Summary
River damming and other anthropogenic disturbances of natural habitats are among the main drivers of species loss through a range of direct and indirect effects. While the effects of river ...damming on aquatic species are relatively well studied, particularly with regard to their impacts on diadromous species and stenotopic riverine specialists, there is a paucity of studies quantifying the effects of dam construction on whole communities.
We conducted a global meta‐analysis focussed on fish communities, comparing species richness, abundance and proportion of alien species between dammed and undammed rivers. Both longitudinal and cross‐sectional studies were examined.
We found that construction of dams did not have a noticeable effect on fish richness and abundance, but the increase in proportion of alien species was significant (mean effect size of 0.62).
Our findings suggest that the conversion of lotic waterbodies into lentic habitats result in the extirpation of species unable to withstand a drastic change in environmental conditions, but the loss is compensated by colonising lacustrine or eurytopic species taking advantage of reduced competition and the availability of new niches specific to lentic habitats. However, when eurytopic natives are absent from waterbodies connected to the newly constructed reservoirs, vacant niches are instead exploited by alien species, resulting in impoverishment of native species richness although overall species richness may be maintained.
The ornamental trade is one of the major vectors of freshwater animal species translocation worldwide. The Australian redclaw crayfish Cherax quadricarinatus was brought into Singapore through the ...trade and culture of aquarium specimens during the late 1980s. From 2000 to the present, redclaw crayfish have been observed in at least 3 of Singapore's 13 reservoirs, including 2 inland reservoirs in the Central Catchment Nature Reserve (CCNR). The current paper presents the first in situ population data of feral C. quadricarinatus populations originating from ornamental trade and includes updated distribution records in Singapore based on recent surveys and museum samples. We report a C. quadricarinatus range expansion in 2 additional reservoirs (1 coastal and 1 inland), and the presence of multiple size cohorts confirms the establishment of reproducing populations in 2 coastal reservoirs and 1 CCNR reservoir. This is alarming as the current distribution borders Singapore's oldest and arguably most important nature reserve (Bukit Timah Nature Reserve: BTNR) and encircles the single remaining substantial freshwater swamp forest in the country (Nee Soon). The Nee Soon swamp forest and BTNR have extremely high conservation value as both areas together harbour the richest native freshwater fauna and flora of the island. Therefore, any range expansion of C. quadricarinatus in Singapore may have severe impacts on its native freshwater fauna and demands immediate attention. As C. quadricarinatus is one of the many invasive freshwater species occurring from the aquarium trade in Singapore, we argue that trade control might prevent further establishment of ornamentals.
Food webs summarise trophic interactions of the biotic components within an ecosystem, which can influence nutrient dynamics and energy flows, ultimately affecting ecosystem functions and services. ...Food webs represent the hypothesised trophic links between predators and prey and can be presented as empirical food webs, in which the relative strength/importance of the respective links are quantified. Some common methods used in food web research include gut content analysis (GCA) and stable isotope analysis (SIA). We combine both methods to construct empirical food web models as a basis for monitoring and studying ecosystem-level outcomes of natural (e.g. species turnover in fish assemblage) and intentional environmental change (e.g. biomanipulation).
We present 12 food webs from tropical reservoir communities in Singapore and summarise the topology of each with widely-used network indices (e.g. connectance, link density). Each reservoir was surveyed over 4-6 sampling occasions, during which, representative animal groups (i.e. fish species and taxonomic/functional groups of zooplankton and benthic macroinvertebrates) and all likely sources of primary production (i.e. macrophytes, periphyton, phytoplankton and riparian terrestrial plants) were collected. We analysed gut content in fishes and bulk isotope (d
C and d
N) profiles of all animals (i.e. fishes and invertebrates) and plants collected. Both sets of information were used to estimate the relative strength of trophic relationships using Bayesian mixing models. We document our protocol here, alongside a script in the R programming language for executing data management/analyses/visualisation procedures used in our study. These data can be used to glean insights into trends in inter- and intra-specific or guild interactions in analogous freshwater lake habitats.
Paedocypris is a new genus of paedomorphic cyprinid fish from highly acidic blackwater peat swamps in Southeast Asia. It includes two new species, one of which (Paedocypris progenetica) appears to be ...the smallest fish and vertebrate known, with the smallest mature female measuring a mere 7.9 mm. Paedocypris has many 'larval' features typically associated with paedomorphic fish (e.g. narrow frontals that leave the brain unprotected dorsally by bone and a precaudal larval-fin-fold), but, uniquely among fishes, males also possess highly modified pelvic fins with hypertrophied muscles and a keratinized pad in front of the pelvic girdle, which, we hypothesize, function together as a clasping or holding device, thereby suggesting an unusual reproductive mode. Unfortunately, habitat destruction jeopardizes the survival of these fishes and thus opportunities for further research.
