Aquatic Ecosystem Health Research Articles

An efficient data fusion model based on Bayesian model averaging for robust water quality prediction using deep learning strategies

Accurate monitoring of dissolved oxygen (DO) levels is critical for stakeholders to effectively safeguard water resources and aquatic ecosystem health. This research presents an innovative data fusion framework based on Bayesian model averaging (BMA) by the combination of several neuroscience models (deep learning methodologies) including multilayer perceptron neural network (MLPNN), recurrent neural network (RNN), convolutional neural network (CNN), gated recurrent unit (GRU), long short-term memory (LSTM), and seasonal autoregressive integrated moving average with exogenous variables (SARIMAX). BMA has the capacity to greatly enhance the results attained by standalone approaches. In this study, two feature selection methods such as mutual information (MI) and recursive feature elimination (RFE) applied to select effective predictors and investigate the importance of each input parameters. The techniques were evaluated based on four different metrics and, finally, to demonstrate the usefulness and effectiveness of the newly implemented strategy, it was applied proficiently at the USGS stations, 01427510 and 02336152 within the USA. The findings from analyzing data based on two stations confirmed that the suggested approach (BMA) outperformed other methods such as MLPNN, RNN, CNN, LSTM, and SARIMAX when it came to predicting the levels of DO on a daily basis. In terms of RMSE, MAE and R2, BMA yielded 0.272 mg/L, 0.216 mg/L, and 0.975 using MI technique and 0.320 mg/L, 0.261 mg/L, and 0.965 using RFE method at 01427510 USGS station, respectively. Similarly, based on RMSE, MAE and R2, BMA produced DO prediction by RMSE = 0.352 mg/L, 0.264 mg/L, and 0.968 by MI approach and RMSE = 0.378 mg/L, 0.282 mg/L, and 0.963 via RFE process at 02336152 USGS station, respectively. After analyzing different combinations of input that obtained from feature selection paradigms, it was observed that the variables with the greatest impact on daily dissolved oxygen levels are the dissolved oxygen levels in the previous time period and the water temperature. On the other hand, the pH and turbidity have minimal influence on the daily DO. Finally, the results of this study confirmed that the BMA tool can be efficiently applied to predict DO concentration based on deep learning model outputs.

Characterizing spatial patterns among freshwater fishes and shrimps of the Poso River (Sulawesi, Indonesia) using DNA barcoding

Fish biodiversity assessments are vital for understanding threats and aquatic ecosystem health. In the Poso River, Central Sulawesi, changes in biodiversity are influenced by habitat alteration, non-native species, and overfishing. This study evaluates fish and crustacean biodiversity in the Poso River system to address these challenges for improving fisheries management, conservation, and fish passage integration into hydropower development. The present biodiversity study utilized a comprehensive methodology that encompassed both traditional taxonomic approaches and DNA barcoding, specifically targeting the mitochondrial cytochrome c oxidase subunit-1 (COI) gene for accurate species identification and spatial boundary validation. The survey was conducted in the upstream, hydropower area and downstream areas of the river. We found 27 species of fish in the Poso River, including both native (e.g., Anguilla celebesensis, Oryzias nebulosus, Rhyacichthys aspro) and non-native species (e.g., Melanochromis auratus, Amphilophus trimaculatus, Oreochromis niloticus). Two International Union for Conservation of Nature (IUCN) red listed endangered species were also observed (e.g., Adrianichthys poptae and Mugilogobius sarasinorum). DNA barcoding was performed to examine species spatial boundaries. The fish population in the Poso River was dominated by non-native species, accounting for 85.70% of the total population. The upstream reaches had the highest fish abundance and diversity, while the downstream reaches had the lowest. There was, however, no significant difference in species richness and diversity across different locations and seasons. The dominance of non-native species in the Poso River necessitates the improvement of existing fishways within the hydropower dams potentially through the development of selective technology that can block the distribution of these non-native species. This research highlights the critical issue of non-native species proliferation and the potential threat they pose to native fish populations, providing valuable insights for conservation and management efforts in Indonesia and similar ecosystems worldwide.

