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In the context of climate change and global trend towards greenfield urbanisation, stormwater and transported pollutants are expected to increase, impairing receiving environments. Constructed floating wetlands (CFWs) can improve stormwater retention pond performance. However, performance data are currently largely restricted to mesocosm experiments, limiting design enhancement fit for field implementation. The present 12-month field study aims to fill part of these gaps by identifying limitations and necessary design improvements for CFWs on a large retention pond/lake. Water in a 2.6-ha lake receiving stormwater from a 45-ha urban area under development in subtropical Queensland, Australia, was recirculated during dry weather periods to minimise algal growth and the risks of blooms. Pollutant removal efficiencies of two full-scale CFWs were evaluated during storm events and dry weather periods as a function of inlet and outlet pollutant concentrations, flow and rainfall. Inlet TSS and TN concentrations in runoff during the construction phase of the development exceeded required water quality limits while TP inflow concentrations were low and often below the detection limit. Median pollutant load reduction efficiencies during storm-events were - 20 % TSS, -2 % TN and 22 % TP at CFW1 and 51 % TSS, 3 % TN and 17 % TP at CFW2, respectively. TSS and TN concentration removal efficiencies at CFW1 were low and highly variable, partly due to low inlet concentrations, high flow velocities and short hydraulic retention times (1 day). However, CFW1 significantly reduced TSS concentrations during dry weather periods. In contrast, CFW2 significantly reduced TSS concentrations during both storm events and during inter-event periods. This study highlights treatment limitations associated to the operational conditions of CFWs at field-scale not identifiable in a mesocosm-scale study. Further research is necessary to investigate treatment performance of CFWs during the operational phase of the development with higher nutrient levels.

Tropical peat swamp forests are waterlogged, acidic, anoxic and oligotrophic ecosystems. They are important terrestrial carbon pools that help mitigating global warming through carbon sequestration in peat. This study aimed at investigating putative roles of bacteria in the carbon and nitrogen cycles in North Selangor peat swamp forest, Malaysia. Whole-genome sequencing was performed on four bacterial isolates using Illumina NextSeq 500 to decipher their genetic information while Gen III Microplate (Biolog) was applied to verify carbon source utilization. The isolates were identified as Dyella sp. strain C9, Dyella sp. strain C11, Klebsiella sp. strain C31 and Paraburkholderia sp. strain C35. Both Dyella spp. and Paraburkholderia sp. strain C35 were likely novel species while Klebsiella sp. strain C31 was a different strain of the type species, Klebsiella pneumoniae. Both genomic and bioassay results suggested the involvement of the isolates in the degradation of lignocellulose, carbohydrates, sugar alcohols, organic acids and aromatic compounds. The isolates could potentially perform methanotrophy, which helps to mitigate methane emissions from tropical peatlands. In addition, the isolates also contained genes encoding enzymes for nitrite, nitrate and nitric oxide reduction, as well as dissimilatory nitrate reduction to ammonium, which retains the nitrogen in the ecosystems. The results generated insights into potential functions of bacteria in the energy production and nutrient cycling of tropical peatlands, which are essential for the sustainability of high biomass and biodiversity in these ecosystems.

A Gram-negative, filamentous aerobic bacterium designated as strain Mgbs1T was isolated on 12 April 2017 from the subsurface soil and leaf litter substrate at the base of a Koompassia malaccensis tree in a tropical peat swamp forest in the northern regions of the state of Selangor, Malaysia (3° 39′ 04.7′ N 101° 17′ 43.7′′ E). Phylogenetic analyses based on the full 16S rRNA sequence revealed that strain Mgbs1T belongs to the genus Chitinophaga with the greatest sequence similarity to Chitinophaga terrae KP01T (97.65 %), Chitinophaga jiangningensis DSM27406T (97.58 %), and Chitinophaga dinghuensis DHOC24T (97.17 %). The major fatty acids of strain Mgbs1T (>10 %) are iso-C15 : 0, C16 : 1 ω5c and iso-C17 : 0 3-OH while the predominant respiratory quinone is menaquinone-7. Strain Mgbs1T has a complete genome size of 8.03 Mb, with a G+C content of 48.5 mol%. The DNA–DNA hybridization (DDH) score between strain Mgbs1T and C. jiangningensis DSM27406T was 15.9 %, while in silico DDH values of strain Mgbs1T against C. dinghuensis DHOC24T and C. terrae KP01T were 20.0 and 19.10% respectively. Concurrently, Average Nucleotide Identity (ANI) scores between strain Mgbs1T against all three reference strains are 73.2 %. Based on the phenotypic, chemotaxonomic, and phylogenetic consensus, strain Mgbs1T represents a novel species of the genus Chitinophaga , for which the name Chitinophaga extrema sp. nov. is proposed (=DSM 108835T=JCM 33276T).