: This study is a parallel-arm randomized controlled trial evaluating choral singing's efficacy and underlying mechanisms in preventing cognitive decline in at-risk older participants.
: ...Three-hundred and sixty community-dwelling, non-demented older participants are recruited for a 2-year intervention. Inclusion criteria are self-reported cognitive complaints, early cognitive impairment based on neuropsychological test scores or multiple risk factors of dementia. Participants are randomized to either weekly choral singing sessions or general health education. The primary outcome is cognitive performance, measured by a composite cognitive test score (CCTS). Secondary outcomes include depression, anxiety and neuropsychiatric symptoms; perceived stress; sleep quality and severity of dementia symptoms. Underlying mechanisms are examined using blood- and urine-based biomarkers and neuroimaging.
: Screening began in July 2016. The first group of participants (
= 93) have been recruited. Intervention and control treatments are ongoing and will end in December 2019.
: An evidence-based singing intervention for dementia prevention holds potential for healthcare savings and societal welfare.
: NCT02919748, IRB Approval Number: NUS 2508.
The peat swamp forests (PSFs) of Sundaland, in Southeast Asia, support many endemic freshwater fish species. However, the future of these species is in doubt, owing to ongoing PSF deforestation. ...Here, we show that, if current rates of PSF conversion to a predominantly agricultural mosaic landscape continue through 2050, 16 fish species may become globally extinct. In the worst-case scenario, where the rate of conversion across the region matches that of the most rapidly deforested river basin, 77% (79 of 102 species) of the narrowly adapted (stenotopic) fish species are likely to become extinct, a figure that would more than double known extinctions of the world's freshwater fishes. As indicated by our analysis, the PSFs of Indonesia's Central Kalimantan region would be most severely impacted.
Aims
Little is known about electroconvulsive therapy (ECT) use in Asian inpatients with schizophrenia. This study examined trends of ECT use for schizophrenia patients in Asia between 2001 and 2009 ...and its independent demographic and clinical correlates.
Methods
Data on 6761 hospitalized schizophrenia patients (2001 = 2399, 2004 = 2136, and 2009 = 2226) in nine Asian countries and territories were collected by either chart review or interviews during a 1‐month period. Patients’ sociodemographic and clinical characteristics, prescriptions of psychotropic drugs and ECT use were recorded using a standardized protocol and data‐collection procedure.
Results
The frequency of ECT was 3.3% in the whole sample; rising from 1.8% in 2001 to 3.3% in 2004 and 4.9% in 2009 (P < 0.0001). However, this increased trend was driven solely by increased ECT use in China (P < 0.0001), and the inclusion of India in the 2009 survey. There were wide inter‐country variations: 2001, 0% (Hong Kong, Korea) to 5.9% (China); 2004, 0% (Singapore) to 11.1% (China); 2009, 0% (Hong Kong) to 13.8% (India) and 15.2% (China). Multiple logistic regression analysis of the whole sample revealed that patients receiving ECT were less likely in the 35–64‐year age group, had shorter length of current hospitalization and fewer negative symptoms, and were more likely to receive second‐generation antipsychotic medications compared to those who were not treated with ECT (R2 = 0.264, P < 0.001).
Conclusions
ECT use for schizophrenia has increased over the past decade in China, being low/relatively stable in other Asian countries/regions. Reasons for substantial variations in ECT frequency in Asia require further study.
Family caregivers of cancer patients often suffer from impaired quality of life (QOL) due to stress arising from the responsibility of caregiving. Most research on such QOL impairments was conducted ...in Western populations. Thus, this exploratory study sought to (a) examine the QOL levels of family caregivers of cancer patients in an Asian population in Singapore, in relation to caregivers from other countries within and outside of Asia; and (b) investigate the association between sociodemographic factors and QOL impairments in family caregivers in Singapore.
A total of 258 family caregivers of cancer patients who were receiving outpatient treatment completed the Caregiver Quality of Life Index-Cancer (CQOLC) and a sociodemographic survey. We compared the published CQOLC total scores from Turkey, Iran, Taiwan, South Korea, the United Kingdom, the United States and Canada with the Singapore dataset and examined the demographic relationships.
Caregivers in Singapore and Asia had lower CQOLC total scores than their Western counterparts. Caregivers who were male, of Chinese ethnicity, had parental relationships with their care recipient, or cared for advanced-stage cancer patients were found to have impaired QOL.
The findings of this study highlight possible areas in which support can be provided for family caregivers of cancer patients, and underscore the need to reconcile cultural diversity, values, societal expectations and demographic characteristics in Singapore.
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