The present study aims to define the possible sources that contribute to the level of Pb into the Brunei Bay, Borneo. The cluster analysis has classified the bay into the northern part with heavy and agriculture-related industries; the southern area with a moderate rural human settlement as well as the southwestern area with a more pristine environment and a low level of human settlement. The score plot of spatial discriminant analysis verified a significant influence of the river system toward the estuary, whereas the temporal discriminant analysis has discriminated the seasonal changes. In comparison to elsewhere, the stable Pb isotopic ratios in Brunei Bay showed a fingerprint similar to coal-related sources and of aerosol input. Briefly, even though Pb in the Brunei Bay ecosystem proved to be at a low level, the stable Pb isotopic ratios showed that human and industrial activities are slowly contributing Pb into the bay ecosystem.
Unsustainable exploitation of natural resources is increasingly affecting the highly biodiverse tropics [1, 2]. Although rapid developments in remote sensing technology have permitted more precise estimates of land-cover change over large spatial scales [3-5], our knowledge about the effects of these changes on wildlife is much more sparse [6, 7]. Here we use field survey data, predictive density distribution modeling, and remote sensing to investigate the impact of resource use and land-use changes on the density distribution of Bornean orangutans (Pongo pygmaeus). Our models indicate that between 1999 and 2015, half of the orangutan population was affected by logging, deforestation, or industrialized plantations. Although land clearance caused the most dramatic rates of decline, it accounted for only a small proportion of the total loss. A much larger number of orangutans were lost in selectively logged and primary forests, where rates of decline were less precipitous, but where far more orangutans are found. This suggests that further drivers, independent of land-use change, contribute to orangutan loss. This finding is consistent with studies reporting hunting as a major cause in orangutan decline [8-10]. Our predictions of orangutan abundance loss across Borneo suggest that the population decreased by more than 100,000 individuals, corroborating recent estimates of decline [11]. Practical solutions to prevent future orangutan decline can only be realized by addressing its complex causes in a holistic manner across political and societal sectors, such as in land-use planning, resource exploitation, infrastructure development, and education, and by increasing long-term sustainability [12]. VIDEO ABSTRACT.
The medicinal plant, Syzygium leucoxylon or commonly known as Obah found in North Borneo was considered as traditional medicine by local committee. Two new phenolics, leucoxenols A (1) and B (2) were isolated and identified as major secondary metabolites from the leaves of S. leucoxylon. Their chemical structures were elucidated based on spectroscopic data such as NMR and HRESIMS. Furthermore, these compounds were active against selected strains of fungi.
Telosticta fugispinosa sp. nov. (holotype male, from Borneo, Sabah, West Coast division, Crocker Range National Park, Inobong, Kimamabang waterfall stream system, 21 ix 2012, deposited in RMNH) is described from Kinabalu National Park and Crocker Range National Park in Sabah, Malaysian Borneo. It is distinguished from all other species of Telosticta by the form of the male anal appendages.
The demersal brown banded bamboo shark Chiloscyllium punctatum is a major component of sharks landed in Malaysia. However, little is known about their population structure and the effect of high fishing pressure on these weak swimming sharks. Both mitochondrial DNA control region (1072 bp) and NADH dehydrogenase subunit 2 (1044 bp) were used to elucidate the genetic structure and connectivity of C. punctatum among five major areas within the Sundaland region. Our findings revealed (i) strong genetic structure with little present day mixing between the major areas, (ii) high intra-population genetic diversity with unique haplotypes, (iii) significant correlation between genetic differentiation and geographical distance coupled with detectable presence of fine scale geographical barriers (i.e. the South China Sea), (iv) historical directional gene flow from the east coast of Peninsular Malaysia towards the west coast and Borneo, and (v) no detectable genetic differentiation along the coastline of east Peninsular Malaysia. Genetic patterns inferred from the mitochondrial DNA loci were consistent with the strong coastal shelf association in this species, the presence of contemporary barriers shaped by benthic features, and limited current-driven egg dispersal. Fine scale population structure of C. punctatum highlights the need to improve genetic understanding for fishery management and conservation of other small-sized sharks.