Microbes play a critical role in plant litter decomposition and influence the fate of carbon in rivers and riparian zones. When decomposing low-nutrient plant litter, microbes acquire nitrogen (N) and phosphorus (P) from the environment (i.e., nutrient immobilization), and this process is potentially sensitive to nutrient loading and changing climate. Nonetheless, environmental controls on immobilization are poorly understood because rates are also influenced by plant litter chemistry, which is coupled to the same environmental factors. Here we used a standardized, low-nutrient organic matter substrate (cotton strips) to quantify nutrient immobilization at 100 paired stream and riparian sites representing 11 biomes worldwide. Immobilization rates varied by three orders of magnitude, were greater in rivers than riparian zones, and were strongly correlated to decomposition rates. In rivers, P immobilization rates were controlled by surface water phosphate concentrations, but N immobilization rates were not related to inorganic N. The N:P of immobilized nutrients was tightly constrained to a molar ratio of 10:1 despite wide variation in surface water N:P. Immobilization rates were temperature-dependent in riparian zones but not related to temperature in rivers. However, in rivers nutrient supply ultimately controlled whether microbes could achieve the maximum expected decomposition rate at a given temperature. Collectively, we demonstrated that exogenous nutrient supply and immobilization are critical control points for decomposition of organic matter. Key Points • Nitrogen (N) and phosphorus (P) immobilization was measured on organic matter (cotton) in 100 rivers and riparian zones representing 11 biomes • Elevated temperature in riparian zones and phosphate in rivers increased immobilization, and consequently accelerated decomposition • N and P immobilization was strongly linked by microbial stoichiometry despite widely varied surface-water nutrient ratios Plain Language Summary Bacteria and fungi contribute to the breakdown of leaf litter in rivers and floodplains. To break down leaf litter, these microbes need the nutrients nitrogen and phosphorus (P), and microbes can get nutrients either from the leaf litter itself or from the environment. Most leaf litter has low nutrient content and microbes must rely on the environment to supply nutrients. We studied microbial nutrient uptake from the environment during litter breakdown to determine whether it varies predictably across the globe and how it is influenced by changing climate and nutrient pollution. In 100 rivers and floodplains in 11 of Earth's major biomes we placed small strips of cotton as stand-ins for leaf litter. Nutrient uptake was consistently greater on cotton strips that were submerged in the river compared to cotton on the floodplain. For microbes in the river, nutrient uptake was faster in instances where there was more P in the water. For microbes in the floodplain, nutrient uptake was faster where temperatures were warmer. Faster nutrient uptake by microbes was linked with faster cotton breakdown in rivers and floodplains. Our study shows that climate change and nutrient pollution can alter the activity of microbes in rivers and floodplains.

he relationship between detritivore diversity and decomposition can provide information on how biogeochemical cycles are affected by ongoing rates of extinction, but such evidence has come mostly from local studies and microcosm experiments. We conducted a globally distributed experiment (38 streams across 23 countries in 6 continents) using standardised methods to test the hypothesis that detritivore diversity enhances litter decomposition in streams, to establish the role of other characteristics of detritivore assemblages (abundance, biomass and body size), and to determine how patterns vary across realms, biomes and climates. We observed a positive relationship between diversity and decomposition, strongest in tropical areas, and a key role of abundance and biomass at higher latitudes. Our results suggest that litter decomposition might be altered by detritivore extinctions, particularly in tropical areas, where detritivore diversity is already relatively low and some environmental stressors particularly prevalent., This study was part of the DecoDiv project conducted by the GLoBE network (www.globenetwork.es), which is coordinated by L. B. Most research was based on crowdfunding (details on specific funding sources at each region are given in Supplementary Information). Project coordination was funded by Basque Government funds (Ref. IT951-16) to the Stream Ecology Group (UPV/EHU, Spain).

Plant litter functional diversity effects on instream decomposition change across latitudes., Running waters contribute substantially to global carbon fluxes through decomposition of terrestrial plant litter by aquatic microorganisms and detritivores. Diversity of this litter may influence instream decomposition globally in ways that are not yet understood. We investigated latitudinal differences in decomposition of litter mixtures of low and high functional diversity in 40 streams on 6 continents and spanning 113° of latitude. Despite important variability in our dataset, we found latitudinal differences in the effect of litter functional diversity on decomposition, which we explained as evolutionary adaptations of litter-consuming detritivores to resource availability. Specifically, a balanced diet effect appears to operate at lower latitudes versus a resource concentration effect at higher latitudes. The latitudinal pattern indicates that loss of plant functional diversity will have different consequences on carbon fluxes across the globe, with greater repercussions likely at low latitudes.

Antimicrobial resistance is a significant threat to the healthcare sector. For the past century, there has been a decline in the discovery of new antibiotics. This has urged researchers to bio-prospect for new bioactive agents from microbes originating from untapped environments, as well as to explore the potential of other microbial genera apart from the wellknown Streptomyces. Tropical peat swamp forests are an example of such an environment. Two novel antimicrobial-producing bacteria from the genera Burkholderia and Paenibacillus have been identified to produce potent antimicrobials. These two genera of bacteria have recently gained tremendous interest due to their genome complexity. They are known as multifaceted organisms not only because of their genetic content, but also due to their positive interactions with the environment along with a plethora of organisms including plants and animals. The interactions observed are attributed to their genomes and to their production of secondary metabolites including antimicrobials. Hence, this review provides an overview of the nature of tropical peat swamp forests, taxonomy and production of secondary metabolites of both Burkholderia and Paenibacillus, as well as discussing the future perspective of isolating antimicrobial-producing microbes from tropical peat swamp forests.