Identification of 2, 4-di-tert-butylphenol from Microcystis lysate after bloom control and its potential risks to aquatic ecosystems

With the increasing concern of cyanobacterial blooms, numerous techniques have been developed to mitigate these environmental nuisances. During bloom control, the allelopathic effects of compounds released from cyanobacterial cells are considered as secondary hazards. In this study, the findings indicated that Microcystis lysate inhibited algal proliferation and disrupted the development of zebrafish embryos. Then, allelochemicals in Microcystis lysate were identified using gas chromatography-mass spectrometry, with 2, 4-di-tert-butylphenol (2, 4-DTBP) being the only identified phenol, which was selected for further study. The results showed that 2,4-DTBP caused oxidative damages, disrupted metabolic activity, and suppressed photosynthetic activity, consequently impeding the growth of Microcystis aeruginosa (M. aeruginosa) and Chlorella pyrenoidosa (C. pyrenoidosa). Moreover, it enhanced the interspecies competitive advantages of M. aeruginosa by increasing phosphate uptake rate. Furthermore, at a concentration of 2 mg L−1, 2, 4-DTBP negatively affected the development of zebrafish embryos, manifesting in mortality, malformation, and hatching delay. Therefore, the investigation identified 2, 4-DTBP as a potential allelochemical within Microcystis lysate. Although the effective concentration for freshwater algae and zebrafish embryos was higher than that found in Microcystis lysate, it highlighted the need for careful monitoring of aquatic ecosystem health during cyanobacterial bloom mitigation.

Decadal Trends and Predictive Insights into Aquatic Ecosystem Health in the Namhan River, South Korea: Longitudinal Analysis of Hydro-Environmental Factors and Stream Health Indices (2008–2022)

The main focus of this study is to explore the complex interactions between aquatic ecosystem health (AEH) and time-varying hydro-environmental factors. We measure AEH in the Namhan River of South Korea using stream health index (SHI) scores for the trophic diatom index (TDI), benthic macroinvertebrate index (BMI), and fish assessment index (FAI) for 2008 to 2022. Key hydro-environmental variables associated with AEH, including their time-lagged responses, are identified. Water quality parameters such as chemical oxygen demand (COD) are significantly and negatively correlated with TDI (), BMI (), and FAI (), highlighting the critical role of water quality in the sensitivities of diatoms, macroinvertebrates, and fish health. The apparent response lag of aquatic ecosystems to hydrological parameters, such as a one-year-lagged correlation of BMI with mean flow () and annual flow anomalies (), suggests their potential use as predictors in AEH models. A longitudinal analysis of SHIs over a decade showed consistent changes in AEH from upstream to downstream, with notable trends in the deterioration and improvement of SHIs in different areas. The upstream TDI and BMI deteriorated, while the upstream FAI improved. A multiple-linear-regression–based predictive model demonstrated efficacy in predicting AEH under various hydro-environmental conditions, achieving R2 values up to 0.85 for BMI and also has the potential to simulate the impacts of anticipated climatic and hydrological changes.

Estimating Concentration of Suspended Solids Load in Estuary System Utilizing Sentinel 2A: A Case Study of Cipatujah Beach, Indonesia

Abstract Total Suspended Soil (TSS) and Total Dissolved Solid (TDS) refer to materials in the form of sediment and organic substances suspended and dissolved in water which are used as water quality parameters to understand sediment transport, the health of aquatic ecosystems, and technical problems. Concentrations in significant amounts in water areas can be caused by the dynamics of the earth’s surface and human activities, the resulting negative impacts will reduce the quality of the ecological system and indicate the presence of pollutants. This research was conducted to determine the concentration of Total Suspended Soil (TSS) and Total Dissolved Solid (TDS) in estuary waters at Cipatujah Beach, West Java, Indonesia using remote sensing satellite imagery, namely Sentinel-2A. The research carried out focused on testing samples for Total Dissolved Solid (TDS) content, which is one indicator of the level of water pollution that is often analyzed. From the results of sample tests carried out using a TDS meter, it shows that the TDS content in Cipatujah Beach is above 400 ppm so it is not suitable for use as drinking water, and further laboratory tests need to be carried out to determine the TSS content in Cipatujah Beach water.

