Aquatic Ecology最新文献

Underwater noise is a common form of environmental pollution, but its effects on fish physiology have not been clarified. In this work, the hybrid sturgeon, which has physiological similarities to Chinese sturgeon (Acipenser sinensis), was chosen to investigate the effects of noise on sturgeon physiology and predict its potential impact on Chinese sturgeon. The fish were exposed to 145 ± 5 dB noise, which is comparable to the noise levels near the natural habitat of sturgeons, for 48 h, followed by a 48-h noise-free period to allow for recovery. Blood physiological parameters of juvenile sturgeons were measured at 0, 24, 48, and 96 h. After 48 h of noise exposure, significant changes were observed in biochemical markers: alkaline phosphatase (ALP) and superoxide dismutase (SOD) increased significantly, while aspartate transaminase (AST), lactate dehydrogenase (LDH), and gamma-glutamyl transferase (GGT) decreased. Hormonal markers showed marked increases in epinephrine (EPI) and cortisol levels. Metabolic markers also exhibited changes, including significant increases in glucose, uric acid (UA), and blood urea nitrogen (BUN). Following 48 h of noise removal, EPI, glucose, UA, BUN, and LDH levels remained significantly elevated, with a significant decrease in alanine transaminase (ALT). This study reveals that noise stress can adversely affect the immune functions of hybrid sturgeons and disrupt their hormone secretion. Furthermore, these effects do not reverse within a short period (48 h). By using blood biomarkers, this study provides valuable data for assessing the environmental impact of underwater noise and offers theoretical guidance for sturgeon aquaculture and conservation.

Graphical abstract

One of the characteristic ducks in Lake Mývatn, Iceland, has been the long-tailed duck (Clangula hyemalis) which was present in large numbers during the early 1900s but declined in numbers during the twentieth century. The long-tailed duck is a circumpolar sea duck, often with longitudinal migratory routes between wintering and breeding sites. In recent decades the species has been in decline throughout its range and it is now classified as vulnerable. In Iceland, the breeding population is 2000–3000 individuals, but the winter population is considerably larger (> 110,000) with wintering birds coming from other areas. To identify the phylogeographic origin of the species in Iceland, for both the breeding and the wintering population, variation in the control region of the mitochondrial DNA (mtDNA) was analyzed and compared with samples obtained from across the species range. Two distinct lineages of the control region were found in Iceland, one of which occurred at high frequency in the Icelandic breeding population. The haplotype lineage found in high frequency in the breeding population in Iceland was absent or in low frequencies elsewhere, except in the Yukon-Kuskokwim Delta, Alaska. The patterns observed in the mitochondria may reflect an overall genetic divergence of the Icelandic breeding population from the other sites studied or alternatively sexual differences in philopatry which may only affect the maternally transmitted markers.

Determining ecological thresholds for natural communities has implications for biodiversity conservation and for identifying reference conditions. Among aquatic communities’ phytoplankton is an important indicator of environmental changes and is highly susceptible to physical, chemical, and biological variations in aquatic ecosystems. This study shows multiple ecological thresholds of the phytoplankton community associated with rainfall, turbidity, water temperature, pH, particulate organic carbon, and total nitrogen, which were key factors influencing the phytoplankton community throughout the hydrological year in Lago Grande do Curuai. Among the six gradients evaluated, five (turbidity, temperature, pH, total nitrogen, and precipitation) influenced the distribution and biovolume of phytoplankton. This influence was associated with multiple points of change in the phytoplankton community along these gradients, phytoplankton species and morphofunctional groups (MBFG). The structure of the phytoplankton community in this system showed great variation throughout the year, as multiple ecological thresholds of the community were detected, which are associated with variations in habitat conditions. The MBFG ecological classification indicated a certain degree of loss of responses, potentially due to the weaker signal and lower amplitude threshold response. In conclusion, both classification methods have the potential to be effective biomonitoring and ecological management tools for this environment.

