Colonization Of Leaf Litter Research Articles

Periphyton growth on allochthonous input in streams may lead to higher individual growth rates of the invasive New Zealand mud snail (<em>Potamopyrgus antipodarum</em>)

The aquatic, invasive New Zealand mud snail (Potamopyrgus antipodarum) exploits a variety of food sources. Here we examine the change in growth of snails that fed on periphyton colonizing leaf litter, wood, rock, and a control. Juveniles were grown in the lab on Spirulina algae powder (control) or periphyton grown on rock, leaf litter, or wood. Length was measured at the beginning of the experiment and after eight weeks. Snails grown on leaf litter increased in length more than twice as much as the control and the snails in the rock treatment, and the snails grown on wood showed an increase in length more than twice as much as snails in the rock treatment. This suggests that allochthonous material may contribute to a more nutritious food source for New Zealand mud snails and possibly aid in their invasion success.

Leaf litter breakdown along an elevational gradient in Australian alpine streams.

The breakdown of allochthonous organic matter, is a central step in nutrient cycling in stream ecosystems. There is concern that increased temperatures from climate change will alter the breakdown rate of organic matter, with important consequences for the ecosystem functioning of alpine streams. This study investigated the rate of leaf litter breakdown and how temperature and other factors such as microbial and invertebrate activities influenced this over elevational and temporal gradients. Dried leaves of Snow Gum (Eucalyptus pauciflora) and cotton strips were deployed in coarse (6 mm), and fine (50 μm) mesh size bags along an 820 m elevation gradient. Loss of mass in leaf litter and cotton tensile strength per day (k per day), fungal biomass measured as ergosterol concentration, invertebrate colonization of leaf litter, and benthic organic matter (mass and composition) were determined. Both microbial and macroinvertebrate activities were equally important in leaf litter breakdown with the abundance of shredder invertebrate taxa. The overall leaf litter breakdown rate and loss of tensile strength in cotton strips (both k per day) were greater during warmer deployment periods and at lower elevations, with significant positive relationships between mean water temperature and leaf breakdown and loss of tensile strength rate, but no differences between sites, after accounting for the effects of temperature. Despite considerably lower amounts of benthic organic matter in streams above the tree line relative to those below, shredders were present in coarse mesh bags at all sites. Ergosterol concentration was greater on leaves in coarse mesh bags than in fine mesh bags, implying differences in the microbial communities. The importance of water temperatures on the rate of leaf litter breakdown suggests the potential effects of climate change‐induced temperature increases on ecological processes in such streams.

Assessment of metal exposure (uranium and copper) in fatty acids and carbohydrate profiles of Calamoceras marsupus larvae (Trichoptera) and Alnus glutinosa leaf litter.

Physiological changes were explored in fatty acids (FA) and carbohydrate (CHO) composition in the shredder Calamoceras marsupus larvae (Trichoptera) and leaf litter (C. marsupus food) exposed to copper and uranium under natural and experimental conditions. We measured FA and CHO content in leaf litter and larvae specimens from reference and impacted streams, and exposed for 5 weeks to four realistic environmental concentrations of copper (35 μg L-1 and 70 μg L-1) and uranium (25 μg L-1 and 50 μg L-1). Regarding FA, (1) leaf litter had a reduced polyunsaturated FA (PUFA) content in metal treatments, s (14 to 33% of total FA), compared to natural conditions (≥39% of total FA). Leaf litter exposed to uranium also differed in saturated FA (SFA) composition, with lower values in natural conditions and higher values under low uranium concentrations. (2) C. marsupus had/showed low PUFA content under Cu and U exposure, particularly in high uranium concentrations. Detritivores also decreased in PUFA under exposure to both metals, particularly in high uranium concentrations. On the other hand, (1) microorganisms of the biofilm colonizing leaf litter differed in CHO composition between natural (impacted and reference) and experimental conditions, with glucose and galactose being consistently the most abundant sugars, found in different amounts under copper or uranium exposure; (2) CHO of detritivores showed similar high galactose and fucose concentrations in contaminated streams and high copper treatments, whereas low copper treatment showed distinct CHO profiles, with higher mannose, glucose, arabinose, and fucose concentrations. Our study provides evidence of metal exposure effects on FA and CHO contents at different trophic levels, which might alter the quality of food flow in trophic webs.

