Aquatic Plant Communities Research Articles

Developing a European aquatic macrophyte transfer function for reconstructing past lake-water chemistry

Quantitative paleoecological reconstructions using biological proxies, such as diatoms, Cladocera, and chironomids, have revolutionized paleolimnology and have greatly contributed to the understanding of the past local and regional environmental changes, as well as to nature conservation. While macrophytes are good ecological indicators, they have rarely been used to reconstruct past lake-water chemistry. The present study investigates which environmental variable best explains aquatic plant community composition in Finnish, Polish, and Swedish lakes for its further use in quantitative paleoenvironmental reconstructions. The method involved the creation of a modern macrophyte-environment calibration dataset, calculation of modern calibration functions using simple averaging regression, and final reconstruction of past environmental conditions in Lake Linówek (NE Poland) from a fossil assemblage using weighted averaging calibration. The data demonstrate that conductivity and alkalinity best explained macrophyte community composition in our dataset. Species “optima” for alkalinity were influenced by the presence/absence of carbon concentrating mechanisms (CCMs), enabling the utilization of HCO3− as a carbon source. Quantitative paleoenvironmental reconstruction indicates that past water conductivity and alkalinity fluctuated depending on internal lake processes and the supply of basic ions to the lake from the catchment related to climate and soil development in the watershed during the late Glacial (∼14,500–11,700 calibrated years before the present; cal BP) and the Holocene (11,700 cal BP–recent). We conclude that macrophytes can be successfully used for past lake-water chemistry reconstruction. Furthermore, calculated modern calibration functions for conductivity and alkalinity can be used in nature conservation for determining habitat requirements of numerous endangered macrophyte species as a basis for successful (re)introductions.

Spores from the K–Pg boundary of the La Colonia Formation, Patagonia, Argentina

A palynological study was carried out based on 157 samples collected from four representative stratigraphic sections of the Maastrichtian-Danian deposits of the La Colonia Formation outcropping in northern Chubut Province, Patagonia, Argentina. About 240 palynomorphs were recognized. Plant communities were dominated in terms of richness by ferns and angiosperms, but algae and gymnosperms are also well-represented. In this contribution, we present the systematic study of bryophyte, lycophyte, and fern spores. Bryophytes comprise eight species (10% of spore diversity), including representatives of Marchantiophyta, Bryophyta, and Anthocerotophyta. Lycophytes encompass 15 species (20% of spore diversity) and are represented by the families Lycopodiaceae and Selaginellaceae. Ferns comprise 53 species (70% of spore diversity), including members of Anemiaceae, Dicksoniaceae, Dipteridaceae, Gleicheniaceae, Lygodiaceae, Marsileaceae, Matoniaceae, Osmundaceae, Polypodiaceae, Salviniaceae, and Schizaeaceae, among others of uncertain affinities. Four new species are erected: a lycophyte (Neoraistrickia loconiensis sp. nov.), a salvinialean (Thecaspora polygonalis sp. nov.), and two fern species of unknown affinities (Clavatosporis varians sp. nov. and Microreticulatisporites patagonicus sp. nov.). The recorded palynoflora reinforces previous environmental interpretation of the La Colonia deposits as coastal plains bathed by shallow seas and barrier island/lagoon complexes and the presence of freshwater bodies where aquatic plant communities developed. The vegetational history of the bryophytes, lycophytes, and ferns in the studied sections of the La Colonia Formation indicates the lack of a significant floristic change across the K–Pg interval at the local scale.

Multidimensional trait space outlines the effects of changes in abiotic filtering on aquatic plant community from sub-Antarctic ponds