Plasmodium knowlesi is the main cause of malaria in Sarawak, where studies on vectors of P. knowlesi have been conducted in only two districts. Anopheles balabacensis and An. donaldi were incriminated as vectors in Lawas and An. latens in Kapit. We studied a third location in Sarawak, Betong, where of 2169 mosquitoes collected over 36 days using human-landing catches, 169 (7.8%) were Anopheles spp. PCR and phylogenetic analyses identified P. knowlesi and/or P. cynomolgi, P. fieldi, P. inui, P. coatneyi and possibly novel Plasmodium spp. in salivary glands of An. latens and An. introlatus from the Leucosphyrus Group and in An. collessi and An. roperi from the Umbrosus Group. Phylogenetic analyses of cytochrome oxidase subunit I sequences indicated three P. knowlesi-positive An. introlatus had been misidentified morphologically as An. latens, while An. collessi and An. roperi could not be delineated using the region sequenced. Almost all vectors from the Leucosphyrus Group were biting after 1800 h but those belonging to the Umbrosus Group were also biting between 0700 and 1100 h. Our study incriminated new vectors of knowlesi malaria in Sarawak and underscores the importance of including entomological studies during the daytime to obtain a comprehensive understanding of the transmission dynamics of malaria.
This is a preliminary report of 46 sera tested for alpha-fetoprotein (AFP) by the Counter immuno-electrophoresis technique in which biopsies for histopathology were also submitted. In 42 cases the needle biopsy of the liver was available. The material was divided into two groups on the basis of AFP positive and AFP negative sera and their histological diagnosis. The overall positivity rate in proven Primary liver cell carcinoma was 64.2 per cent.
Tropical forest ecosystems are facing unprecedented levels of degradation, severely compromising habitat suitability for wildlife. Despite the fundamental role biodiversity plays in forest regeneration, identifying and prioritizing degraded forests for restoration or conservation, based on their wildlife value, remains a significant challenge. Efforts to characterize habitat selection are also weakened by simple classifications of human-modified tropical forests as intact vs. degraded, which ignore the influence that three-dimensional (3D) forest structure may have on species distributions. Here, we develop a framework to identify conservation and restoration opportunities across logged forests in Borneo. We couple high-resolution airborne light detection and ranging (LiDAR) and camera trap data to characterize the response of a tropical mammal community to changes in 3D forest structure across a degradation gradient. Mammals were most responsive to covariates that accounted explicitly for the vertical and horizontal characteristics of the forest and actively selected structurally complex environments comprising tall canopies, increased plant area index throughout the vertical column, and the availability of a greater diversity of niches. We show that mammals are sensitive to structural simplification through disturbance, emphasizing the importance of maintaining and enhancing structurally intact forests. By calculating occurrence thresholds of species in response to forest structural change, we identify areas of degraded forest that would provide maximum benefit for multiple high-conservation value species if restored. The study demonstrates the advantages of using LiDAR to map forest structure, rather than relying on overly simplistic classifications of human-modified tropical forests, for prioritizing regions for restoration.
Nearly 20% of tropical forests are within 100 m of a nonforest edge, a consequence of rapid deforestation for agriculture. Despite widespread conversion, roughly 1.2 billion ha of tropical forest remain, constituting the largest terrestrial component of the global carbon budget. Effects of deforestation on carbon dynamics in remnant forests, and spatial variation in underlying changes in structure and function at the plant scale, remain highly uncertain. Using airborne imaging spectroscopy and light detection and ranging (LiDAR) data, we mapped and quantified changes in forest structure and foliar characteristics along forest/oil palm boundaries in Malaysian Borneo to understand spatial and temporal variation in the influence of edges on aboveground carbon and associated changes in ecosystem structure and function. We uncovered declines in aboveground carbon averaging 22% along edges that extended over 100 m into the forest. Aboveground carbon losses were correlated with significant reductions in canopy height and leaf mass per area and increased foliar phosphorus, three plant traits related to light capture and growth. Carbon declines amplified with edge age. Our results indicate that carbon losses along forest edges can arise from multiple, distinct effects on canopy structure and function that vary with edge age and environmental conditions, pointing to a need for consideration of differences in ecosystem sensitivity when developing land-use and conservation strategies. Our findings reveal that, although edge effects on ecosystem structure and function vary, forests neighboring agricultural plantations are consistently vulnerable to long-lasting negative effects on fundamental ecosystem characteristics controlling primary productivity and carbon storage.
