The Sulu-Sulawesi Sea, with neighboring Indonesian Seas and South China Sea, lies at the center of the world's tropical marine biodiversity. Encircled by 3 populous, developing nations, the Philippines, Indonesia and Malaysia, the Sea and its adjacent coastal and terrestrial ecosystems, supports ca. 33 million people, most with subsistence livelihoods heavily reliant on its renewable natural resources. These resources are being impacted severely by rapid population growth (> 2% yr-1, with expected doubling by 2035) and widespread poverty, coupled with increasing international market demand and rapid technological changes, compounded by inefficiencies in governance and a lack of awareness and/or acceptance of some laws among local populations, particularly in parts of the Philippines and Indonesia. These key root causes all contribute to illegal practices and corruption, and are resulting in severe resource depletion and degradation of water catchments, river, lacustrine, estuarine, coastal, and marine ecosystems. The Sulu-Sulawesi Sea forms a major geopolitical focus, with porous borders, transmigration, separatist movements, piracy, and illegal fishing all contributing to environmental degradation, human suffering and political instability, and inhibiting strong trilateral support for interventions. This review analyzes these multifarious environmental and socioeconomic impacts and their root causes, provides a future prognosis of status by 2020, and recommends policy options aimed at amelioration through sustainable management and development.
Relatively, little is known about the relationship between biodiversity and ecosystem functioning in forests, especially in the tropics. We describe the Sabah Biodiversity Experiment: a large-scale, long-term field study on the island of Borneo. The project aims at understanding the relationship between tree species diversity and the functioning of lowland dipterocarp rainforest during restoration following selective logging. The experiment is planned to run for several decades (from seed to adult tree), so here we focus on introducing the project and its experimental design and on assessing initial conditions and the potential for restoration of the structure and functioning of the study system, the Malua Forest Reserve. We estimate residual impacts 22 years after selective logging by comparison with an appropriate neighbouring area of primary forest in Danum Valley of similar conditions. There was no difference in the alpha or beta species diversity of transect plots in the two forest types, probably owing to the selective nature of the logging and potential effects of competitive release. However, despite equal total stem density, forest structure differed as expected with a deficit of large trees and a surfeit of saplings in selectively logged areas. These impacts on structure have the potential to influence ecosystem functioning. In particular, above-ground biomass and carbon pools in selectively logged areas were only 60 per cent of those in the primary forest even after 22 years of recovery. Our results establish the initial conditions for the Sabah Biodiversity Experiment and confirm the potential to accelerate restoration by using enrichment planting of dipterocarps to overcome recruitment limitation. What role dipterocarp diversity plays in restoration only will become clear with long-term results.
The stages of decomposition and the faunal succession on rabbit carcasses in three different habitats, namely jungle, rural, and highland areas, were studied. Three New Zealand White rabbit (Oryctolagus cuniculus) carcasses weighing ∼2 kg were sampled daily until the decomposition process was completed. Representative specimens of adult flies, larvae, pupa, and mites were collected from the carcasses and processed in the laboratory. There were differences in decomposition rate and faunal succession between the carcasses. The fastest rate of decomposition was recorded in rural area, and the slowest rate of decomposition was recorded in highland area. The carcasses exhibited the same pattern of colonization by adult flies, but the dominant species of larvae and adult flies on each carcass in specific habitats were different. The primary species of flies recorded in jungle were Chrysomya megacephala F., Chrysomya rufifacies (Macquart), Chrysomya chani Kurahashi, Chrysomya villenuevi Patton, Chrysomya nigripes Aubertin, Chrysomya pinguis (Walker), Hemipyrellia ligurriens (Wiedemann), Hemipyrellia tagaliana (Bigot), Hypopyiopsis fumipennis (Walker), Hypopygiopsis violacea (Macquart), and Hydrotaea spinigera Stein represented by both adults and larvae. Musca domestica L., Atherigona sp., Lioproctia pattoni (Senior-White), Lioproctia saprianovae Pape & Bänziger, and Seniorwhitea princeps (Wiedemann) were represented by adults only. The biodiversity of flies in the rural area were C. megacephala, C. rufifacies, H. ligurriens, Fannia canicularis L., Hydrotaea chalcogaster (Wiedemann), and Hyd. spinigera represented by both adults and larvae, meanwhile M. domestica, Atherigona sp., Boettcherisca peregrina (Robineau-Desvoidy), Parasarcophaga taenionota Wiedemann, Parasarcophaga scopariiformis Senior-White, and S. princeps were represented by adults only. The species of flies collected in the highland area were Lucilia porphyrina (Walker), C. megacephala, C. rufifacies, C. villenuevi, C. pinguis, H. ligurriens, Hyd. spinigera, Hyd. chalcogaster, F. canicularis, and Boettcherisca highlandica Kurahashi & Tan represented by both adults and larvae, whereas C. nigripes, Chrysomya thanomthini Kurahashi & Tumrasvin, M. domestica, Atherigona sp., Parasarcophaga albiceps Meigen, P. taenionota, Sepsidae, Phoridae, and Millichidae were represented by adults only. Faunal succession followed the sequence of dominant flies, i.e., Calliphoridae, Sarcophagidae, Muscidae, Sepsidae, and lastly Stratiomyidae for jungle, or Sepsidae for rural and highland studies. Mites, from suborders Mesostigmata, Prostigmata, Astigmatina, and Oribatida, were also recovered throughout decomposition, which could be used for future implementation in forensic investigations. The data obtained from this study could provide more accurate indicators for local forensic scientists in solving criminal cases especially on the determination of time and primary location of death.
Background: Heat stress disorders may cause negative health outcome and subsequent productivity reduction especially in those who work under direct sunlight for an extended number of hours.
Objective: This study assessed the impact of heat on the health and productivity among maize farmers in a hot tropical country.
Methods: A cross-sectional study was conducted among 396 maize farmers, randomly selected across Gombe province, Nigeria. The wet bulb globe temperature monitor (WBGT) Model QuesTemp036 was used in determining the heat index. Health was determined using a validated questionnaire, while productivity was determined by recording work output based on the number of ridges cultivated during the working hours.
Results: The farms recorded mean heat index with standard deviation (SD) of 31.56 (2.19) and 34.08 (1.54) in the hours of 9 am to 12 pm and 12-3 pm respectively, which exceeded the threshold level set by the ACGIH. Heavy sweating (93.2%), tiredness (48.5%), dizziness (34.1%), and headache (40.4%) were experienced by the respondents almost on daily basis. The finding further showed a significant difference in the farmers' productivity during the three time duration of the work day (p < 0.001). The productivity was significantly higher between the hours of 6-9 am (p < 0.001) and 12-3 pm (p < 0.001), compared to the hours of 9 am to 12 pm (p < 0.001). The factors that significantly predict the productivity outcome include temperature (p < 0.001), gender (p < 0.001), age (p=0.033), and BMI (p=0.008).
Conclusion: The farmers were frequently experiencing heat exhaustion which decreased their productivity.
Falciparum malaria may have infected Homo sapiens (and perhaps H erectus) in the Asia Pacific region for more than 100,000 years. This estimate is based on the gene frequency of alpha-thalassaemia, the protection it affords against falciparum malaria and assumptions of untreated mortality from the infection. Up until the end of the 19th century, there was a high mortality from malaria in the coastal parts of Malaya, but the malaria control campaign, begun in 1901 at Klang, was described by Sir Ronald Ross as the first successful antimalarial work in the (then) British Empire. This was extended to Singapore in 1911. When the Far Eastern Association of Tropical Medicine held its Fifth Biennial Congress in Singapore in 1923, malaria was still a major killing disease in parts of Malaya and Sarawak. The mechanism of life-threatening malaria involves cytoadherence of parasitised erythrocytes in microvascular beds, a process enhanced by the products of macrophage activation induced by malarial pyrogen. Improvements in the chemotherapy of life-threatening falciparum malaria with chloroquine and quinine have been countered by the emergence of resistant strains. Artemisinin derivatives may become the treatment of choice during the coming decade. Apart from traditional anti-mosquito methods, control of malaria now involves the use of insecticide-impregnated bed nets, new entomological strategies, including genetic manipulation of mosquitoes and selective chemoprophylaxis. Antigenic diversity and antigenic variation of the malaria parasite have so far defeated attempts to produce an effective vaccine.