In the current context of climate changes, which causes strong habitat variation, an understanding of the mechanisms underlying plant community dynamics is crucial to predict species fates. The taking of inter- and intraspecific trait variability into account would aid the identification of these mechanisms. Recently, a method involving the calculation of hypervolumes (n-dimensional spaces of trait values) was developed for the study of plant responses to their environments. Through hypervolume comparison, we examined the effects of interannual variations in abiotic conditions on aquatic plant communities in ponds of the sub-Antarctic Iles Kerguelen. This model system is particularly relevant for the examination of the consequences of climate changes–related habitat variation, as aquatic plant communities are adapted to cold and overall stable habitat conditions and the sub-Antarctic climate is changing rapidly. We conducted field sampling over four years at three sites. For all aquatic species, we measured five foliar, shoot, and clonal traits characterizing individual growth strategies that are likely to respond to variations in abiotic conditions on 1565 ramets over the four years. We measured 10 abiotic variables to characterize the plants’ habitats every three months during the survey period. Hypervolumes were calculated for each site and year to assess variation in aquatic plant strategies at the community level. We demonstrated (i) the importance of spatiotemporal gradients of trophic status, temperature, and pH and dissolved oxygen concentration for the functional structure of aquatic plant communities; (ii) that the shape of the mean response was trait dependent, with traits related to plant metabolism (specific leaf area and specific internode mass) and three-dimensional space exploration (height and internode length) responding to the three spatiotemporal abiotic gradients; (iii) that selection pressures were especially high on aerial traits relative to clonal traits; and (iv) that given the community response to interannual variations of abiotic conditions, environmental changes should impact macrophyte community productivity. Synthesis. We conclude that the examination of interannual abiotic variation over four years is sufficient to detect rapid responses of macrophyte communities, with likely reliance on phenotypic plasticity. Our findings may inform the characterization of future functional changes in aquatic plant communities of the sub-Antarctic region, where similar species are found.

The impact of drought duration on two Potamogeton species with different growth forms

When facing new climate extremes, aquatic plant communities may experience more frequent or increasing durations of water shortages. Aquatic macrophytes of permanently inundated habitats (true hydrophytes) may lack the physiological or morphological characteristics that protect terrestrial plants from drying out. Aquatic hydrophytes with floating or emergent leaves are expected to be more resilient to droughts than completely submerged plants, as they have morphological characteristics adapted to air-exposed conditions. Therefore, we expected the latter to survive longer periods of air exposure and perform better with increasing drought than a completely submerged growing species. Here, we conducted a microcosm experiment and exposed two Potamogeton species—the completely submerged growing Potamogeton perfoliatus and the areal leaf producing Potamogeton nodosus—to different drought conditions (1, 5, and 15 days). We aimed to detect how two species with different growth strategies cope with and respond to increasing air exposures with waterlogged sediment. Both species showed a resistance to 1–5 days of drought but showed high mortality after 15 days. They displayed significant differences in all measured morphological responses (shoot length, side shoot, and leaf counts), plant chemistry (carbon, nitrogen, and phosphate), and the produced biomass (shoot, root, leaves), and reacted significantly to increasing drought durations. Differences in their resistance were observed based on the mortality rate and morphological responses. To prevent long-term droughts and keep mortality low, we recommend to the water managers to identify areas of risk and increase water levels during dry periods.

Water Composition, Biomass, and Species Distribution of Vascular Plants in Lake Agmon-Hula (LAH) (1993–2023) and Nearby Surroundings: A Review

A significant change to the land cover in the Hula Valley was carried out during the 1950s: A swampy area densely covered by aquatic vegetation and the old shallow lake Hula were drained. The natural shallow lake and swamps land cover were converted into agricultural development land use in two stages: (1) Drainage that was accomplished in 1957; (2) Implementation of the renovated hydrological system structure, including the newly created shallow Lake Agmon-Hula (LAH), was completed in 2007. The long-term data record of the restored diversity of the submerged and emerged aquatic plant community, and its relation to water quality in the newly created shallow Lake Agmon-Hula LAH, was statistically evaluated. Internal interactions within the LAH ecosystem between aquatic plants and water quality, including nitrification, de-nitrification, sedimentation, photosynthetic intensity, and plant biomass and nutrient composition, were statistically evaluated. The plant community in LAH maintains a seasonal growth cycle of onset during late spring–summer and dieback accompanied by decomposed degradation during fall–early winter. The summer peak of aquatic plant biomass and consequent enhancement of photosynthetic intensity induces a pH increase during daytime and carbonate precipitation. Nevertheless, the ecosystem is aerobic and sulfate reduction and H2S concentration are negligible. The Hula reclamation project (HP) is aimed at the improvement of eco-tourism’s integration into management design. The vegetation research confirms habitat enrichment.