Temephos is an organophosphorus insecticide used as a common larvicide. Although no studies to our knowledge report the presence of temephos in Mexican waterbodies, the Latin American government still uses the larvicide to control Aedes aegypti and illnesses associated with dengue. Freshwater systems and wastewater treatment plants contain microorganisms such as zooplankton species. Non-target organisms can interact directly with the larvicide due to the application in water producing adverse effects in their populations. Most ecotoxicological assays using zooplankton species are based on previously unexposed populations, discarding multigenerational point of view and in silico methods. In the present study, chronic effects were evaluated through life table demography for Moina macrocopa (0, 0.25, 0.5, 1 µg L^-1) and Ceriodaphnia dubia (0, 0.06, 0.125, 0.25 µg L^-1) exposed to sublethal levels of temephos in the medium for two generations (F0 and F1). Regardless of the concentrations used, temephos produced effects on both cladocerans species in the two generations. Induced maternal effects can be observed in the tolerance of the offspring of M. macrocopa, compared to C. dubia, where the impacts were far greater in the F1 generation. This can be explained due to the interactions of binding sites on arginine kinase, suggesting potential inhibitory effects of temephos on the amino acid.

Intermittent rivers are hydrologically extreme freshwater systems that periodically cease to flow. Such habitats occur worldwide, but they are most common in semi-arid regions of the world, such as the Mediterranean region. Trichoptera are frequently used in biomonitoring programmes worldwide. However, their biodiversity and ecological requirements in intermittent Mediterranean karst habitats are still poorly understood. Here, we provide data on Trichoptera assemblage metrics (taxa richness, diversity and abundance), assemblage structure (trophic structure and stream zonation preference), and their relationship with environmental variables in the lotic phase of four intermittent rivers in the Dinaric karst region of the Mediterranean in the Western Balkans. Due to the extreme hydrological conditions in the studied habitats, Trichoptera showed a low taxa richness (10 taxa). The highest diversity was recorded in rivers with greater habitat heterogeneity. In addition, rivers with higher conductivity and water temperature, and lower water velocity had more diverse assemblages. The trophic structure and stream zonation preferences of Trichoptera were significantly different among the intermittent rivers studied, with the influence of anthropogenic activities evident in certain rivers. However, the variability of Trichopteran assemblages along the course of each intermittent river, was generally low, which could be attributed to the uniform microhabitat composition and physico-chemical water parameters in the studied rivers. The results of this study could provide a valuable background for further research and the development of conservation measures for both Trichoptera and intermittent karst habitats in the Mediterranean.

Our work is based on the assumption of a connection between the development of phytoplankton as chlorophyll a (CHL) and the long-term dynamics of solar activity expressed as sunspot numbers (Wolf numbers, W) by the example of the Rybinsk Reservoir (Upper Volga, Russia). We analyzed the possible relationship between mean for the growing season CHL and W over the period of solar cycles 20–24 (1969–2019), as well as the relationship between CHL in water and bottom sediments with W during the entire cycle 24 (2009–2019). A moderate tendency towards a decrease in CHL with increasing W was revealed for cycles 20 and 22, but for cycle 21 there was no correlation between them at all. A linear increase in CHL with increasing W was detected for cycle 23 and the most distinct for the cycle 24. A close relationship with high positive correlation coefficients equal to 0.74 and 0.70 have been established between W and CHL in water and bottom sediments during cycle 24. For sedimentary pigments, the degree of correlation with W depends on the type of bottom sediments. A reliable connection is typical for deep areas with a high rate of sludge accumulation; in areas with unfavorable conditions for sedimentation, such a relationship has not been identified. It is assumed that the increased correlation between CHL and solar activity in the cycle 24 compared to the previous cycles is due to the anomaly of this cycle, characterized by unprecedentedly low W values.

