Aquatic Ecology最新文献

The present study investigates the distribution of zooplankton communities and heavy metals (HMs) contamination across aquatic ecosystems (pond, canal, and waterlogged sites) in four regions of East Medinipur, West Bengal—Tamluk, Haldia, Contai, and Egra. Zooplankton distribution showed clear group-specific and seasonal variations: Rotifer dominated with maximum densities up to 52.33 ± 8.33 ind./L, followed by Copepod (45.67 ± 2.08 ind./L) and Cladocera (21.33 ± 11.15 ind./L). Post-monsoon (POM) supported peak rotifer populations, whereas pre-monsoon (PEM) favoured copepods. The dominant taxa, including Heliodiaptomus viduus, Brachionus calyciflorus, and Moina brachiata, served as biotic indicators of environmental conditions. Haldia showed higher pollution and organic load, while Egra and Contai exhibited better water quality with stable physicochemical conditions. Heavy metal concentrations varied widely, with Zn (3.45–16.01 mg/L) and Ni (3.41–10.75 mg/L) dominating the contamination profile, while Hg (0.07–2.93 mg/L) and Fe (0.09–0.89 mg/L) remained comparatively low. Pollution Load Index (PLI) values ranged from 0.039 to 1.213, classifying most sites as unpolluted, except localized moderate pollution in Haldia and Contai. Potential Ecological Risk Index (PERI) spanned from 5.85 (Egra) to 252.80 (Haldia), indicating highest ecological risk in canal and waterlogged ecosystems. Geo-accumulation Index (Igeo) suggested study sites were largely uncontaminated, with cadmium enrichment (0.61–0.86) confined to Haldia. Correlation and redundancy (RDA) analyses demonstrated strong negative associations between zooplankton abundance and metals. Overall, the study highlights that zooplankton, particularly rotifers and copepods, serve as sensitive bioindicators of heavy metal stress in freshwater systems influenced by industrial and anthropogenic activities.

Helminth infections in freshwater fish affect fish health, aquaculture productivity, and food safety. This study examined the ecology of gastrointestinal helminths infecting freshwater fish along with other food fishes from the Lucknow region, India. The fish were sampled monthly (January-December 2024) and seasonally from fishers from the Gomti river wetlands. Fish were necropsied, and helminths were identified using standard taxonomic methods. Four major helminth groups trematodes, cestodes, nematodes, and acanthocephalans were detected. Prevalence peaked in snakeheads (65–75%; mean intensity (6–10 worms/host), followed by catfishes (60–80%) and carps (55–70%); salmonids showed the lowest (30–40%). Monsoon seasons showed infection peaks up to 85%, linked to intermediate-host abundance and favorable water conditions. Larger carnivorous hosts, lentic habitats, and cultured ponds were associated with higher burdens, notably Bothriocephalus acheilognathi in cultured carps. The role of host traits, environment in helminth transmission and the need for seasonal parasite-control strategies in northern India were emphasized.

Tolyltriazole (TTA) is one of the contaminants detected in groundwater near major airports, necessitating further investigation into the fate and effects of this chemical. This study examined the impact of TTA on African catfish (Clarias gariepinus) and explored Chlorella vulgaris as a bioremediation agent. Five groups of fish were established, including four treatment groups and a control group: low-dose TTA (1.1 µg/L) group, low-dose TTA with C. vulgaris (1.1 µg/L TTA + 50 g/kg C. vulgaris) group, high-dose TTA (2.2 µg/L) group, and high-dose TTA with C. vulgaris (2.2 µg/L TTA + 50 g/kg C. vulgaris) group. The exposure period was two weeks. Moreover, neurological parameters—acetylcholinesterase (AchE), cortisol, and monoamine oxidase (MAO)—were evaluated. Exposure to TTA led to a significant increase in AchE in the low-dose TTA with C. vulgaris group and a substantial decrease in the high-dose TTA group. In contrast, there was a notable rise in cortisol only in the high-dose TTA group. In comparison with the control group, MAO significantly increased in each group. Superoxide Dismutase was markedly reduced only in the group receiving a high dose of TTA. Catalase and Total Antioxidant Capacity were substantially lower in all groups than in the control group, except for fish given a low dose of TTA with C. vulgaris. Furthermore, TTA exposure revealed seeral histopathological alterations, including hydropic degeneration, along with karyolysis and pyknotic nuclei. On the other hand, C. vulgaris treatment enhanced the regular liver configuration. In conclusion, exposure to TTA causes changes in neurological parameters, antioxidant capacity, and normal liver histology; nevertheless, chlorella supplementation guards against these adverse effects.

