Project description:Gross primary production (GPP) is a fundamental ecosystem process that sequesters carbon dioxide (CO2) and forms the resource base for higher trophic levels. Still, the relative contribution of different controls on GPP at the whole-ecosystem scale is far from resolved. Here we show, by manipulating CO2 concentrations in large-scale experimental pond ecosystems, that CO2 availability is a key driver of whole-ecosystem GPP. This result suggests we need to reformulate past conceptual models describing controls of lake ecosystem productivity and include our findings when developing models used to predict future lake ecosystem responses to environmental change.
Project description:A new species, Achnanthidiumbratanense, is described from Lake Bratan, located on the island of Bali (Indonesia). The morphology of this species was analyzed with light (LM) and scanning electron microscopy (SEM). A.bratanense is characterized by linear-elliptic to nearly elliptic valves with convex margins and rounded, broadly subcapitate apices. The striae of this species are hardly discernable under LM; they are weakly radiate throughout the valve and composed of one to four large transapically elongated areolae of different length and shape. The most similar taxon to A.bratanense is A.macrocephalum, a species described from Sumatra, another Indonesian island. The differences of A.bratanense from similar taxa are discussed.
Project description:A significant proportion of carbon (C) captured by terrestrial primary production is buried in lacustrine ecosystems, which have been substantially affected by anthropogenic activities globally. However, there is a scarcity of sedimentary organic carbon (OC) accumulation information for lakes surrounded by highly productive rainforests at warm tropical latitudes, or in response to land cover and climate change. Here, we combine new data from intensive campaigns spanning 13 lakes across remote Amazonian regions with a broad literature compilation, to produce the first spatially-weighted global analysis of recent OC burial in lakes (over ~50-100-years) that integrates both biome type and forest cover. We find that humid tropical forest lake sediments are a disproportionately important global OC sink of ~80 Tg C yr-1 with implications for climate change. Further, we demonstrate that temperature and forest conservation are key factors in maintaining massive organic carbon pools in tropical lacustrine sediments.
Project description:Microorganisms catalyze carbon cycling and biogeochemical reactions in the deep subsurface and thus may be expected to influence the fate of injected supercritical (sc) CO2 following geological carbon sequestration (GCS). We hypothesized that natural subsurface scCO2 reservoirs, which serve as analogs for the long-term fate of sequestered scCO2 , harbor a 'deep carbonated biosphere' with carbon cycling potential. We sampled subsurface fluids from scCO2 -water separators at a natural scCO2 reservoir at McElmo Dome, Colorado for analysis of 16S rRNA gene diversity and metagenome content. Sequence annotations indicated dominance of Sulfurospirillum, Rhizobium, Desulfovibrio and four members of the Clostridiales family. Genomes extracted from metagenomes using homology and compositional approaches revealed diverse mechanisms for growth and nutrient cycling, including pathways for CO2 and N2 fixation, anaerobic respiration, sulfur oxidation, fermentation and potential for metabolic syntrophy. Differences in biogeochemical potential between two production well communities were consistent with differences in fluid chemical profiles, suggesting a potential link between microbial activity and geochemistry. The existence of a microbial ecosystem associated with the McElmo Dome scCO2 reservoir indicates that potential impacts of the deep biosphere on CO2 fate and transport should be taken into consideration as a component of GCS planning and modelling.
Project description:Background:Dengue, an acute febrile illness caused by infection with dengue virus (DENV), is endemic in Bali, Indonesia. As one of the world's most popular tourist destinations, Bali is regularly visited by domestic and international travellers, who are prone to infection by endemic pathogens, including DENV. Currently, limited data are available on the characteristics of dengue in travellers visiting Bali. Information on the epidemiology and virological aspects of dengue in these tourists is important to gain a better understanding of the dengue disease in international travellers. Methods:We performed a prospective cross-sectional dengue study involving foreign travellers visiting Bali, Indonesia in the period of 2015-17. Patients presenting at Kasih Ibu Hospital with fever and clinical symptoms of dengue were asked to participate in the study. Clinical and laboratory assessments were performed and sera were collected for molecular analysis, which included DENV serotyping, genome sequencing and phylogenetic analysis. Results:Among the 201 patients recruited, dengue was confirmed in 133 (66.2%) of them, based on detection of NS1 antigen and/or viral RNA. Of these, 115 (86.5%) manifested dengue fever (DF) and 18 (13.5%) dengue haemorrhagic fever (DHF). The temporal predominance of infecting DENV serotype was DENV-2 (48.7%), followed by DENV-3 (36.1%), DENV-1 (9.2%) and DENV-4 (3.4%). Phylogenetic analysis of DENV based on envelope gene sequences revealed that the source of DENVs was local endemic viruses. Conclusion:Our study confirms that dengue is one of the causes of fever in travellers visiting Bali. Although it is a cause of significant morbidity, the majority of patients only experienced mild DF, with only a small proportion developing DHF. We revealed that DENVs isolated were autochthonous. Accurate diagnosis, preventive measures and continuous disease surveillance will be useful for better management of dengue infection in travellers.
Project description:Background:Chikungunya virus (CHIKV) infections have been reported sporadically within the last 5 years in several areas of Indonesia including Bali. Most of the reports, however, have lacked laboratory confirmation. Method:A recent fever outbreak in a village in the North Bali area was investigated using extensive viral diagnostic testing including both molecular and serological approaches. Results and conclusions:Ten out of 15 acute febrile illness samples were confirmed to have CHIKV infection by real-time PCR or CHIKV-specific IgM enzyme-linked immunosorbent assay (ELISA). The outbreak strain belonged to the Asian genotype with highest homology to other CHIKV strains currently circulating in Indonesia. The results are of public health concern particularly because Bali is a popular tourist destination in Indonesia and thereby the potential to spread the virus to non-endemic areas is high. GenBank accession numbers:KY885022, KY885023, KY885024, KY885025, KY885026, KY885027.