An improved hydraulic method for calculating ecological flow considering the changes of rainfall and temperature within a year

Ecological flow (Hereinafter referred to as EF) is vital for sustaining the health of aquatic ecosystems, whereas fluctuations in rainfall and temperature markedly influence the water needs of riverine aquatic organisms. However, traditional hydrological methods for calculating EF provide a single, fixed EF value throughout the year or for specific periods (such as the flood season or non-flood season), neglecting the dynamic effects of these environmental variables on flow requirements. Building on regression analyses of rainfall and temperature, this study proposes an improved hydraulic method (Hereinafter referred to as IHM) that integrates both rainfall and temperature effects. Utilizing the three cascade hydropower plants on the mainstream of the Liuxi River in Guangdong Province, China, as case studies, the proposed method expands upon traditional hydraulic methods by establishing a relationship between river hydraulic parameters and flow, and employing the ecological suitability thresholds of indicator species as constraints to calculate the EF solution sets for the three hydropower plants. By fitting functions to the basin’s rainfall and temperature data, linear interpolation was applied to distribute the EF solution sets across 12 months within a year. The IHM is subsequently compared and validated with the evaluation standards of the traditional method. The results demonstrate that the monthly EFs by the IHM for the three cascaded hydropower plants address the constraints of fixed EFs by traditional hydraulic methods, offering more accurate and context-specific EFs for each month. The monthly EFs by the IHM also typically conform to the Tennant method’s 10 % standard (fair status) and, during certain months, reach the 40 % standard (good status), thereby effectively preserving the stability of the river’s aquatic environment. The IHM provides a robust technical foundation and theoretical framework for the accurate determination of EFs in riverine hydropower plants.

A Review on the Impact of Vertical Slotted Fish Passages on Fish Populations in River Basins

The interruption of fish migration routes has a negative impact on the health of aquatic populations and ecosystems. To address this issue, vertical seam fishways are designed to assist fish in crossing dams and embankments. This article integrates the concept and design ideas of vertical seam fishways, the impact assessment of vertical seam fishway construction on fish in the watershed, as well as the problems and challenges encountered, by searching and reading relevant materials. The aim is to provide reference for ecological restoration and fish protection in hydraulic engineering.

Landsat data reveal lake deoxygenation worldwide

Dissolved oxygen (DO) is a fundamental requirement for the survival of aquatic organisms, which plays a crucial role in shaping the structure and functioning of aquatic ecosystems. However, the long-term DO change in global lakes remains unknown due to limited available data. To address this gap, we integrate Landsat data and geographic features to develop DO estimation models for global lakes using machine learning approaches. The results demonstrated that the trained random forest (RF) model has better performance (R2 = 0.72, and RMSE = 1.24 mg/L) than artificial neural network (ANN) (R2 = 0.66, and RMSE = 1.39 mg/L), support vector machine regression (SVR) (R2 = 0.62, and RMSE = 1.45 mg/L) and extreme gradient boosting (XGBoost) (R2 = 0.72, and RMSE = 1.29 mg/L). Then, we used the trained RF model to reveal the DO long-term (1984–2021) change in surface water (epilimnetic) of 351,236 global lakes with water area ≥ 0.1 km2. The results show that the average epilimnetic DO concentration of global lake was 9.72 ± 1.07 mg/L, with higher DO in the polar regions (latitude > 66.56 °) (10.87 ± 0.54 mg/L) and lower in the equatorial regions (−5 ° < latitude < 5 °) (6.29 ± 0.63 mg/L). We also find widespread deoxygenation in surface water of global lakes, with a rate of − 0.036 mg/L per decade. Meanwhile, the number of lakes and surface area that experiencing DO stress are continuously increasing, with rate of 39 and 212.85 km2, respectively. Our results offer a comprehensive dataset of DO variation spanning nearly 40 years, furnishing valuable insights for formulating effective management strategies, and enhancing the maintenance of the health of aquatic ecosystems.

Evolution of hydrochemical characteristics and the influence of environmental background in the Hailar River basin, China.

