Aquatic Sciences最新文献

The multifaceted threats to global freshwater ecosystems, especially in urban environments, impact hydrological cycles, flora and fauna, habitats and ecosystem processes. While these ecosystems can potentially offer important services to the urban populations by providing natural areas inside cities, the constraints imposed by urbanisation and a high population density may result in the loss of those benefits. Thus, it is important to adopt a quantitative approach to assess the value of urban freshwater ecosystem services in order to enable strategic urban planning that balances urban development with the protection of these ecosystems. We have therefore performed a systematic review of Scopus database publications from 2006 to 2022 that focused on provisioning, regulating and maintenance, as well as cultural services, provided by urban river ecosystems. The screening identified 118 papers, 43% of which focused on urban stream ecosystems (stream and/or riparian area). For provisioning services, indicators were related to water and food supply, while regulation indicators were linked to water quality and flood mitigation; cultural services were mainly related to physical interactions with the ecosystems, education and aesthetic experiences. The economic valuation of urban river ecosystem services is the subject of study in 19% of the identified articles, mainly in relation to potential river restoration. Finally, 18% of articles incorporated public opinions of stakeholders and citizens, underlining the significant role of their input in understanding and managing urban river ecosystems. More studies on urban streams are needed, and standardising indicators and promoting greater citizen involvement in the evaluation of ecosystem services are challenges that remain to be overcome.

Alpine freshwater ecosystems are biodiversity hotspots providing key ecosystem services. These ecosystems face threats from climate change and anthropogenic activities. Snowmaking reservoirs have emerged across the globe as a response to snow rarefaction and increasing winter tourism, and despite efforts to assess their environmental impact, our understanding of their ecological quality after being built remains limited. In the present study, we evaluated representative snowmaking reservoirs in French Alpine counties (départements) and their potential to serve as aquatic ecosystems. A comprehensive approach was employed encompassing ski resort surveys and geographical analyses of 136 reservoirs, complemented by investigations into abiotic characteristics and biodiversity surveys in 28 sampled reservoirs. The findings indicated that the multiplication and proximity of these reservoirs to freshwater habitats make them components of the alpine aquatic landscape. Terrestrial vegetation, although sparse, was commonly present on the banks of these reservoirs, but they systematically lacked aquatic vegetation. Faunal diversity appeared to be limited, and consisted of both indigenous and non-native species. Comparisons of snowmaking reservoirs with mountain lakes revealed similarities in water quality, implying the potential for similar oligotrophy and biotic communities. However, differences in conductivity, alkalimetry and pH were observed, possibly linked to distinct differences in water sources or retention times. Snowmaking reservoirs displayed unique habitat features through their structure and functioning. Although these reservoirs are attractive in terms of their biodiversity, there are concerns regarding their capacity to support species due to observations of drowned mammals and stranded amphibians and dragonflies. Our observations reveal potential ecological traps in the design, exploitation and uses of snowmaking reservoirs. Recommendations are made to enhance existing structures and future designs by increasing ecological processes and better protecting biodiversity.

Climate warming has been projected to alter the habitat ranges of cold-water fish species. To numerically model these changes, a simple dissolved oxygen (DO) sub-model has been embedded into a one-dimensional thermodynamic lake-tile model that simulates small unresolved lakes within the land surface scheme of a climate model. To account for the lack of monitoring data for most small lakes, the components of the DO budget were parameterized as functions of lake surface area and depth, a light extinction coefficient and meteorological variables prescribed by the climate model. The model predicted the temperature and DO profiles with root-mean-square error < 1.5 °C and < 3 mg l⁻¹, respectively, based on 38 years of data from two Canadian Shield lakes. For the smaller lake (~ 71 ha), simulations of future (2071–2100) lake conditions show a warming-induced reduction in the frequency of seasonal lake turnover and consequently prolonged periods of hypolimnetic hypoxia. This will reduce the end-of-summer volume weighted hypolimnetic dissolved oxygen concentration (VWHO) from ~ 6 mg l⁻¹ (1978–2005) to < 3.6 mg l⁻¹ (2071–2100), below the 7 mg l⁻¹ standard for lake trout. As a result, the height of water column with temperatures and DO concentrations suitable for lake trout will decrease from ~ 17 m to < 6 m. For the larger lake (~ 614 ha), VWHO < 5 mg l⁻¹ is predicted in the future; however, vertical mixing during turnover events and warming-induced shallowing of the thermocline depth will combine to increase the height of the suitable water column from ~ 16 m to > 18 m in the future. Hence, the lake trout populations in smaller temperate lakes may be at greater risk for earlier extirpation than in larger lakes.