Southeast Asia is undergoing extensive conversion to oil palm (Elaeis guineensis) monocultures with fast growth expected in West Africa and South America. Despite rapid conversion rates, few tropical studies evaluate land-use change impacts on stream communities, with even fewer studies examining oil palm plantations (OP). In this pioneer study we compare macroinvertebrate community assemblages and their relationships with physico-chemical properties in OP streams bordered by different riparian buffer types to streams in a lowland dipterocarp forest in Sabah, Malaysian Borneo. Our study sites were in increasing levels of riparian disturbance (reduced vegetation density, diversity and structural complexity): (i) Native reference forested sites (NF); (ii) OP streams buffered with patches of natural forest (OPF); (iii) OP streams buffered with untreated oil palm (no chemical application at buffer sites; OPOP); and (iv) OP streams without buffer (OPNB). Macroinvertebrates were collected from leaf litter bags deployed with leaves of varying quality - native Macaranga tanarius and exotic oil palm, and retrieved after 14 days. We found that although invertebrates are typically influenced by resource quality, no differences were detected in their assemblages between the leaf species. All litter bags were dominated by collector-gatherers, with few shredding invertebrates, indicating that they were using the leaves as a habitat rather than a food source. We found no significant differences in macroinvertebrate abundance, richness and sensitive taxa richness (EPT) regardless of the rate of riparian disturbance. However, PERMANOVA showed significant differences between the macroinvertebrate community composition of heavily disturbed OPNB and pristine NF streams. Retaining high quality riparian buffers in OPF streams and lower quality understory in OPOP streams posed intermediate effects on macroinvertebrate community composition. The differences between sites were explained by the increase in nutrients, particularly potassium and phosphorus, stream water temperatures and erosion levels that negatively correlated with macroinvertebrate assemblages in oil palm streams. These findings support the use of riparian buffers in oil palm plantations to mitigate land conversion impacts on macroinvertebrate communities in tropical streams.

Urbanization is increasingly compromising lakes in the rapidly developing countries of tropical Southeast Asia. Greater understanding of the ecology of tropical lakes is essential in order to determine the best ways to protect and manage them. A comparison was made of the species richness, abundance and diets of Chironomidae in two forest lakes (both created by damming rivers - one in an urban forest reserve, one adjacent to an urban area) and two urban park lakes (ex- tin mine lakes) in Kuala Lumpur, Malaysia. 19 species of chironomids were recorded (10 collector-gatherers, one collector-filterer, one shredder, 3 predators and 4 predators/grazers). The most abundant species were Polypedilum leei, Tanytarsus formosanus, Zavreliella marmorata and Procladius sp.. Conductivity was highest in the urban park lakes due to pollution. Temperature was also highest in the urban park lakes due to lower riparian canopy cover and lower macrophyte abundance. Larval abundance (mostly collector-gathering Chironominae) was significantly higher in the forest lakes compared to the urban park lakes, which could be related to cleaner water and higher vegetation cover which provided more food resources (leaf litter and periphyton) and more microhabitats. Predatory tanypods were most abundant in forest lakes which also had the highest numbers of their prey (Chironominae). Four predatory species of Tanypodinae supplemented their diet with blue-green algae in two of the urban lakes. Only one collector-filterer (Corynoneura sp.) was recorded (only in the forest lakes).

Southeast Asia experiences frequent fires in fuel‐rich tropical peatlands, leading to extreme episodes of regional haze with high concentrations of fine particulate matter (PM2.5) impacting human health. In a study published recently, the first field measurements of PM2.5 emission factors for tropical peat fires showed larger emissions than from other fuel types. Here we report even higher PM2.5 emission factors, measured at newly ignited peat fires in Malaysia, suggesting that current estimates of fine particulate emissions from peat fires may be underestimated by a factor of 3 or more. In addition, we use both field and laboratory measurements of burning peat to provide the first mechanistic explanation for the high variability in PM2.5 emission factors, demonstrating that buildup of a surface ash layer causes the emissions of PM2.5 to decrease as the peat fire progresses. This finding implies that peat fires are more hazardous (in terms of aerosol emissions) when first ignited than when still burning many days later. Varying emission factors for PM2.5 also have implications for our ability to correctly model the climate and air quality impacts downwind of the peat fires. For modelers able to implement a time‐varying emission factor, we recommend an emission factor for PM2.5 from newly ignited tropical peat fires of 58 g of PM2.5 per kilogram of dry fuel consumed (g/kg), reducing exponentially at a rate of 9%/day. If the age of the fire is unknown or only a single value may be used, we recommend an average value of 24 g/kg., Key Points In this study we show that emissions of PM2.5 from Malaysian peat fires are likely 3 times larger than previously assumedWe show that the emissions of fine particulate matter from peat fires in the field decrease rapidly with the age of the fireWe show that the likely cause is the accumulation of an ash layer as the peat burns below the surface

Large-scale conversion of tropical forests into agricultural plantations, particularly oil palm (OP) across South East Asia exerts enormous pressure on freshwater systems. To mitigate impacts on aquatic ecosystems, the retention of riparian buffer zones along stream banks are often advocated for freshwater management. However, there is a severe lack in ecological information available on tropical stream systems advising on the efficacy of different riparian buffer types (with varying quality) to mitigate stream physico-chemical properties after conversion for agricultural use. To test the hypothesis that greater riparian disturbance will have negative effects on stream geomorphology and water quality, we assessed the impacts of riparian vegetation structure and density on stream chemical and physical properties in different riparian buffer types commonly used in OP plantations subjected to a gradient of disturbance: (i) Native forest (NF); (ii) OP – forested buffer (OPF); (iii) OP – untreated palms buffer (no fertilizer and pesticide application) (OPOP); and (iv) OP – treated palms (OPNB). Across the disturbance gradient, riparian species diversity and density decreased with taller trees and high foliage cover. Foliage cover heavily influenced the amount of light received at the stream, bank and buffer zone that concur with stream water temperatures. In-stream litter substrate decreased with increased riparian disturbance. OP streams had higher phosphorus and potassium concentrations that can be attributed to the use of fertilizers while sodium concentrations were higher in NF streams. Generally, OPF was most similar to NF sites whereas OPOP and OPNB sites had similar characteristics showing that riparian vegetation type influences the physical and chemical characteristics of streams. Thus, the use of high quality riparian buffers with forested riparian vegetation in OP plantations to reduce the impacts of land conversion on streams is supported.