Over 27 years in Great Salt Lake (GSL: Utah, USA), phytoplankton relative abundances of chlorophytes, diatoms and cyanobacteria varied dramatically (monthly < 10–90% for each). This observed variability within the lake was compared to laboratory experimental results with pure cultures (> > 90%) of several of the most common GSL phytoplankton (chlorophyte–Dunaliella viridis, diatom–Nitzschia epithemioides, cyanobacterium–Euhalothece sp.). Maximum abundances and growth rates were measured across ranges of temperature (10–30 °C), salinity (30–150 ppt) and nutrients (nitrogen: 0.0–0.64 mg/L, silica:17–51 mg/L) observed within GSL. Experimental results indicated the abundance and growth rate of D. viridis increased as salinity and nitrogen increased and decreased as temperature increased. The abundances and growth rates of N. epithemioides and Euhalothece decreased as salinity increased, and increased as temperature and nitrogen increased, and N. epithemioides increased as silica increased. Observed GSL phytoplankton relative abundances responded to environmental conditions as observed in the experiments, but correlations were weak except for chlorophytes, as diatoms and cyanobacteria relative abundances occasionally increased with unfavorable experimental conditions. The weak correlations between laboratory results and GSL observations could be due to the release of diatoms and cyanobacteria from microbialite biofilms in the lake’s benthos with cold stress and high winds, as a 5–10% release can produce diatom and cyanobacteria phytoplankton relative abundances of 24–48%. This suggests a novel potential link between GSL pelagic and benthic zones.

Freshwater rock pools formed due to erosion and weathering in outcrops are known to act as essential frog breeding habitats. In the northern part of the Western Ghats-Sri Lanka biodiversity hotspot, large freshwater rock pools are shown to be important for adult stage of three species of frogs: Jaladhara Skittering Frog (Euphlyctis jaladhara), Nilphamari Narrow-mouthed Frog (Microhyla nilphamariensis), and Common Indian Treefrog (Polypedates maculatus). Previous studies have thus recommended conservation of existing rock pools and restoration or creation of rock pools for amphibian conservation, in light of reduced rock pool availability due to rapid conversion of outcrops to orchards. To this end, knowledge of tadpole ecology in the rock pools is essential for further research and conservation actions. We assessed the influence of abiotic (pool size, monsoon progression) and biotic (predator abundances) factors on occurrence and abundance of tadpoles of the three species by periodically monitoring the ephemeral freshwater rock pools in lateritic plateaus of the northern Western Ghats. Tadpole occurrences and abundances were negatively associated with monsoon progression, and not associated with predator abundances for all species, while they were positively associated with rock pool size, species-specifically.

We detected the first occurrence of Nile tilapia (Oreochromis niloticus) in the brackish and marine ecosystems of Rio Grande do Sul, the southernmost state of Brazil, following the catastrophic floods that impacted the region in the fall of 2024. We conducted seven beach surveys from the Tramandaí Lagoon inlet, extending 80 km north and 50 km south. These surveys were carried out using a four-wheel-drive pickup truck traveling at speeds up to 40 km/h, with 2–4 observers scanning the entire beach from the wash zone to the base of the dunes. For every 10 km of beach surveyed, we performed transect walks of 1 km in length. A total of 188 specimens were found stranded up to 80 km north of the Tramandaí Lagoon inlet. Oreochromis niloticus can be managed under controlled conditions with restrictions, subject to specific regulations according to the official list of invasive exotic species in the State of Rio Grande do Sul. The escape of this species from aquaculture facilities and recent records (post-2019) in Tramandaí Lagoon underscore the need to establish a long-term monitoring program for invasive exotic species in the Tramandaí River Hydrographic Basin and to improve measures to prevent escapes.

This study examines how the invasion of Hydrilla verticillata affects native submerged macrophytes in the Rosana Reservoir, focusing on its impact at both species and family levels. The research analyzed data on the presence and absence of aquatic macrophytes in both invaded and non-invaded sites before and after the introduction of H. verticillata. Our findings indicate that H. verticillata alters the probability of occurrence of native species through both competitive suppression and facilitation. For the Hydrocharitaceae family and the species Egeria najas, the presence of H. verticillata decreased their probability of occurrence in invaded sites. In contrast, the probability of occurrence of the Characeae family, along with Nitella furcata and Chara guairensis, increased in post-invasion conditions within invaded sites. This suggests that non-native plants can have divergent impacts on native species, with some being negatively affected while others may benefit. These results highlight that invasive species can have divergent effects, influencing species and family-level interactions in aquatic ecosystems. Additionally, the influence of native species richness on the probability of occurrence of different species and families was found to be affected by the presence or absence of H. verticillata. Overall, the research underscores the importance of assessing the impact of non-native species not only at the species level but also in terms of their broader effects on native species families and ecosystems.