Asian Journal of Fisheries and Aquatic Research

Plastic Pollution in Aquatic Environments: Connecting Water and Wastewater, Hydrology, Groundwater and Its Impacts on Sustainable Aquaculture and Fisheries

Akinbobola Taiwo Eunice — 2026-11-05

Plastic pollution is commonly investigated within separate compartments, although particles and plastic-associated materials move through wastewater infrastructure, stormwater networks, rivers, sediments, aquifers, aquaculture facilities and fishing grounds. This disciplinary separation impedes source attribution, comparison of exposure estimates and evaluation of controls. This critical narrative review integrates evidence published from 2008 to 31 August 2026, drawing on verified experimental, observational, modelling and synthesis studies. It examines how material properties, hydrological connectivity and treatment processes jointly shape plastic transport, retention and biological exposure, with particular attention to sustainable aquaculture and fisheries. Conventional wastewater treatment captures substantial fractions of the particles measured in plant influent, but retained material is frequently transferred to sludge, and residual discharge remains relevant where effluent volumes are large. River emissions are strongly influenced by episodic runoff, floodplain retention and remobilisation; consequently, instantaneous concentrations poorly approximate catchment-scale delivery. Groundwater contamination is documented in karst, shallow and other vulnerable aquifers, yet filtration, preferential flow, sampling artefacts and limited temporal coverage restrict the estimation of subsurface fluxes. Aquaculture systems receive plastics through source water, equipment, feed and atmospheric inputs, while fishing activity generates additional macroplastic hazards through lost gear. Laboratory studies demonstrate organism-level responses under some exposure conditions, including oxidative stress and reproductive effects, but these findings cannot automatically be translated into population-level losses or human health risks. A source-to-receptor framework is proposed that separates particle abundance from mass flux, identifies changes in particle characteristics across compartments, and links biological evidence to environmentally plausible exposure. Priorities include harmonised size-resolved measurements, paired surface-water–groundwater monitoring, event-based mass balances, realistic chronic exposure designs and intervention evaluation across the entire material lifecycle. Sustainable management requires upstream plastic prevention alongside independently assessed treatment and gear-retention measures, rather than reliance on end-of-pipe removal alone.

Food and Feeding Habits of Clarias gariepinus and Oreochromis niloticus from Merowe Lake Reservoir, Sudan

Fathia A. Nasor — 2026-11-04

Information on dietary composition and feeding patterns of economically important freshwater fish in Merowe Reservoir remains limited, particularly regarding temporal and spatial variation. This study examined the stomach contents of Oreochromis niloticus and Clarias gariepinus, with emphasis on monthly and location-related differences. A total of 398 specimens of each species were collected with gillnets and traditional local nets between September 2021 and August 2022. Stomach contents were examined visually and microscopically, and food items were assessed using frequency of occurrence and percentage abundance. For O. niloticus, plant material was the most prominent recorded food category (53.1%), followed by sand/mud (43.4%), blue-green algae (36.6%), green algae (24.8%), zooplankton (21.4%) and unidentified food (17.2%). For C. gariepinus, the reported categories included sand/mud (approximately 79%), insect parts (69.7%), zooplankton (54.9%) and fish remains (32.6%). The recorded food categories varied among months and sampling locations. At Sad, unidentified food reached 60% of the location-specific values for O. niloticus, while zooplankton reached 45.2% at Bearty and green algae reached 44.4% at Shery. For C. gariepinus, fish remains reached 38.6% at Shery. The observations indicate that both species consumed diverse food categories and exhibited temporal and spatial differences in recorded stomach contents. These findings provide descriptive baseline information for future assessments of feeding ecology in the reservoir.

Sea Surface Temperature, Depth, and Octopus (Octopus cyanea) Production in the Fishing Grounds of the Northern Alas Strait, West Nusa Tenggara, Indonesia

M. Junaidi — 2026-11-04

Aims: To describe monthly sea surface temperature (SST) and depth of octopus fishing grounds in the northern Alas Strait, Indonesia, and their relationships with Octopus cyanea production and catch per unit effort (CPUE).

Study Design: Descriptive-correlational observational study.

Place and Duration of Study: Fishing grounds used by fishers from Seruni Mumbul (East Lombok) and Poto Tano (West Sumbawa) villages, West Nusa Tenggara, April–August 2025.

Methodology: Sixteen fishing grounds were identified through fisher interviews. Each landed octopus was weighed and recorded with its vessel code and date; CPUE was calculated as kg per trip. Monthly SST was derived from daily level-4 OSTIA data (0.05°) and depth from BATNAS bathymetry. Spearman and repeated measures correlation (r_rm) were applied to 59 fishing ground–month pairs.

Results: Mean monthly SST ranged from 28.15 °C (August) to 29.45 °C (May), while within-month differences among fishing grounds were 0.27–0.41 °C. Production totalled 1568 kg (1400 individuals) from 499 trips, peaking in May (539 kg); 66.3% came from the Sumbawa side. Monthly CPUE was stable (3.0–3.3 kg per trip), so production followed the number of trips. SST was not significantly correlated with production (ρ = 0.21; P = .11) or CPUE (ρ = −0.04; P = .77). Within fishing grounds, production was slightly higher in warmer months (r_rm = 0.31; P = .04), but not after effort standardisation (r_rm = −0.06; P = .71), because trips were more frequent in warmer months (r_rm = 0.36; P = .02). Depth (2.7–41.2 m) was not significantly correlated with production (ρ = −0.16; P = .57; n = 15).