Phenolic compounds are abundant in tropical peat swamp forests and peat mostly comprises lignin and other phenolics. Water in these forests is darkened by tannins and humic acids and the flora exhibit high total phenolic contents (TPC). To further understand the functions of phenolics in peat swamp forests we investigated phenolic compounds (Folin Ciocalteu assays, HPLC) in a common tree, Macaranga pruinosa (Euphorbiaceae), over 18 months. We simultaneously studied peat phenolics with respect to composition, depth and season. TPC were highest in mature leaves compared with trunks, branches and roots, probably relating to their role in defence against herbivory and pathogens in low nutrient environments. Relative concentrations of low (phenolic acids, flavonoids) to high (tannins, derivatives) molecular weight phenolics decreased as leaves matured indicating conversion within leaves. TPC increased significantly at the peat surface and during the wet seasons. TPC of mature leaves were significantly higher during the wet season. This implies either plants synthesise phenolic compounds in response to flooding or phenolics are more readily available during the wet season due to increased detrital leaching and plants can absorb phenolics via their roots. Waterlogged conditions may not be stressful to adapted plants but may facilitate recycling of protective phenolic compounds. © Forest Research Institute Malaysia.

Many stream invertebrates consume substantial amounts of plant litter at some time during their life cycle and thus play a key role in plant litter decomposition. These litter-consuming invertebrates include mainly shredders, a functional feeding group defined by their ability to shred litter, but also some scrapers, leaf miners, wood borers, and generalist consumers. This chapter describes methods to estimate invertebrate abundance and biomass in litter samples, and to identify litter-consuming invertebrates through gut content analysis. The latter involves gut dissection and mounting, and subsequent identification and quantification of different food items under a microscope. Additionally, the chapter provides an extensive list of litter-consuming invertebrate families recorded from different biogeographic regions with a particular focus on the tropics.

Hyperspectral image (HSI) analysis has the potential to estimate organic compounds in plants and foods. Curcumin is an important compound used to treat a range of medical conditions. Therefore, a method to rapidly determine rhizomes with high curcumin content on-farm would be of significant advantage for farmers. Curcumin content of rhizomes varies within, and between varieties but current chemical analysis methods are expensive and time consuming. This study compared curcumin in three turmeric (Curcuma longa) varieties and examined the potential for laboratory-based HSI to rapidly predict curcumin using the visible–near infrared (400–1000 nm) spectrum. Hyperspectral images (n = 152) of the fresh rhizome outer-skin and flesh were captured, using three local varieties (yellow, orange, and red). Distribution of curcuminoids and total curcumin was analysed. Partial least squares regression (PLSR) models were developed to predict total curcumin concentrations. Total curcumin and the proportion of three curcuminoids differed significantly among all varieties. Red turmeric had the highest total curcumin concentration (0.83 ± 0.21%) compared with orange (0.37 ± 0.12%) and yellow (0.02 ± 0.02%). PLSR models predicted curcumin using raw spectra of rhizome flesh and pooled data for all three varieties (R2c = 0.83, R2p = 0.55, ratio of prediction to deviation (RPD) = 1.51) and was slightly improved by using images of a single variety (orange) only (R2c = 0.85, R2p = 0.62, RPD = 1.65). However, prediction of curcumin using outer-skin of rhizomes was poor (R2c = 0.64, R2p = 0.37, RPD = 1.28). These models can discriminate between ‘low’ and ‘high’ values and so may be adapted into a two-level grading system. HSI has the potential to help identify turmeric rhizomes with high curcumin concentrations and allow for more efficient refinement into curcumin for medicinal purposes.

To understand the role of abiotic leaching in nutrient release within the nutrient-deficit tropical peat swamp forest (TPSF), an experiment was conducted over 30 days using leaf litter from two common emergent TPSF trees, Koompassia malaccensis and Shorea uliginosa. The main objectives were to determine leaf litter nutrient leaching dynamics, and the effect of water pH and potential microbial influence on nutrient release. Leaf litter (single species and combined) was subjected to 3 treatments: peat water (natural acidic conditions), poisoned peat water (NaN3 as microbial poison) and deionized water (control). Despite loss of nutrients from the leaves, this was not associated with the loss of mass or carbon (C) from the leaves because they are resistant to decomposition. Nutrient loss occurred in the order of phosphorus (P) > nitrogen (N) > C whereby litter P content was quickly exhausted. Microbial activity only affected the bioavailable P (PO4 −) whereby initial litter P release stimulated microbial growth, which resulted in the subsequent immobilization of P. Lastly, the effect of pH was not profound in this study. In conclusion, abiotic leaching from leaf litter releases considerable amounts of nutrients (notably PO4 3−) and functions as an important autochthonous nutrient source for the TPSF.

Sampling of aquatic macroinvertebrates requires techniques that are efficient and representative. Stratification of sampling units is a practical way of ensuring representative coverage of the habitat. However, efficiency of sampling devices used in the field and techniques for extraction of specimens from samples has rarely been assessed. Commonly used qualitative and quantitative samplers are described as well as the situations in which a particular device is most likely to be useful. The efficiency of these devices can be estimated using a technique known as removal sampling, whose underlying statistical theory is well understood. The laboratory examination of samples is straightforward but tedious. Flotation of specimens from inorganic material and subsampling are two methods of speeding up laboratory processing. Small cryptic species or small instars are easily obscured by detritus when picking specimens from samples under low magnification. By scanning samples twice the efficiency of extraction of specimens can be estimated.