Understanding the evolution of hydrochemical characteristics in river systems is essential for environmental assessment and water resource management. This study explores the spatiotemporal distribution and the determinants of hydrochemical characteristics in the Hailar River basin, China, over an extensive period. Our results revealed that CODMn and CODCr were the primary concerns for long-term river management, with exceedance rates of 42.92% and 50.62%, respectively. These exceedances were predominantly driven by interactions between riparian soils and surface water, rather than anthropogenic pollution, as suggested by the strong correlations between dissolved organic carbon and soil water-extractable organic carbon, and the limited human footprint in this region. Piper trilinear and Gibbs diagram analysis further revealed that long-term rack weathering shaped the basin's hydrochemical characteristics, resulting in distinct HCO3--Ca2+ and HCO3--Ca2+-Na+ signatures. In addition, APCS-MLR analysis identified that elevated of CODMn and CODCr levels were mainly attributed to the interactions with adjacent soils, which are extensively covered by forests and grasslands. In contrast, leaching and migration processes contributed significantly on total dissolved solids and total phosphorus. The study also found that environmental self-purification processes played a key role in regulating Fe concentrations. This investigation provides a nuanced understanding of the environmental background's influence on hydrochemistry and dissolved organic matter (DOM) in the Hailar River basin, which offers valuable insights and methodologies for the rational assessment of water quality and aquatic ecosystem health in similar riverine systems.

Climate Warming and Mismanagement Drive the Shift of Fish Communities in the Wadi El-Rayan Arid Lakes

The Wadi El-Rayan lakes are important aquatic environments located at the border of the great North African Sahara. Quantifying the temporal changes in these lakes due to natural and/or anthropogenic stressors is critical when assessing potential impacts on aquatic ecosystem health and the sustainability of fisheries. To detect the changes in fish communities and their drivers, the landing composition of the Wadi El-Rayan lakes over the past 30 years was quantitatively analyzed. The areas of the lakes dramatically decreased from 110 km2 in 1991 to 73 km2 in 2019. The loss of the lake area was attributed to climate warming, where the evaporation rate exceeded the volume of recharge and the recharge decreased due to an increase in agriculture and aquaculture. The total landing significantly increased in the past three decades due to an increase in the fishing effort (number of licensed boats). Nile tilapia, mullet, and grass carp dominated the landings. The pelagic-to-demersal ratio indicated a shift in the fish community composition towards demersal species. This shift was attributed to an increase in the eutrophication level. The fish communities of the landing data were clustered into four distinct groups. These clusters were significantly differentiated (p &lt; 0.001) in both a PERMANOVA test and a PCA plot. There was a gradual replacement of the dominant species among these clusters. The most recent cluster (2018–2019) was characterized by rare species dominating the community. This shift in species composition suggests that target taxa may have been overexploited. The total landing also decreased, which may have been a result of climate warming. Furthermore, the presence of alien and warm-water species significantly increased. The fish community structure and composition shift could be attributed to anthropogenic (mismanagement) and natural climatic changes (warming).

Effect of sponge city facilities on the exposure characteristics and ecological risks of antibiotics in urban inland lakes: A case study at Fuzhou, China.

Antibiotics are increasingly found in urban lakes, posing significant ecological risks to lake ecosystems. The impact of sponge city facilities on urban flood control is significant; however, their influence on the exposure characteristics and risks associated with antibiotics in urban inland lakes remains unclear. This study investigated the exposure characteristics and evaluated the ecological risks of 15 antibiotics across seven lakes of Fuzhou (as the target of sponge city) in different seasons, in comparison to non-sponge cities. The results revealed that 12 antibiotics were consistently detectable across all lakes, with concentrations ranging from non-detectable (ND) to 20.61ng/L, with sulfamethoxazole (SMX) emerging as the predominant contaminant. Most antibiotics exhibited higher concentrations in the dry season, attributed to environmental conditions, biological mechanisms, and their physicochemical properties. SMX, tetracycline (TTC), oxytetracycline (OTC), and ciprofloxacin (CIP) posed moderate to high ecological risks, with risk quotient (RQ) values of 0.46, 0.14, 0.17, and 0.61, respectively, while the remaining antibiotics presented lower ecological risks in both seasons. Notably, the RQ values for TTC, OTC, and CIP were elevated during the dry season, whereas SMX displayed a higher RQ value in the wet season, indicating an increased ecological risk during the dry months. In comparison to non-sponge cities, sponge cities exhibited significantly lower concentrations of nearly all antibiotics, particularly during the wet season (p ≤ 0.05). Moreover, over 85% of the antibiotics in non-sponge cities were classified as high risk, contrasted with only 55% in sponge cities, underscoring the heightened ecological risks associated with non-sponge urban designs. This study provides critical insights for controlling antibiotic pollution in the lakes of Fuzhou and serves as a valuable reference for maintaining aquatic ecosystem health through the implementation of sponge city infrastructure.