Response of Functional Traits of Aquatic Plants to Water Depth Changes under Short-Term Eutrophic Clear-Water Conditions: A Mesocosm Study.

Aquatic plants play a key role in the structuring and functioning of shallow lake ecosystems. However, eutrophication often triggers shifts in plant communities and species diversity, especially in the early stages when the water is still clear. Additionally, water depth is an important factor regulating aquatic plant communities. We conducted a 50-day mesocosm study to investigate how water depth (50 cm and 100 cm) affected the functional traits (vertical expansion versus horizontal colonisation) of 20 aquatic plants under eutrophic clear-water conditions. Among the selected species, the submerged plants Hydrocotyle vulgaris and Limnophila indica exhibited higher plant height or biomass in deeper water, while the emergent plants Myriophyllum aquaticum showed the opposite trend. Additionally, Ludwigia peploides subsp. stipulacea exhibited better vertical growth than the remaining species, and the submerged species Vallisneria denseserrulata had better horizontal colonisation. There was a positive correlation between plant height and rhizome length, indicating the absence of a trade-off between vertical growth and horizontal expansion. Our findings suggest an overall resilience of aquatic plants to varying water depths within our study range and highlight the importance of analysing functional traits when selecting appropriate species in freshwater ecosystem restoration, particularly in the face of climate change-induced water depth fluctuations.

Control of overgrowth of Potamogeton crispus in shallow lakes by light shading and artificial introductions

Potamogeton crispus is a common submersed aquatic plant in shallow lakes in China, and its overgrowth and rapid decomposing have become an important environmental problem affecting the water quality of lakes every summer. Introducing other submersed plants to substitute Potamogeton crispus can improve the structure of the aquatic plant community and to reduce the growth of Potamogeton crispus to some degree, but the effect is poor and short-lived. Considering the fact that Potamogeton crispus is sensitive to changes in light intensity, the two methods of shading the water surface and introduction of other submerged plants were used synergistically. In a large simulated experimental pool, light intensity was reduced by placing black polyethylene floating spheres on the water surface and planting three species of submerged plants, namely, Vallisneria natans, Hydrilla verticillata and Potamogeton wrightii. Changes in the physico-chemical properties of the experimental pool water and the physiological and biochemical characteristics (morphology, chlorophyll, biomass, antioxidant enzymes and malondialdehyde) of the submerged plants during the period of 0–40 d were analyzed. The results showed that: (1) After the light intensity was reduced by 85%, Potamogeton crispus seedlings showed a significant decrease in biomass and chlorophyll content and died in large numbers within 20–30 days. (2) Catalase is the main tool for Potamogeton crispus to cope with low light stress. The activities of various antioxidant enzymes and the malondialdehyde content of Potamogeton crispus showed a decreasing trend under shade conditions, but the catalase activity increased dramatically. (3) Vallisneria natans is more tolerant of low light conditions than the other two submersed plant species. Therefore, we tried to reduce the biomass of Potamogeton crispus by combing introduction of other submersed plants and shading treatment. (4) The water quality objectives remained stable over the period of the trial, indicating that short-term shading does not have a negative impact on the quality of the water quality.

Vegetation Spatial Distribution on Taean Duung Wetland Protect Area

In this study, we conduct for providing information on the status of vegetation space distribution in the Duung wetland protected area and to help manage the wetland protected area. To understand the spatial distribution of vegetation in Duung Wetland, used the results of surveys in 2019 and 2023. As a result of the study, the number of vegetation types increased by 4 from 20 to 24. Four communities were newly investigated, including the <i>Utricularia tenuicaulis</i> community, <i>Pueraria montana</i> var. <i>lobata-Elymus tsukushiensis</i> community, <i>Spiraea prunifolia</i> for. <i>simpliciflora</i> community, and <i>Miscanthus sinensis</i> var. <i>purpurascens</i> community. In accordance with the environment, the range of aquatic plant communities such as <i>Trapa japonica</i> community and <i>Nymphaea tetragona</i> var. <i>angusta</i> community increased, and the succession zone of cultivated land expanded dry grassland. The survey results can be used as basic data for systematic management of the Duung wetland protected area.

