Aquatic Botany最新文献

Constructed wetlands (CW) treating runoff from agricultural catchments reduce the nutrient load of water, however, they can also be significant sources of greenhouse gases, especially methane (CH₄). We simultaneously assessed CH₄ emission potentials and phosphorus (P) removal efficiency in a 0.45 ha in-stream surface flow CW to determine the main drivers of CH₄ emissions, and to analyze the temporal dynamics of CH₄ emissions and P removal during an almost 4-year period. The TP (total phosphorus) removal efficiency had a clear seasonal dynamic, with the highest removal occurring during summer and early autumn (monthly average 60.5%), when the flow rate was lowest and water residence time longest. Due to increasing sedimentation and related anaerobic conditions, the mean hourly CH₄ emissions for each year demonstrated an increasing trend over the years: from 88 µg CH₄-C m⁻² h⁻¹ in 2018–2505 µg CH₄-C m⁻² h⁻¹ in 2021. There was a clear seasonality in CH₄ emissions: up to 90% of CH₄ fluxes occurred during the warm period (from May to October). We assume that maintenance of treatment wetlands is essential and predominantly regular removal of aboveground vegetation at the second half of the growing season would decrease CH₄ emissions. Nevertheless, due to the P saturation in sediments, regular sediment removal in the long term is also necessary.

Eleocharis carniolica is included in the EU Habitat Directive and legally protected in many European countries. It is also considered as one of the most threatened plants in Poland. It typically occurs in muddy habitats, wet meadows, lake or pond shores or temporary puddles, but in Poland this species usually occurs at disturbed anthropogenic sites such as road verges or drainage ditches. Despite being the focus of a number of ecological and conservation studies, E. carniolica still does not have a fully recognized ecology and life-strategy, particularly with regard to breaking seed dormancy and germination. To find out the population performance and species propagation potential in Poland, we have conducted experiments aimed at assessing the seed germination conditions and efficiency. The main goal was to discover the crucial factors that stimulate germination. The results of the experiments suggest that light is a pivotal factor for triggering germination of E. carniolica seeds. Moreover, E. carniolica’s seed bank consisted of about 80 % dormant seeds. The only effective method for dormancy breaking was warm stratification (placing the seeds at high temperature on a moist substrate) with application of gibberellic acid (GA₃)_, and even a few days of warm stratification resulted in effectively overcoming dormancy. Eleocharis carniolica's germination features are typical for plants adapted to frequent disturbances with a short life expectancy and large reproductive effort. Our results strongly suggest that E. carniolica has a ruderal life strategy at its northern distribution limits and probably can be considered as an alien species in Poland.

Massive blooms of pelagic Sargassum algae have caused serious problems to coastal communities and ecosystems throughout the tropical Atlantic, Caribbean Sea, and Gulf of Mexico since 2011. Efforts to monitor and predict these occurrences are challenging owing to the vast area impacted and the complexities associated with the proliferation and movement of Sargassum. Sargassum Inundation Reports (SIRs) were first produced in 2019 to estimate the potential risk to coastlines throughout the Intra-American Sea at weekly intervals at 10 km resolution. SIRs use satellite-based data products to estimate beaching risk from the amount of offshore Sargassum (quantified by a Floating Algal density index). Here we examine whether including wind metrics improves the correspondence between the offshore Floating Algal density index and observations of Sargassum along the coastline. For coastal observations, we quantified the percent coverage of Sargassum in photos obtained from the citizen science project "Sargassum Watch" that collects time-stamped, georeferenced photos at beaches throughout the region. Region-wide analyses indicate that including shoreward wind velocity with SIR risk indices greatly improves the correspondence with coastal observations of Sargassum beaching compared to SIR risk indices alone. Site-specific analyses of photos from southeast Florida, USA, and data from a continuous video monitoring study at Puerto Morelos, Mexico, suggest potential uncertainties in the suite of factors controlling Sargassum beaching. Nonetheless, the inclusion of wind velocity in the SIR algorithm appears to be a promising avenue for improving regional risk indices.

Due to the massive proliferation and stranding of holopelagic Sargassum spp. over the last decade, different strategies for the sustainable valorisation of Sargassum biomass have been explored and investigated. One limitation to the development of Sargassum biomass valorisation is related to its high arsenic (As) content. The toxicity of As depends on the chemical forms present and their oxidation or valence state, classified as inorganic and organic compounds, with the inorganic As compounds being much more toxic than the organic ones. The aim of the present study was to determine the inorganic arsenic (iAs) content in holopelagic Sargassum spp. for which almost no information on stranded biomass is available. In this study, we examined the iAs content in the three holopelagic Sargassum morphotypes collected over a seasonal cycle in 2018–2019. The iAs concentrations ranged from 12.7 to 62.9 mg kg⁻¹, representing 14.1–81.7% of total arsenic (TotAs). The iAs content was compared between species and seasons and discussed in the context of existing international regulations and guidelines.

