Emergent Macrophytes Research Articles

Incidence of Freshwater Aquatic Macrophytes in Relation to the Nutrients Content of Gwaigwaye and Mairuwa Reservoirs, Funtua, Nigeria

Studies were conducted between (September, 2017 to October, 2018) to investigate the variation in the compositional distribution of macrophyte communities in relation to the nutrient contents in the water and sediments of Mairuwa and Gwaigwaye reservoirs, Funtua located in the Northern vegetation of Nigeria. All the nutrients from sediments were analyzed using Standard procedures using Spectrophotometer, flame photometer and titration methods. Nitrogen, Phosphorus and Calcium were higher in Mairuwa reservoir than in Gwaigwaye; while Potassium on the other hand, was higher in Gwaigwaye than in Mairuwa reservoir. Magnesium was not detected in either of the two reservoirs. The modified method of flora collection was used with a random sampling technique. The correlation analysis indicated that the distribution and abundance of aquatic macrophyte composition were significantly (P<0.05) different. The overall community structure was made up of nine (9) from Mairuwa and eleven 11 species from Gwaigwaye reservoirs. Both the number of species present and the densities of such species were higher in Mairuwa than in Gwaigwaye reservoir. Four growth patterns of macrophytes were observed viz; Emergent macrophytes were the dominant (56.7%), Floating macrophytes (26.5%), submerged macrophytes (13.4%) and the least marginal macrophytes (3.4%). Similarly, species densities (stands per square metre) ranged from 1-29m, in Mairuwa, and 4-90m in Gwaigwaye. Implications of these trends to the well being of the two ecosytems are highlighted. Government and non-governmental organizations at all levels should ensure that the precious aquatic resources are solely protected by enacting laws against the anthropogenic action of the inhabitants in and around the catchment.

Lipid biomarkers in Lake Wudalianchi record abrupt environmental changes from the volcanic eruption in 1776

Volcanic eruptions can cause abrupt changes in surrounding environments, but detailed sediment records of such changes are rare. The very high sediment accumulation rate in Lake Wudalianchi, a volcanic-dammed freshwater lake in northeastern China, provides an excellent opportunity for reconstructing volcanic-induced environmental change. Here we use multiple lipid biomarkers to reconstruct changes in aquatic ecosystems, hydrology, and methane cycling before and after a regional explosive volcanic eruption in 1776. Our results indicate that the Wudalianchi catchment was a shallow organic-rich marsh environment with abundant aquatic emergent macrophytes and an intense microbial methane cycle before the volcanic eruption. Following the volcanic eruption, the marsh was rapidly transformed into an oligohaline lake environment due to river channel damming by lava. Associated with the abrupt environmental change, we observe corresponding changes of cyclisation ratios of branched glycerol dialkyl glycerol tetraethers or brGDGTs (CBT and CBT′ indices), and the inferred pH displays an abrupt increase of ∼1.3. Group 1 alkenones emerge abruptly after the eruption when the inferred pH exceeds 8. Our results provide the first high-resolution reconstruction of environmental change induced by volcanic eruption and demonstrate the high efficacy of the lipid biomarkers in recording aquatic and terrestrial changes.

Anthropogenic effect on wetland biodiversity in Lake Tana Region: A case of Infranz Wetland, Northwestern Ethiopia

This study evaluates the effect of anthropogenic activities on Infranz Wetland biodiversity in Lake Tana area. Plant biodiversity data were collected from quadrants that were established in transect lines and macroinvertebrates were collected using 500 μm mesh size. A survey with 386 households, four focus group discussions and 24 key informant interviews were conducted to capture socioeconomic data. Shannon-Wiener diversity index, species percentage distribution and dominance, regeneration status and ecological importance index were computed to evaluate the plant and macroinvertebrates condition. Descriptive statistics were used to analyze the survey data and qualitative data were analyzed thematically. The results of the biodiversity data showed ecological degradation of the study wetland. Though woody plants had rich (3.08) species diversity, more than 30% of species were represented only by four families which reflects overharvesting of the desired woody plant species. The non-ecological importance of 81.5% floristic plant species and the dominance of few macroinvertabrates such as tolerant taxa, predators and scrapers also implied the existence of habitat degradation. Furthermore, the dominance of emergent macrophytes implied the biodiversity loss of the wetland. Extraction of more than 15 billion cubic meter water for public water supply and khat irrigation, farmland expansion, eucalyptus plantation within the wetland, overgrazing and, overuse of papyrus were the principal factors for the wetland degradation and consequent loss of its biodiversity. Efforts have not been made to regulate the use of wetland resources. Thus, local governments should establish bylaws for sustainable use of the wetland.