Assessing and Optimizing Ecological Flow Rates for the Habitat of Zacco platypus in the Tan River

As rivers face growing environmental challenges due to climate change and the construction of artificial structures, it is essential that we improve river ecosystems to maintain their ecological functions and preserve the health of aquatic habitats. The aim of this study was to assess the aquatic ecosystem health of the lower reaches of the Tan River. We employed the Physical Habitat Simulation System and Hydrologic Engineering Center’s River Analysis System to calculate the ecological flow rate based on the weighted usable area (WUA) of Zacco platypus, which is a representative fish species in the Tan River, and the flow rate relationship curves. By analyzing the flow rates in the Tan River across different seasons from 2012 to 2021, we determined that the seasonal optimal ecological flow rate was 10.21–10.27 m3/s. Meanwhile, the WUAs for spring, summer, and autumn and winter were 90–100%, 95–100%, and 75–100%, respectively. Despite meeting the ecological flow criteria for summer, fall, and winter over 50% of the time, spring fell short at 41%; hence, the Tan River flow rates should be secured particularly in spring. This study highlights the urgency of addressing seasonal variations to ensure the overall health of the Tan River ecosystem.

Impacts of fish pond effluent on the water quality of an afrotropical stream: a comprehensive evaluation using the water quality index

This study highlights the importance of managing fishpond effluent to minimize its impact on aquatic environments. Fish effluents are a major concern worldwide in aquatic environments. It also provides information on the impacts of effluents on the water quality index of streams when released into aquatic environments. Streams and fishponds were sampled bimonthly for two annual cycles, covering different sampling stations both upstream and downstream of the fishpond effluents at 50-m intervals. Water quality parameters associated with in situ conditions were determined in the field. In the laboratory, other physicochemical parameters were determined via proper standard protocols. The results of the study revealed that water quality parameters such as turbidity, total suspended solids, total solids, conductivity, total dissolved solids, dissolved oxygen, biological oxygen demand and organic matter recorded in water samples collected from 50 m upstream at the point of effluent discharge were significantly (p < 0.05) different from those recorded at other sampling stations. The WQI value of the discharge point was higher than the WQI recorded in both the upstream and downstream sections of the stream. The findings of this study showed that the point of discharge of fishpond effluents is particularly concerning for the receiving stream compared with other sampling points. This localized area has experienced marked deterioration in water quality, posing significant threats to the health and biodiversity of aquatic ecosystems. The effluent's impact, though slight when dispersed in the receiving waterbody, underscores the necessity for adequate management practices to mitigate its adverse effects. Effective strategies, including regular monitoring, effluent treatment, and sustainable pond management, are imperative to ensure the long-term health and resilience of the aquatic environment.

Screening of Characteristic Pollutants and Risk Pollutants in Different Media in the Yangtze River Basin Using Comprehensive Evaluation and Risk Quotient Methods