Threespine stickleback (Gasterosteus aculeatus) are known for their rapid adaptation to a wide range of environments. However, despite having served as a model species for ecology, evolution, and developmental biology, little is known about the ontological dietary changes of juvenile individuals in the wild. This has created a gap in our knowledge, given that the organismal phenotype is largely moulded during the juvenile phase, and natural selection during this life stage is often strong. Lake Mývatn, Iceland, offers a unique setting to explore these early-life organism-environment interactions due to its high habitat and resource heterogeneity, as well as divergent adult stickleback feeding morphologies across habitats. Here, we tested whether diet, based on gut content analysis, and trophic morphology have diverged between juveniles from different habitats and if diet composition covaries with morphology and body size. Overall, we saw clear differences in diet composition among distinct habitats within the lake, and morphological divergence in head morphology (e.g. gape size) among contrasting habitats. Juveniles tended to either have many small Cladocera or Chironomidae larvae in their diet; smaller individuals tended to have more Cladocera, and bigger individuals consumed more Chironomidae larvae. Such an ontogenetic diet shift is congruent with laboratory and other field studies on juvenile stickleback. However, this is one of the first studies, to investigate the association between juvenile diet and head morphology in wild freshwater stickleback. Thus, the study delivers unique insight into the development of trophic morphology, as well as diet-mediated diversification in threespine stickleback.

Untreated urban wastewater is a major driver of aquatic ecosystem degradation, yet its impacts on saline wetlands, notably Sabkha ecosystems, remain poorly understood. We investigated the fine-scale responses of benthic macroinvertebrates to wastewater discharge in Sabkhat El Mahmal, a Mediterranean Sabkha in northeastern Algeria. During monthly surveys over a one-year period, we concurrently measured physicochemical and bacteriological water parameters and sampled benthic macroinvertebrates at six stations along a pollution gradient, followed by community analyses using multivariate and indicator-species approaches. Urban wastewater inputs induced localised desalination, elevated phosphate concentrations, and increased faecal coliform counts, leading to significantly degraded water quality near the discharge outlet. While taxonomic richness, abundance, and diversity did not vary significantly among stations, community structure shifted markedly. Polluted stations were dominated by pollution-tolerant taxa such as Chironomidae (Diptera) and Corixa (Hemiptera, Corixidae), whereas less impacted stations were characterised by Cordulegaster (Odonata, Cordulegastridae). These results demonstrate that urban wastewater alters community structure through biotic homogenisation and the replacement of sensitive taxa with tolerant ones, without necessarily reducing coarse diversity metrics. Our findings provide empirical evidence of wastewater impacts in Mediterranean Sabkhas and underscore the urgent need for improved wastewater management to safeguard these ecologically valuable saline wetlands.

This study, conducted during 2022–23, evaluates the ecological status of the Mirusha River using macrophytes as bioindicators. Industrial pollution, sewage, agricultural runoff, and climate change significantly affect river ecosystems, leading to degradation of water quality and biodiversity. The Mirusha River, heavily polluted by untreated sewage, solid waste, and agricultural runoff, was examined through macrophyte sampling and analysis of physicochemical parameters at six locations. The research used standard methodologies to assess macrophyte diversity and abundance, identifying 53 species across 25 families. The average values indicate severe water pollution, with a high biochemical oxygen demand (BOD) of 24.3 mg/L and a chemical oxygen demand (COD) of 38.4 mg/L, indicating a high organic load. In addition, the average nutrient concentrations were very high including Nitrites (NO₂⁻) reaching a value of 0.95 mg/L, Total nitrogen (NT) 16.4 mg/L, Ammonia (NH₄⁺) 2.42 mg/L, Total phosphorus (PT) 0.72 mg/L and Nitrates (NO₃⁻) 7.1 mg/L. The study identified distinct pollution impacts: the upper areas (SP1–SP3) were the most polluted due to industrial and residential waste, while the lower regions (SP4–SP6) faced pollution from gastronomy and infrastructure. The findings suggest that anthropogenic activities and poor water quality significantly affect macrophyte communities, highlighting the need for targeted restoration efforts to improve river health and biodiversity.

Ice cover is common phenomena in aquatic systems of cold regions; however community succession and community assembly of aquatic organism in relation to ice cover have received less attention. Since ice cover usually dominate a majority period of freshwater ecosystem, especially in high latitude or high altitude regions, it is crucial to evaluate the impacts of ice cover on aquatic systems. In this study, effects of ice cover on environments and benthic algal communities were studied with a six-month field investigation in a stream system of northern China to verify ecological succession between the ice-free period and the ice-covered period. Results showed that ice cover significantly altered environmental conditions, manifest as decreased dissolved oxygen and water temperature, as well as increased total phosphorous (TP). We also observed obvious changes in benthic algal community structure, characterized by a rise in Chlorophyta and Euglenophyta, alongside declines in species richness and multiple facets of functional diversity. In addition, functional homogenization in algal community was found because ice cover reduced β-functional diversity. At last, we observed that community assembly of benthic algae was governed by deterministic processes both before and after ice cover, although strength of these processes was significantly weaker during ice cover. This work demonstrates that ice cover can act as a strong environmental filter, reducing biodiversity and altering community assembly, which may provide crucial insights for forecasting ecological responses in seasonally frozen streams.