Explorando o impacto da presença de detritos exóticos na comunidade de invertebrados aquáticos e no processo de decomposição foliar em um riacho na Mata Atlântica

Abstract: Aim In this study, we examined the effects of non-native leaf litter on the functioning of an Atlantic Forest stream ecosystem. Methods Were tested two predictions: (i) Leaf litter from the native trees with high nutritional quality will have higher decomposer’s activity and faster litter decomposition; (ii) Given the presence of anti-grazing defenses, we also hypothesized that non-native leaf litter would be colonized by fewer invertebrates and that native species would be more species-rich. For this, in a forest stream (Florianópolis, SC, Brazil) we conduct the experiment to understand the decomposition and biological colonization of leaf litter among two non-native (Eucalyptus sp. and Pinus radiata D. Don) and two native trees (Ficus eximia Schott and Alchornea triplinervia (Spreng) Mull. Arg). Results Our predictions were partially corroborated. The percentage of dry mass remaining was lower for the native leaf litter. The invertebrate abundance and richness, and functional feeding groups vary between native and non-native leaf litter. Invertebrate abundance was higher in non-native Eucalyptus detritus, largely due to the high larval abundance of Chironomidae (Diptera). Conclusions Our results indicate that the presence of non-native riparian species can modify leaf decomposition and aquatic invertebrate communities in subtropical streams, with potential consequences for ecosystem functioning.

A comparison of decomposition rates and biological colonization of leaf litter from tropical and temperate origins

Litter decomposition is an ecosystem process that allows energy and nutrients transfer from dead plant matter into detrital food webs. Several studies revealed that leaf litter decomposition rates differ across biomes, but the reasons for these differences are not yet clear. Here, we test the role of several leaf litter physical and chemical characteristics as predictors of decomposition rates and whether life forms (evergreen vs. deciduous) differ in decomposition rates. Leaves from dominant riparian trees were collected in four ecoregions (temperate deciduous forest, subtropical seasonal semideciduous forest, tropical Cerrado and subtropical dense ombrophylous forest) and their physical and chemical characteristics were measured. We then determined leaf litter decomposition, colonization by aquatic hyphomycetes and macroinvertebrates in a same stream (i.e., under the same environmental conditions), and consumption rates by shredders under laboratory conditions. Deciduous and evergreen tree species did not differ in the measured litter characteristics, but deciduous leaves decompose faster than evergreens. Leaf litter from tree species from the four ecoregions differed in their physical and chemical characteristics. Litter from temperate deciduous species decomposed faster than litter from the other three ecoregions, generally supported higher aquatic hyphomycete species richness and sporulation rates and higher consumption rates by shredders. There were significant negative correlations between litter decomposition and associated biotic variables and litter initial lignin concentration and lignin:N ratio. We conclude that lignin concentration and lignin:N ratio are important predictors of litter decomposition, although other unmeasured parameters such as micronutrients may also play important roles in this key ecosystem process.

<strong><em>Cladosporium</em> species from submerged decayed leaves in Brazil, including a new species and new records</strong>

Fungi belonging to the genus Cladosporium are cosmopolitan and occur in various substrates and hosts. Nevertheless, this is the first time that we have described this genus colonizing leaf litter submerged in water. We surveyed Cladosporium spp. associated with submerged leaf litter, from three localities belonging to the Atlantic Forest biome in the State of Minas Gerais, Brazil. A multilocus DNA sequence typing approach employing ITS, Actin, and Translation elongation factor 1-α region/genes associated with morphological and cultural analyses were used to identify these species. The species C. angulosum and C. anthropophilum are reported for the first time in Brazil, and a new species for the genus is described here as C. puris.