Flow regime and nutrient input control invasive alien aquatic plant distribution and species composition in small closed estuaries

Nutrient pollution is facilitating the encroachment of invasive aquatic plants in various water bodies globally. This study investigated seasonal aquatic macrophyte responses in two temporarily closed estuaries with different nutrient inputs. Consistent effluent discharge from the upstream wastewater treatment works (WWTW) facilitated the establishment of numerous freshwater invasive alien aquatic plants (IAAPs) in the uThongathi Estuary. IAAPs (Myriophyllum aquaticum, Pistia stratiotes and Pontederia crassipes) were only displaced from the estuary after high flow events (>5 m3 s−1). In the less polluted uMdlotane Estuary nutrient pulses (>1 mg/L DIN) associated with high rainfall changed the aquatic macrophyte composition. The nutrient tolerant non-rooted Ceratophyllum demersum outcompeted the rooted submerged macrophyte Stuckenia pectinata. Species composition changed in response to flow and nutrient inputs, with the exception of emergent macrophytes, such as the grass Echinochloa pyramidalis, that remained consistent in cover and distribution in the uMdlotane Estuary. This study demonstrated that aquatic macrophytes are more responsive to nutrient inputs in unimpacted estuaries compared to consistently nutrient-rich systems where flow is an important driver of IAAPs community dynamics. Many temporarily closed estuaries are subjected to nutrient pollution from WWTWs and restoration efforts such as diversion of discharges to constructed wetlands needs urgent implementation.

Restoration of aquatic macrophytes with the seed bank is difficult in lakes with reservoir-like water-level fluctuations: A case study of Chaohu Lake in China

Aquatic vegetation in lakes along the middle and lower reaches of the Yangtze River has been seriously degraded by human disturbances such as river–lake disconnection and water eutrophication. Chaohu Lake is a typical lake with reservoir-like water-level fluctuations (WLFs). Since a sluice was built in 1962, the coverage of aquatic vegetation in Chaohu Lake has been very low (0.77%). In this study, field investigations of the aquatic vegetation and seed bank of Chaohu Lake were conducted, and aboveground vegetation diversity was found to be low. Forty-eight species were recorded, of which submerged, floating-leaved, and emergent macrophytes were 1, 5, and 10, respectively. Currently, artificially planted Phragmites australis and Salix communities have become the main community types. A total of 18 aquatic macrophytes were identified in the seed bank, of which the number of submerged, floating-leaved, and emergent macrophytes and hygrophytes were 2, 2, 3, and 11, respectively; the seed density was 2.05, 2.05, 16.93, and 9.30 ind./m2, respectively. The seed density of aquatic macrophytes was much lower in Chaohu Lake than in the lakes with quasi-natural WLFs, and the seeds were mainly distributed in the estuary area. Only two emergent macrophyte species (Typha) germinated in the open water area. Spearman correlation analysis showed that the distance to bank was the main environmental factor that affected aquatic macrophyte diversity and seed density in the seed bank. It is not feasible to promote the natural reconstruction and restoration of aquatic macrophytes in Chaohu Lake by decreasing the water level or increasing water transparency, but the area near the estuary can be identified as a priority restoration area (PRA) for aquatic macrophytes. Artificial transformation of the micro-topography can be used to guide some hydrochorous seeds in the tributaries to the PRA and restore aquatic vegetation in the local area.