Interactions shape aquatic microbiome responses to Cu and Au nanoparticle treatments in wetland manipulation experiments

In natural systems, organisms are embedded in complex networks where their physiology and community composition is shaped by both biotic and abiotic factors. Therefore, to assess the ecosystem-level effects of contaminants, we must pair complex, multi-trophic field studies with more targeted hypothesis-driven approaches to explore specific actors and mechanisms. Here, we examine aquatic microbiome responses to long-term additions of commercially-available metallic nanoparticles [copper-based (CuNPs) or gold (AuNPs)] and/or nutrients in complex, wetland mesocosms over 9 months, allowing for a full growth cycle of the aquatic plants. We found that both CuNPs and AuNPs (but not nutrient) treatments showed shifts in microbial communities and populations largely at the end of the experiment, as the aquatic plant community senesced. we examine aquatic microbiomes under chronic dosing of NPs and nutrients Simplified microbe-only or microbe + plant incubations revealed that direct effects of AuNPs on aquatic microbiomes can be buffered by plants (regardless of seasonal As mesocosms were dosed weekly, the absence of water column accumulation indicates the partitioning of both metals into other environmental compartments, mainly the floc and aquatic plants photosynthetically-derived organic matter. Overall, this study identifies the potential for NP environmental impacts to be either suppressed by or propagated across trophic levels via the presence of primary producers, highlighting the importance of organismal interactions in mediating emerging contaminants’ ecosystem-wide impacts.

Effect of sodium dodecyl sulfate (SDS) on microbial community structure and function in lake–terrestrial ecotones: A simulation experiment

Even a low concentration of sodium dodecyl sulfate (SDS), a widely used bactericidal surfactant, can significantly change the species, quantity and genetic functions of microorganism communities in natural waters. Lake–terrestrial ecotones are areas where microorganisms are highly active, and they are also the lake areas most vulnerable to SDS pollution. Because microorganisms are very sensitive to environmental changes, their activities vary greatly among lakes and laboratories, so it is difficult to simulate their real dynamics using small-scale experiments. To study the interaction between SDS and microorganisms in a lake–terrestrial ecotone, a large artificial simulation device was used to analyse microbial community structure, phospholipid fatty acid (PLFA) content, gene function and ability to degrade SDS in a lake–terrestrial ecotone contaminated with SDS. The results showed that (1) the period from 2 to 4 days after the beginning of the experiment was the key stage for the biodegradation of SDS. The biodegradation cycle of SDS in the natural environment is shorter than that in small-scale experimental setups, and more than 90% of SDS was removed within 4 days in the simulation device. (2) Low-level SDS pollution (≤ 6 mg/L) has different effects on different types of lacustrine microorganisms. The presence of SDS can lead to a significant decrease in microbial diversity and biomass in lake–terrestrial ecotones with a high density of aquatic plants, but the opposite is true in ecosystems with degraded aquatic plant communities. (3) After SDS pollution occurred, pollution-resistant bacteria such as Chitinophaga and Flavobacterium became dominant. The relative abundance of carbon cycle functional genes increased rapidly in microorganisms, while the relative abundance of nitrogen cycle functional genes decreased. These changes were not readily reverse even after 20 days, although the communities recovered to a certain extent.

Seasonality strongly affects short‐term C‐storage in coastal macrophyte communities