Conclusion: Within the narrow SST range of one season, SST did not explain CPUE, and landed production mainly reflected fishing effort. Monitoring should record effort, including zero-catch trips, and environmental data at each fishing ground over several seasons.

Effect of Aloe Vera Aloe barbadensis miller on Growth Performance and Hematology of Clarias gariepinus Juveniles

N. A. Jamabo — 2026-11-05

This study evaluated the effects of dietary Aloe vera gel on growth performance and haematological characteristics of juvenile African catfish (Clarias gariepinus). A total of 300 juveniles, initially weighing 14.00 g and measuring 12.00 cm, were distributed among 15 aquaria at 20 fish per aquarium in a completely randomised design with five dietary treatments and three replicates per treatment. The experimental feeds contained 40 g (T1), 30 g (T2), 20 g (T3), 10 g (T4) or 0 g (T5; control) of aloe vera gel and feeding continued for 56 days. Growth, feed utilisation, survival and selected blood indices were assessed. Table 3 recorded the highest mean weight value in T1 (48.92 ± 0.42), alongside the highest feed intake (37.53 ± 1.66), reported length value (17.28 ± 0.05) and specific growth rate (4.49 ± 0.08). The control exhibited the lowest corresponding weight (35.87 ± 0.42), feed intake (25.66 ± 0.06) and length (15.12 ± 0.05) values, together with the highest recorded survival measure (3.00 ± 1.00) and feed conversion ratio (1.51 ± 0.00). Haematological indices differed among treatments (p < 0.05). T1 showed the lowest red blood cell count and haemoglobin concentration, whereas T4 showed the highest haemoglobin concentration. Overall, the findings indicate a growth response to dietary aloe vera, accompanied by treatment-dependent differences in blood indices, and do not establish a uniformly favourable inclusion level.

Species Diversity and Socioeconomic Conditions of Dry Fish Traders in Lalmonirhat and Kurigram Districts, Bangladesh

Md. Ahosanul Haque — 2026-11-05

Dry-fish trading provides market opportunities in northern Bangladesh, yet local evidence on species composition, trade patterns, and traders' circumstances remains limited. This study assessed dried-fish species diversity, supply routes, marketing practices, and the socioeconomic conditions of retailers in Lalmonirhat and Kurigram districts. A market survey was undertaken from March to December 2025 in six purposively selected markets. Questionnaire-based interviews were conducted with 30 retailers, and information was cross-checked with key informants. Descriptive data were processed using Microsoft Excel. Across the selected markets, 38 dried-fish species were recorded, comprising 21 freshwater and 17 marine species. Commonly available products included Loitta, Churi, Bata, Baim, Puti, Mola, Ilish, Poa, Rupchanda, Icha, Chela, and Kachki. Recorded prices ranged from BDT 240 to 1,300 per kilogram. The Teesta dried-fish market served as a distribution point for products supplied from several production and wholesale centres. The rainy season accounted for the largest reported share of peak marketing activity (56%), followed by winter (34%) and summer (10%). Among retailers, 53.3% were aged 35–50 years, while 46.6% reported daily earnings of BDT 1,000–2,000. Four marketing channels were identified. Respondents reported insufficient capital, high transportation costs, limited storage facilities, and unhygienic market conditions as major constraints. These findings describe the diversity and trading arrangements of the surveyed markets and indicate practical areas for improving storage, transportation, and market conditions.

Diurnal Variations in Zooplankton Community Structure and Abundance in Two Sites of the Negua Canal, West Bengal, India

Subhra Sankha Khila — 2026-11-10

Zooplankton community composition reflects environmental variability in estuarine systems, but within-day patterns in the Negua Canal have received limited site-specific assessment. This study investigates the spatial distribution and diurnal variations of zooplankton community structure and abundance at two contrasting sites along the Negua Diversional Canal in Purba Medinipur, West Bengal, from March to May 2026. Sampling was conducted at Site A (Nyaykali Bridge), a typical marine environment, and Site B (Essex Marine Ltd.), an area subjected to industrial wastewater discharge, across three distinct times of day: morning, noon, and evening. A total of 7–8 major zooplankton taxa were recorded, with Cyclops sp. emerging as the dominant species, followed by Diaptomus sp., Undinula vulgaris, crustacean larvae, and other copepod forms. Site A consistently supported a much higher abundance and diversity of zooplankton compared to the ecologically stressed Site B. This spatial disparity was associated with water quality parameters, as Site A maintained favorable conditions, including higher dissolved oxygen (4.8–6.4 mg L⁻¹) and lower carbon dioxide levels (12–16 mg L⁻¹), whereas Site B exhibited prominent organic and industrial pollution stress, characterized by severe oxygen depletion (2.4–3.2 mg L⁻¹) and elevated carbon dioxide concentrations (20–76 mg L⁻¹). Furthermore, a distinct diurnal pattern was observed across both locations, with zooplankton abundance peaking during the morning, dropping to its lowest levels during the afternoon, and showing a moderate recovery by evening. The independent and interactive effects of sampling site and time of day significantly influenced (p < 0.05) zooplankton density. This temporal fluctuation may reflect the behavioral phenomenon of diel vertical migration (DVM) as an adaptive response to avoid intense midday solar radiation, thermal stress, and visual predation. Ultimately, these findings underscore the high sensitivity of zooplankton to anthropogenic and environmental stressors, supporting their potential utility as reliable biological indicators for monitoring water quality and establishing crucial baseline data for the conservation and sustainable management of the Negua Canal ecosystem.

