Aquatic Ecology最新文献

This study investigates the variability of phytoplankton characteristics—namely species richness, and Shannon diversity index—as well as Reynolds functional group (RFG) attributes, including composition, total biovolume of the species classified within those groups, and RFG richness, across 16 predefined lake types. The analysis is based on data collected from 70 lentic systems in Türkey during the spring, summer, and autumn seasons between 2017 and 2019. Patterns of variation and similarity in both lake types and individual lentic systems were evaluated in relation to type descriptors (altitude, latitude, longitude, lake depth, surface area, and geological features-alkalinity) and additional environmental parameters. The results of the multivariate analyses revealed that the 16 lake types differed from one another in terms of RFG composition, phytoplankton biovolume, dominant RFGs, species richness, the Shannon index, and RFG richness. In addition, while typological descriptors such as surface area, lake depth, alkalinity, and spatial factors played a key role in distinguishing typologies based on their composition of RFGs and dominant RFGs, the environmental parameters, such as electrical conductivity, also had an impact. Despite similarities in RFGs composition and the distribution of dominant RFGs among systems within the same lake type, the presence of significant differences underscores the importance of local environmental conditions. These findings suggest that incorporating supplementary descriptors—especially electrical conductivity—may enhance the accuracy of phytoplankton-based classification of lentic ecosystems in Türkiye.

Microplastic pollution has been widely studied across diverse environmental matrices; however, knowledge gaps persist regarding the source-specific characterisation of fishing-related plastics. This study investigates the bioaccumulation and biochemical effects of microplastics derived from boat-building Fibreglass Reinforced Plastic (FRP-MPs) in Oreochromis niloticus (Nile tilapia). Fish were exposed to different concentrations of virgin and weathered FRP-MPs via dietary intake for 120 days. Growth parameters, feed conversion ratio, faecal egestion, microplastic leaching from feed, bioaccumulation in tissues, biochemical and haematological changes were assessed. Growth performance and feed conversion were significantly affected only at higher concentration (p<0.05). The highest MPs accumulation occurred in the gut (61.2 particles/g), followed by the skin (11.1 particles/g). Muscle tissue (0.55 particles/g) showed minimal retention. Faecal egestion of MPs increased with exposure concentration (1.4–47.33 particles/g). Tissue-specific responses showed altered carbonyl, amine, and silicate profiles, with pronounced changes in the liver and a marked loss of amino and benzenoid groups in the gills, while muscle tissue retained silicates but exhibited a loss of carbonyl and amide groups, as revealed by FTIR. MPs affected antioxidant enzyme activity (catalase and superoxide dismutase) and elevated hepatic biomarker enzyme levels (alanine aminotransferase and aspartate aminotransferase) across various organs. Haematological parameters such as Red Blood Cell (RBC), White Blood Cell (WBC), Packed Cell Volume (PCV), Haemoglobin (HGB), Mean Corpuscular Volume (MCV), Mean Corpuscular Haemoglobin (MCH), and Plateletcrit (PCT) showed significant differences between the groups fed with weathered and virgin FRP-MPs. This study reports the first evidence of FRP-derived MPs bioaccumulation and physiological alterations in fish, offering critical baseline data for understanding the ecological implications and the urgency for policy requirements.