Microcystis aeruginosa, a common cyanobacterium in freshwater ecosystems, releases harmful microcystin and algal organic matter, posing serious risks to aquatic ecosystems and water quality. This study aimed to identify effective biological approaches for the removal of M. aeruginosa and to optimize the operational control conditions. Five aquatic animals: Paramecium caudatum, Daphnia magna, Macrobranchium nipponense, Bellamya aeruginosa, Unio douglasiae were selected to investigate their individual and combined effect on the removal of M. aeruginosa. Temporal variations in M. aeruginosa concentration and key water quality indicators pH, DO, COD, TP, TN, NH₄⁺-N, and NO₃⁻-N, were monitored. Results demonstrated that introduction of these aquatic animals at different densities achieved M. aeruginosa removal efficiencies exceeding 78%. Notably, a high-density treatment of P. caudatum (160 ind/L) resulted in a maximum removal efficiency of 92.58%. Moreover, polyculture systems—particularly the combination of P. caudatum and M. nipponense—exhibited high removal efficiencies (> 90%), comparable to those obtained with the most effective single-species treatment. These findings indicate that well-designed multi-trophic biomanipulation strategies can achieve algal removal performance comparable to high-density single-species applications, offering a potentially robust and sustainable approach for controlling M. aeruginosa blooms in freshwater systems.

The genera Ceriodaphnia and Scapholeberis (Crustacea: Cladocera, family Daphniidae) are representative pelagic and neustonic zooplankton, respectively, with important ecological roles in lentic ecosystems. Accurate estimation of their biomass is essential for understanding matter cycling within aquatic food webs. In this study, we advanced biomass estimation methods for Ceriodaphnia quadrangula (O. F. Müller, 1785) and Scapholeberis rammneri Dumont & Pensaert, 1983 by reviewing existing length–weight regression equations and deriving new models with greater explanatory power, based on directly measured morphometric parameters (length, width, lateral area, etc.) and corresponding biomass (dry weight). Traditionally, body length has been the standard for estimating the biomass of cladocerans, but in this study, the regression analysis between width and biomass resulted in the smallest error between estimated and measured values. Consequently, the most suitable biomass estimation equations for C. quadrangula and S. rammneri were identified as the width-weight exponential regression model and the width-weight power regression model, respectively. In addition, our review of existing equations for these species revealed both the issue of biomass underestimation when using equations derived only from non-egg/embryo-bearing individuals and the potential applicability of genus-level biomass estimation equations. The morphometric parameters and corresponding dry weight data for C. quadrangula and S. rammneri collected in this study can be usefully applied to morphological research on cladocerans. Furthermore, such research can enhance the precision of biomass estimation for cladoceran species and provide fundamental data for various aquatic ecosystem studies that require biomass information.

The red snow crab Chionoecetes japonicus inhabits physically stable deep waters of the Sea of Japan, providing a well-defined setting to evaluate the influence of ecological trade-offs on ontogenetic distribution and timing. We conducted nearly year-round pot surveys from 2020 to 2023 at depths of approximately 800–1,050 m and integrated size classes with high-resolution biological indicators: molt stage for adolescent males, dry matter content of the first walking leg (DML) for adult males as a proxy for time since molt, and embryo developmental staging for ovigerous females. Among 3,375 males and 1,272 females, small adolescents were prevalent at increased depths; after a growth molt, adolescents typically migrated to shallower depths, whereas newly molted adults remained near their molting depth. In adults, DML increased significantly with depth across most size classes. Additionally, high-DML males were relatively more frequent where females concentrated (> 950 m), consistent with post-molt recovery followed by movement toward deep reproductive grounds. Periodic models showed winter peaks in premolt adolescents (< 100 mm CW) and corresponding winter minima in adult DML of adjacent small size classes, indicating size-dependent molting synchrony. Ovigerous females with fertilized eggs were predominantly concentrated at depth and exhibited seasonal shifts in cohort composition, suggesting short-term redistributions during the reproductive period. These patterns indicate that size- and stage-specific strategies, which balance energy acquisition, cannibalism risk, and mating opportunities, structure the spatiotemporal dynamics of the red snow crab, with direct implications for depth-targeted harvests and stock assessment.