalence in the Kani tribe settlements of Western Ghats in India was investigated. A total of 1,279 sandflies comprising 17 species was obtained. Sandfly abundance showed a negative correlation (r = -0.97, p = 0.003) with increase in altitudinal ranges from 0-1,000 m. When sandfly samples were grouped according to landscape characteristics of the location, the estimated Shannon-Weiner index (H) and species richness index (S) were high and species evenness index (J) was low in settlements located at 0-300 m altitudinal range. On the contrary, the values of H and J were high, while S was low at 301-600 m altitudinal range. With further increase in altitude, species diversity, S and J were low. Though the relative abundance of sandflies decreased with increase in altitude, the influence of altitudinal variation could not be attributed to determine sandfly diversity, since the number of sampling units were not uniform at all the altitudinal gradients due to nonavailability of suitable resting shelters. Sandfly species showed great aggregation at 0-300 m altitude interval, where not only the number of settlements were maximum (n = 19), but also the environmental conditions favoured sandfly abundance due to the concentration of tribal settlements, human dwellings and his activities.     

Enzymatic studies of the extracellular mucilage of two aquatic hyphomycetes,Lemonniera aquatica andMycocentrospora filiformis

The effect of three carbohydrate-digesting enzymes, β-glucuronidase, lyticase and α-mannosidase and three proteolytic enzymes, α-chymotrypsin, papain and pronase E, on the strength of conidial attachment ofLemonniera aquatica andMycoentrospora filiformis was determined using the LH_Fowler cell Adhesion Measurement Module. Carbohydrate-digesting enzyme treatments showed significant differences in number of attached and detached, conidia versus control samples; little or no effect was observed for the proteolytic enzymes. Scanning and transmission electron microscopy showed different degrees of mucilage digestion by the carbohydrate-digesting enzymes on the germ hyphae, hyphae subtending appressoria, and appressoria of the two species. The loss of mucilage integrity and decrease in mucilage thickness were more pronounced on the hyphal sheaths than on the appressorial sheaths. Lyticase caused the most severe damage to the mucilage and cytoplasm of both fungi, particularlyL. aquatica. β-Glucuronidase and α-mannosidase exhibited more effective mucilage digestion onM. filiformis than onL. aquatica. Results indicate that the mucilage of the two species is mainly polysaccharide, containing more β-1,3-glucans than β-glucuronide and α-mannosyl residues. Variability of mucilage composition exists between these species and also between different structures of the same fungus.     

Diversity patterns of leaf-associated aquatic hyphomycetes along a broad latitudinal gradient

Information about the global distribution of aquatic hyphomycetes is scarce, despite the primary importance of these fungi in stream ecosystem functioning. In particular, the relationship between their diversity and latitude remains unclear, due to a lack of coordinated surveys across broad latitudinal ranges. This study is a first report on latitudinal patterns of aquatic hyphomycete diversity associated with native leaf-litter species in five streams located along a gradient extending from the subarctic to the tropics. Exposure of leaf litter in mesh bags of three different mesh sizes facilitated assessing the effects of including or excluding different size-classes of litter-consuming invertebrates. Aquatic hyphomycete evenness was notably constant across all sites, whereas species richness and diversity, expressed as the Hill number, reached a maximum at mid-latitudes (Mediterranean and temperate streams). These latitudinal patterns were consistent across litter species, despite a notable influence of litter identity on fungal communities at the local scale. As a result, the bell-shaped distribution of species richness and Hill diversity deviated markedly from the latitudinal patterns of most other groups of organisms. Differences in the body-size distribution of invertebrate communities colonizing the leaves had no effect on aquatic hyphomycete species richness, Hill diversity or evenness, but invertebrates could still influence fungal communities by depleting litter, an effect that was not captured by the design of our experiment.     

Diversity and activity of aquatic fungi under low oxygen conditions

1. The objective was to test whether a decrease in oxygen concentration in streams affects the diversity and activity of aquatic hyphomycetes and consequently leaf litter decomposition. 2. Senescent leaves of Alnus glutinosa were immersed for 7 days in a reference stream, for fungal colonization, and then incubated for 18 days in microcosms at five oxygen concentrations (4%, 26%, 54%, 76% and 94% saturation). Leaf decomposition (as loss of leaf toughness), fungal diversity, reproduction (as spore production) and biomass (ergosterol content) were determined. 3. Leaf toughness decreased by 70% in leaves exposed to the highest O₂ concentration, whereas the decrease was substantially less (from 25% to 45%) in treatments with lower O₂. Fungal biomass decreased from 99 to 12 mg fungi g⁻¹ ash‐free dry mass on exposure to 94% and 4% O₂ respectively. Sporulation was strongly inhibited by reduction of dissolved O₂ in water (3.1 × 10⁴ versus 1.3 × 10³ spores per microcosms) for 94% and 4% saturation respectively. 4. A total of 20 species of aquatic hyphomycetes were identified on leaves exposed to 94% O₂, whereas only 12 species were found in the treatment with 4% O₂ saturation. Multidimensional scaling revealed that fungal assemblages exposed to 4% O₂ were separated from all the others. Articulospora tetracladia, Cylindrocarpon sp. and Flagellospora curta were the dominant species in microcosms with 4% O₂, while Flagellospora curvula and Anguillospora filiformis were dominant at higher O₂ concentrations. 5. Overall results suggest that the functional role of aquatic hyphomycetes as decomposers of leaf litter is limited when the concentration of dissolved oxygen in streams is low.     