AbstractEcosystem functions provided by aquatic plants are context dependent and mediated by environmental conditions and plant growth form. This impedes our ability to predict the carbon (i.e., C) sink potential of multispecies coastal meadows characterized by marked seasonal succession of environmental conditions, causing a clear need to explore the distinct patterns of both C capture and release associated with seasonal succession of macrophyte growth forms and life‐history strategies in aquatic plant communities. We conducted four field surveys throughout 2022–2023 (i.e., October, March, June, and August), where we sampled six soft bottom locations dominated by aquatic vascular plants in the northern Baltic Sea. Temporal differences in biomass‐bound C stocks (i.e., structural elements and non‐structural carbohydrates) were linked to the plant production‐decomposition cycle and peaked when environmental conditions became increasingly permissive for growth and development (i.e., summer). Species identity influenced seasonal patterns of non‐structural carbohydrate concentrations in both leaf and rhizome tissue by shaping the timing of short‐term accumulation (i.e., photosynthesis) of C in plant tissue or release through respiration. Overall, our study illustrates that biomass‐bound C stocks were shaped by both seasonality and the variation of functional structure and life history strategies found within the vegetated seascapes. This highlights the importance of addressing both biodiversity and short‐term C dynamics and suggests that estimations of C budgets or stock assessments should be based on data incorporating the intra‐annual variation in C dynamics to fully comprehend the C sink potential of vegetated seascapes.

THE PHYTOCOENOTIC STUDY REGARDING THE WET HABITATS FOUND ON THE COPĂNIȚA ISLAND, DOLJ COUNTY, ROMANIA

The territory under study is an island located very close to the flow of the Jiu into the Danube, in the lower course of the Danube, and represents a protected area for important species and habitats of community and priority interest, as well as an important migration area for an impressive number of protected birds.This territory is part of the ROSCI0045 Coridorul Jiului Protected Area. Considering the extremely varied and rich biodiversity of this area, we started in 2022 the realization of complex studies regarding the flora, vegetation as well as the habitats of community and priority interest found on Copanița Island. In the present work, a study is presented regarding the phytocenology of wet habitats of conservation interest as well as the anthropogenic impact on them. Thus, the following wetland habitats were identified: 3160 - Natural dystrophic lakes and ponds (CLAS. PAL.: 22.14), 3150 - Natural eutrophic lakes with Magnopotamion or Hydrocharition-type vegetation (CLAS. PAL.: 22.13 x (22.41 sau 22.421), 3130 - Oligotrophic to mesotrophic standing waters with vegetation of the Littorelletea uniflorae and/or Isoëto-Nanojuncetea (CLAS. PAL.: 22.12 x (22.31 şi 22.32) and 3270 - Rivers with muddy banks with Chenopodion rubri p.p. and Bidention p.p. vegetation (CLAS. PAL.: 24.52). From the phytocoenotic point of view, the following aquatic and palustre plant communities were identified: Myriophyllo verticillati-Nupharetum luteae Koch 1926, Trapo-Nymphoidetum Oberd. 1957, Lemno-Spirodeletum Koch 1954, Spirodelo-Salvinietum natantis Slavnič 1965, Lemno-Salvinietum natantis Miyawaki et Tüxen 1960, Cyperetum flavescentis Koch ex Aichinger 1933 and Bidenti-Polygonetum hydropiperis Lohm. in Tüxen 1950, Polygono lapathifolio – Bidentetum Klika 1935; Echinochloo – Polygonetum lapathifolii Soo et Csurrs 1974. The climate changes of recent years had a particularly negative effect on these habitats with a particular impact on the surfaces of the habitats but also on the structure and physiognomy of the edifying plant communities.

Engineering aquatic plant community composition on floating treatment wetlands can increase ecosystem multifunctionality

Phytoremediation using floating treatment wetlands (FTWs) is an emerging nature-based solution for freshwater restoration. However, the potential to design these systems by manipulating macrophyte community composition to provide multiple ecosystem services remains unexplored. Using a tank experiment, we simulated aquatic environments impacted by multiple pollutants and employed a comparative ecological approach to design emergent macrophyte communities using the trait of plant stature (plant height) to structure communities. Ecosystem functions were quantified, and a threshold-based method used to compute an ecosystem multifunctionality index that was weighted based on three different management-driven restoration objectives: equal importance, phytoremediation, and regulation and cultural services. Across all restoration scenarios, ecosystem multifunctionality was higher when community types performed more diverse functions. Small emergent plant communities outperformed all other community types due to their increased provision of both regulation and maintenance, cultural, and provisioning services. Conversely, large emergent communities that are more typical candidates for phytoremediation had the highest levels of multifunctionality only when function was lower. Arranging emergent macrophytes in mixed-statured communities led to intermediate or poorer performance both in terms of multifunctionality and specific functions, suggesting that diversity on the plant stature axis leads to negative plant interactions and represents a ‘worst of both worlds’ combination. Employing comparative ecology to generalise plant selection by stature demonstrates that large emergent macrophytes are more likely to better deliver provision-based services, while small emergent communities can provide additional benefits from cultural and regulatory services. Selecting macrophytes for FTWs employed in freshwater restoration by stature is a simple and widely applicable approach for designing plant communities with predictable outcomes in terms of (multiple) ecosystem service provision and highlights the need for environmental managers to closely align restoration objectives with potential community types.