New plantations can either cause deforestation by replacing natural forests or avoid this by using previously cleared areas. The extent of these two situations is contested in tropical biodiversity hotspots where objective data are limited. Here, we explore delays between deforestation and the establishment of industrial tree plantations on Borneo using satellite imagery. Between 1973 and 2015 an estimated 18.7 Mha of Borneo's old-growth forest were cleared (14.4 Mha and 4.2 Mha in Indonesian and Malaysian Borneo). Industrial plantations expanded by 9.1 Mha (7.8 Mha oil-palm; 1.3 Mha pulpwood). Approximately 7.0 Mha of the total plantation area in 2015 (9.2 Mha) were old-growth forest in 1973, of which 4.5-4.8 Mha (24-26% of Borneo-wide deforestation) were planted within five years of forest clearance (3.7-3.9 Mha oil-palm; 0.8-0.9 Mha pulpwood). This rapid within-five-year conversion has been greater in Malaysia than in Indonesia (57-60% versus 15-16%). In Indonesia, a higher proportion of oil-palm plantations was developed on already cleared degraded lands (a legacy of recurrent forest fires). However, rapid conversion of Indonesian forests to industrial plantations has increased steeply since 2005. We conclude that plantation industries have been the principle driver of deforestation in Malaysian Borneo over the last four decades. In contrast, their role in deforestation in Indonesian Borneo was less marked, but has been growing recently. We note caveats in interpreting these results and highlight the need for greater accountability in plantation development.
The origin of the elephant on the island of Borneo remains elusive. Research has suggested two alternative hypotheses: the Bornean elephant stems either from a recent introduction in the 17th century or from an ancient colonization several hundreds of thousands years ago. Lack of elephant fossils has been interpreted as evidence for a very recent introduction, whereas mtDNA divergence from other Asian elephants has been argued to favor an ancient colonization. We investigated the demographic history of Bornean elephants using full-likelihood and approximate Bayesian computation analyses. Our results are at odds with both the recent and ancient colonization hypotheses, and favour a third intermediate scenario. We find that genetic data favour a scenario in which Bornean elephants experienced a bottleneck during the last glacial period, possibly as a consequence of the colonization of Borneo, and from which it has slowly recovered since. Altogether the data support a natural colonization of Bornean elephants at a time when large terrestrial mammals could colonise from the Sunda shelf when sea levels were much lower. Our results are important not only in understanding the unique history of the colonization of Borneo by elephants, but also for their long-term conservation.
Small populations are often exposed to high inbreeding and mutational load that can increase the risk of extinction. The Sumatran rhinoceros was widespread in Southeast Asia, but is now restricted to small and isolated populations on Sumatra and Borneo, and most likely extinct on the Malay Peninsula. Here, we analyse 5 historical and 16 modern genomes from these populations to investigate the genomic consequences of the recent decline, such as increased inbreeding and mutational load. We find that the Malay Peninsula population experienced increased inbreeding shortly before extirpation, which possibly was accompanied by purging. The populations on Sumatra and Borneo instead show low inbreeding, but high mutational load. The currently small population sizes may thus in the near future lead to inbreeding depression. Moreover, we find little evidence for differences in local adaptation among populations, suggesting that future inbreeding depression could potentially be mitigated by assisted gene flow among populations.
With many non-human primates (NHPs) showing continued population decline, there is an ongoing need to better understand their ecology and conservation threats. One such threat is the risk of disease, with various bacterial, viral and parasitic infections previously reported to have damaging consequences for NHP hosts. Strongylid nematodes are one of the most commonly reported parasitic infections in NHPs. Current knowledge of NHP strongylid infections is restricted by their typical occurrence as mixed infections of multiple genera, which are indistinguishable through traditional microscopic approaches. Here, modern metagenomics approaches were applied for insight into the genetic diversity of strongylid infections in South-East and East Asian NHPs. We hypothesized that strongylid nematodes occur in mixed communities of multiple taxa, dominated by Oesophagostomum, matching previous findings using single-specimen genetics. Utilizing the Illumina MiSeq platform, ITS-2 strongylid metabarcoding was applied to 90 samples from various wild NHPs occurring in Malaysian Borneo and Japan. A clear dominance of Oesophagostomum aculeatum was found, with almost all sequences assigned to this species. This study suggests that strongylid communities of Asian NHPs may be less species-rich than those in African NHPs, where multi-genera communities are reported. Such knowledge contributes baseline data, assisting with ongoing monitoring of health threats to NHPs.