The anatomy of two species of emergent macrophytes of the genus Polygonum differentially changes in response to water‐level fluctuations

AbstractTemporal fluctuations in water levels are important ecological driving forces in shallow aquatic ecosystems. Alterations to fluviometric levels are even more conspicuous after the construction of dams, and aquatic macrophytes respond with anatomical and morphological adaptations to such changes. We performed an experiment to analyse the anatomical responses of two common Neotropical species of emergent macrophytes (Polygonum ferrugineum and P. acuminatum) to water‐level fluctuations. The experiment simulated three water‐level variations: constant low water, constant deep water and fluctuating water levels (0.8‐m oscillation/6 days; commonly caused by dam operation). We measured anatomical responses of roots (perimeter and number of the intercellular spaces), stems (perimeter and number of the intercellular spaces and cortical thickness) and leaves (palisade and lacunous parenchyma thickness). Water level affected all anatomical traits we measured and all increased when plants remained submerged (high‐depth treatment). Compared with P. ferrugineum, P. acuminatum had higher values of both perimeter of the intercellular space in the roots and number of intercellular spaces in the stems. These results indicate that water‐level fluctuations influence the anatomy of both species and that, compared with P. ferrugineum, P. acuminatum has greater plasticity and better tolerates submersion. These responses may be explained by the different survival strategies of each species when growing under submersion. Thus, our results reflect the different selective pressures from water levels experienced by these two species during their evolution.

Leaf reflectance can surrogate foliar economics better than physiological traits across macrophyte species

BackgroundMacrophytes are key players in aquatic ecosystems diversity, but knowledge on variability of their functional traits, among and within species, is still limited. Remote sensing is a high-throughput, feasible option for characterizing plant traits at different scales, provided that reliable spectroscopy models are calibrated with congruous empirical data, but existing applications are biased towards terrestrial plants. We sampled leaves from six floating and emergent macrophyte species common in temperate areas, covering different phenological stages, seasons, and environmental conditions, and measured leaf reflectance (400–2500 nm) and leaf traits (dealing with photophysiology, pigments, and structure). We explored optimal spectral band combinations and established non-parametric reflectance-based models for selected traits, eventually showing how airborne hyperspectral data could capture spatial–temporal macrophyte variability.ResultsOur key finding is that structural—leaf dry matter content, leaf mass per area—and biochemical—chlorophyll-a content and chlorophylls to carotenoids ratio—traits can be surrogated by leaf reflectance with normalized error under 17% across macrophyte species. On the other hand, the performance of reflectance-based models for photophysiological traits substantively varies, depending on macrophyte species and target parameters.ConclusionsOur main results show the link between leaf reflectance and leaf economics (structure and biochemistry) for aquatic plants, thus envisioning a crucial role for remote sensing in enhancing the level of detail of macrophyte functional diversity analysis to intra-site and intra-species scales. At the same time, we highlighted some difficulties in establishing a general link between reflectance and photosynthetic performance under high environmental heterogeneity, potentially opening further investigation directions.

Interspecific relationships between submerged and emergent aquatic plants along a nitrogen gradient in a mesocosm experiment

The responses of plant populations and communities to environmental factors play a key role in the ecological protection and restoration of lakes. However, little is known about how interspecific relationships respond to environmental gradients, especially for relationships between different growth forms such as submerged and emergent aquatic plants in shallow lakes, which can further affect species composition as community dynamics. We carried out a mesocosm experiment to investigate the responses of two focal aquatic plants (Ceratophyllum demersum and Phragmites australis) at two density levels and six levels of total nitrogen (TN) levels. Our results suggested that interspecific competition exist between C. demersum and P. australis, especially at high nitrogen levels. The competition relationship was mainly influenced by variations of relative growth rates of C. demersum and population density of P. australis along the nitrogen gradient. The interspecific neighbor effect on C. demersum shifted from facilitation to competition as TN increased, whereas on P. australis showed no significant facilitation effect along the TN gradient. Ceratophyllum demersum and P. australis adopted stress-tolerance and competition strategies for nitrogen, respectively, in co-culture. As a result, the dominant species in the plant community is likely to shift from the submerged macrophyte (C. demersum) to the emergent macrophyte (P. australis) as TN increases. Moderate TN (2.5 mg/L) can potentially support high biodiversity in macrophyte-dominated shallow lakes in our study. This finding has implications for different community composition at different nitrogen levels. Furthermore, it has important implications for protecting biodiversity and guiding vegetation restoration in shallow lakes.