Project description:Streptococcus suis is an emerging agent of zoonotic bacterial meningitis in Asia. We describe the epidemiology of S. suis cases and clinical signs and microbiological findings in persons with meningitis in Bali, Indonesia, using patient data and bacterial cultures of cerebrospinal fluid collected during 2014-2017. We conducted microbiological assays using the fully automatic VITEK 2 COMPACT system. We amplified and sequenced gene fragments of glutamate dehydrogenase and recombination/repair protein and conducted PCR serotyping to confirm some serotypes. Of 71 cases, 44 were confirmed as S. suis; 29 isolates were serotype 2. The average patient age was 48.1 years, and 89% of patients were male. Seventy-seven percent of patients with confirmed cases recovered without complications; 11% recovered with septic shock, 7% with deafness, and 2% with deafness and arthritis. The case-fatality rate was 11%. Awareness of S. suis infection risk must be increased in health promotion activities in Bali.
Project description:Samples from three stations in Kranji Reservoir, Singapore (n = 21) were collected and analyzed for cyanomyovirus abundance and diversity. A total of 73 different g20 (viral capsid assembly protein genes) amino acid sequences were obtained from this study. A phylogenetic analysis revealed that the 73 segments were distributed in six major clusters (? to ?), with four unique subclusters, which were identified as KRM-I, KRM-II, KRM-III, and KRM-IV. The cyanophage community in Kranji Reservoir exhibited a large degree of diversity; the clones obtained in this study showed similarities to those from many different environments, including oceans, lakes, bays, and paddy floodwater, as well as clones from paddy field soils. However, the sequences in this study were generally found to be more closely related to the g20 sequences of freshwaters and brackish waters than those from marine environments. The rarefaction curves and Chao 1 indices from this study showed that the diversity of the cyanomyovirus community was greater during the Inter-monsoon periods than the Southwest and Northeast Monsoons. A few seasonal changes in the taxa were observed: (i) Cluster ? was absent during the Southwest Monsoon, and (ii) most of the samples fell into Group 3 in the PCA score plot during the Northeast Monsoon, and the fraction of Cluster ? increased significantly.
Project description:In Southeast Asia, primary tropical rainforests are usually dominated by ectomycorrhizal (ECM) trees belonging to Dipterocarpaceae, although arbuscular mycorrhizal trees often outcompete them after disturbances such as forest fires and clear-cutting, thus preventing dipterocarp regeneration. In some secondary tropical forests, however, potentially ECM trees belonging to Tristaniopsis (Myrtaceae) become dominant and may help ECM dipterocarp forests to recover. However, we have no information about their mycorrhizal status in these settings. In this study, we analyzed ECM fungal communities in tropical secondary forests dominated by Tristaniopsis and investigated which ECM fungal species are shared with other tropical or temperate areas. In total, 100 samples were collected from four secondary forests dominated by Tristaniopsis on Bangka Island. ECM tips in the soil samples were subjected to molecular analyses to identify both ECM and host species. Based on a >97% ITS sequence similarity threshold, we identified 56 ECM fungal species dominated by Thelephoraceae, Russulaceae, and Clavulinaceae. Some of the ECM fungal species were shared between dominant Tristaniopsis and coexisting Eucalyptus or Quercus trees, including 5 common to ECM fungi recorded in a primary mixed dipterocarp forest at Lambir Hill, Malaysia. In contrast, no ECM fungal species were shared with other geographical regions, even with Tristaniopsis in New Caledonia. These results imply that secondary tropical forests dominated by Tristaniopsis harbor diverse ECM fungi, including those that inhabit primary dipterocarp forests in the same geographical region. They may function as refugia for ECM fungi, given that dipterocarp forests are disappearing quickly due to human activity.
Project description:Despite the pandemic's negative effect on the economy, it can help reduce emissions from energy consumption activities in line with the Paris Agreement, especially for high-emitter countries such as Indonesia. However, the policy response to COVID-19 may rebound the emissions to their pre-pandemic levels. To design an efficient policy that considers both economic and environmental variables, this study uses a computable general equilibrium model that assesses how COVID-19 and its stimulus policy will affect the macroeconomic indicator, energy consumption, and emissions at the national and regional levels. The results show that macroeconomic indicators generally performed worse with the current stimulus policy in the short run than in the long run. Refined petroleum energy consumption took the highest hit, followed by coal-based energy consumption and overall electricity demand. The pattern in emissions reduction is similar to the pattern of gross domestic product declination as well. The Sulawesi region particularly experienced the largest decrease in refined petroleum energy consumption. In contrast, the Java-Bali and Sumatra regions experienced the most coal-based energy consumption reduction and the largest emissions reduction. Should COVID-19 provide the impetus to develop more environmentally sound economic development, we would need better policy to address the recovery. Returning to pre-pandemic development will not lead to long-term environmental gain. This study offers policy recommendations for economic recovery and environmental improvement. The government should promote low-carbon technology, clean energy transition, more energy efficiency, and sustainable development to avoid the rebound effect of energy consumption and carbon emission. Coordination between central and local governments is also needed to formulate a fiscal policy inclined toward low-carbon pathways.