Asian Journal of Environment & Ecology

Delineating Ecologically Important Fish Habitats Using Ichthyoplankton Assemblages in the Coastal Waters of Tam Hai, Central Vietnam

Tran Cong Thinh — 2026-08-28

Fish eggs and larvae provide biological information for identifying areas associated with spawning and early development, yet ichthyoplankton remains poorly documented in tropical estuarine–coastal systems. This study examined ichthyoplankton at 16 stations in the coastal waters of Tam Hai, central Vietnam, during the dry season (April 2022) and rainy season (December 2022) to assess taxonomic composition, abundance, spatial organisation, seasonal variation, and associations with surface salinity. A total of 20,888 fish eggs and 1,812 fish larvae were collected, with 24 larval families identified. Mean fish egg density was substantially higher in the dry season than in the rainy season (634.30 ± 157.10 versus 60.18 ± 25.23 eggs/100 m³), while mean larval density was 50.28 ± 15.03 and 20.20 ± 5.71 ind./100 m³, respectively. Larval assemblage composition showed marked seasonal turnover and spatial differentiation across mangrove, transitional, and coral reef-associated habitats. Salinity was significantly associated with the abundance of four larval families: Gobiidae showed a negative association, whereas Nemipteridae, Dorosomatidae, and Terapontidae showed positive associations. The spatial separation between egg-rich and larva-rich stations indicates that early-life-stage distributions may reflect processes operating after spawning as well as habitat conditions. These findings provide baseline information for identifying areas associated with fish spawning and early development and for supporting fisheries conservation and ecosystem-based coastal management.

Assessment of Pest Pressure and the Severity of Attacks by Rice (Oryza sativa L.) Insect Pests in the Maniema Production Basins, Democratic Republic of the Congo

Adiyo Sumbu Henriette — 2026-08-28

Rice (Oryza sativa L.) production in the Democratic Republic of the Congo faces significant biotic constraints, particularly attacks by insect pests that hinder yield stability.

Aims: To evaluate the spatial variability of agro-morphological traits, pest pressure, and the severity of damage caused by insect pests to rainfed rice (Oryza sativa L.) across major production basins in Maniema Province, Democratic Republic of the Congo, to inform targeted integrated pest management strategies.

Study Design: A multi-site comparative field evaluation combining agro-morphological measurements with a quantitative phytosanitary diagnosis.

Place and Duration of Study: Agricultural fields across the production basins of Kailo, Kasongo, and Kibombo, Maniema Province, Democratic Republic of the Congo, during the crop maturity phase.

Methodology: A two-stage stratified sampling scheme was implemented across 384 rice fields (128 per basin), with 10 randomly selected plants evaluated per field (N = 3,840 plants). Recorded agronomic parameters included plant height, collar diameter, tiller count, and panicle grain load. In situ visual counts were used to assess pest abundance, infestation rate, and attack incidence. Qualitative canopy sweep sampling (n = 176) was used to identify pest taxonomic structure. Foliar and panicle attack severity were scored on a 0–9 scale to compute McKinney’s severity index (I_s). Data were analysed using ANOVA, Tukey’s HSD test, Pearson’s chi-square (χ2) test, and ecological diversity indices in R.

Results: Plant height was homogeneous across basins (1.25 to 1.31 m; p = 0.0351), whereas collar diameter, tiller count, and grain load showed significant spatial variation (p < 0.001). Orthoptera dominated the entomofauna (60.80%), led by Oxya hyla (31.25%), followed by Hemiptera (15.34%). Kailo achieved the highest grain load (139.13 ± 23.92 grains/panicle) but had high grain damage (3.66 ± 1.72 grains/sample). Kibombo emerged as the primary epidemic hotspot, exhibiting the lowest Pielou evenness (J’= 0.68), the highest mean pest abundance (1.16 ± 1.46 ind./plant; p = 8.37 times 10-13), a 57.97% infestation rate, 88.05% attack incidence, and an alarming McKinney index of 53.03% (compared to 18.05% in Kailo and 20.56% in Kasongo).

Conclusion: Entomological pressure and damage severity in rainfed rice are highly spatially dependent in Maniema. Kibombo requires urgent, localised intervention focusing on cultural controls and targeted biopesticides during tillering, whereas Kailo requires monitoring against sucking pests during grain filling.

Pharmaceutical Contaminants in Aquatic Environments: A Critical Synthesis of Sources, Ecological Risks and Bioremediation Strategies

Yogita Basene — 2026-08-28

Pharmaceutical residues are now routinely detected in wastewater-impacted aquatic environments because medicinal compounds and their metabolites enter sewerage, industrial effluents, agricultural drainage and receiving waters through multiple, often continuous pathways. Their environmental significance cannot be inferred from occurrence alone: risk depends on potency, exposure duration, mixtures, transformation products, species sensitivity and the capacity of treatment systems to reduce biologically active mass. This critical narrative review integrates evidence on sources, ecological effects and bioremediation, with emphasis on wastewater-impacted freshwaters and on technologies that rely substantially on microbial, fungal, algal or plant-associated processes. Literature was selected through live searches of multidisciplinary and environmental or biomedical scholarly sources, supplemented by citation searching and DOI verification. The strongest causal ecological evidence comes from whole-ecosystem work with endocrine-active pharmaceuticals, while laboratory and field studies also support concern for behavioural disruption, chronic sublethal effects and antibiotic-driven selection for antimicrobial resistance. Nevertheless, extrapolation remains difficult because monitoring is dominated by parent compounds and targeted analytes, whereas mixtures and transformation products are incompletely characterised. Conventional activated sludge provides variable and compound-specific attenuation; apparent parent removal may reflect sorption or transformation rather than mineralisation. Membrane bioreactors, adapted bacterial consortia, white-rot fungi, microalgae and constructed wetlands can improve removal under favourable conditions, but evidence is uneven across scales and frequently relies on high test concentrations or parent disappearance. The synthesis indicates that no single biological technology provides universal control. Risk reduction is more defensibly pursued through source control, robust biological treatment and targeted polishing, supported by mass balances, transformation-product screening, effect-based endpoints and antimicrobial-resistance assessment. Future research should prioritise trace-level, full-scale comparisons and standardised demonstrations that connect chemical removal to reduced biological hazard.