Phytoremediation of partially treated MSW leachate by selected free floating and emergent macrophytes in subsurface vertical flow constructed wetlands

Phytoremediation of partially treated municipal solid waste (MSW) leachate with selected free floating (Eichhornia crassipes and Pistia stratiotes) and emergent macrophytes (Typha angustifolia and Chrysopogon zizanioides) was assessed at three steps in order to improve the quality of leachate prior to discharge to the environment. At the 1st step, growth performance of macrophytes was assessed at leachate dilutions of 0%, 25%, 50% and 75%. Results revealed that all leachate dilutions were detrimental to P. stratiotes. Nevertheless, leachate greater than 50% dilutions and all leachate dilutions favored the growth of E. crassipes and emergent macrophytes respectively. At the 2nd and 3rd steps, phytoremediation with E. crassipes and emergent macrophytes at 50% and phytoremediation with emergent macrophytes at 0% leachate dilution were assessed respectively. Results revealed that the percentage reductions of measured parameters (pH, EC, turbidity, color, TSS, BOD, COD, phosphate, ammonium nitrogen, nitrate, sulfate and color) increased in remediated leachate. Of the emergent macrophytes, C. zizanioides significantly reduced EC, COD, TSS, nitrates, ammonium nitrogen, sulphates and color (P<0.05: one way ANOVA) when compared with their controls and T. angustifolia. Moreover, C. zizanioides proved its higher ability in accumulating nitrogen and phosphorous from leachate than that of T. angustifolia. Nevertheless, accumulation of nitrogen was higher than phosphorous in shoots of both plants. Although both species performed better in harsh conditions, C. zizanioides could be recommended as the best plant for the remediation of partially treated MSW leachate.

Recent advances on the removal of phosphorus in aquatic plant-based systems

Phosphorus (P) is a vital nutrient for the ecosystems and its excess in wastewater streams leads to some environmental issues such as extensive algae growth (eutrophication). Phytoremediation is a green technology that is based on the combined actions of plants and their associated microbial groups to remove and transfer the toxic compounds in surface water, groundwater and soil. Aquatic plants are widely used for the remediation of contaminated rivers, eutrophic lakes, and other water bodies. In the past three decades, free-floating, submerged, emergent macrophytes and microalgae species have been used for P removal in aquatic plant-based systems such as constructed wetlands (CWs). This paper reviews the recent studies on the potential of aquatic plants such as free-floating, submerged, and emergent plants, and also microalgae for removal of P in different types of wastewaters. Several parameters such as plant species, hydraulic retention time, temperature, type of CWs, effluent concentration, and seasonal changes have effects on P removal. Based on the findings, some of the species such as Azolla and water hyacinth had the highest uptake ability up to 90% while algae species such as Chlorella showed about 70% of P removal. In addition, the mixed culture of aquatic plants can increase P removal if the interaction of the species is considered before cultivation in CWs. • The potential of different aquatic plants on phosphorous (P) removal is reviewed. • Azolla and water hyacinth had the highest P removal ability. • The algae are sensitive to the low P effluent concentration and the removal is quite low. • Submerged and emergent plants showed different removal patterns in P removal. • The recovered P can be used in beneficial applications such as biofertilizers.

Changes of a Landfill Leachate Toxicity as a Result of Treatment With Phragmites australis and Ceratophyllum demersum–A Case Study

Most phytoremediation studies are limited to several of the most common plants and in most cases these studies are performed to a very limited extent. There are also few publications on the assessment of the effectiveness of the removal of pollutants, performed simultaneously with various plants and using physicochemical analyses as well as toxicity tests. Therefore, the conducted studies focused on assessing the removal of pollutants from leachate by physicochemical analyses and toxicity tests. The leachate was collected from four municipal waste landfills of different ages (2 non-operational facilities and 2 active). The studies were conducted for two biological systems: using emergent macrophytes (Phragmites australis) and submergent macrophytes (Ceratophyllum demersum L.). It has been observed that efficiency of biological treatment of leachates with Phragmites australis and Ceratophyllum demersum shows significant differences at lower concentrations of solutions. Even after the treatment with Phragmites australis and Ceratophyllum demersum, the analyzed leachate samples produced a toxic effect on the test organisms. A reduction or no toxicity of the leachate after the biological treatment was observed only in some cases. The observed effects of the biological leachate treatment were not conclusive. Particular attention should be paid to the persistent toxicity, which can pose a real threat to the environment when discharging leachates after treatment.

The contribution of sediment desiccation and rewetting process to eutrophication in the presence and absence of emergent macrophytes.

