TROPHIC ECOLOGY OF TROPICAL RESERVOIR COMMUNITIES

Ph.DDOCTOR OF PHILOSOPHY (FOS

Empirical food webs of 12 tropical reservoirs in Singapore

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 (d13C and d15N) 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

Bottom-up influences on tropical freshwater food web structure support the “environmental filtering” hypothesis

10.1002/lno.10813Limnology and Oceanography6351877-189

Efficacy of Interventions That Incorporate Mobile Apps in Facilitating Weight Loss and Health Behavior Change in the Asian Population: Systematic Review and Meta-analysis

BackgroundSmartphone apps have shown potential in enhancing weight management in Western populations in the short to medium term. With a rapidly growing obesity burden in Asian populations, researchers are turning to apps as a service delivery platform to reach a larger target audience to efficiently address the problem. ObjectiveThis systematic review and meta-analysis aims to determine the efficacy of interventions that incorporate apps in facilitating weight loss and health behavior change in the Asian population. MethodsA total of 6 databases were searched in June 2020. The eligible studies included controlled trials in which an app was used in the intervention. The participants were aged 18 years or older and were of Asian ethnicity. A meta-analysis to test intervention efficacy, subgroup analyses, and post hoc analyses was conducted to determine the effects of adding an app to usual care and study duration. The primary outcome was absolute or percentage weight change, whereas the secondary outcomes were changes to lifestyle behaviors. ResultsA total of 21 studies were included in this review, and 17 (81%) were selected for the meta-analysis. The pooled effect size across 82% (14/17) of the randomized controlled trials for weight change was small to moderate (Hedges g=–0.26; 95% CI –0.41 to –0.11), indicating slightly greater weight loss achieved in the intervention group; however, this may not be representative of long-term studies (lasting for more than a year). Supplementing multicomponent usual care with an app led to greater weight loss (Hedges g=–0.28; 95% CI –0.47 to –0.09). Asian apps were largely culturally adapted and multifunctional, with the most common app features being communication with health professionals and self-monitoring of behaviors and outcomes. ConclusionsMore evidence is required to determine the efficacy of apps in the long term and address the low uptake of apps to maximize the potential of the intervention. Future research should determine the efficacy of each component of the multicomponent intervention to facilitate the designing of studies that are most effective and cost-efficient for weight management. Trial RegistrationPROSPERO CRD42020165240; https://tinyurl.com/2db4tvn

International socioeconomic inequality drives trade patterns in the global wildlife market

10.1126/sciadv.abf7679Science Advances719eabf767

Source data

Simplified carbon source d13C data file for analyses in the R environment

Liew et al_R script

R script written to run all statistical analyses detailed in the original publication

Aggregated d13C data and metadata

Spreadsheet file of d13C data and metadata of organic carbon sources. This includes primary data collected by the authors of the associated publication, as well as secondary data from other publications cited in the file

Fish data

Amino acid d13C data of a Cryptotora thamicola individual analysed in the original publication

Data from: Effects of macrophytes on lake‐water quality across latitudes: a meta‐analysis

Macrophytes are widely recognized for improving water quality and stabilizing the desirable clear‐water state in lakes. The positive effects of macrophytes on water quality have been noted to be weaker in the (sub)tropics compared to those of temperate regions. We conducted a global meta‐analysis using 47 studies that met our set criteria to assess the overall effects of macrophytes on water quality (measured by phytoplankton chlorophyll a concentration, total nitrogen concentration, total phosphorus concentration, Secchi depth, and the trophic state index) and to investigate how these effects correlate with latitude using meta‐regressions. We also examined if the effects of macrophytes on lake‐water quality differ with growth form in (sub)tropical and temperate areas by grouping the data and then comparing the effect sizes. We found that macrophytes significantly reduced phytoplankton chlorophyll a concentration, total nitrogen concentration, total phosphorus concentration, as well as the trophic state index, but they did not have a significant overall effect on Secchi depth. The effects of macrophytes on reducing phytoplankton chlorophyll a concentration, total nitrogen concentration, and the trophic state index did not differ with latitude. However, the reduction of total phosphorus concentration was greater at lower latitudes. We showed that at lower latitudes, the positive effects of macrophytes on water quality are similar to or greater than those at higher latitudes, thus challenging the prevailing paradigm of macrophytes being less effective at enhancing lake‐water quality in the (sub)tropics. Furthermore, our data showed that the macrophyte effects vary by growth forms, and the growth forms that positively affect water quality differ between the (sub)tropical and temperate areas. We showed a lack of significant macrophyte effects in surveys within and outside macrophyte stands, suggesting difference in the sensitivities of study designs or possibly weaker effects of macrophytes in lakes compared to experimental settings