Litter movement pathways across terrestrial–aquatic ecosystem boundaries affect litter colonization and decomposition in streams

Abstract Streams and their riparian zones are connected by spatial flows of organic matter and constitute a model example of a meta‐ecosystem. Fluxes of leaf litter from the riparian zone to the stream are a major energy source in stream food webs. Leaf litter can enter the stream vertically, falling from the tree and into the stream, or laterally, washing into the stream after a period of exposure in the terrestrial ecosystem. The latter can contribute up to 23% to the total amount of litterfall entering streams. To determine if decomposition, microbial and invertebrate colonization of lateral litter inputs are similar to those of vertical inputs, we assessed leaf decomposition of alder, poplar and a 1:1 mixture of the two species in three scenarios across a gradient of terrestrial:aquatic exposures. Overall, decomposition was explained by a negative exponential model and decreased with the increase in the period of terrestrial exposure in all cases. Invertebrate colonization tended to decrease with the increase in the period of terrestrial exposure, but total invertebrate richness and biomass were more affected by litter type than by the exposure scenario, attaining higher values in the mixture than in the species alone. As the length of exposure in the terrestrial ecosystem increased, in‐stream decomposition rates of leaf litter decreased. Comparing leaf species treatments, alder decomposition rates were faster than poplar and the alder–poplar mixture. The richness of the aquatic hyphomycete community colonizing leaf litter after submergence decreased, and sporulation rates were strongly inhibited with an increasing terrestrial exposure period. While fungi colonizing leaf litter exposed only in the stream invested in rapid reproduction, fungi colonizing litter with prior terrestrial exposure built up more biomass. We conclude that the path taken by the litter fluxes has important effects on the functioning of the receiving ecosystem. Studies relying only on the fate of freshly abscissed leaf litter (vertical inputs) may not present a complete picture of the decomposition process in streams and may have been overestimating the overall richness and reproductive activity of the aquatic hyphomycetes colonizing leaf litter.

Tree species richness and fungi in freshly fallen leaf litter: Unique patterns of fungal species composition and their implications for enzymatic decomposition

A major gap in understanding the relationship between tree diversity and litter decomposition concerns knowledge of the saprotrophic fungal communities mediating decomposition processes. Making use of experimental tree diversity plots in subtropical China, our objective was to disentangle the effects of tree species richness on diversity, abundance, and composition of saprotrophic fungal communities in freshly fallen leaf litter. We employed a meta-genomic approach and analysed enzymatic decomposition. Our results indicate the dominance of Ascomycota, with species from this phylum colonizing leaf litter more rapidly than Basidiomycota. Furthermore, Ascomycota was the most abundant when tree richness was intermediate. Both Ascomycota and Basidiomycota differed significantly in their species composition in response to varying tree species richness. However, saprotrophic fungal species diversity did not respond to tree species richness. Instead, litter C/N ratio, litter Ca and plot altitude were the strongest determinants of fungal species diversity. Carbon-degradation enzyme activities were also significantly associated with litter C/N ratio, Ca and Fe concentration and, in addition, with tree species richness. The responses of fungal species and enzyme activity to tree species richness were uncoupled from each other, although the two variables were significantly correlated. Overall, our findings highlight a significant effect of tree species richness on litter fungal species composition, but not diversity. Our findings also provide insight into the importance of enzyme-mediated C degradation for the response to tree species richness in early-stage leaf decay in subtropical forests.

Contribution of aquatic shredders to leaf litter decomposition in Atlantic island streams depends on shredder density and litter quality