Rapid and extensive conversion of tropical forests into oil palm (Elaeis guineensis) (OP) plantations pose serious threats to tropical stream processes. To mitigate land use change impacts on stream ecosystems, retention of riparian vegetation is typically proposed. We evaluated the effectiveness of a gradient of riparian qualities in oil palm streams: (1) natural forest; (2) OP-native forested buffer; (3) OP-native understory, no chemical input (OPOP) and (4) OP-no buffer, to mitigate impacts on in-stream litter processing. Leaf bag method entry using two leaf species of contrasting litter quality (Macaranga tanarius and OP) were deployed into streams. Across all riparian types, microbes were the main drivers of decomposition with negligible macroinvertebrate shredding activities. Leaf decomposition rates were more influenced by litter quality than changes in environmental conditions in the different riparian types. Across all sites, native Macaranga litter decomposed approximately 5× faster than OP litter possibly due to high structural compounds in OP leaves. Macaranga litter was also more susceptible to changes in environmental conditions as leaf decomposition positively correlated to phosphorus and potassium content. However, OP leaves were resilient to stream environmental changes and decomposed slower only at OPOP sites. These varying responses reveal complex interactions within tropical stream ecosystems. We suggest that riparian management strategies as well as plans to restore functioning in degraded tropical streams should ensure a wide diversity of native riparian tree species in order to effectively mitigate adverse OP plantation impacts on tropical stream functioning.

The bacterium Dyella sp. strain C9 was isolated from North Selangor Peat Swamp Forest, Malaysia, and studied using whole-genome sequencing., The bacterium Dyella sp. strain C9 was isolated from North Selangor Peat Swamp Forest, Malaysia, and studied using whole-genome sequencing. The putative genes involved in biogeochemical processes were annotated, and the genome sequence is publicly available in the NCBI database.

Tropical peatlands are globally important ecosystems with high C storage and are endangered by anthropogenic disturbances. Microbes in peatlands play an important role in sustaining the functions of peatlands as a C sink, yet their characteristics in these habitats are poorly understood. This research aimed to elucidate the responses of these complex ecosystems to disturbance by exploring greenhouse gas (GHG) emissions, nutrient contents, soil microbial communities and the functional interactions between these components in a primary and secondary peat swamp forest in Peninsular Malaysia. GHG measurements using closed chambers, and peat sampling were carried out in both wet and dry seasons. Microbial community phenotypes and nutrient content were determined using phospholipid fatty acid (PLFA) and inductively-coupled plasma mass spectrometry (ICP-MS) analyses respectively. CO2 emissions in the secondary peat swamp forest were > 50% higher than in the primary forest. CH4 emission rates were ca. 2 mg m−2 h−1 in the primary forest but the secondary forest was a CH4 sink, showing no seasonal variations in GHG emissions. Almost all the nutrient concentrations were significantly lower in the secondary forest, postulated to be due to nutrient leaching via drainage and higher rates of decomposition. Cu and Mo concentrations were negatively correlated with CO2 and CH4 emissions respectively. Microbial community structure was overwhelmingly dominated by bacteria in both forest types, however it was highly sensitive to land-use change and season. Gram-positive and Gram-negative relative abundance were positively correlated with CO2 and CH4 emissions respectively. Drainage related disturbances increased CO2 emissions, by reducing the nutrient content including some with known antimicrobial properties (Cu & Na) and by favouring Gram-positive bacteria over Gram-negative bacteria. These results suggest that the biogeochemistry of secondary peat swamp forest is fundamentally different from that of primary peat swamp forest, and these differences have significant functional impacts on their respective environments.

We report here the draft genome of Klebsiella sp. strain C31, a bacterial isolate from the North Selangor peat swamp forest in Malaysia. The putative genes for the biogeochemical processes of the genome were annotated and investigated.

We report the draft genome sequence of a bacterial isolate, Paraburkholderia sp. strain C35, which was isolated from a Malaysian tropical peat swamp forest. The putative genes for the biogeochemical processes were annotated and are publicly available in the online databases.

We report here the draft genome sequences of a bacterial isolate, Dyella sp. strain C11, which was isolated from a Malaysian tropical peat swamp forest. The putative genes for the biogeochemical processes were annotated, and the genome was deposited in an online database.

Many forested headwater streams are heterotrophic ecosystems in which allochthonous inputs of plant litter are a major source of energy. Leaves of riparian vegetation entering the stream are broken down by a combination of biotic and abiotic processes and, in most temperate and boreal streams, provide food and habitat for dense populations of detritivorous invertebrates. However, tropical streams in different parts of the world show substantial variability in the number and diversity of leaf-shredding detritivores (hereafter detritivores). We used data obtained with standardized methods from multiple streams in Africa, the Americas, Asia, and Australia to test the hypothesis that this variability would lead to differences in the relative role of detritivores and microorganisms in the breakdown process. We also tested the hypotheses that variability in litter breakdown rates changes with litter type (native litter mixtures vs nonnative alder [Alnus glutinosa]) and is higher across regions within th...

Breakdown of litter in streams is an important terrestrial–aquatic C pathway in forests. Macroinvertebrate detritivore shredders that feed on litter may be more abundant in temperate than tropical streams because the feeding guild is generally restricted to cool waters and because temperate streams may have more high-quality resources. However, rich shredder communities have been found in some high-altitude tropical streams. We investigated litter breakdown and the variation in resource quality of native riparian vegetation in tropical streams at different altitudes (86–3393 m) in eastern Malaysia (Borneo). At each stream, we collected 3 native local leaf species, analyzed their initial resource quality, and incubated them for 56 d in coarse- (shredder and microbial colonization) and fine- (only microbial colonization) mesh bags. We incubated Macaranga tanarius litter in all streams to compare breakdown rates directly. Shredder-mediated breakdown of native litter was detected in only 5 of 24 cases...