A variety of pollutants have frequently been detected in the Yangtze River Basin with the rapid economic development, the population increase, and the acceleration of urbanization, which threaten the aquatic ecosystem and human health. A multi-criteria comprehensive evaluation method was developed to identify the characteristic pollutants, and the risk quotient method was used to derive the risk pollutants in water and sediment samples in this article. A total of 155 pollutants from 11 categories were detected in the Yangtze River Basin according to the literature research. Then, the K-means method was used to analyze the cluster of pollutant comprehensive scores. All pollutants were graded based on their scores and recorded as Ⅰ-Ⅵ according to the number of cases in each cluster. A total of 43 pollutants with high scores of Ⅰ and Ⅱ were listed as the characteristic pollutants, which included 11 polycyclic aromatic hydrocarbons, 11 organochlorine pesticides, 10 polychlorinated biphenyls, eight dioxins, two heavy metals, and one phthalate ester. The top five median concentrations of contaminants in water and sediment samples were heavy metals, polycyclic aromatic hydrocarbons, phthalates esters, bisphenols, and pharmaceuticals and personal care products. According to the principle of risk maximization, the risk entropy value （RQ） was calculated based on the highest pollutant concentration. A total of 38 risky pollutants were screened in the water samples （RQ ≥ 0.1）. There were eight high-risk pollutants with RQ ≥ 1, which included benzo[a,h]-anthracene, anthracene, benzo[a]anthracene, pyrene, methoxychlor, aldrin, 2,4'-dichlorodiphenyl, and cadmium. There were 15 high-risk contaminants in the sediment, which included benzo[b]fluoranthene, anthracene, acenaphthene, fluoranthene, cadmium, lead, chromium, arsenic, selenium, dibutyl phthalate, dimethyl phthalate, diisobutyl phthalate, norfloxacin, perfluorobutyric acid, and bisphenol A. The risk pollutants contained emerging pollutants, which included ten pollutants in water samples and nine pollutants in sediments. Antibiotic pollutants accounted for the largest proportion of these emerging pollutants. The information provided in this article may be useful for the relevant departments to monitor the pollutants and propose management programs for the Yangtze River Basin. Additionally, it is of great significance for the ecological environmental protection and management of the Yangtze River Basin.

A Study the concept and legal principles of Water Management

Water management is a multifaceted concept that encompasses the planning, development, distribution, and optimal use of water resources. It is crucial for ensuring the sustainable supply of water for various human needs, including drinking, agriculture, industry, and recreation, while also maintaining the health of aquatic ecosystems. Effective water management involves the integration of scientific, technical, economic, and social considerations to balance competing demands and protect water quality. Legal principles play a pivotal role in guiding water management practices. These principles provide a framework for regulating water use, resolving conflicts, and promoting sustainable practices. Key legal principles in water management include the doctrine of equitable and reasonable use, which ensures fair allocation of water resources among users; the precautionary principle, which mandates proactive measures to prevent water pollution and degradation; and the principle of public participation, which emphasizes the importance of involving stakeholders in decision-making processes. International agreements and national laws often incorporate these principles to address transboundary water issues and domestic water governance. Effective implementation of these legal frameworks requires robust institutional arrangements, transparent governance, and enforcement mechanisms.

Microplastic in tissue of marine organisms

Plastic microwaste pollution poses a significant threat to biodiversity and the health of aquatic and terrestrial ecosystems. Microplastics (MPs) are synthetic polymers less than 5mm in size and currently classified as emerging contaminants. They are considered a global problem due to their ubiquity, infeasibility of substantial removal from the environment and exposure, and almost irreversible effects. Marine filter-feeding organisms are widely used in analyzing the occurrence of MPs due to their ecological and commercial importance. This work presents a literature review on the effects of bioaccumulation of plastic microwaste in the tissues of aquatic filter-feeding organisms, mainly bivalves. The data analyzed in the present study conclude that MPs have a high capacity for contamination and bioaccumulation, negatively influencing the quality of life of the biota. Its effects are related not only to physiological buffering in organisms but also to toxicity due to the release of compounds present in incorporated plastic particles, and the transport of various pollutants into the environment.

The parasite prevalence in Clarias gariepinus from artificial and natural habitats in Oguta imo state Nigeria

This study revealed the presence of parasites in the two habitats under study. The endoparasites recovered were found to belong to Cammallanida, Pseudophyllida, and Plagiorchiida taxonomic group. Both habitats were noted to be sparingly infected; however, the natural habitat was more infected than the cultured habitat. The physicochemical parameters assayed in this study of the water and sediment samples from all the locations indicate that the water samples fall within the stipulated range of acceptability by the World Health Organization (WHO). The heavy metal concentrations in fish tissues were also within WHO set limits for the survival of aquatic organisms. However, prolonged consumption of the fish species will have adverse effects since heavy metals can bioaccumulate overtime. By implication, from the current result it may be confirmed that catfish obtained from fish pond is healthier than the uninhabited fish type in relationships of nutrient substances for human feeding. This could be due to the fact different habitat of different species the body pattern varies nutritionally. Findings from this work showed that constant monitoring of water parameters provide insight to the health of fish and aquatic ecosystems as whole. Finally, it can be inferred from the results of this study that for consumers purchasing the products in large quantities on a regularly basis, a public health hazard will definitely exist especially from natural catfish where pollution is more pronounced as a result of human activities. On the other side, no hazard might exist through the consumption of average amount of such fishes since it is within WHO permissible limits.