It has been widely reported that shredders play an important role in leaf decomposition, especially in continental temperate streams. However, the paucity of shredders in many oceanic island streams leads to a greater contribution of microbes to litter decomposition in these streams. In this study, we investigated the importance of shredder presence and density (three levels) and leaf litter identity (Alnus glutinosa, Clethra arborea and Acacia melanoxylon) on leaf litter decomposition in one stream located in the Azores Archipelago. Coarse and fine mesh bags were used to allow natural colonisation of leaf litter by benthic macroinvertebrates or to exclude macroinvertebrates respectively. Treatments with one and three shredders were accomplished by enclosing one or three shredders in the fine mesh bags. Rates of litter decomposition differed significantly among shredder density treatments only for A. glutinosa and C. arborea. Decomposition rates were significantly faster for the natural within-stream shredder density treatment than for other shredder treatments. Shredder density differed significantly among litter species, being higher in A. glutinosa than in C. arborea and A. melanoxylon. The results indicate that when shredders are present at high densities in oceanic island streams they can substantially contribute to the decomposition of high-quality leaf litter, whereas the decomposition of hard leaf litter is mostly performed by the microbial community.

Environmental degradation results in contrasting changes in the assembly processes of stream bacterial and fungal communities

Environmental degradation may have strong effects on community assembly processes. We examined the assembly of bacterial and fungal communities in anthropogenically altered and near‐pristine streams. Using pyrosequencing of bacterial and fungal DNA from decomposed alder Alnus incana leaves, we specifically examined if environmental degradation deterministically decreases or increases the compositional turnover of bacterial and fungal communities. Our results showed that near‐pristine streams and anthropogenically altered streams supported distinct fungal and bacterial communities. The mechanisms assembling these communities were different in near‐pristine and altered environments. Environmental disturbance homogenized bacterial communities, whereas fungal communities were more dissimilar in disturbed sites than in near‐pristine sites. Compositional variation of both bacteria and fungi was related to water chemistry variables in disturbed sites, further implying the influence of environmental degradation on community assembly. Bacterial and fungal communities in near‐pristine streams were weakly controlled by environmental factors, suggesting that the relative importance of niche‐based versus neutral processes in assembling microbial communities may strongly depend on the spatial scale and local environmental context. Our results thus suggest that environmental degradation may strongly affect the composition and β‐diversity of stream microbial communities colonizing leaf litter, and that the direction of the change can be different between bacteria and fungi. A better understanding of the environmental tolerances of microbes and the mechanisms assembling microbial communities in natural environmental settings is needed to predict how environmental alteration is likely to affect microbial communities.

Effects of multiple but low pesticide loads on aquatic fungal communities colonizing leaf litter

In the first tier risk assessment (RA) of pesticides, risk for aquatic communities is estimated by using results from standard laboratory tests with algae, daphnids and fish for single pesticides such as herbicides, fungicides, and insecticides. However, fungi as key organisms for nutrient cycling in ecosystems as well as multiple pesticide applications are not considered in the RA. In this study, the effects of multiple low pesticide pulses using regulatory acceptable concentrations (RACs) on the dynamics of non-target aquatic fungi were investigated in a study using pond mesocosm. For that, fungi colonizing black alder (Alnus glutinosa) leaves were exposed to multiple, low pulses of 11 different pesticides over a period of 60days using a real farmer's pesticide application protocol for apple cropping. Four pond mesocosms served as treatments and 4 as controls. The composition of fungal communities colonizing the litter material was analyzed using a molecular fingerprinting approach based on the terminal Restriction Fragment Length Polymorphism (t-RFLP) of the fungal Internal Transcribed Spacer (ITS) region of the ribonucleic acid (RNA) gene(s). Our data indicated a clear fluctuation of fungal communities based on the degree of leaf litter degradation. However significant effects of the applied spraying sequence were not observed. Consequently also degradation rates of the litter material were not affected by the treatments. Our results indicate that the nutrient rich environment of the leaf litter material gave fungal communities the possibility to express genes that induce tolerance against the applied pesticides. Thus our data may not be transferred to other fresh water habitats with lower nutrient availability.