Urbanization is occurring rapidly in southeastern Asia where streams are increasingly pressured. We assessed the ecological integrity of Ampang River in Kuala Lumpur by comparing structural and functional measures between forested and urban sites. We assessed 4 forested, 1 intermediate (deforested, not channelized), and 5 urban, channelized sites. Urbanization altered substrate (concrete at urban sites), riparian vegetation, light, temperature, O2, conductivity, nutrients, and major ion levels, and simplified food webs. Invertebrate composition shifted from pollution-intolerant taxa at forested sites to tolerant taxa at urban sites. Richness in Surber samples was 56 species at forested sites and 27 taxa at urban sites. Basal food sources at forested sites were leaf litter and biofilm, whereas at urban sites they were a sediment mat comprising organic matter, cyanobacteria, iron bacteria, and algae. Organic matter biomass on ceramic tiles was greater at urban than forested sites, but chlorophyll a ...

The first International Peat Congress (IPC) held in the tropics – in Kuching (Malaysia) – brought together over 1000 international peatland scientists and industrial partners from across the world (“International Peat Congress with over 1000 participants!,” 2016). The congress covered all aspects of peatland ecosystems and their management, with a strong focus on the environmental, societal and economic challenges associated with contemporary large-scale agricultural conversion of tropical peat.

This study compared plant growth, nutrient partitioning and total nutrient uptake by tall sedge (Carex appressa) plants in large-scale Constructed Floating Wetlands (CFWs). Two CFWs with a total area of 2088 m2 were installed in a 2.6 ha man-made urban lake to treat stormwater runoff during the construction phase of a 45-ha residential development. After 12 months of operation, parts of the CFWs, with a total area of 147 m2, were removed from the urban lake and relocated into a well-established 0.127-ha stormwater retention pond at another site. Biomass and nutrient concentrations of C. appressa shoots above the floating mat and roots below the mat were analysed at both sites 12, 16 and 25 months after initial planting. Plants at the urban lake maintained an extensive root network but there was no increase in total plant biomass at 16 and 25 months after planting. In contrast, the relocated plants in the stormwater pond showed extensive shoot growth but a significant decline in root biomass. C. appressa at the urban lake removed and sequestered 1.00 ± 1.04 g m−2 N, 0.11 ± 0.07 g m−2 P and 1.03 ± 0.81 g m−2 K while plants at the pond removed 11.20 ± 2.29 g m−2 N, 1.37 ± 0.26 g m−2 P and 16.13 ± 2.88 g m−2 K during 12 and 25 months after planting. This study demonstrated that C. appressa adapted rapidly to changes in nutrient availability. The implications are interesting as nutrient levels can be low in constructed lakes during the initial phase of urban developments but can increase rapidly as the development progresses. The study demonstrated multiple benefits of CFWs for stormwater treatment during the early construction stages of an urban development and the potential benefits of relocating and establishing CFWs in existing stormwater retention ponds and lakes.

This study shows that two emergent tree species growing in a nutrient-limited tropical peat swamp forest use different mechanisms for nutrient regulation. The main aim of this study is to understand the contribution of litterfall to nutrient supply and regulation of two emergent tree species in a tropical peat swamp forest (TPSF) in Peninsular Malaysia. The questions posed by this study include: (1) Do coexisting tree species in TPSF differ in terms of litter production, physico-chemical traits and litterfall patterns? (2) How do these relate to possible nutrient regulation mechanisms of the tree species and do the strategies involved differ between a nitrogen (N) fixing legume (Koompassia malaccensis, Family Fabaceae) and a dipterocarp (Shorea uliginosa, Family Dipterocarpaceae)? (3) Is litterfall timing of the selected tree species driven by climatic variables? Litterfall was collected from litter traps placed under the selected trees in the Sungai Karang TPSF. Green leaves of the selected tree species were also collected. Both leaf litter and green leaves were assessed for their physico-chemical properties (toughness, total phenols, total tannins, proximate fibre–cellulose–lignin and a range of nutrients) and compared. Results obtained indicate that K. malaccensis relies on a combination of high litter quality (higher N coupled with lower amount of tannins, fibre and cellulose) and low annual litterfall mass (388.17 g m−2) for nutrient regulation while the opposite strategy is used by S. uliginosa, which was found to produce an annual litterfall mass of 918.14 g m−2. Due to the aseasonal environment, no significant relationships were observed between climatic variables and litterfall. Therefore, litterfall characteristics in aseasonal tropical regions may depend more on species-specific physico-chemical properties than on climatic variables.

Plant litter represents a major basal resource in streams, where its decomposition is partly regulated by litter traits. Litter-trait variation may determine the latitudinal gradient in decomposition in streams, which is mainly microbial in the tropics and detritivore-mediated at high latitudes. However, this hypothesis remains untested, as we lack information on large-scale trait variation for riparian litter. Variation cannot easily be inferred from existing leaf-trait databases, since nutrient resorption can cause traits of litter and green leaves to diverge. Here we present the first global-scale assessment of riparian litter quality by determining latitudinal variation (spanning 107°) in litter traits (nutrient