Molecular and Phylogenetic Analysis of Monetaria annulus (Linnaeus, 1758) Based on Mitochondrial DNA Sequences in the Waters of Sambelia, East Lombok

Eureeka Ananda Azzahra — 2026-11-10

The ring cowry, Monetaria annulus, occurs across the Indo-Pacific, but variation in shell morphology can complicate identification. This study examined the molecular identity and phylogenetic placement of a specimen collected from the intertidal waters of Sambelia, East Lombok, Indonesia, using the mitochondrial cytochrome c oxidase subunit I (COI) marker. The study was conducted between May 2025 and July 2026. Tissue was preserved in absolute ethanol, and DNA was extracted using a modified cetyltrimethylammonium bromide method combined with sonication. The COI region was amplified using the LCO1490 and HCO2198 primers, and the amplified DNA was sequenced. Sequence editing, database comparison and phylogenetic reconstruction were undertaken using MEGA-X, BLAST and the maximum-likelihood method with the Kimura two-parameter model and 1,000 bootstrap replicates. The specimen, designated SBL CYP 09, was identified as M. annulus. Its COI sequence showed 98.61% similarity to a reference sequence from Sambelia, East Lombok. In the reconstructed phylogenetic tree, the specimen grouped with a sequence from North Maluku, with bootstrap support of 86. The analysed specimen had a higher proportion of adenine and thymine (58.7%) than cytosine and guanine (41.2%) in its COI sequence. The findings support COI-based molecular identification of this Sambelia specimen and provide a regional sequence comparison for further studies of M. annulus.

Integrated Biological and Physicochemical Assessment of Ecological Condition in Two Oyster-producing Brackish Systems: Implications for Sustainable Fisheries Management

Sandra Akugpoka Atindana — 2026-11-10

Background: Oyster-producing lagoons and estuaries are exposed to environmental pressures that may affect habitat condition and fishery sustainability.

Aims: To assess and compare the ecological condition of the Densu estuary and Anyanui lagoon by integrating benthic macroinvertebrate assemblages with physicochemical characteristics and water-quality indices and to examine the implications of the findings for sustainable oyster fisheries management in Ghana.

Study Design: Water and benthic macroinvertebrate samples were collected from four ecologically distinct zones selected to represent the major environmental gradients within the lagoon: (i) the upstream freshwater-influenced section, (ii) the central channel, (iii) the downstream section adjacent to the lagoon outlet, (iv) an area adjacent to agricultural lands/graveyards where diffuse runoff was expected to influence water quality (mapped using QGIS). These locations were selected to capture spatial variability in physicochemical conditions and benthic communities across the lagoon. The modified Delphi technique was adopted to identify priority water quality parameters affecting Crassostrea tulipa growth.

Place and Duration of Study: The Densu Estuary and Anyanui Lagoon were studied from November 2023 to December 2024.

Methodology: Physicochemical variables were analysed using the Canadian Council of Ministers of the Environment Water Quality Index (CCME-WQI), while benthic macroinvertebrate assemblages were used as biological indicators of ecological integrity. Expert consultation informed the selection and weighting of key physicochemical variables included in the index. Macroinvertebrate assemblages revealed greater taxonomic diversity and ecological integrity in the Anyanui Lagoon than in the Densu Estuary.

Results: Macroinvertebrate assemblages revealed greater taxonomic diversity and ecological integrity in the Anyanui Lagoon than in the Densu Estuary.

The occurrence of taxa such as Lithophaga lithophaga and Leptocerus sp. indicated relatively stable environmental conditions in Anyanui, whereas the higher Hilsenhoff Biotic Index in Densu (5.06), compared with Anyanui (3.82), suggested greater organic pollution pressure in the Densu Estuary. CCME-WQI scores classified the Anyanui lagoon as marginal (47.14) and the Densu estuary as poor (38.69), indicating environmental conditions that may limit oyster growth, recruitment and long-term fishery productivity. Although both approaches provided complementary information, benthic macroinvertebrates offered a more integrative assessment of ecological condition than physicochemical measurements alone.

Conclusion: These findings demonstrate the value of integrating biological and physicochemical indicators for ecosystem assessment and provide a scientific basis for prioritising habitat restoration, long-term ecological monitoring and adaptive management to sustain Ghana's brackish-water oyster fisheries.