Small stonefly predators affect microbenthic and meiobenthic communities in stream leaf packs

Summary Predators affect benthic communities and ecological processes through consuming and scaring prey as well as through engineering effects on the habitat. Experimental evidence of top–down predatory effects in leaf packs comes from studies assessing how large predators affect shredders and therefore the litter decomposition rate. In this study, we investigated the effects of smaller invertebrate predators on micro‐ and meiobenthic communities. In outdoor, flow‐through stream channels, we created a gradient in the density of predacious Chloroperlidae stonefly larvae in enclosures containing alder leaf litter and exposed to natural colonisation by invertebrates and decomposers. We expected that: (i) predators would reduce the biomass and density of invertebrate colonisers, (ii) the strength of predator effects on invertebrates would vary with prey body size; and (iii) increasing predator numbers in enclosures would diminish the per capita strength of predator–prey interactions due to intraguild interference. We also anticipated that litter decomposition would be slower in the presence of predators providing that microbial decomposers did not compensate for the reduction in shredders by an increase in their biomass. Chloroperlidae had negative effects on the biomass of most major invertebrate taxa, including rotifers, nematodes and larvae of the Chironomidae Corynoneura and Brillia (the dominant shredder in leaf packs). The predatory effect on nematode biomass was strongest for dominant small‐bodied species. Fungal biomass in leaf litter was reduced in the presence of predators, whereas bacterial biomass was not affected. In addition to feasible direct predation on Chironomidae, Chloroperlidae apparently inhibited meiofauna colonisation of leaf litter, probably through the bioturbation of fine sediment trapped on leaf surfaces. At the end of the experiment, the mortality of Chloroperlidae in enclosures was considerable at the highest predator density treatment. This observation, along with evidence of the reduced per capita strength of predator–prey interactions with increasing predator density, suggested that intraguild interference moderates the effect of predators in leaf packs. Our findings are consistent with a key role of small predators in determining the abundance of invertebrates and microbial decomposers in leaf packs. However, in our study, there was no cascade down to the standing stock of leaf litter.

Experimental manipulation of leaf litter colonization by aquatic invertebrates in a third order tropical stream.

Through a manipulative experiment, the colonization of leaf litter by invertebrates was investigated in two sections of a tropical stream (spatial scale) that differed in function of the canopy cover, one with the presence (closed area) and another without riparian vegetation (open area), during one month of the dry and one of the wet season (temporal scale). The work aimed to verify differences related to four variables: season, canopy cover, leaf type and leaf condition. Litter bags containing arboreal and herbaceous leaves (leaf type variable), non-conditioned and preconditioned (leaf condition variable) were placed at the bottom of the stream in each area (canopy cover variable) and season (dry and wet), and removed after 13-day colonization. The analysis of the remaining litter dry mass per leaf bag emphasizes differences related mainly to seasonality, canopy cover and leaf type, although leaf condition was also important when combined with those three factors. Comparing the abundance of invertebrates per treatment, there was a tendency of high predominance of Chironomidae during the dry season and greater taxa diversity and evenness during the wet season, when the water flow increase could alter the availability of microhabitats for local fauna. Even though canopy cover alone was not a significant source of variation in the abundance of invertebrates, the results showed a tendency of a combined effect of canopy cover with seasonality and leaf condition.

New record of Porobeltraniella porosa (Piroz. & S.D. Patil) Gusmão, 2004 (Fungi: asexual Ascomycota) for South America

Porobeltraniella porosa (Piroz. & S.D. Patil) Gusmao is an asexual fungus colonizing leaf litter. Previously known for India, from where it was described, and for Australia and Mexico, now it has been collected for the first time in Brazil, in Ribeirao Preto county, Sao Paulo State. The characteristics of the Brazilian material are given here and its geographical distribution is expanded to South America.

Stable isotope variation during fungal colonisation of leaf detritus in aquatic environments

Measuring C and N stable isotopes at natural abundance can provide information on the role of fungi associated with litter decay in the nutrient cycle of freshwater ecosystems. However, uncertainty regarding isotopic fractionation by decomposer fungi during uptake or metabolic turnover is a serious limitation, weakening the description of taxon-specific ecological differences in nutrient transfer in aquatic detritus-based systems. We performed two laboratory experiments to assess C and N isotopic changes during leaf litter colonization by: (1) mixed fungal communities on three different leaf litter species, and (2) four different fungal strains growing on the same leaf litter. Our approach served to decouple the isotopic effects of different fungal taxa from those arising from structural changes occurring in leaf litter during decomposition. N isotopic changes were directly related to fungal biomass accrual on litter, whereas carbon isotopic changes were mainly dependent on the remaining lignin fraction. Isotopic mixing model equations enabled us to calculate strain-specific isotopic fractionation, indicating that fungi were enriched in 15N by 3.6–5.9‰ with respect to bulk N litter.