A novel Gram negative rod-shaped bacterium, designated strain MSh1T, was isolated from Southeast Pahang tropical peat swamp forest soil in Malaysia and characterized using a polyphasic taxonomy approach. The predominant cellular fatty acids (>10.0%) were C16:0 (31.7%), C17:0 cyclo (26.6%) and C19:0 cyclo w8c (16.1%). The polar lipids detected were phosphatidylglycerol, phosphatidylethanolamine and diphosphatidylglycerol. The predominant ubiquinone was Q-8. This revealed that strain MSh1T belongs to the genus Burkholderia. The type strain MSh1T can be differentiated from other Burkholderia cepacia complex (Bcc) species by phylogenetic analysis of 16S rRNA gene sequence, multilocus sequence analysis (MLSA), average nucleotide identity (ANI) and biochemical tests. DNA-DNA relatedness values between strain MSh1T and closely related type strains were below the 70% threshold value. Based on this polyphasic study of MSh1T, it can be concluded that this strain represents a novel species within the Bcc, for which the name Burkholderia paludis sp. nov. is proposed. The type strain is MSh1T (=DSM 100703T =MCCC 1K01245T). The dichloromethane extract of MSh1T exhibited antimicrobial activity against four Gram positive bacteria (Enterococcus faecalis ATCC 29212, Enterococcus faecalis ATCC 700802, Staphylococcus aureus ATCC 29213, Staphylococcus aureus ATCC 700699) and a Gram negative bacteria (Escherichia coli ATCC 25922). Further purification work has led to the isolation of Compound 1, pyochelin. Pyochelin demonstrated antimicrobial activity against four S. aureus strains and three E. faecalis strains with MIC values of 1.57 µg/ml and 3.13 µg/ml respectively. SEM analysis showed that the cellular morphology of E. faecalis ATCC 700802 was not affected by pyochelin; suggesting that it might target the intracellular components. Pyochelin, a siderophore with antimicrobial activity might be useful in treating bacterial infections caused by S. aureus and E. faecalis, however further work has to be done.

Plant litter breakdown is a key ecological process in terrestrial and freshwater ecosystems. Streams and rivers, in particular, contribute substantially to global carbon fluxes. However, there is little information available on the relative roles of different drivers of plant litter breakdown in fresh waters, particularly at large scales. We present a global-scale study of litter breakdown in streams to compare the roles of biotic, climatic and other environmental factors on breakdown rates. We conducted an experiment in 24 streams encompassing latitudes from 47.8° N to 42.8° S, using litter mixtures of local species differing in quality and phylogenetic diversity (PD), and alder ( Alnus glutinosa ) to control for variation in litter traits. Our models revealed that breakdown of alder was driven by climate, with some influence of pH, whereas variation in breakdown of litter mixtures was explained mainly by litter quality and PD. Effects of litter quality and PD and stream pH were more positive at higher temperatures, indicating that different mechanisms may operate at different latitudes. These results reflect global variability caused by multiple factors, but unexplained variance points to the need for expanded global-scale comparisons.

Pristine tropical peat swamp forests (PSFs) represent a unique wetland ecosystem of distinctive hydrology which support unique biodiversity and globally significant stores of soil carbon. Yet in Indonesia and Malaysia, home to 56% of the world's tropical peatland, they are subject to considerable developmental pressures, including widespread drainage to support agricultural needs. In this article, we review the ecology behind the functioning and ecosystem services provided by PSFs, with a particular focus on hydrological processes as well as the role of the forest itself in maintaining those services. Drawing on this, we review the suitability of current policy frameworks and consider the efficacy of their implementation. We suggest that policies in Malaysia and Indonesia are often based around the narrative of oil palm and other major monocrops as drivers of prosperity and development. However, we also argue that this narrative is also being supported by a priori claims concerning the possibility of sustainability of peat swamp exploitation via drainage-based agriculture through the adherence to best management practices. We discuss how this limits their efficacy, uptake and the political will towards enforcement. Further, we consider how both narratives (prosperity and sustainability) clearly exclude important considerations concerning the ecosystem value of tropical PSFs which are dependent on their unimpacted hydrology. Current research clearly shows that the actual debate should be focused not on how to develop drainage-based plantations sustainably, but on whether the sustainable conversion to drainage-based systems is possible at all.

Indo-Malaysian tropical peat swamp forests (PSF) sequester enormous stores of carbon in the form of phenolic compounds, particularly lignin as well as tannins. These phenolic compounds are crucial for ecosystem functioning in PSF through their inter-related roles in peat formation and plant defenses. Disturbance of PSF causes destruction of the peat substrate, but the specific impact of disturbance on phenolic compounds in peat and its associated vegetation has not previously been examined. A scale was developed to score peatland degradation based on the three major human impacts that affect tropical PSF—logging, drainage, and fire. The objectives of this study were to compare the amount of phenolic compounds in Macaranga pruinosa, a common PSF tree, and in the peat substrate along a gradient of peatland degradation from pristine peat swamp forest to cleared, drained, and burnt peatlands. We examined phenolic compounds in M. pruinosa and in peat and found that levels of total phenolic compounds and total tannins decrease in the leaves of M.pruinosa and also in the surface peat layers with an increase in peatland degradation. We conclude that waterlogged conditions preserve the concentration of phenolic compounds in peat, and that even PSF that has been previously logged but which has recovered a full canopy cover will have high levels of total phenolic content (TPC) in peat. High levels of TPC in peat and in the flora are vital for the inhibition of decomposition of organic matter and this is crucial for the accretion of peat and the sequestration of carbon. Thus regional PSF flourish despite the phenolic rich, toxic, waterlogged, nutrient poor, conditions, and reversal of such conditions is a sign of degradation.

We report here the first high-quality draft genome sequence of Pasteurella multocida sequence type 128, which was isolated from the infected finger bone of an adult female who was bitten by a domestic dog. The draft genome will be a valuable addition to the scarce genomic resources available for P. multocida .