Recent research in Europe, Africa, and Southeast Asia suggests that we can no longer assume a direct and exclusive link between anatomically modern humans and behavioral modernity (the 'human revolution'), and assume that the presence of either one implies the presence of the other: discussions of the emergence of cultural complexity have to proceed with greater scrutiny of the evidence on a site-by-site basis to establish secure associations between the archaeology present there and the hominins who created it. This paper presents one such case study: Niah Cave in Sarawak on the island of Borneo, famous for the discovery in 1958 in the West Mouth of the Great Cave of a modern human skull, the 'Deep Skull,' controversially associated with radiocarbon dates of ca. 40,000 years before the present. A new chronostratigraphy has been developed through a re-investigation of the lithostratigraphy left by the earlier excavations, AMS-dating using three different comparative pre-treatments including ABOX of charcoal, and U-series using the Diffusion-Absorption model applied to fragments of bones from the Deep Skull itself. Stratigraphic reasons for earlier uncertainties about the antiquity of the skull are examined, and it is shown not to be an 'intrusive' artifact. It was probably excavated from fluvial-pond-desiccation deposits that accumulated episodically in a shallow basin immediately behind the cave entrance lip, in a climate that ranged from times of comparative aridity with complete desiccation, to episodes of greater surface wetness, changes attributed to regional climatic fluctuations. Vegetation outside the cave varied significantly over time, including wet lowland forest, montane forest, savannah, and grassland. The new dates and the lithostratigraphy relate the Deep Skull to evidence of episodes of human activity that range in date from ca. 46,000 to ca. 34,000 years ago. Initial investigations of sediment scorching, pollen, palynomorphs, phytoliths, plant macrofossils, and starch grains recovered from existing exposures, and of vertebrates from the current and the earlier excavations, suggest that human foraging during these times was marked by habitat-tailored hunting technologies, the collection and processing of toxic plants for consumption, and, perhaps, the use of fire at some forest-edges. The Niah evidence demonstrates the sophisticated nature of the subsistence behavior developed by modern humans to exploit the tropical environments that they encountered in Southeast Asia, including rainforest.
Termites perform key ecological functions in tropical ecosystems, are strongly affected by variation in rainfall, and respond negatively to habitat disturbance. However, it is not known how the projected increase in frequency and severity of droughts in tropical rainforests will alter termite communities and the maintenance of ecosystem processes. Using a large-scale termite suppression experiment, we found that termite activity and abundance increased during drought in a Bornean forest. This increase resulted in accelerated litter decomposition, elevated soil moisture, greater soil nutrient heterogeneity, and higher seedling survival rates during the extreme El Niño drought of 2015-2016. Our work shows how an invertebrate group enhances ecosystem resistance to drought, providing evidence that the dual stressors of climate change and anthropogenic shifts in biotic communities will have various negative consequences for the maintenance of rainforest ecosystems.
A synthesis is presented of sampling work conducted under a UK government-funded Darwin Initiative grant undertaken predominantly within the Danum Valley Conservation Area (DVCA), Sabah, East Malaysia. The project concerned the assemblage structure, gas physiology and landscape gas fluxes of termites in pristine and two ages of secondary, dipterocarp forest. The DVCA termite fauna is typical of the Sunda region, dominated by Termes-group soil-feeders and Nasutitermitinae. Selective logging appears to have relatively little effect on termite assemblages, although soil-feeding termites may be moderately affected by this level of disturbance. Species composition changes, but to a small extent when considered against the background level of compositional differences within the Sunda region. Physiologically the assemblage is very like others that have been studied, although there are some species that do not fit on the expected body size-metabolic rate curve. As elsewhere, soil-feeders and soil-wood interface-feeders tend to produce more methane. As with the termite assemblage characteristics, gross gas and energy fluxes do not differ significantly between logged and unlogged sites. Although gross methane fluxes are high, all the soils at DVCA were methane sinks, suggesting that methane oxidation by methanotrophic bacteria was a more important process than methane production by gut archaea. This implies that methane production by termites in South-East Asia is not contributing significantly to the observed increase in levels of methane production worldwide. Biomass density, species richness, clade complement and energy flow were much lower at DVCA than at a directly comparable site in southern Cameroon. This is probably due to the different biogeographical histories of the areas.
