Aquatic Ecology最新文献

The Citarum River, renowned as one of the most polluted waterways globally, traverses a basin exhibiting an urban–rural gradient and is inundated with diverse industrial activities, known to be significant contributors to its pollution levels. This study aims to evaluate the ecological health of the Upper Citarum watershed's industrial zones by utilizing macroinvertebrates as bioindicators. Throughout our investigation, we found that industrial sectors, particularly textiles, were closely linked to deteriorating water quality. This decline manifested in an increase in tolerant taxa and a decrease in sensitive ones. Such trends corresponded with escalating pollution index and low biomonitoring scores, indicating not only a decline in water quality but also significant sedimentation. Notably, Tubifex sp. emerged as the predominant organism in the Upper Citarum watershed, especially prevalent in textile and mixed industrial areas, accounting for 79% of the dissimilarity across all stations. However, this organism was conspicuously absent in pharmaceutical industry site. This absence resulted in significant differences in community composition compared to other industrial stations, as confirmed by both the analysis of similarities and the canonical correspondence analysis (CCA) graph. The separation of pharmaceutical industry sites from others in the CCA graph underscores distinct pollution and ecological statuses, primarily reflected to variations in the benthic macroinvertebrate community. Our study underscores the detrimental impact of industrial activities on the water quality of the Citarum River, urging future research to delve into the concealed risks posed by pharmaceutical waste. It emphasizes the urgent need for stringent pollution control and management strategies in this vital waterway.

Debris dam removal serves as a conservation strategy to enhance landscape connectivity. However, we still do not know the joint effects of debris dam removal and seasonality on riverine species. Using multi-year data in a monsoonal stream, we examined the response of macroinvertebrate communities to the removal of one debris dam using a Before-After-Control-Impact design (BACI). We found that the debris dam removal did not affect organic matter quantity, invertebrate abundance and diversity, and community structure, except for the abundance of invertebrate filter-feeders. On the other hand, seasonality influences nearly all of the ecological metrics which suggests that seasonality can override debris dam removal as the main driver of these ecological metrics. Moreover, extreme flooding during the wet season affects the abundance of invertebrates, suggesting that the seasonal life cycle of invertebrates after recovering from the dry season, may not fully compensate for the impact of extreme flooding. Evaluating the ecological impacts of debris dam removal in monsoonal areas with dynamic weather conditions could benefit the decision-making of using debris dam removal as conservation practices by restoring freshwater habitat with minimal impact on riverine species (e.g., macroinvertebrates) as far as freshwater ecosystem, especially with the occurrence of extreme floods.

The aim of the current study is to investigate urban region’s influence on the incidence of pesticides, and on physical, chemical and microbiological variables in the Potiribu River, in order to analyze their association with biochemical biomarkers in the Neotropical fish Astyanax spp. Water, sediment and fish samples were collected in both an upstream (S1) and downstream (S2) located in a city in Southern Brazil, at three different periods of the year (summer, autumn, and winter). Four pesticide active ingredients were detected in the Potiribu River: one fungicide, two herbicides and one insecticide (two of them recorded higher concentration in S2). Based on redundancy analyses results, pH, electrical conductivity, oxidation/reduction potential, turbidity and temperature were the water quality variables mostly contributing to biomarker responses in Astyanax spp. Pearson’s correlation analysis has shown that pesticides have both positive and negative correlation to biomarkers. In addition, physicochemical variables have overall shown positive correlation to lipid peroxidation and non-protein thiols levels, mainly in fish liver; as well as negative correlation to protein carbonylation levels in fish brain, gill, liver and muscle tissues. These results demonstrate the importance of evaluating physicochemical variables together with biomarkers, since the correlation of these variables demonstrated that fish already have damage in their tissues (lipid peroxidation and protein carbonylation) and that can compromise the fitness of the species in the long term. Water quality results indicated that Potiribu River is contaminated by agricultural and urban sources. Finally, both the water physicochemical variables and the pesticides are related to the biomarker responses in Astyanax spp.