In Malaysia, mushroom poisoning poses a significant public health concern, particularly as local communities frequently consume wild mushrooms without fully recognizing the potential dangers they present. Ingestion of wild mushrooms, which resemble edible species but contain deadly chemicals, is the main cause of poisoning risk. The genus Entoloma (Fr.) P. Kumm is dispersed worldwide, with over 1500 species recorded. Entoloma mastoideum, a poisonous mushroom, was recorded for the first time at Kota Marudu district, Sabah, Malaysia, where ten cases of mushroom poisoning outbreaks were recorded during the rainy season of October 2019. The morphological characters of the specimens were documented and their microscopic features were analyzed using compound microscope and scanning electron microscope. A phylogenetic tree was constructed using Maximum likelihood and Bayesian analysis. Chemical profiling of the poisonous mushroom specimen was done via liquid chromatograph mass spectrometry (LC-MS/MS) to identify toxic metabolites. The phylogenetic analysis showed that the Bornean E. mastoideum is closely related to the Chinese isolates (100% BS/1.0 PP). LC-MS/MS profiling detected a total of 162 metabolites that were classified into ten general groups, where several toxic compounds were detected amongst the aromatics, essential amino acids, and fatty acid derivatives. The toxic compounds identified in the mushroom extract, including amino acid derivatives such as 3,4,5,6-tetrahydroxyynorleucine, valpromide, and betaine, have been reported to cause neurotoxicity, cardiotoxicity, liver damage, and gastrointestinal harm. The presence of these toxic compounds underscores the need for caution when consuming wild mushrooms. Further research on poisonous Entoloma species is vital for developing accurate identification methods and understanding their toxic potential. This knowledge is essential for enhancing public awareness, preventing mushroom poisoning incidents and safeguarding public health.
Scorodocarpus borneensis (Baill.) Becc. is attracting increased attention as a potential commercial medicinal plant product in Southeast Asia. This review summarizes the current knowledge on the taxonomy, habitat, distribution, medicinal uses, natural products, pharmacology, toxicology, and potential utilization of S. borneesis in the pharmaceutical/nutraceutical/functional cosmetic industries. All data in this review were compiled from Google Scholar, PubMed, Science Direct, Web of Science, ChemSpider, PubChem, and a library search from 1866 to 2022. A total of 33 natural products have been identified, of which 11 were organosulfur compounds. The main organosulfur compound in the seeds is bis-(methylthiomethyl)disulfide, which inhibited the growth of a broad spectrum of bacteria and fungi, T-lymphoblastic leukemia cells, as well as platelet aggregation. Organic extracts evoked anti-microbial, cytotoxic, anti-free radical, and termiticidal effects. S. borneensis and its natural products have important and potentially patentable pharmacological properties. In particular, the seeds have the potential to be used as a source of food preservatives, antiseptics, or termiticides. However, there is a need to establish acute and chronic toxicity, to examine in vivo pharmacological effects and to perform clinical studies.
Characterizing the feeding ecology of threatened species is essential to establish appropriate conservation strategies. We focused our study on the proboscis monkey (Nasalis larvatus), an endangered primate species which is endemic to the island of Borneo. Our survey was conducted in the Lower Kinabatangan Wildlife Sanctuary (LKWS), a riverine protected area that is surrounded by oil palm plantations. We aimed to determine the diet of multiple proboscis monkey groups by using two methods. First, we conducted boat-based direct observations (scan and ad libitum sampling) and identified 67 plant species consumed by the monkeys at their sleeping sites in early mornings and late afternoons. Secondly, we used the DNA metabarcoding approach, based on next-generation sequencing (NGS, MiSeq Illumina) of faecal samples (n = 155), using the short chloroplast sequence, the trnL (UAA) P6 loop. In addition, we built a DNA reference database with the local plants available in the LKWS. When combining feeding data from both methods, we reported a diverse dietary ecology in proboscis monkeys, with at least 89 consumed plant taxa, belonging to 76 genera and 45 families. Moreover, we were able to add 22 new genera as part of the diet of this endangered colobine primate in the LKWS. The two methods provided congruent and complementary results, both having their advantages and limitations. This study contributed to enhance the knowledge on the feeding ecology of proboscis monkeys, highlighting the significance of several plant species that should further be considered in habitat restoration plans or corridor establishment.
The incidence of zoonotic malaria, Plasmodium knowlesi, infection is increasing and now is the major cause of malaria in Malaysia. Here, we describe a WarmStart colorimetric loop-mediated isothermal amplification (LAMP) assay for the detection of Plasmodium spp. The detection limit for this assay was 10 copies/µL for P knowlesi and Plasmodium ovale and 1 copy/µL for Plasmodium falciparum, Plasmodium vivax, and Plasmodium malariae. To test clinical sensitivity and specificity, 100 microscopy-positive and 20 malaria-negative samples were used. The WarmStart colorimetric LAMP was 98% sensitive and 100% specific. Amplification products were visible for direct observation, thereby eliminating the need for post-amplification processing steps. Therefore, WarmStart colorimetric LAMP is suitable for use in resource-limited settings.