COMPOSITION AND STRUCTURE OF HYDROPHYTE COMMUNITIES IN DIFFERENT TYPES OF WATER BODIES IN THE CITY OF POLTAVA

The article highlights the results of studying the composition and structure of the true aquatic plant communities in different types of water bodies of the city of Poltava (artificial and natural reservoirs, the urban section of the middle River Vorskla), where, according to the ecological and floristic classification, 21 associations (including 8 subassociations) of eight alliances, three orders and two classes were identified. Of these, only association Ceratophylletum demersi is the most typical in urban area. The class POTAMETEA differs in the relatively higher coenotic diversity (13 associations), and the class LEMNETEA differs in the lower diversity (8 associations). 
 The studied plant associations are characterized by a low species richness, the absolute majority of them represents a simplified version of the original natural associations. Communities of class POTAMETEA, observed in urban reservoirs, are especially depleted (1–3 species in the descriptions). There is a general tendency to increase the coenotic activity of the floristic elements that are tolerant to anthropogenic load and eutrophication.
 In the rank of associations there are 18 communities in urban lentic water bodies and 9 communities on the urban section of the middle river. Most of the identified associations (12) are confined exclusively to urban reservoirs, while only 3 associations are specific to the urban section of the river. Of those 6 associations found both in urban reservoirs and in the urban section of the middle river, it is the river coenoses that are more diverse and better developed.
 In the conditions of an urbanized environment, the middle river ecosystems show a higher resistance to anthropogenic influence compared to ecosystems of artificial urban water bodies, which is evidenced, in particular, by a more complex coenotic structure of common associations, as well as the presence of sozologically valuable communities specifically in the river hydroecotopes.

High intensity perturbations induce an abrupt shift in soil microbial state

Soil microbial communities play a pivotal role in regulating ecosystem functioning. But they are increasingly being shaped by human-induced environmental change, including intense “pulse” perturbations, such as droughts, which are predicted to increase in frequency and intensity with climate change. While it is known that soil microbial communities are sensitive to such perturbations and that effects can be long-lasting, it remains untested whether there is a threshold in the intensity and frequency of perturbations that can trigger abrupt and persistent transitions in the taxonomic and functional characteristics of soil microbial communities. Here we demonstrate experimentally that intense pulses of drought equivalent to a 30-year drought event (<15% WHC) induce a major shift in the soil microbial community characterised by significantly altered bacterial and fungal community structures of reduced complexity and functionality. Moreover, the characteristics of this transformed microbial community persisted after returning soil to its previous moisture status. As a result, we found that drought had a strong legacy effect on bacterial community function, inducing an enhanced growth rate following subsequent drought. Abrupt transitions are widely documented in aquatic and terrestrial plant communities in response to human-induced perturbations. Our findings demonstrate that such transitions also occur in soil microbial communities in response to high intensity pulse perturbations, with potentially deleterious consequences for soil health.

Ecological Niche Modeling of Invasive Macrophyte (Urochloa subquadripara) and Co-Occurrence with South American Natives