Brief Overview of Methods for Assessing the Health of Aquatic Ecosystems. Problems and Prospects of Development

Brief Overview of Methods for Assessing the Health of Aquatic Ecosystems. Problems and Prospects of Development

Characteristics and Comparative Analysis of Six Mitogenomes of Genus Kiefferulus Goetghebuer, 1922 (Diptera: Chironomidae).

Chironomidae is a cosmopolitan and species-rich family of insects, with many species serving as useful indicators of aquatic ecosystem health. In this study, we newly sequenced six species of Kiefferulus Goetghebuer, 1922 (Chironomidae: Chironominae) by high-throughput sequencing technology. We analyzed characters of the mitochondrial genome, including the sequence length, nucleotide composition, and evolutionary rates of this genus. The size of the newly obtained sequences ranged from 15,588 to 15,767 bp, and all of them included 22 tRNAs, 13 PCGs, 2 rRNAs, and 1 CR. The CR showed the highest AT content relative to the PCGs, rRNAs, and tRNAs. Relative synonymous codon usage analysis showed that UUA, UUU, and AUU are the preferred codons. The ratio of nonsynonymous (Ka) to synonymous (Ks) substitution rates showed that all Ka/Ks of PCGs were lower than 1, with ATP8 having the highest evolution rate, while COX1 exhibited the lowest evolution rate. We reconstructed the phylogenetic relationship of the genus Kiefferulus based on eight species (six ingroups and two outgroups), using five matrices and employing Maximum likelihood and Bayesian inference approaches. Phylogenetic analysis of the Kiefferulus showed that six species within this genus were classified into a monophyletic clade.

Response of benthic assemblages to heavy metal contamination from shipbreaking operations in a tropical coastal area

The response of macrobenthic communities to both environmental and anthropogenic pressures serves as a valuable indicator of ecosystem integrity. This study aimed to unravel the benthic community structure, examine the heavy metal contamination status, and explore the response of the microbenthic community to heavy metals in a tropical shipbreaking region. For this, sediment and benthos samples were taken from different sampling stations of the shipbreaking area and the non-shipbreaking sites. The results showed the benthic community consisted of 23 taxa, including Polychaeta, Oligochaeta, Amphipoda, Decapoda, Gastropoda, Bivalvia, and Priapulida, with polychaetes being the predominant group. The benthic community and diversity values were significantly varied between the two sampling sites (p <0.05). Taxa richness was lower in the shipbreaking area, primarily characterized by the dominance of opportunistic benthic groups, particularly Capitella sp. The concentrations of heavy metals (µg. g−1) in the sediment varied within the following ranges: 35.54–258.021 for Zn, 4.84–132.08 for Pb, 22.82–75.25 for Cu, 198.74–764.16 for Mn, 14.57–42.13 for Cr, 4.03–42.23 for Ni, and 3.82–14.85 for Co. Based on concentration levels, Zn, Pb, and Cu were identified as major contaminants with moderate to high potential for adverse effects, particularly evident in the shipbreaking area compared to non-shipbreaking areas. Pollution indices, including enrichment factors and contamination factors, also highlighted contamination by Zn, Pb, and Cu. Among the benthic taxa, Polychaeta demonstrated a high degree of tolerance to elevated concentrations of these heavy metals. Amphipoda density was significantly negatively correlated with Zn, Pb, and Cu concentrations, with significant coefficients of determination (r2= 0.38, p <0.10; r2= 0.64, p <0.01 and r2 = 0.63, p <0.01, respectively). Multivariate analyses (cluster analyses, MDS and CCA) demonstrated both positive and negative relationships among heavy metals and benthic groups. Canonical Correspondence Analysis (CCA) showed the benthic community was negatively correlated with Zn, Pb, and Cu. This finding provided critical insights into the ecological health of aquatic ecosystems, aiding in the development of informed conservation and management strategies.