The effect of mixtures on colonisation of leaf litter decomposing in a stream and at its riparian zone

Abstract. The effect of mixing litter on decomposition and colonisation has been the focus of many studies carried independently in terrestrial and aquatic ecosystems. Those studies are carried out in different regions, use different experimental protocols and methodologies for the assessment of additive or non-additive effects, and the conclusions on the effect of mixtures vary accordingly. In this study I tested the hypothesis, via a short-term decomposition experiment, that, when using the same experimental protocol, mixtures have similar additive effects on decomposition and associated biota in a stream and at its riparian zone. The effect of mixing litter was assessed by comparing values in mixtures with the average of single species, alder and poplar (method 1); comparing the value of a species in mixture with the value of that species alone (method 2); and by a graphical analysis of the average difference between observed and expected values and the 95% confidence intervals (method 3). Method 1 was the most conservative, detecting non-additive effects on macroinvertebrate abundance only; method 2 detected non-additive effects on both dry mass remaining and ergosterol, with differential responses of the leaf species and the habitat; and method 3 detected non-additive effects on all variables except ergosterol and percentage detritivore abundance and also identified different responses of the leaves exposed in the terrestrial and the aquatic habitats. These results show that (i) the methodology used to detect the effects of mixtures deeply influences the results obtained, and may partially explain the diversity of responses available in literature; and (ii) the effect of mixtures may differ in the stream and at the riparian area. However, the findings of the present work should be assessed in a larger-scale experiment in order to generalise the effects of mixing litter on terrestrial and aquatic habitats.

Colonisation of leaf litter by aquatic invertebrates in an Atlantic Forest stream.

Riparian vegetation along streams in the Atlantic Forest in Brazil contributes to the formation of a highly heterogeneous leaf litter in streambeds. To investigate the structure and composition of the aquatic invertebrate community during the process of leaf decomposition of two plant species present along the banks of the stream studied, 21 plastic mesh bags containing 2.5g (dry weight) of leaf matter from each species (Alchornea glandulosa (Vell) and Cabralea canjerana End. and Poeppig), for a total of 5.0g, were placed in the streambed. Three bags were removed after 3, 6, 9, 12, 24, 48 and 96 days. The taxonomic density was negatively correlated with the remaining weight. The high density of collector organisms, such as Chironomidae, Oligochaeta and Amphipoda, on the last day of incubation, probably occurred due to the increased amount of fine organic matter in the more advanced decomposition stages. The highest α diversity (Shannon-Wiener) values were observed for the 3rd and 96th days of the experiment, while the β diversity values showed that these days presented the highest variation in the taxonomic composition, thus presenting a different faunistic composition. This study showed that the trophic structure and composition of aquatic invertebrates changes during the decomposition of leaf litter. The faunistic abundance and diversity observed in this study indicate that the entrance of material from plants growing along streams provides favorable conditions for the colonisation and establishment of invertebrates in lower-order streams, and thus points to the need to preserve riparian vegetation.