The tropical forests of Borneo and Amazonia may each contain more tree species diversity in half a square kilometre than do all the temperate forests of Europe, North America, and Asia combined. Biologists have long been fascinated by this disparity, using it to investigate potential drivers of biodiversity. Latitudinal variation in many of these drivers is expected to create geographic differences in ecological and evolutionary processes, and evidence increasingly shows that tropical ecosystems have higher rates of diversification, clade origination, and clade dispersal. However, there is currently no evidence to link gradients in ecological processes within communities at a local scale directly to the geographic gradient in biodiversity. Here, we show geographic variation in the storage effect, an ecological mechanism that reduces the potential for competitive exclusion more strongly in the tropics than it does in temperate and boreal zones, decreasing the ratio of interspecific-to-intraspecific competition by 0.25% for each degree of latitude that an ecosystem is located closer to the Equator. Additionally, we find evidence that latitudinal variation in climate underpins these differences; longer growing seasons in the tropics reduce constraints on the seasonal timing of reproduction, permitting lower recruitment synchrony between species and thereby enhancing niche partitioning through the storage effect. Our results demonstrate that the strength of the storage effect, and therefore its impact on diversity within communities, varies latitudinally in association with climate. This finding highlights the importance of biotic interactions in shaping geographic diversity patterns, and emphasizes the need to understand the mechanisms underpinning ecological processes in greater detail than has previously been appreciated.
How tropical trees flower synchronously near the equator in the absence of significant day length variation or other meteorological cues has long been a puzzle. The rubber tree (Hevea brasiliensis) is used as a model to investigate this phenomenon. The annual cycle of solar radiation intensity is shown to correspond closely with the flowering of the rubber tree planted near the equator and in the subtropics. Unlike in temperate regions, where incoming solar radiation (insolation) is dependent on both day length and radiation intensity, insolation at the equator is due entirely to the latter. Insolation at the upper atmosphere peaks twice a year during the spring and autumn equinoxes, but the actual solar radiation that reaches the ground is attenuated to varying extents in different localities. The rubber tree shows one or two flowering seasons a year (with major and minor seasons in the latter) in accordance with the solar radiation intensity received. High solar radiation intensity, and in particular bright sunshine (as distinct from prolonged diffuse radiation), induces synchronous anthesis and blooming in Hevea around the time of the equinoxes. The same mechanism may be operational in other tropical tree species.
Five formulated insecticides (lambda-cyhalothrin at 10 mg m⁻², bifenthrin at 50 mg m⁻², fipronil at 10 mg m⁻², fenitrothion at 50 mg m⁻², imidacloprid at 5 mg m⁻²) and one active ingredient (DDT at 500 mg m⁻²) were evaluated using a surface contact method against early and late instars and adults of two strains of the tropical bed bug, Cimex hemipterus (F.). Synergism of lambda-cyhalothrin and fipronil using piperonyl butoxide (PBO) was also assessed.
The superovulatory response to gonadotrophin treatment during different months of the year was investigated in Kambing kacang goats, a tropical breed, in Malaysia. Sixty-three cycling does, fitted with progesterone impregnated intravaginal sponges for 17 days, received two days before sponge withdrawal, an intramuscular injection of either 10, 15 or 20 mg of follicle stimulating hormone (FSH) or 500, 1000 or 1500 iu of equine chorionic gonadotrophin (eCG). The dose of FSH was divided into four decreasing daily doses and each daily dose was subdivided into two and administered at 07.00 and 19.00. Fifty-four does detected in oestrus were mated with fertile bucks. The ovarian response was determined by laparoscopy and eggs were recovered surgically five or six days after oestrus. The ovulatory response (mean +/- standard deviation) based on corpora lutea was higher in the FSH (13.4 +/- 8.4 corpora lutea per doe, n = 20) than the eCG-treated groups (6.4 +/- 5.1 corpora lutea per doe, n = 25) but the difference was not significant (P greater than 0.05). Does responded to gonadotrophins throughout the year with more than 50 per cent of does responding during the rainy months compared with less than 35 per cent responding during the dry months. This difference was statistically significant (P less than 0.05). Egg recovery was better in the FSH (6.8 +/- 5.3 per doe, n = 20) than the eCG groups (3.0 +/- 3.8 per doe, n = 21) but the difference was not significant (P greater than 0.05).