Seagrasses are clonal plants that can form meadows in shallow coastal water. Under natural conditions, drift macroalgae can be found associated with seagrass but when facilitated by high nutrient input, opportunistic macroalgae can grow excessively and form mats that impose stressful and highly competitive conditions for seagrasses. In this study, we experimentally investigate the ecological significance of clonal integration in the ability of Cymodocea nodosa to tolerate biotic stress triggered by interactions with the drift macroalgae Chaeotomorpha linum. Our findings provide little support for the hypothesis that clonal integration can influence C. nodosa response to stress, as disconnected plants did not show significant differences in structural and morphological characteristics compared to intact plants. However, the physiological analysis suggests that C. nodosa may still benefit from shared resources with neighbouring plants to mitigate stress caused by C. linum. Moreover, the results indicate that C. nodosa adapts to the presence of the filamentous drift macroalgae C. linum by increasing leaf photosynthetic content, reducing growth rate, and modulating its morphology, regardless of its integration status.

Utilizing and discharging chemical products containing trace metals lead to widespread contamination in the aquatic environment. Although copper (Cu) and zinc (Zn) are essential plant micronutrients, excessive concentrations may induce stress and mortality. This study investigated the physiological responses of a common aquatic plant, Ceratophyllum demersum, exposed to Cu (0, 2, 5, 10, and 50 μM) or Zn (0, 50, 100, 500, and 1000 μM) for 3 days. Both Cu and Zn were accumulated in plant tissues. Cu exposure led to severe phytotoxicity effects, manifested as a rapid decrease in photosynthetic efficiency (Fv/Fm and ՓPSII), a significant reduction in pigments and an increase in oxidative stress markers. In contrast, minor effects were observed in Zn-treated plants. In addition, Cu exposure suppressed the expression of D1, rubisco large subunit, and alpha-tubulin proteins but did not affect the PSI-B core subunit of PSI. Our study suggested that Cu is a potent phytotoxin by disturbing the principal reactions of photosynthesis and inducing oxidative stress and protein degradation. The overall health status of C. demersum was assessed by adopting the biomarker response index (BRI) approach. The effects of Cu were categorized as moderate in 2 μM and severe in 5, 10, and 50 μM whereas the effects of Zn were categorized as slight in 50 μM, negligible in 100 μM and major in 500 and 1000 μM. BRI effectively substantiates data interpretation of complex plant responses to trace metals and should be further adapted into biomonitoring suites in aquatic systems.

Vallisneria is a cosmopolitan genus of aquatic plants comprising 14 species within the family Hydrocharitaceae. Previous research suggests Vallisneria is a more speciose genus than current taxonomy indicates, and there remains contention on the level of species diversity within the genus. In order to address some of these taxonomic issues, this study estimates phylogenetic relationships within the genus using a previously published molecular dataset augmented with previously unsampled species through the use of maximum likelihood analyses for all molecular data partitions (e.g., nrITS, cpDNA, and combined nuclear and cpDNA datasets). Based on our findings, we recommend the resurrection of two Vallisneria species (V. gracilis and V. neotropicalis), and formally recognize and describe a new species (V. jacobsii). Morphological data was shown to be useful for some species delimitation but overall, molecular sequence data provided the best estimates of species identification for cultivated specimens. We also show the presence of naturally occurring putative Vallisneria hybrids within Northern Territory, Australia, and give conclusive evidence that non-native hybrids are being used for a restoration project in Crystal River, Florida.

Species may respond to variation in environmental conditions by modifying their phenotype to match local levels of resource availability. This phenotypic response can be driven by plastic physiological change, or by adaptive genetic change. Here we use Lemna minor (lesser duckweed), a small aquatic macrophyte that is increasingly used as a model in ecology and evolution, to investigate the source and maintenance of phenotypic variation in natural environments. We found substantial phenotypic variation in L. minor in the field, with its frond area and root length changing predictably over natural environmental gradients of resource availability. Separating environmental and genetic variation in these traits in a common garden, we attribute the majority of phenotypic variation we observed in the field to phenotypic plasticity. Despite this, there was substantial within-site genetic variation. We found evidence of strong purifying selection in the field, that is necessarily balanced by mutation and migration. Using measures of environmental and genetic variation in phenotype and fitness, we estimate the rates of dispersal and evolution of fitness necessary to sustain the observed levels of genetic variation.

The increasing spread of Undaria pinnatifida has caused concern in many parts of the world in recent decades, and this alga has been listed as invasive in the introduced countries. Its most recent spread in Europe was reported on Sylt island in the northern Wadden sea (German Bight, Eastern North Sea) between 2016 and 2017. Its direct origin remained unknown. In the present study, we obtained the mitochondrial DNA sequences including the partial coding region of cox3 and intergenic noncoding loci tatC-tLeu, atp8-trnS and trnW-trnI from one drifting population and one attached population of U. pinnatifida on Sylt and compared them with the available sequences published in previous studies. For the concatenated sequences of atp8-trnS and trnW-trnI, two haplotypes (Up01 and Up03) were detected in Sylt populations with Up01 being the dominant haplotype, which was most similar to the haplotype composition identified previously in European populations. For the concatenated sequences of cox3 and tatC-tLeu, two haplotypes (H1 and H9) were found in Sylt populations and they were the same as those identified previously in Brittany, France. These results suggest that European populations were most likely the direct origin of the newly established U. pinnatifida population on Sylt. The combined use of these sequences will be a robust tool to infer the origins of newly established populations of this seaweed in the future.