Graphical abstract

Land use has emerged as a key driver for anthropogenic impacts on stream ecosystems. Given the small and semi-isolated nature of the Kapıdağ Peninsula, we hypothesized that land-use patterns would be directly reflected in diatom metacommunity structure. To test this, we evaluated the effects of land use and environmental variables on diatom composition and diversity across 19 stream sites, and further examined whether estuarine proximity and micro-scale salinity variations influence community structure. Multivariate analyses, including Heat Maps, TWINSPAN, Redundancy Analysis (RDA), and Variation Partitioning Analysis (VPA), revealed that agricultural land use significantly altered water chemistry—particularly soluble silica (Si), salinity (SAL), and sulphate (({SO}_{4}))—compared to forested areas. These changes were strongly associated with shifts in diatom species composition. Notably, increasing ({SO}_{4}) concentrations were linked to higher species richness and diversity. In contrast, while macro-scale SAL levels at estuarine sites did not differ from upstream sections—indicating limited direct seawater intrusion—RDA forward selection identified SAL as a significant environmental filter shaping specific tolerant assemblages at lower reaches. Among the 18 diatom indices evaluated, DESCY demonstrated the highest performance in reflecting ecological status, based on its strong alignment with environmental gradients and indicator species distribution. Overall, our findings highlight land use as a primary determinant of environmental variability and diatom community dynamics in semi-isolated systems, emphasizing its critical role in ecological assessment frameworks.

Spring phytoplankton development is a key event in temperate areas, influencing water community structure and ecosystem dynamics. This study investigates the relationship between phytoplankton species composition, abundance, photosynthetic activity and prompt chlorophyll a fluorescence induction kinetics (OJIP transients) during the spring development of phytoplankton. Sampling was conducted in April, May, and June of 2024 and 2025 at the station in the lower course of the Velikaya River (within Pskov city, Russia). The OJIP transients exhibited strongly reduced yield of the JI phase and a decrease in the ratio F_V/F_M indicating suboptimal conditions for photosynthesis. A rapid increase in the phytoplankton biomass occurred in May accompanied by structural reorganization and changes of the dominating species composition that indicates phytoplankton development. During this period OJIP transients were characterized by an extra phase (a slow peak) appeared between one and three seconds whose origin and underlying mechanisms are poorly investigated. The shape of the OJIP transients measured during phytoplankton development period showed similarity with that one observed earlier in the delta of the Velikaya river where conditions were favorable for water eutrophication. In particular, the OJIP transients, recorded in the river delta, showed a modified JI phase and a slow peak between 1 and 3 s. The obtained results allowed us to conclude that the JI phase can be considered as important indicator of physiological state of phytoplankton, whereas a slow peak rather reflects structural changes of the phytoplankton community and domination of certain microalgal species.

Household washing machines release synthetic textile-derived microfibres into wastewater systems. Yet, standardised questionnaires assessing household laundering practices linked to microfibre emissions remain limited. This study developed and preliminarily evaluated a household microfibre emission behaviour questionnaire and proposed a framework for estimating potential washing-machine-derived microfibre release through Malaysian household wastewater pathways. The questionnaire was developed through literature-informed domain identification, expert review, content and face validity assessments, guided by an integrated Knowledge–Attitudes–Practices and Theory of Planned Behaviour framework. Content validity was assessed by 10 experts and face validity by 20 adult public respondents, followed by pilot testing among 43 Malaysian adults. The revised questionnaire comprised 58 items across six domains, plus one laundering-frequency input item. Internal consistency was assessed for 48 knowledge and Likert-scale items, while 10 barriers were analysed descriptively as binary indicators. Content and face validity index values ranged from 0.96 to 0.98. Preliminary internal consistency was acceptable, with a KR-20 value of 0.885 for the knowledge domain and Cronbach’s alpha values ranging from 0.817 to 0.849 across the Likert-scale domains. The proposed equation estimates annual washing-machine-derived microfibre release through laundry-wastewater pathways. It incorporates laundering frequency, household numbers, washing-machine penetration, per-cycle release and sewered, septic and unmanaged wastewater fractions. Other behavioural indicators can refine the framework as empirical coefficients become available. The framework was neither calibrated nor validated and does not estimate environmental transport or confirmed aquatic loading. Together, these components provide a context-specific approach to assessing laundering behaviours and potential microfibre release in Southeast Asia.