The purpose of current study was to investigate the effects of sediment desiccation on nutrient dynamics and eutrophication in wetlands during the presence or absence of wiry and sturdy rooted emergent macrophytes, based on the hypothesis that sediment desiccation negatively correlated with plants nutrient uptake abilities and positively with nutrients fluxes at sediment-water interface. Growth of four emergent macrophytes, including two wiry rooted plants, i.e., Alocasia cucullata and Aglaonema commutatum, and two sturdy rooted plants, i.e., Cannabis indica and Acorus calamus, were grown and investigated in dried-rewetted sediments (DS) and constantly wet sediments (WS), respectively, for 6 months. The findings revealed that sediment drying and rewetting process significantly decreased the diffusion of overlying nutrient into sediment and the particle size density, porosity, and nutrients' repository ability in DS treatments, while the sediment bulk density and mineralization of organic macronutrients increased. Compared to WS treatments, the DS treatments impaired plant growth, root biomass, shoot biomass, and stimulated higher fluxes of ammonium nitrogen ([Formula: see text]-N, 0.042-0.081 mg m - 2 d - 1) and phosphate (P[Formula: see text] 0.009-0.030 mg m-2 d-1) at sediment-water interface upon rewetting. The higher internal release of macronutrients and dissolved organic carbon (DOC) from DS led to the higher chlorophyll-a (Chl-a) concentrations (34.47-21.28 to 41.76-33.36 μg L-1) in their water column than in the water column of WS. The wiry rooted plants with higher root biomass displayed lower internal release of [Formula: see text]-N, PO43-P and DOC and water column Chl-a concentrations than the sturdy rooted plants in two sediment types. Root biomass of plants correlated positively with TN (63-87%) and TP (56-78%) removal percentages from WS and DS. These results demonstrated that sediment desiccation process reduced plant growth and enhanced internal loading of nutrients and consequently accelerated eutrophication in these wetlands.

Salinity exerted little effect on decomposition of emergent macrophytes in coastal peatlands

Climate-warming-driven sea level rise may change the vegetation composition of coastal wetlands, influencing ecosystem functions including photosynthetic activity, biomass production, litter decomposability and nutrient cycling. Litter decomposition rates of the most dominant macrophytes, Phragmites australis, Carex sp. and Schoenoplectus tabernaemontani, in two nearby freshwater and oligohaline peatlands were compared to determine the impact of salinity on litter decomposition. Electrical conductivity difference of 1.2–8.0 mS cm-1 (mean difference = 4.8 mS cm-1) between freshwater and oligohaline peatlands did not significantly affect the decomposition of macrophyte litter. Between species, S. tabernaemontani lost a significantly higher mass (29%) in the first month of decomposition compared to P. australis and Carex sp. Overall, litter decay rates for S. tabernaemontani was k = 0.0064–0.0078 d-1 while P. australis and Carex sp. both had k = 0.0017–0.0028 d-1. After one year, S. tabernaemontani litter was totally decomposed while the other species had 40–60% mass remaining relative to their initial dry mass confirming that P. australis and Carex sp. contribute to peat formation while S. tabernaemontani does not. Apparent differences in decomposition kinetics between S. tabernaemontani and the other species tested indicated that litter quality, especially C:P, C:N, N:P and C:Ca, is of great importance for both microbial colonization (initial phase) as well as for sustaining decomposition after colonization. This study shows that litter quality controls litter decomposition more than narrow salinity ranges. Hence, we suggest that sea level rise, combined with increased precipitation, may not have significant impact on the decomposition of these macrophytes in the future. However, sea level rise may lead to changes in vegetation composition replacing the peat-forming species by S. tabernaemontani which favors relatively deep, oligohaline wetlands. This would eventually affect carbon sequestration rates.

Bulk and compound-specific \u03b413C and n-alkane indices in a palustrine intermontane record for assessing environmental changes over the past 320\xa0ka: the Padul Basin (Southwestern Mediterranean realm)

