Aquatic Ecology最新文献

Fish are the key groups for maintaining the health and stability of aquatic ecosystems. However, due to limitations in existing fish survey techniques, there has been insufficient systematic research on fish resources and community structures in the context of Yangtze River fish conservation. Given this, taking the upstream area of the Taihu Lake Basin, a region with a developed freshwater fishery in China, as a case study, this research adopted environmental DNA (eDNA) technology to monitor the structural characteristics, diversity, and spatial distribution of fish communities in different water body types. The research findings showed that a total of 88 fish species were detected at 127 monitoring sites, with 79 species in rivers, 71 species in lakes, 73 species in reservoirs, and 57 species in streams. Among them, the fish composition in rivers and lakes presented homogenisation, with pollution-tolerant fish such as Carassius auratus, Cyprinus carpio, and Aristichthys nobilis being the dominant species. Although the fish communities in some reservoirs and streams also showed a slight trend of homogenisation, more fish species with higher water quality requirements, like the Rhinogobius giurinus and Odontobutis potamophila were retained. In areas with a high degree of human aggregation, namely the Yangtze River-the Grand Canal (CY), the Tao Lake-Ge Lake area (TG), and the area flowing into Lake Taihu (RT), the fish communities were dominated by tolerant fish species. In the Maoshan-Tianmu Mountain area (MT), where human activities were sparsely dispersed, the fish communities were relatively richer in clear-water fish species. TN, EC, pH, WT, and the natural shoreline retention rate (NSR) were the key environmental influencing factors for the composition of fish communities in the study area. The fish communities in rivers and lakes were more significantly affected by water environmental quality factors such as TN, EC, pH, and WT, while the fish communities in reservoirs and streams were more influenced by the aquatic habitat factor NSR. There was a significantly positive correlation between NSR and the fish diversity in rivers and lakes, and a significantly negative correlation between NSR and that in reservoirs and streams. This study has completed the inventory of fish species resources in the upper reaches of the Taihu Lake Basin, laid a scientific foundation for the restoration and protection of fish resources in the Taihu Lake Basin, and contributed to the sustainable protection and restoration of the aquatic ecosystem in the Taihu Lake Basin.

Understanding drivers of phytoplankton assemblage structure is essential given the ecological, aesthetic, and health consequences that vary among taxonomic groups. In this study, we examined phytoplankton assemblage structure over a three-year period in a natural riverine lake in the Upper Mississippi River. Phytoplankton samples along with a suite of limnological variables were collected along a longitudinal gradient of the lake to investigate potential relationships, mechanisms, and drivers between environmental conditions and phytoplankton assemblage structure. We found over 100 phytoplankton taxa and assemblage structure varied between years, months, and sites. With the use of a distance-based linear model, 32.6% of the total variation in phytoplankton assemblages was explained by a combination of chemical, hydrological, and physical variables. Additionally, we noted a one-year absence of the common diatom, Stephanodiscus hantzschii, that may have been related to an unusual spring of warm water temperature and low soluble reactive phosphorus concentrations, indicating possible nutrient limitation in a large river system. Insights into the relationships between environmental conditions and individual and co-occurring species of phytoplankton should aid in developing a greater predictability of assemblages and may enable large river scientists and managers to better anticipate and address water quality conditions under changing climate and hydrologic regimes.

In floodplains, the depth of water can directly impact the development of aquatic macrophytes. In this study, we used the emergent macrophyte Polygonum ferrugineum Wedd to investigate whether increased nutrient availability in the sediment alleviates submergence stress caused by flood conditions. Using a factorial design, we planted seedlings in two types of sediment (unenriched and enriched with P and N), subjecting them to deep and shallow water treatments. The effects of these treatments on plant attributes were assessed using a two-way ANOVA. The interaction between nutrients and depth significantly influenced most measured attributes (total biomass, shoot length, shoot biomass, leaf area, and root biomass). The highest values for these variables were observed when plants were grown in shallow water with high nutrient concentrations in the sediment. Root length and root:shoot ratios were influenced solely by depth, both of which were greater in the shallow treatment compared to the deep treatment. Our findings demonstrate that the growth of P. ferrugineum only occurs in shallow water where shoots are exposed to the atmosphere. Furthermore, our data indicate that greater depths (> 0.7 m) negatively impact growth regardless of nutrient availability. Therefore, we reject the hypothesis that high nutrient availability mitigates submersion stress. Our results contribute to the discussion on the impact of floods on emergent macrophyte species, highlighting the rapid morphological changes observed due to nutrient conditions in flooded sediments.