This study investigated the environmental variables that influence heterotrophic protozoan assemblages in streams located in urban-agricultural landscapes of Argentina and estimated their potential as water quality indicators through environmental optimum distribution calculations. We sampled nine streams across all four seasons, collecting data on relevant environmental variables and protozoans in the water. For the analysis, we compared richness and total abundance across seasons and among streams and then focused on dominant genera. We performed a canonical correspondence analysis, multiple regression models, and calculations of optimum and tolerance levels. A total of 109 taxa most of them belonging to ciliates were identified. Total density distribution among seasons (spring was different from the other seasons) and streams were variable. Stentor and Zoothamnium were associated with higher water flow and high chlorophyll-a (Chl-a) content. At the same time, Paramecium, Blepharisma, Holophyra, and Litonotus were linked to lower oxygen availability or higher organic matter concentrations. Results showed that Pleuronema and Holophrya had lower optimum temperature values than Difflugia and Arcella. For dissolved oxygen, Holophrya had a higher optimum value than Litonotus while for Chl-a content, Stentor and Zoothamnium had a higher optimum value than Vorticella. The other showed similar optimum values for soluble reactive phosphorus, water temperature, and biochemical oxygen demand (BOD₅), all displaying broad tolerance ranges. Results suggest that protozoa assemblages respond to environmental changes in lowlands streams, and optimum distribution values of some genera suggest that these groups could be used in the future to design water quality indexes.

The ecological role of planktonic harpacticoid copepods within marine ecosystems remains understudied. While primarily benthic, a subset of these organisms exhibits pelagic lifestyles. This research investigates the relationship between environmental factors and planktonic harpacticoid communities at Marina Beach, Chennai, a coastal area impacted by pollution from the Adyar and Cooum rivers. Zooplankton samples and environmental data were collected monthly from January to December 2021. Among the seven observed harpacticoid species, Longipedia weberi and Euterpina acutifrons displayed dominance, with mean abundances of 178.2 ± 190.54 ind./m³ and 196.5 ± 155.8 ind./m³, respectively. Notably, the distributional pattern of L. weberi differed from that of E. acutiforns, with the former prevailing when micro-nutrient content in the water was high, particularly from June onwards. Regression analyses revealed a positive correlation between L. weberi abundance and nitrite and phosphate concentrations (R = 0.31 and 0.358, respectively). Furthermore, redundancy analysis indicated a close association between L. weberi and other nutrient parameters, suggesting its potential as an indicator species for coastal eutrophication along the Chennai coast. Throughout the study period, the diversity and distribution of harpacticoid copepods exhibited variations across different months.

The bivalve industry faces significant financial losses due to fluctuating salinity levels, highlighting the need to determine the optimal salinity for Saccostrea cucullata cultivation. This study investigates how salinity affects growth, filtration rate, nutritional composition, and antioxidant status. Oysters, averaging 6.26 ± 0.82 cm in shell length and 62.70 ± 15.01 g in weight, were randomly divided into four groups (10 individual each) within 10 L containers with salinities of S20, S25, S30, and S35 PSU. Over eight weeks, they were fed Chaetoceros sp microalgae twice daily. Also, at one- and two-hour intervals, their density was again counted to determine the filtration rate. Fatty acid and amino acid compositions were analyzed using gas chromatography (GC) and high-performance liquid chromatography (HPLC), respectively. Antioxidant enzyme activities (superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GPx)) were measured by spectrophotometr. Filtration rates were measured at one- and two-hour intervals, with the highest rates observed at 30 and 35 PSU after one hour and at 35 PSU after two hours, significantly differing from other salinities (P < 0.05). Analysis revealed that a salinity of 35 PSU resulted in elevated levels of several amino acids including arginine, alanine, taurine, threonine, serine, glutamic acid, tyrosine, phenylalanine, histidine, and valine compared to other levels (P < 0.05). Additionally, 35 PSU showed the lowest levels of myristic acid (C14:0), palmitic acid (C16:0), and total saturated fatty acids (SFA), significantly differing from other salinities (P < 0.05). In terms of monounsaturated fatty acids (MUFA), the highest levels of palmitoleic acid (C16:1) and total MUFA were found at a salinity of 35 PSU, with significant differences from other levels (P < 0.05). Similarly, 35 PSU exhibited the highest total polyunsaturated fatty acids (PUFA) content, including linolenic acid (C18:3), arachidonic acid (C20:4), docosahexaenoic acid (DHA, C22:6), and eicosapentaenoic acid (EPA, C20:5), along with favorable ratios of n-3 to n-6 series fatty acids. Moreover, the lowest levels of CAT, GPx, and SOD were recorded at a salinity of 35 PSU (P < 0.05). Overall, these findings suggest that a salinity of 35 PSU optimally enhances the filtration rate, nutritional profile, and antioxidant capacity of S. cucullata. These results underscore the significant influence of salinity on physiological and biochemical processes in this species, providing valuable insights for improved management and cultivation practices in the bivalve industry.