Tree diversity and distribution in undisturbed and human-impacted sites of tropical wet evergreen forest in southern Western Ghats, India

The composition, abundance, population structure and distribution patterns of all woody species ( 30 cm gbh) were investigated in an undisturbed and two adjacent human-impacted sites of a tropical wet evergreen forest in Kalakad National Park, Western Ghats, south India. Three 1-ha plots were established, one each in (i) an undisturbed site (named site UD), (ii) in a site selectively felled 35 years ago (site SF – small stems felled leaving the large trees (as shade) for developing it into a cardamom estate, on the failure of which the site was abandoned) and (iii) a frequently disturbed site (site FD – round woods logged for use in ovens for curing cardamom). These sites are 1 to 3 km apart in the same wet evergreen forest. In the three study plots a total of 2150 stems (mean density 716 ha^–1) covering 122 species in 89 genera and 41 families were enumerated. Species richness was greatest (85 species ha^–1) in the undisturbed site UD, intermediate (83) in SF and lowest (80) in FD. Tree density was greatest (855 stems ha^–1) in site SF, intermediate (720) in UD and lowest (575) in FD. The forest stand was exceptionally voluminous in site UD (basal area 94.64 m² ha^–1), intermediate (66.9 m²) in SF and least (61.7 m²) in FD, due to tree removal for fuel in the latter sites. Species composition and abundance patterns markedly varied between the three sites. In UD and SF, primary forest species (Cryptocarya bourdillonii , Cullenia exarillata Myristica dactyloides etc.) occurred in greater density. In FD heliophilic secondary forest species (Elaeocarpus venustus, Litsea wightiana, Viburnum punctatum and Vitex altissima) were abundant, while these were absent in UD and SF. The species–area curve did not reach an asymptote in any of the sites on the 1-ha scale. The stand population structure was clearly reverse J shaped in UD and SF, while small stems were 2- to 3-fold fewer in FD. Most trees exhibited clumped distribution of individuals on the 1-ha scale. Variation in the kind and richness of species and their abundance is related to human interference and the need for forest conservation is emphasized.     

Incorporating landscape transformation into local conservation prioritization: a case study in the Western Ghats, India

In fast-changing tropical landscapes, effective strategies for conservation must incorporate information on ecosystems and species distribution with that on landscape change. A possible methodology for conservation prioritization is developed and illustrated using a 27.5 km² tropical landscape in the Western Ghats hill chain of southern India. Vegetation types or ecosystems within the landscape are ranked based on the ecosystem services they might provide: number of endemic species harbored, species richness, contribution to carbon uptake, economic value of produce per ha and contribution to soil renewal. For a vegetation type, the weighted average of these ranks indicates its net conservation value. Weights thus provide a means of ascribing differential importance to an ecosystem service. Information on landscape change is also summarized by a matrix depicting the likelihood of transformations between vegetation types present in the landscape, projected 5 years into the future. For each transformation between two vegetation types, information on ecosystem service and dynamics is then integrated. Implications from the perspective of conservation are assessed as the product of transformation probability and the resultant gain/loss in conservation value. Strongly positive transformations are likely to result in positive impacts on conservation value, and occur without any additional conservation effort. Strongly negative transformations are likely to occur and have a strong negative impact on conservation value. Maximum conservation effort may be directed at halting or reversing these. This study thus describes a method for conservation prioritization, which integrates information on ecosystem function and services with ecosystem dynamics.     

Exotic fish species in a global biodiversity hotspot: observations from River Chalakudy,part of Western Ghats,Kerala, India

We record here the occurrence of five exotic fish species viz Oreochromis mossambicus, Gambusia affinis, Osphronemus goramy, Xiphophorus maculatus and Poecilia reticulata in the Chalakudy River, part of the Western Ghats, a global biodiversity hotspot in Kerala, India. O. mossambicus was ubiquitous in occurrence with large shoals being encountered at all sampling sites spread along the downstream-upstream gradient of the river, including at an altitude of 1050 m ASL. Osphronemus goramy was recorded from the downstream region of the river while Gambusia affinis was recorded from three sampling sites located downstream as well as midstream. Xiphophorus maculatus was collected from a second order stream flowing through a tea plantation at an altitude of 1050 m ASL. Samples of brooders and early fry of Poecilia reticulata indicate that the fish has already established a breeding population in the river. Possible threats to the indigenous fish fauna of the Chalakudy River as a result of the invasion and proliferation of these exotics is discussed.