Heat stroke, which is also known as "sun stroke," is a medical emergency, and fatalities can occur unless it is diagnosed early and treated efficiently. Heat stroke may manifest quite suddenly, giving little time to differentiate it from extreme physical exhaustion in collapsed subjects. It is also known to lead to serious disseminated intravascular coagulation. Sudden death in a young female is presented who collapsed after trekking in a hilly, jungle area in Malaysia on a warm, humid day. She had joined a weight reduction programme a few weeks earlier. She was found collapsed and in a semiconscious state in the jungle by her groupmates and was taken to hospital. On admission she was unconscious, hyperpyrexic, with rapid, thready pulse and a low blood pressure. Biochemical studies revealed metabolic acidosis, elevated liver and cardiac enzymes and impairment of renal function. Her coagulation profile was found to be impaired and she started bleeding through the mouth and nostrils. She also developed watery diarrhoea and initially a septicaemic condition, including acute enteritis was suspected. Despite active treatment, her condition deteriorated and she died eight hours after admission. Autopsy confirmed a generalised bleeding tendency, with pulmonary, oesophageal and gastrointestinal mucosal haemorrhages. Flame-shaped subendocardial shock haemorrhages were seen in the interventricular septum on the left side of the heart. The findings support a diagnosis of heat stroke. Various aspects related to heat stroke, the autopsy diagnosis and its prevention are discussed.
Time-series data offer a way of investigating the causes driving ecological processes as phenomena. To test for possible differences in water relations between species of different forest structural guilds at Danum (Sabah, NE Borneo), daily stem girth increments (gthi), of 18 trees across six species were regressed individually on soil moisture potential (SMP) and temperature (TEMP), accounting for temporal autocorrelation (in GLS-arima models), and compared between a wet and a dry period. The best-fitting significant variables were SMP the day before and TEMP the same day. The first resulted in a mix of positive and negative coefficients, the second largely positive ones. An adjustment for dry-period showers was applied. Interactions were stronger in dry than wet period. Negative relationships for overstorey trees can be interpreted in a reversed causal sense: fast transporting stems depleted soil water and lowered SMP. Positive relationships for understorey trees meant they took up most water at high SMP. The unexpected negative relationships for these small trees may have been due to their roots accessing deeper water supplies (if SMP was inversely related to that of the surface layer), and this was influenced by competition with larger neighbour trees. A tree-soil flux dynamics manifold may have been operating. Patterns of mean diurnal girth variation were more consistent among species, and time-series coefficients were negatively related to their maxima. Expected differences in response to SMP in the wet and dry periods did not clearly support a previous hypothesis differentiating drought and non-drought tolerant understorey guilds. Trees within species showed highly individual responses when tree size was standardized. Data on individual root systems and SMP at several depths are needed to get closer to the mechanisms that underlie the tree-soil water phenomena in these tropical forests. Neighborhood stochasticity importantly creates varying local environments experienced by individual trees.