Sea trout, the anadromous ecotype of the species Salmo trutta, are subject to multiple threats, including exploitation and aquaculture impacts in the marine environment, habitat fragmentation and pollution in freshwaters, loss of genetic resilience due to interbreeding with hatchery strains and environmental change. Small streams contribute relatively little biomass to European sea trout stocks but are thought to be important in maintaining genetic diversity and therefore wider population resilience. The current study combined data from acoustic telemetry, stable isotopes, genetics and scalimetry to assess the current status of sea trout in the rivers Stiffkey and Glaven, two locally important chalkstreams in East Anglia, UK, to provide an evidence base for future management. The incidence of anadromy was low, and most sea trout were near migrants, residing in the lower reaches of rivers and close to the tidal outfalls. A small number migrated to the North Sea where they were vulnerable to exploitation in the coastal fishery, which comprises a mixed stock. Straying between the two rivers was recorded among 10% of sea trout, leading to apparent high gene flow. Nonetheless, genetic data also demonstrated structuring of River Glaven trout into two distinct groups. Quantification of patterns of freshwater and estuarine habitat use, and of passage at cross-channel obstructions, was used to identify where remedial measures such as habitat restoration would be most effectively targeted. Findings are discussed in the context of local supplementary stocking and the potential impact of the nearshore fishery on limited and vulnerable small stream anadromous trout populations.

The breadcrumb sponge, Halichondria panicea, is a cosmopolitan marine species. Life functions, such as feeding, metabolism and defence, are maintained through microbial symbiosis. As such, perturbations to the symbiotic balance can be expected to affect the health and survival of the sponge. Although generally tolerant of environmental variables, such as temperature, pH and salinity, responses to anthropogenic factors are poorly understood. In this study, the microbial community of the H. panicea was examined over the course of 1 year. Sponge and seawater samples were collected in January, April, July and October 2022, from three locations with different levels of bathing water quality, according to the UK’s Environment Agency. Samples were sequenced using the 16S ribosomal RNA (rRNA) gene, and amplicon sequence variants (ASVs) were inferred from the generated data. Differences in bacterial diversity and abundance among sponge samples from the three locations were examined. A correlation test was used to study the effect of physical and chemical environmental factors along with faecal indicator bacteria on the abundance of the top ten most abundant bacterial phyla. Environmental factors (determined from seawater physicochemical properties) and pollution (determined from trace metals, nutrients and faecal bacteria levels) were found to play an important role in shaping the microbial community of this sponge. The sponge microbiome showed a noticeable seasonal shift, with some species flourishing in January and others emerging in April, notably the faecal and coliform bacteria. Sponge microbiomes from sites with poor-quality bathing water were generally less diverse and had lower microbial abundance, resulting in a greater range of intra-species dispersion than those of sponges living in excellent–good quality waters.

This study explores the efficacy of hydrogen isotopes in tracing the origins and dynamics of particulate organic matter (POM) in the Loire River, employing a novel dual vapor equilibration method to measure its non-exchangeable hydrogen (δ²H_n). By integrating δ²H_n with traditional carbon (δ¹³C) and nitrogen (δ¹⁵N) isotopes and C/N ratios of POM, we compared the ecological information using multivariate analyses. Fortnightly river sampling over 3 years showed seasonal patterns in the δ²H_n values of POM, highlighting two primary POM end-members: phytoplankton and terrestrial matter. Bayesian mixing models confirmed that using δ²H_n as a tracer effectively discriminated these riverine POM end-members, with phytoplankton predominating in spring–summer and terrestrial matter in winter. Redundancy analyses revealed the main environmental drivers of POM composition, identifying significant correlations between the POM sources, chlorophyll a, suspended particulate matter, and river discharge. Our findings demonstrate that δ²H_n, alone or combined with δ¹³C, δ¹⁵N, or N/C ratio, provided a new robust tracer for POM source dynamics, thereby offering valuable insights into riverine biogeochemical cycles and ecosystem functioning. Our study underscores the novel potential of δ²H_n as a tool in environmental and ecological research, advocating for its broader application across various aquatic ecosystems to enhance our understanding of organic matter dynamics.

The Winam Gulf of Lake Victoria has been increasingly subjected to anthropogenic disturbances, which pose significant threats to its ecological health and water quality. This study examined the spatiotemporal variations in phytoplankton diversity, community structure, and abundance in response to changing environmental conditions from February to September 2020. Key physicochemical parameters, including water transparency, pH, chemical oxygen demand (COD), dissolved oxygen (DO), temperature, chlorophyll a, total nitrogen (TN), total phosphorus (TP), silicate, and ammonia nitrogen (NH₄⁺–N), were measured. The phytoplankton community was dominated by eight phyla, with Cyanobacteria (50%), Chlorophyta (28.05%), and Bacillariophyta (14.63%) being the most prevalent. The most common cyanobacteria species identified were Microcystis aeruginosa and Dolichospermum flosaquae. Phytoplankton abundance ranged from 45 to 4900 individuals/mL, peaking in July. Shannon–Weaver diversity indices varied from 1.1 to 4.2, with an average of 1.9, indicating moderate pollution levels in the Winam Gulf. Redundancy analysis (RDA) revealed that significant shifts in the phytoplankton community were statistically correlated with water quality variables, notably NH₄⁺–N, temperature, transparency, and DO. NH₄⁺–N was identified as the key limiting factor for cyanobacterial abundance in the gulf. The dominance of Cyanobacteria, along with their seasonal fluctuations influenced by major environmental factors, underscores the complexity of this lake ecosystem. These findings emphasize the urgent need for continued efforts to mitigate adverse impacts and improve the overall health of this aquatic environment.