The present study identified a new barnacle species from Malaysian waters, Chthamalus ngankeeae sp. nov., on morphological and molecular grounds. Chthamalus ngankeeae sp. nov. is an intertidal species that is abundant on high shores, above the oyster zone. Chthamalus ngankeeae sp. nov. has two morphotypes, based on shell colour. Brown morphs have brown shells with pale brown ridges and look similar to Microeuraphia withersi (Pilsbry, 1916). Chthamalus ngankeeae sp. nov. has four teeth on the mandible, while M. withersi has but three. White morphs of C. ngankeeae sp. nov. possess white shells with gray ridges. The white morph of C. ngankeeae sp. nov. is similar to C. moro Pilsbry, 1916, but a major morphological difference includes a more prominent articular ridge on the scutum of C. ngankeeae sp. nov. compared to C. moro. Molecular analyses of sequence divergence in the COI and NaK genes of C. ngankeeae sp. nov. with other chthamalids showed that it forms an individual monophyletic group and does not belong to any of the cryptic lineages of C. moro, supporting its designation as a new species.
We here report on freshwater cave crabs of the families Potamidae and Gecarcinucidae in East Kalimantan, Sarawak, Indonesia in Borneo. A new genus and species of potamid crab, Ngan mayla, is described from Lubang Gedung Cave in the Merabu Karst. With its bullet-shaped eyes, Ngan mayla gen. et sp. nov. is totally blind and also displays the characters associated with an obligate cave-dwelling life, namely that it is dolichopod and fully depigmented. The closest genus and species is Cerberusa caeca Holthuis, 1979, from northern Sarawak. Highly modified, Ngan mayla gen. et sp. nov. proves to be among the most troglobitic of the known subterranean potamids, of which there were currently only seven in the Old World, with only four simultaneously being completely blind, entirely depigmented and dolichopod (Cerberusa caeca Holthuis, 1979, Diyutamon cereum Huang, Shih & Ng, 2017 and Phasmon typhlops Huang, Ahyong & Shih, 2020, to which must be added today Ngan mayla gen. et sp. nov.). Ngan mayla gen. et sp. nov. is easily distinguished from other potamid genera by its chelipeds bearing numerous acute teeth, spines (some horn-tipped) and short simple setae or spine-like setae on all articles. Two young female crabs collected in 2010 at the same area (Merabu Karst) but from a different cave, the Lubang Tebot Cave, could not be identified to specific level: an Isolapotamon sp., and a gecarcinucid with very long legs, pale colouration and slightly modified but black-pigmented eyes, close to Balssiathelphusa Bott, 1969, could possibly belong to a new genus. Some information on New World troglobitic crabs is provided.
A first experiment on malaria control in the interior of Borneo by spraying with residual insecticides is described. The work was carried out in the isolated, sparsely populated valleys of the Baram River and its tributary, the Tinjar, in northern Sarawak. The experimental area was divided into three parts: a DDT test area, where a 75% suspension of wettable powder was applied at the rate of 2 g of DDT per m(2) of surface; a BHC test area, where a 50% suspension of wettable powder was applied at the rate of 0.10 g of gamma isomer per m(2); and a check area.Entomological investigations made before the spraying operations were started showed that Anopheles leucosphyrus Dönitz, 1901 was the main malaria vector in both the test and the check areas. Out of a total of 7568 A. leucosphyrus dissected, 30 gland infections were detected-a sporozoite-rate of 0.40%. A. barbirostris was found to be a secondary vector throughout the experimental area.THE RESULTS OF INSECTICIDE SPRAYING WERE SATISFACTORY: in the DDT test area, the spleen-rate fell from 51.8% to 25.1%, and the parasite-rate from 35.6% to 1.6%, in 21 months, and a similar reduction in the rates was observed in the BHC test area. In the check area, the spleen- and parasite-rates rose during the period of observations. It is considered that if such a degree of control can be obtained in 21 months, complete eradication can be expected in the near future.Although BHC spraying proved effective, the fact that it has to be repeated every three months makes it impracticable in the interior of Sarawak, where communications are very poor and difficulties of transport very great. DDT spraying, which need only be done twice a year, is therefore to be preferred. The cost of the DDT operations-US$ 0.45 per person protected per year-is comparatively high, owing to the difficulty of communications and to the necessity for spraying not only the village "longhouses", but also the temporary shelters which the semi-nomadic people in the interior of Sarawak build each year in the rice-fields.