Here we provide valuable information about the palaeoenvironmental evolution of Southwestern Mediterranean region during the last ca. 320 ka through a biomarker-based study of the longest continuous continental Quaternary record in the Iberian Peninsula. The n-alkane content and δ13C values of these lipids were measured in 300 samples taken from the uppermost 55 m of the Padul Basin (PB) record. The δ13C signal of long-chain n-alkanes was a reliable proxy for C4/C3 terrestrial vegetation composition in the basin, as emergent macrophytes made a minor contribution to these homologues. In contrast, the δ13C values of C23 and C25 alkanes reflected mainly phases of increasing water level of the lacustrine/palustrine water body since aquatic macrophytes contain a large proportion of these compounds. Low δ13C values were attributed to a marked contribution of plants using the C3 photosynthetic pathway. Intervals with the lowest δ13C values were attributed to an important input of angiosperms, although they could also be explained by changing environmental conditions or environmental stress, as large shifts in δ13C occurred in long-chain homologues typically abundant in terrestrial plants. Shifts in δ13C of medium-chain homologues reflected limited CO2 availability induced by water temperature, salinity, pH, enhanced productivity, low atmospheric pCO2, or stagnant barriers, rather than the abundance of aquatic macrophytes. Our results also suggest enhanced isotopic fractionation during lipid synthesis by aquatic macrophytes within MIS 7 and the Holocene, leading to increased δ13C values of bulk OM and of long-chain n-alkanes. Hence, the δ13C logs were ideal for studying the contribution of aquatic macrophytes to the lipid and isotopic composition of sediments and for the reconstruction of palaeoenvironmental conditions. These results confirmed that C4 plants had a low presence in the PB. Comparison with biomarker analysis and pollen data of the PB and other records of the Southwestern Mediterranean revealed that δ13C values of bulk OM and of long-chain n-alkanes reflected global climatic oscillations during MIS 7 and the episodes Heinrich Events 3, 2, 1 and Younger Dryas.

Low-decomposition rates of riparian litter in a North Patagonian ultraoligotrophic lake

Littoral zones of lakes are important for carbon and nutrient recycling because of the accumulation and decomposition of organic matter (OM) coming from terrestrial and aquatic plants. Here, we aimed to study OM decomposition from the most abundant riparian trees (Nothofagus dombeyi and Myrceugenia exsucca), and an emergent macrophyte (Schoenoplectus californicus), in the littoral zone of an ultraoligotrophic North-Patagonian Andean lake. We analysed the initial 2-days leaching, and litter mass loss and litter nutrient changes after one year of decomposition in a litter-bag experiment. The three studied species had very slow decay rates (k < 0.005 day−1), and initial nutrient release by leaching was not related to differences in decomposition rates. However, differences in leaf traits (lignin content) were related to interspecific variation in decomposition rates. The highest decomposition rates were observed for the macrophyte S. californicus, the species with the lower lignin content, while the opposite was observed in the Myrtaceae M. exsucca. In the three studied species, nitrogen content increased during decomposition. Our results indicated that in the shore of ultra-oligotrophic lakes, litter remains for long periods with net nutrient immobilization, thus OM of the riparian vegetation represents a carbon and nutrient sink.

Sources and depositional changes of aliphatic hydrocarbons recorded in sedimentary cores from Admiralty Bay, South Shetland Archipelago, Antarctica during last decades

Organic biomarkers, as aliphatic hydrocarbons, are present in sedimentary organic matter and have been largely applied to the evaluation of recent environmental changes in the marine environment around the globe, including the Antarctic continent. Five sediment cores were taken in the Admiralty Bay, South Shetland Archipelago, Antarctica to evaluate changes in the signature of aliphatic hydrocarbons such as n-alkanes (n-C10 to n-C40) and isoprenoids as pristane and phytane, over the last decades. The total n-alkanes concentration ranged from 0.17 to 1.67 μg g−1 (mean = 0.74 ± 0.42) which is considered low and similar to pristine sediments. Aliphatic hydrocarbons present in the sedimentary pool came mostly from terrestrial sources as Antarctic lichens and mosses, and from marine sources as the macroalgae forest debris and emergent macrophytes. Anthropogenic inputs of aliphatic hydrocarbons (e.g., petroleum and their by-products) may be neglected based on the multi-proxy approach used to distinct sources of these organic compounds. In general, no significant changes in the sources of aliphatic hydrocarbons were observed along the sediment cores; however, an increased aliphatic hydrocarbons input registered between 1975 and 1992 may be related to the increase in meltwater runoff and the relatively high abundance of marine producers more adapted to increased sea temperatures.