Microalgae are increasingly recognized for their potential in renewable energy, nutrition, and wastewater treatment applications. In this study, the effects of salinity on the growth and productivity of two microalgal species were examined, with a focus on their responses to salinity variations ranging from 0 to 10 g l⁻¹. A novel aspect of this research is the employment of salinity as the sole limiting factor in kinetic growth models, a less conventional approach that has been found to effectively delineate the growth patterns of both species. This method allows for the exploration of alternative substrates beyond the commonly used nutrients and light, thus enhancing the understanding of the diverse factors influencing microalgal growth. It was observed that salinity levels above 2 g l⁻¹ inhibited the growth of Chlorella vulgaris Beijerinck 1890, indicating a preference for freshwater and low salinity conditions. In contrast, resilience to salinity up to 5 g l⁻¹ was demonstrated by Desmodesmus communis (E.Hegewald) E.Hegewald 2000, suggesting its suitability for cultivation in brackish or moderately saline conditions. Despite some reports of high salinity tolerance in C. vulgaris, variability in halotolerance among different strains was revealed by this research, highlighting the importance of meticulous strain selection. The modified Richards model was identified as the most appropriate kinetic model for both species. These findings underline the necessity for species-specific models to accurately predict microalgal growth under saline conditions, contributing to a better understanding of microalgal salinity tolerance and aiding in the optimization of strain selection and cultivation for diverse applications, including saline wastewater treatment.

Graphical abstract

Nitrite accumulation in aquatic habitats can induce toxicity and cause spleen injury in fish. This study identified forkhead box (FOX) transcription factors involved in the splenic response to nitrite stress in largemouth bass through transcriptomic analysis. Phylogenetic analysis classified 93 FOX genes into 17 subgroups, with FOXN, FOXP and FOXO showing significant upregulation after nitrite treatment. Further analysis identified msFOX_29, msFOX_81, msFOX_89 and msFOX_7 as key FOX transcriptional regulators mediating spleen injury. Co-expression network analysis revealed that these FOX transcription factors may regulate downstream targets involved in pathways such as apoptosis (CASP8), immune cell infiltration (CD34), protein synthesis (UBA52, FARSB), signal transduction (PPP2CB), and metabolism (GUK1). These targets contained FOX binding sites in promoter regions and were upregulated under nitrite stress. Additionally, FOX expression was found correlated with changes in immune cell infiltration. Cross-species analyses revealed phylogenetic conservation and functional importance of FOXN, FOXP and FOXO subgroups in the splenic responses more fish species. Our study delineates the FOX transcriptional regulatory networks mediating nitrite-induced spleen injury in largemouth bass and provides insights into nitrite toxicity mechanisms in fish.

Improvement in water quality of several rivers was noted during COVID lockdowns by several studies but no report was dedicated to trace the water quality after COVID. Our study observed the water quality of Balili River, Philippines from 2018–2023 to address this data gap and learn lessons and ways forward towards the attainment of SDG 6 Water and Sanitation. The river exhibited significant improvement during COVID at TSS, color, DO, BOD, PO4 and Cl. The cumulative parameters namely water quality index and comprehensive pollution index showed that the water quality of Balili River improved during COVID at 27–40% but deteriorated again after COVID, though not as polluted as the pre-COVID state. The fecal coliform got worse during COVID but drastically improved after COVID. The water quality generally is worst during dry season then improves in the rainy months due to dilution from rain. These results show that upland tropical rivers, particularly in the case of Balili River, Benguet, Northern Philippines has a natural means of purification namely dilution from rain. Hence, the floating constructed wetland could be implemented during dry months starting from November to May. During heavy rains, the floating constructed wetland could be allowed to be swept downstream, allowing dilution as the next mode of remediation. Then after the rainy season, another floating constructed wetland would be established for another cycle.