Aim. We tested the hypothesis that shredder detritivores, a key trophic guild in stream ecosystems, are more diverse at higher latitudes, which has important ecological implications in the face of potential biodiversity losses that are expected as a result of climate change. We also explored the dependence of local shredder diversity on the regional species pool across latitudes, and examined the influence of environ- mental factors on shredder diversity. Location: World-wide (156 sites from 17 regions located in all inhabited continents at latitudes ranging from 67° N to 41° S). Methods: We used linear regression to examine the latitudinal variation in shredder diversity at different spatial scales: alpha (a), gamma (g) and beta (b) diversity. We also explored the effect of g-diversity on a-diversity across latitudes with regression analysis, and the possible influence of local environmental factors on shredder diversity with simple correlations. Results: Alpha diversity increased with latitude, while g- and b-diversity showed no clear latitudinal pattern. Temperate sites showed a linear relationship between g- and a-diversity; in contrast, tropical sites showed evidence of local species saturation, which may explain why the latitudinal gradient in a-diversity is not accompanied by a gradient in g-diversity. Alpha diversity was related to several local habitat characteristics, but g- and b-diversity were not related to any of the environmental factors measured. Main conclusions: Our results indicate that global patterns of shredder diversity are complex and depend on spatial scale. However, we can draw several conclusions that have important ecological implications. Alpha diversity is limited at tropical sites by local factors, implying a higher risk of loss of key species or the whole shredder guild (the latter implying the loss of trophic diversity). Even if regional species pools are not particularly species poor in the tropics, colonization from adjacent sites may be limited. Moreover, many shredder species belong to cool-adapted taxa that may be close to their thermal maxima in the tropics, which makes them more vulnerable to climate warming. Our results suggest that tropical streams require specific scientific attention and conservation efforts to prevent loss of shredder biodiversity and serious alteration of ecosystem processes.

The decomposition of plant litter is one of the most important ecosystem processes in the biosphere and is particularly sensitive to climate warming. Aquatic ecosystems are well suited to studying warming effects on decomposition because the otherwise confounding influence of moisture is constant. By using a latitudinal temperature gradient in an unprecedented global experiment in streams, we found that climate warming will likely hasten microbial litter decomposition and produce an equivalent decline in detritivore-mediated decomposition rates. As a result, overall decomposition rates should remain unchanged. Nevertheless, the process would be profoundly altered, because the shift in importance from detritivores to microbes in warm climates would likely increase CO2 production and decrease the generation and sequestration of recalcitrant organic particles. In view of recent estimates showing that inland waters are a significant component of the global carbon cycle, this implies consequences for global biogeochemistry and a possible positive climate feedback.

Stream shredders have been reported as scarce in several tropical areas. This pattern is in contrast to observations in temperate streams, which support an abundant and diverse shredder fauna. Two possible explanations for this pattern are that most shredders are adapted to cool conditions and that temperate riparian vegetation often produces more palatable and more nutritious leaves than do the more diverse, tropical rainforests. In peninsular Malaysia, most streams flow through lowland dipterocarp forests that are characterized by strikingly high tree diversity and by many species with tough leathery leaves that are high in lignin and toxic secondary compounds and low in protein. In contrast, highland streams flow through montane rain forests and are more similar to temperate streams. We hypothesized that shredder fauna would be distributed along an altitudinal gradient, with more abundant and diverse assemblages in highland streams. We sampled leaf litter in 12 sites at altitudes from 55 to 156...

The methanolic fresh leaf extracts of Macaranga gigantea, Macaranga pruinosa, Macaranga tanarius and Macaranga triloba were screened for their antioxidant properties (AOP), tyrosinase inhibition and antibacterial activities. Total phenolic content (TPC), 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging, ferric-ion reducing power (FRAP), ferrous-ion chelating (FIC) and lipid peroxidation inhibition (LPI) activities were used to evaluate the AOP. Modified 3,4-dihydroxy- L -phenylalanine ( L -DOPA) method was used to determine tyrosinase inhibition activity, whereas antibacterial activity was determined using the disc-diffusion technique. TPC screening of the same species from different collection sites showed no significant difference between sites. M. triloba showed the highest ascorbic acid equivalent antioxidant activity (AEAC), FRAP and LPI values. M. tanarius, which showed the lowest TPC, AEAC, FRAP and LPI activities, exhibited the best FIC activity. M. pruinosa showed the best tyrosinase inhibition activity, whereas M. triloba showed the best antibacterial activity against Gram-positive bacteria species, with minimal inhibition dosage (MID) values as low as 10 μg/disc.

The tropical peat swamp forests of Indonesia and Malaysia are unusual ecosystems that are rich in endemic species of flora, fauna and microbes despite their extreme acidic, anaerobic, nutrient poor conditions. They are an important refuge for many endangered species including orang utans. Ecosystem functioning is unusual: microbial decomposition is inhibited because the leaves are sclerophyllous and toxic to deter herbivory in the nutrient poor environment, yet bacteria are abundant and active in the surface layers of the peat, where they respire DOC leached from newly fallen leaves. The bacteria are subsequently consumed by aquatic invertebrates that are eaten by fish, and bacterially respired CO2 is assimilated by algae, so bacteria are thus vital to carbon and nutrient cycling. Peat swamp forests are highly sensitive to the impacts of logging, drainage and fire, due to the interdependence of the vegetation with the peat substrate, which relies on the maintenance of adequate water, canopy cover and leaf litter inputs. Even minor disturbances can increase the likelihood of fire, which is the major cause of CO2 emissions from regional peat swamp forests and which impact ecosystems worldwide by contributing to climate change. Indo-Malayan peat swamps affect the hydrology of surrounding ecosystems due to their large water storage capacity which slows the passage of floodwaters in wet seasons and maintains stream base flows during dry seasons. These forests are of global importance yet they are inadequately protected and vanishing rapidly, particularly due to agricultural conversion to oil palm, logging, drainage and annual fires.