Colonisation of leaf litter by lotic macroinvertebrates in a headwater stream of the Phachi River (western Thailand)

Leaf litter decomposition has been widely studied during the last 60 years. However, the relative im- portance of various processes, such as physical abrasion, microbial activity and macroinvertebrates consumption, remains unclear in tropical streams. The aim of this study was to gain insights into the ecological processes leading to the decomposition of leaf litter in headwater streams of Thailand, with a particular focus on the role played by macroinvertebrates. The breakdown rate of two leaf species, Bambusa bambos and Lagerstroemia floribunda, was investigated in a 1 st order tropical stream of Ratchaburi province (western Thailand) using litter bags submerged over an 8-week period. Litter bags were retrieved after 2, 14, 28, 42 and 56 days of immersion and characterised by two metrics, remaining AFDM and faunal composition of macroinvertebrates. Most rapidly decomposed leaves were those of B. bambos placed in riffles and most slowly decomposed were those of L. floribunda placed in pools (k = 0.030 and 0.006 d -1 , respectively). The highest amount of invertebrates per leaf bag were found after 14 days of immersion for B. bambos (174 individuals, SE = 10.0, n = 4) and after 28 days of immersion for L. floribunda (174 individuals, SE = 15.8, n = 5). Faunal composition of invertebrates differed between pools and riffles but not within leaf species. The low influence of shredders (accounting for maximum 5 % of total invertebrate abundance in leaf bags) is in accordance with previous findings in tropical zones, while there is a new thought that physical abrasion may play an important role in leaf decay. Nevertheless, non-shredder invertebrates may indirectly contribute to the decomposition of leaf material. In both pools and riffles, macroinvertebrate communities varied with time, showing a diminution of stream habitability, correlated with progressive water withdrawal.

DNA barcoding survey of Trichoderma diversity in soil and litter of the Colombian lowland Amazonian rainforest reveals Trichoderma strigosellum sp. nov. and other species

The diversity of Trichoderma (Hypocreales, Ascomycota) colonizing leaf litter as well as the rhizosphere of Garcinia macrophylla (Clusiaceae) was investigated in primary and secondary rain forests in Colombian Amazonia. DNA barcoding of 107 strains based on the internal transcribed spacers 1 and 2 (ITS1 and 2) of the ribosomal RNA gene cluster and the partial sequence of the translation elongation factor 1 alpha (tef1) gene revealed that the diversity of Trichoderma was dominated (71 %) by three common cosmopolitan species, namely Trichoderma harzianum sensu lato (41 %), Trichoderma spirale (17 %) and Trichoderma koningiopsis (13 %). Four ITS 1 and 2 phylotypes (13 strains) could not be identified with certainty. Multigene phylogenetic analysis and phenotype profiling of four strains with an ITS1 and 2 phylotype similar to Trichoderma strigosum revealed a new sister species of the latter that is described here as Trichoderma strigosellum sp. nov. Sequence similarity searches revealed that this species also occurs in soils of Malaysia and Cameroon, suggesting a pantropical distribution.Electronic supplementary materialThe online version of this article (doi:10.1007/s10482-013-9975-4) contains supplementary material, which is available to authorized users.

The colonisation of leaf litter by Chironomidae (Diptera): The influence of chemical quality and exposure duration in a subtropical stream

This study tested the hypothesis that the community composition of Chironomidae will change according to the duration of the exposure of plant leaves in a subtropical stream. In addition, we expected the chemical quality of the detritus to affect the association of Chironomidae with decaying plant materials. The chironomid colonisation of leaf litter from Campomanesia xanthocarpa and Sebastiania brasiliensis was assessed in a subtropical Atlantic forest stream. Litter bags containing leaves from these two species were incubated in the stream for 22 days. We identified 7245 invertebrates associated with the leaf detritus of both plant species (5110 were Chironomidae, 70.7% of the total). Thirteen genera of Chironomidae were identified, with Rheotanytarsus , Thienemanniella and Corynoneura the most abundant (94% of all Chironomidae collected). Chironomidae assemblages changed with the duration of incubation in the stream. The dissimilarity and the functional composition of the Chironomidae communities were related to the chemical composition of the detritus. The chemical components that best explained the composition of the fauna were tannins, the C:N ratio, calcium, and magnesium. However, the functional feeding groups were explained by the chemical variables organic matter and C:N. This study found that the exposure time of the detritus and therefore its level of degradation and chemical composition are important factors determining the characteristics of the Chironomidae assemblage in subtropical streams.