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 FV/FM 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.
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.
Understanding how freshwater species move through changing environments is critical for conservation, yet movement in riverine systems is shaped by interacting hydrological, landscape and biological processes that are difficult to disentangle across studies. For semi-aquatic species, these challenges are compounded by methodological differences and limitations in tracking approaches, sampling duration and study design, which can obscure ecological patterns and limit inference across environmental contexts. Using the platypus (Ornithorhynchus anatinus) as a model semi-aquatic mammal, we synthesised 530 movement records from 17 studies (1971–2024) using a bias-aware modelling framework to examine how demography, land use, flow regulation and season shape movement while accounting for methodological variation. Land-use differences were pronounced in unregulated systems, with the largest home ranges occurring in urban systems. Differences were comparatively weak in regulated rivers. Males consistently exhibited larger home ranges and greater daily movement distances than females, while juvenile movement varied seasonally. Study duration varied systematically across methods and environmental contexts and weakly influenced cumulative movement metrics. These findings demonstrate that movement responses in freshwater systems emerge from interactions among hydrology, landscape context and species biology and may differ from the widespread movement reductions reported for terrestrial mammals in human-modified landscapes. Freshwater conservation will require movement monitoring that spans environmental gradients, flow regimes, seasons and life stages, while explicitly accounting for methodological variation. Integrating ecological and methodological perspectives in this way can improve our ability to distinguish biological responses to environmental change from sampling effects and establish robust movement benchmarks for increasingly modified freshwater ecosystems.