Invasive macrophytes are considered problematic in natural environments and hydroelectric reservoirs. Climate changes, the occurrences of watercourses, and biotic interactions influence biological invasions of macrophytes. The abundance of native species can be positively or negatively correlated with the occurrences of invasives. Urochloa subquadripara is an invasive in natural or disturbed habitats co-occurring with the natives Eichhornia crassipes and Salvinia minima in South America. Aquatic plant communities can be altered by climate change, so species distribution models (SDMs) are important tools for predicting invaded areas. This study aimed to apply an SDM to study correlations of U. subquadripara with the potential distributions of native species E. crassipes and S. minima. Occurrence data for U. subquadripara, E. crassipes, and S. minima were collected from databases and in consultation with the published literature. Parameters encompassing biological information of the species were entered into the CLIMEX software and used to generate the Ecoclimatic Index (EI). The species co-occurrence was performed based on multicriteria decision-making (MCDM), and weights were assigned using the analytical hierarchy process (AHP). It was observed that U. subquadripara, E. crassipes, and S. minima had a higher occurrence in tropical and subtropical regions. However, it is predicted that these species may move to high latitudes from climatic changes. Considering climate changes, such as the increase in temperature and CO2, the risk of invasion by U. subquadripara in the northern hemisphere is mainly in lakes, whereas the areas conducive to invasions are rivers and reservoirs in the southern hemisphere. In general, emerging and floating macrophyte species such as U. subquadripara, E. crassipes, and S. minima will be favored, causing suppression of submerged species. Therefore, identifying the potential distribution of these species allows the creation of pre-invasion intervention strategies.

Shifting enzyme activity and microbial composition in sediment coregulate the structure of an aquatic plant community under polyethylene microplastic exposure

It has been shown that microplastics (MPs) interfere with critical biological processes (including development, growth and fitness); however, there is no information about the impact of MPs on plant productivity and community structure in freshwater ecosystems. Here, we investigated the effects of two sizes (MIC: 20–300 μm, MAC: 2–3 mm) and three concentrations (0.03 %, 0.3 %, and 0.6 %) of low-density polyethylene MPs on submerged plant communities. The results showed that plant responses to MPs were species specific, which can affect plant community structure. For canopy-forming species (Hydrilla verticillata), total biomass increased by 4 %–46 % and relative abundance increased by 23 %–34 % under MP exposure, while rosette-forming species (Vallisneria natans) decreased by 44 %–67 % in total biomass and relative abundance decreased by 54 %–71 %. Myriophyllum spicatum growth was largely unaffected by MPs. Community diversity was negatively correlated with MAC treatments, and the community root to shoot ratio decreased by 40 %, while community productivity increased by 41 % at a 0.6 % MAC concentration. Although MPs did not change the microbial community composition, alpha diversity was reduced at the 0.6 % concentration. It is worth noting that 0.6 % is a higher concentration than most field sediment investigations. During the experiment, the activity of functional enzymes related to carbon and nitrogen increased under most MP treatments. Structural equation modelling showed that MIC changed the community structure mainly by driving sediment enzyme activity, while MAC changed the community structure mainly by driving plant growth. The results implied that MPs may affect sediment enzymatic activities, microbial alpha diversity and aquatic plant growth, potentially altering the diversity and stability of aquatic ecosystems.

Intraspecific trait variability is relevant in assessing differences in functional composition between native and alien aquatic plant communities

AbstractThe loss of plant functional diversity associated with biological invasion is a main subject of invasion biology, but still understudied in case of aquatic plants. We calculated functional richness, evenness, divergence and community-weighted mean trait values of aquatic plant communities for 20 plots, half invaded and half non-invaded by alien species, in a thermal effluent of West Hungary. Three traits [specific leaf area (SLA), leaf dry matter content (LDMC), leaf area (LA)] were considered to explain how alien species alter ecosystem function. We differentiated interspecific and intraspecific trait variation and investigate its effect on the community-level functional diversity. We found that alien species invasion causes significant changes in the functional composition of aquatic plants whereby alien species become able to absorb light more efficiently, which will directly enhance their increased biomass production. Our study highlights the importance of local adaptation, showing that calculating functional diversity with global pooling of trait measurements causes significant over- or underestimation of functional diversity indices. Consequently, this can potentially result in erroneous conclusions regarding the impact of invasion.

Correction: Disturbance and resilience of aquatic plant communities in fish ponds after temporary dry periods

Correction: Disturbance and resilience of aquatic plant communities in fish ponds after temporary dry periods

Disturbance and resilience of aquatic plant communities in fish ponds after temporary dry periods

Disturbance and resilience of aquatic plant communities in fish ponds after temporary dry periods