Coral reefs are among the most productive marine ecosystems, sustained by the tight coupling between physiological processes and environmental conditions, in which nutrition plays a central regulatory role. This review synthesizes the multifactorial nutritional ecology of tropical scleractinian corals, emphasizing how autotrophic and heterotrophic pathways are dynamically integrated to support metabolic performance, calcification, and stress resilience. Particular attention is given to the acquisition, assimilation, and functional roles of key—macronutrients (nitrogen-containing compounds and lipids) and micronutrients (essential minerals and trace elements)—in regulating symbiotic stability and holobiont homeostasis, while explicitly distinguishing a coral’s carbon budget—which tracks the sources and sinks of carbon-containing molecules—from its energy budget, which additionally requires conversion of these molecules into caloric equivalents relative to metabolic demand. We further examine trophic plasticity as a central adaptive mechanism, enabling corals to adjust energy acquisition strategies under environmental stressors such as thermal anomalies, ocean acidification, and eutrophication. This includes shifts in feeding rates, prey selectivity, and reliance on dissolved and particulate organic matter, which collectively determine the capacity for metabolic compensation during periods of reduced autotrophic input. In addition, we evaluate emerging approaches in coral nutrition research, including artificial diets, probiotic-based interventions, and biochemical and isotopic markers. By integrating experimental and biogeochemical evidence, we demonstrate that nutrient availability, stoichiometric balance, and environmental drivers jointly regulate coral performance through tightly coupled metabolic feedbacks, positioning a species’ “nutritional niche”—its capacity for compensatory heterotrophy relative to its dependence on symbiont-derived carbon—as a primary determinant of resilience under global change. Overall, this review advances a mechanistic framework in which coral nutrition is understood as an integrated, dynamic system, linking resource acquisition, metabolic allocation, and environmental variability, with direct implications for predicting coral resilience under ongoing climate change.

Seston stoichiometry links nutrient availability to the structure and functioning of aquatic food webs, yet how in-lake conditions interact with broader climatic, geomorphological and land-use drivers to shape seston carbon-to-phosphorus (C:P) ratios remains poorly understood in tropical systems. We used regression tree analysis (RTA) to evaluate the relative importance of in-lake, lake–catchment and climate variables in explaining seston C:P variation across 95 shallow lakes and reservoirs spanning a semi-arid-to-humid climatic gradient in northeastern Brazil. The RTA explained nearly half of the variance in seston C:P (49.6%) and revealed a hierarchical structure among predictors. Cumulative precipitation over the two years preceding sampling was the primary split, separating the lower- and higher-precipitation portions of the sampled gradient at 882 mm. Within the higher-precipitation branch, total dissolved phosphorus (TDP) was the only additional predictor, and the highest C:P ratios occurred where TDP was also high. Within the lower-precipitation branch, the partial pressure of CO₂ (pCO₂) and land use further partitioned C:P variation. A complementary Random Forest analysis also ranked precipitation as the strongest global predictor, although overall out-of-bag predictive performance was low. Because bulk seston integrates algal and non-algal particles, these associations cannot be assigned to a single physiological mechanism. Instead, our results show that antecedent hydrological context changes which local and catchment variables are associated with seston stoichiometry, highlighting the importance of integrating climate, landscape and in-lake conditions when predicting freshwater elemental balance under climate and land-use change.

Zoosporic parasites and fungal-like microorganisms are important components of planktonic food webs, yet their macroscopically visible manifestations in lakes remain rarely documented. Here, we describe two unusual surface phenomena observed in the Lipno Reservoir, Czechia, during summer 2025. Floating surface scums of Daphnia cucullata carcasses colonized by filamentous fungal-like structures and dark spherical bodies were first recorded in July. Approximately three weeks later, conspicuous brown surface accumulations appeared in the same central part of the reservoir. Light microscopy showed that the brown material was dominated by abundant free-floating spherical to subspherical bodies, typically 30–50 µm in diameter. Although these structures showed resemblance to spherical bodies observed in the earlier Daphnia-associated scums, their direct connection could not be demonstrated. Calcofluor White staining and scanning electron microscopy indicated wall-bearing biological structures, including bodies with rupture-like openings. Cultivation yielded opportunistic fungi, and direct PCR from selected spherical bodies produced inconsistent taxonomic signals, including Pythium, Aureobasidium, and vampyrellid endomyxans. We therefore interpret the July scums as probable zooplankton-associated fungal colonisation or infection, whereas the identity of the August free-floating morphotype remains unresolved. These observations show how microbial and surface-accumulation processes can generate visually striking but taxonomically ambiguous freshwater phenomena.