Extinction rates in the Anthropocene are three orders of magnitude higher than background and disproportionately occur in the tropics, home of half the world's species. Despite global efforts to combat tropical species extinctions, lack of high-quality, objective information on tropical biodiversity has hampered quantitative evaluation of conservation strategies. In particular, the scarcity of population-level monitoring in tropical forests has stymied assessment of biodiversity outcomes, such as the status and trends of animal populations in protected areas. Here, we evaluate occupancy trends for 511 populations of terrestrial mammals and birds, representing 244 species from 15 tropical forest protected areas on three continents. For the first time to our knowledge, we use annual surveys from tropical forests worldwide that employ a standardized camera trapping protocol, and we compute data analytics that correct for imperfect detection. We found that occupancy declined in 22%, increased in 17%, and exhibited no change in 22% of populations during the last 3-8 years, while 39% of populations were detected too infrequently to assess occupancy changes. Despite extensive variability in occupancy trends, these 15 tropical protected areas have not exhibited systematic declines in biodiversity (i.e., occupancy, richness, or evenness) at the community level. Our results differ from reports of widespread biodiversity declines based on aggregated secondary data and expert opinion and suggest less extreme deterioration in tropical forest protected areas. We simultaneously fill an important conservation data gap and demonstrate the value of large-scale monitoring infrastructure and powerful analytics, which can be scaled to incorporate additional sites, ecosystems, and monitoring methods. In an era of catastrophic biodiversity loss, robust indicators produced from standardized monitoring infrastructure are critical to accurately assess population outcomes and identify conservation strategies that can avert biodiversity collapse.
Spatial subsidies increase local productivity and boost consumer abundance beyond the limits imposed by local resources. In marine ecosystems, deeper water and open ocean subsidies promote animal aggregations and enhance biomass that is critical for human harvesting. However, the scale of this phenomenon in tropical marine systems remains unknown. Here, we integrate a detailed assessment of biomass production in 3 key locations, spanning a major biodiversity and abundance gradient, with an ocean-scale dataset of fish counts to predict the extent and magnitude of plankton subsidies to fishes on coral reefs. We show that planktivorous fish-mediated spatial subsidies are widespread across the Indian and Pacific oceans and drive local spikes in biomass production that can lead to extreme productivity, up to 30 kg ha-1 day-1. Plankton subsidies form the basis of productivity "sweet spots" where planktivores provide more than 50% of the total fish production, more than all other trophic groups combined. These sweet spots operate at regional, site, and smaller local scales. By harvesting oceanic productivity, planktivores bypass spatial constraints imposed by local primary productivity, creating "oases" of tropical fish biomass that are accessible to humans.
Seagrass species in the tropics occur in multispecies meadows. How these meadows are maintained through species co-existence and what their ecological drivers may be has been an overarching question in seagrass biogeography. In this study, we quantify the spatial structure of four co-existing species and infer potential ecological processes from these structures.
Analyses of the spatial distribution pattern, spatial genetic structure and of genetic diversity were carried out in two tropical tree species with contrasting breeding systems and different ploidy levels using a 50-ha demographic plot in a lowland dipterocarp forest in Peninsular Malaysia. Shorea leprosula is a diploid and predominantly outcrossed species, whereas S. ovalis ssp. sericea is an autotetraploid species with apomictic mode of reproduction. Genetic diversity parameters estimated for S. leprosula using microsatellite were consistently higher than using allozyme. In comparisons with S. leprosula and other tropical tree species, S. ovalis ssp. sericea also displayed relatively high levels of genetic diversity. This might be explained by the lower pressure of genetic drift due to tetrasomic inheritance, and for autotetraploids each locus can accommodate up to four different alleles and this allows maintenance of more alleles at individual loci. The observed high levels of genetic diversity in S. ovalis ssp. sericea can also be due to a random retention of more heterogeneous individuals in the past, and the apomictic mode of reproduction might be an evolutionary strategy, which allows the species to maintain high levels of genetic diversity. The spatial distribution pattern analyses of both species showed significant levels of aggregation at small and medium but random distribution at the big diameter-class. The decrease in magnitude of spatial aggregation from small- to large-diameter classes might be due to compensatory mortality during recruitment and survival under competitive thinning process. Spatial genetic structure analyses for both species revealed significant spatial genetic structure for short distances in all the three diameter-classes. The magnitude of spatial genetic structure in both species was observed to be decreasing from smaller- to larger-diameter classes. The high spatial genetic structuring observed in S. ovalis ssp. sericea at the small-diameter class is due primarily to limited seed dispersal and apomictic mode of reproduction. The similar observation in S. leprosula, however, can be explained by limited seed and pollen dispersal, which supports further the fact that the species is pollinated by weak fliers, mainly of Thrips and Megalurothrips in the lowland dipterocarp forest.