The analysis of functional trait composition in aquatic macroinvertebrate communities is a valuable tool for assessing the impacts of environmental changes on fluvial ecosystems. We investigated Patagonian watercourses subjected to different land use practices (natural, agricultural, and urban) and predicted that disturbances would decrease trait diversity while favoring certain trait modalities over others. RLQ and fourth corner analysis were utilized to explore potential relationships between species, traits, and environmental gradients. Differences in macroinvertebrate taxonomic and functional diversity metrics among land uses was also tested. Our results showed that land use had a significant impact on macroinvertebrate communities, with water pollution and riparian condition being the most important factors shaping their functional structure. The RLQ ordination grouped sites according to a disturbance gradient and revealed that traits positively associated with urbanization included deposit feeding, aquatic reproductive stage, non-flyer dispersion mode, cylindrical form, low body armoring, and adhesive secretions as adaptation to the flow. In contrast, natural sites favored respiration through gills, streamlined body, low flexibility, moderate body armoring, crawlers, and species with terrestrial reproductive stage, among others. The agricultural sites displayed moderate disturbance, and no specific trait modalities were associated with this particular land use. Functional diversity metrics mirrored the patterns observed in taxonomic diversity indexes, but only functional evenness showed the expected decline with increased disturbance. The trait-based approach complemented traditional methods for assessing land use impacts, providing insights into the mechanisms by which environmental stressors affect macroinvertebrates. This approach has emerged as a valuable tool for river management and land use policy.

Fish biodiversity assessments are vital for understanding threats and aquatic ecosystem health. In the Poso River, Central Sulawesi, changes in biodiversity are influenced by habitat alteration, non-native species, and overfishing. This study evaluates fish and crustacean biodiversity in the Poso River system to address these challenges for improving fisheries management, conservation, and fish passage integration into hydropower development. The present biodiversity study utilized a comprehensive methodology that encompassed both traditional taxonomic approaches and DNA barcoding, specifically targeting the mitochondrial cytochrome c oxidase subunit-1 (COI) gene for accurate species identification and spatial boundary validation. The survey was conducted in the upstream, hydropower area and downstream areas of the river. We found 27 species of fish in the Poso River, including both native (e.g., Anguilla celebesensis, Oryzias nebulosus, Rhyacichthys aspro) and non-native species (e.g., Melanochromis auratus, Amphilophus trimaculatus, Oreochromis niloticus). Two International Union for Conservation of Nature (IUCN) red listed endangered species were also observed (e.g., Adrianichthys poptae and Mugilogobius sarasinorum). DNA barcoding was performed to examine species spatial boundaries. The fish population in the Poso River was dominated by non-native species, accounting for 85.70% of the total population. The upstream reaches had the highest fish abundance and diversity, while the downstream reaches had the lowest. There was, however, no significant difference in species richness and diversity across different locations and seasons. The dominance of non-native species in the Poso River necessitates the improvement of existing fishways within the hydropower dams potentially through the development of selective technology that can block the distribution of these non-native species. This research highlights the critical issue of non-native species proliferation and the potential threat they pose to native fish populations, providing valuable insights for conservation and management efforts in Indonesia and similar ecosystems worldwide.

The aim of this study was to investigate the effects of oil palm (Elaeis guineensis) plantations on the water quality and physical structure of streams in the Amazon region and on the diversity of adult odonates (Insecta: Odonata). We tested the hypotheses: (1) that streams draining palm oil monocultures have low water quality and physical integrity and (2) that changes in water quality (local variables) and physical structure (landscape variables) of streams affect the abundance and species richness of the Odonata. A total of 22 streams were studied, of which 15 were in drainage areas used for oil palm plantations and seven were in primary forest areas in the eastern Amazon, Pará State, Brazil. To represent environmental conditions, we selected local variables (e.g., temperature, dissolved oxygen, and turbidity) and landscape variables (e.g., vegetation at 50 and 500 m distance from sampling points) known to be important for the Odonata community. Our results showed that oil palm plantations impact both the physical structure of Amazonian streams and Odonata diversity. The analyses revealed that Odonata abundance and species richness were influenced differently by the variables tested, with dissolved oxygen positively related to Odonata abundance and water temperature and turbidity negatively related to Odonata abundance. Changes in the surrounding vegetation were found to affect the physical structure of streams and influence dragonfly communities. Based on these results, we recommend the implementation of integrated approaches that consider local and landscape factors when monitoring aquatic ecosystems.