Coral reef ecosystems in Pomalaa, Southeast Sulawesi, are subjected to compounding anthropogenic pressures: chronic sedimentation from nickel mining overburden runoff and physical substrate degradation from historical and ongoing blast fishing. This study presents the first report on the localized population proliferation of the sessile vermetid gastropod Dendropoma cf. maximum across these dually disturbed reef matrices and evaluates the environmental correlates associated with this ecological shift. We evaluated benthic community structures and environmental parameters along a spatial disturbance gradient across three discrete sampling zones: High-Impact Zone (HIZ/DRM), Moderate-Impact Zone (MIZ), and Comparative Reference Sites (CRS/RS). Field surveys conducted monthly from October 2025 to February 2026 revealed a severe spatial phase-shift. In the HIZ/DRM, where the Smothering Index reached 3.8 ± 0.2, Total Suspended Solids (TSS) averaged 92.4 ± 15.6 mg/L, and Live Coral Cover collapsed to 4.2 ± 1.8%, D. cf. maximum exhibited high ecological resilience, reaching extraordinary population densities of 212 ± 28 ind/m² and forming massive biogenic crusts. Concurrently, gastropod diversity in this zone dropped drastically to H' = 0.42 ±0.12. Conversely, reference sites (CRS/RS) characterized by minimal sediment stress (Smothering Index: 0.2 ± 0.1; TSS: 6.4 ± 1.2 mg/L) and high structural complexity (Live Coral Cover: 74.8 ± 5.6%) maintained D. cf. maximum at baseline densities of 4 ± 2 ind/m². Multiple linear regression modeling confirmed that D. cf. maximum density strongly correlates with sediment smothering (r = 0.92, p < 0.001) and coral rubble cover (r = 0.89, p < 0.001). Blast fishing may have cleared native benthic competitors, while persistent lateritic overburden sedimentation likely excludes key predators. This synergistic mechanism provides vacant hard substrates that D. cf. maximum opportunistically colonizes via its sediment-tolerant mucus-net feeding strategy.

In tropical rivers, aquatic macrophytes constitute complex habitats that mediate predator–prey interactions and support diverse fish assemblages. In the present study, we examined how seasonality influences prey use and the trophic network structure of macrophyte-associated ichthyofauna in the lower São Francisco River, Brazil. Fishes were sampled bimonthly in the wet and dry periods at four independent sites. Stomach contents of adult individuals were analyzed to quantify prey richness, composition, and origin (autochthonous vs. allochthonous). Bipartite networks were constructed to investigate nestedness and modularity. Empirical patterns were compared to null models using Z-scores. No differences were found in prey richness between hydrological periods. Prey composition showed a significant but weak shift between hydrological periods (R² = 0.02), reflecting the dominance of autochthonous resources (algae, detritus, microcrustaceans, and immature insects) supported by aquatic macrophytes. The predator–prey network was predominantly nested in the wet period, indicating hierarchical interactions mediated by generalist species, whereas no clear pattern of nestedness or modularity was found in the dry period compared to null expectations. These results highlight the central role of macrophytes in ensuring prey availability and stabilizing trophic networks, even under hydrological fluctuations. Despite this apparent stability, low allochthonous input and increasing human impact make these networks functionally vulnerable to change. Therefore, protecting riparian vegetation and mitigating anthropogenic stressors are critical for maintaining trophic complexity and resilience in tropical river ecosystems.