Due to the rapid rate of climate change, aquatic species might acclimate via phenotypic plasticity as a first defense. Parental effects, where the phenotype of an individual depends on the environment of its parents, could play an important role in driving population responses to climate change. Furthermore, characteristics of the species and stress exposure could be important for determining the outcome of this plasticity. Using a meta-analysis approach, we investigated the role of parental effects in allowing marine invertebrate species to cope with climate change. We summarized 107 fully-factorial sets of comparisons from 23 peer-reviewed papers that assessed how exposing parents to ambient or stressful conditions influenced responses of offspring exposed to ambient or stressful conditions. We calculated effect sizes (Hedges’ g) for these four contexts of ancestral-progeny experimental environments and collected life history information from the literature for the 20 species included in our study. We conducted subgroup analyses and meta-regressions to assess important characteristics leading to significant parental effects. We found that the level of environmental predictability between parents and offspring determined whether offspring performed better when their parents had also been exposed to stressful conditions representative of climate change. These observed parental effects were significant for species exposed to elevated CO₂ levels that were subtidal, sessile as adults, and had non-feeding larvae (i.e., recruit relatively locally). Understanding links between life stages, including characteristics associated with the strongest links, will aid in evaluating whether adults are likely to prime their offspring for future climates.

The energetic balance of organisms depends on the energy assimilated from food to fulfill vital functions (e.g. maintenance and somatic growth). Temperature drives the energetic balance and the performance of organisms. Evaluating the effect of temperature on multiple components is relevant to understanding the response to climate change. Here, we evaluated the thermal performance curve (TPC) for oxygen consumption (OC), ammonia excretion (AER) and ingestion rates (IR) in temperatures from 6 to 30 °C in the freshwater apple snail Pomacea sp. Additionally, we evaluated the evolution of somatic growth, IR and survival for ca. 400 days in snails exposed to fluctuating environmental temperature (OT; T range = 7–27 °C) and laboratory conditions (IT; T range = 12–19.6 °C). The TPC of OC and AER showed a unimodal pattern, with an optimum at 22 and 28 °C, respectively. IR showed a monotonic increase towards the warmest temperature (30 °C). Between ~ 15–20 °C weight increases with temperature while IR remains constant; suggesting snails invest energy mostly in growth. The final size achieved by snails in IT and OT were similar (~ 500 mg) while maximum IR was lower in IT (~ 400 mg/g.d vs ~ 800 mg/g.d of ET). Survival was similar between treatments, but growth parameters fitted by a modified Von Bertalanffy growth function with a temperature dependence on growth coefficient differed. TPC were different, which could generate mismatch between resource acquisition, assimilation and excretion affecting growth patterns. Evidence on a high capacity to deal with large thermal variability suggests adaptations of the snail to cope with climate change.

The present study assessed the diversity, distribution, and composition of aquatic insects and their relation to water quality parameters in the selected stations of the Chalakudy River. A total of 595 individuals belong to 7 orders, and 22 families were identified from the study area. Athirappilly exhibited the highest Shannon diversity (2.657) and species richness (3.374). In contrast, the lowest Shannon diversity (2.161) and species richness (2.009) were recorded at Ezhattumugham. The elevated diversity and richness at Athirappilly, coupled with sensitive taxa belonging to Ephemeroptera, Plecoptera, and Trichoptera, indicate favourable ecological conditions and minimal anthropogenic impact. Conversely, diminished diversity and richness with a lack of sensitive taxa at Ezhattumugham were attributed to deteriorated water quality. A two-way analysis of variance was performed to assess variations in physicochemical parameters between stations and seasons, revealing significant spatial and seasonal variations. Water temperature, electrical conductivity, dissolved oxygen, and biological oxygen demand exhibited statistically significant differences between stations and across seasons. Canonical correspondence analysis elucidated a significant relationship between the distribution and composition of aquatic insects and the water quality variables measured. The pre-monsoon season was characterized by a higher prevalence of tolerant taxa, while the post-monsoon season was distinguished by sensitive taxa, reflecting improved water quality. These patterns highlight the temporal fluctuations in water quality and their impact on aquatic insects. The finding emphasizes the interplay between water quality parameters and biodiversity, offering valuable insight for conservation efforts and sustainable river basin management.

Plerocercoid infection rates in fish may result from factors influencing individual and species-specific susceptibility to procercoid infection in copepods. In this paper, we examine the infection rates of fish communities in Spanish mountain lakes by Ligula plerocercoids and explore potential factors that may influence the differences across 9 fish species and 13 lake systems. This study is the first to report the presence of plerocercoids in endemic Bermejuela del Esla (Achondrostoma asturicense), with prevalence rates ranging from 0 to 42.5%. We significantly observed low feeding intensities (gut fullness) and gonadal atrophy in infected A. asturicense compared to non-infected individuals, but zooplankton was absent in the gut contents of A. asturicense. We posit that the absence of fish-eating birds in high-altitude lakes, along with fish abundance and species-specific differences in fish foraging behaviours, likely explains the geographical variations in plerocercoid prevalence across lake-dwelling fish communities.

Although rainbow trout Oncorhynchus mykiss has been widely introduced throughout Europe, self-sustaining populations are rare and unevenly distributed. In Cyprus, this invasive salmonid was introduced for recreational fishing at the end of the nineteenth century. To test whether rainbow trout have established in some water catchments of the island, between September 2020 and September 2022 we assessed the species’ distribution and analysed the age structure (by Bhattacharya’s method) and weight-length relationship of its major populations. The rainbow trout was recorded in 17 out of 86 sampling sites (19.7%), belonging to nine rivers and five catchments. Well-structured populations (N of cohorts ≥ 4) occurred in the River Kryos, where water temperatures were suitable for reproduction. Only a few individuals older than 4 years were sampled. Overall, both environmental conditions and population parameters suggest that the rainbow trout may self-sustain at least in the central, mountainous part of the island (rivers Kryos and Limnatis), where it occasionally coexists only with other introduced species. Nonetheless, its impact on native freshwater communities needs to be carefully assessed.

Macroplastic pollution remains a growing global environmental concern, and our understanding of its interaction with aquatic organisms is underdeveloped. It is also less clear how hydraulic biotopes influence macroinvertebrates colonisation of macroplastic relative to natural substrates. We investigated temporal and spatial patterns of macroinvertebrate colonisation on macroplastic litters in contrasting stream hydraulic biotopes (riffle, pool, and run) in minimally impacted headwater streams of Eastern Cape, South Africa. Plastic substrates of different proportions of natural and plastic litter were deployed across four sites. The Substrate group included 100% natural substrates (NS), 50% natural material and 50% plastic litters (NP), and 100% plastic (PD) litters. Each substrate group was deployed in riffle, pool, and run habitats for six months at each site. Across hydraulic biotopes, macroinvertebrate colonised substrate groups equally (PERMANOVA, p > 0.05). Macroinvertebrate diversity indices were statistically different across substrate groups in pools but not in other hydraulic habitats (PERMANOVA, p < 0.05). We observed that NS had significantly higher macroinvertebrate Margalef’s richness, Shannon, and Simpson diversity values than macroplastic substrates in pools. This difference suggests that specific-hydraulic biotope characteristics, such as sediment accretion and stream discharge, influence macroinvertebrate diversities. However, the dominant taxa had a marked presence in all substrate groups within hydraulic biotopes throughout the study, resulting in temporal variance that was not significant. Our findings highlight the importance of hydraulic biotope influence on macroinvertebrate colonisation of macroplastic substrates. It also provides a baseline for further research involving riverine macroplastic pollution.

The globally invasive freshwater snail, Physella acuta (Draparnaud, 1805) is genetically diverse, with cox1 haplotype markers identifying an invasive lineage (A) and a non-invasive lineage (B) restricted to its native North American habitat. This study investigated the differential fitness of A and B lineages within the species. Field-collected P. acuta were genetically characterized to establish laboratory strains representing mitotypes A and B. While the nuclear rDNA cassette (7,023 nt) differed only by 0.03% between A and B, the mitogenome haplotypes differed in size (14,383 vs. 14,333 bp) and sequence content (~ 9%). Fitness (growth rate, age and size at maturity, reproductive output) of A and B did not differ under laboratory conditions. A rewilding approach (exposure to native range field conditions) revealed greater fitness of P. acuta A relative to B snails, indicated by greater population-level fecundity, greater realized fecundity of A versus B, and higher survival rates of A in 3 of 7 experiments. While laboratory-based studies indicated only minor differences, the rewilding approach revealed significant differential fitness between A and B lineages of the species P. acuta, potentially influencing geographical distribution.