Constructed floating wetlands made of natural materials as habitats in eutrophicated coastal lagoons in the Southern Baltic Sea

Eutrophication remains an environmental challenge in lagoons along the Southern Baltic Sea. Floating islands planted with emergent macrophytes are an option to remove nutrients from eutrophicated waters. Furthermore, floating wetlands offer other ecosystem services such as the provision of habitats. Numerous scientific studies have been conducted; however most remain on the laboratory scale. This research explores the challenges associated with installations in coastal environments and focuses on sustainability of the island design, the habitat function as well as nutrient removal. Most floating wetland designs use polyethylene, polypropylene, polyurethane or polyvinyl alcohol foam to ensure the buoyancy. For this study an artificial polymer free island design was developed and tested. The floating constructions in the Darss-Zingst-Bodden-Chain were planted with native macrophytes which have the potential to act as ‘biodiversity-supplements’ to the adjacent coastal wetlands: Bolboschoenus maritimus, Carex acutiformis, Iris pseudacorus, Juncus effesus, Lythrum salicaria, Schoenoplectus lacustris, Typha latifolia. The chosen macrophytes survived fluctuating salinities. After three months the above-ground biomass was harvested and analyzed for the nutrient concentrations. Phosphorus concentrations were highest in L. salicaria and nitrogen in I. pseudacorus. Video monitoring and field observations were applied in order to observe animals. Birds did not use the floating wetlands as breeding grounds, but the grey heron (Ardea cinerea) was a common visitor for foraging. Especially surprising was the large amount of juvenile eels (Anguilla anguilla). A diverse and large root network below the floating islands boosts not only nutrient removal but serves as a shelter and refuge for fish such as the endangered eel.

Hydrological alteration induced changes on macrophyte community composition in sub-tropical floodplain wetlands of Nepal

In wetland ecosystems, macrophytes are sensitive to water level fluctuations. However, studies specific to the effects of water level fluctuations on distribution and composition of macrophytes are limited in sub-tropical floodplain wetlands of Nepal. This study aimed to examine the association between macrophytes and water levels in the floodplain wetlands of Koshi Tappu, in south-eastern Nepal. Sixty-four samples of macrophyte, along with twelve water quality parameters, five soil parameters and weekly water level information were collected from four shallow wetlands during summer, autumn, winter and spring over 2018 and 2019. Altogether, 52 macrophyte species belonging to 25 families were documented. Of them, 15, 6, 5 and 26 were emergent, submerged, floating and amphibian species, respectively. 10 species (5 emergent, 2 submerged, 2 floating and 1 amphibian species) were common across seasons. Regression analysis showed the decreasing trend in diversity, richness and evenness with increased water levels while at the same time overall macrophyte biomass increased. During summer, high water level supported the growth of floating invasive macrophytes, while medium and low water level during autumn and winter, respectively, supported submerged macrophytes. However, low-water level during spring supported emergent and amphibian macrophyte species. Canonical correspondence analysis (CCA) indicated that water depth and physico-chemical parameters such as water temperature, dissolved oxygen, pH, conductivity, nitrate-nitrogen, and phosphate were highly correlated with macrophyte assemblages across the wetlands. The study elucidated that management of water levels can ensure ecological integrity of wetlands and hence maintain biodiversity, and provide key indicators of water quality change.

Removal of 27 micropollutants by selected wetland macrophytes in hydroponic conditions

In this work, the primary focus is given on a mixture of 27 micropollutants (pharmaceuticals, pesticides, herbicides, fungicides and others) and its removal from aqueous solution by phytoremediation. Phytoremediation belongs to technologies, which are contributing on removal of micropollutants from wastewater in constructed wetlands. Constructed wetlands can be used as an additional step for elimination of micropollutants from municipal medium-sized wastewater treatment plants. To our knowledge, such a broad variety of micropollutants was never targeted for removal by phytoremediation before. In this work, we carry out experiments with 3 emergent macrophytes: Phragmites australis, Iris pseudacorus and Lythrum salicaria in hydroponic conditions. The selected plants are exposed to mixture of micropollutants in concentrations 1–14 mg/l for a time period of 30 days. The highest affinity for phytoremediation is detected at groups of fluorosurfactants (removal rate up to 30%), beta-blockers (removal rate up to 50%) and antibiotics (removal rate up to 90%). The leading capability for micropollutant uptake is detected at Lythrum salicaria, where 25 out of 27 compounds are removed with more than 20% efficiency. The results demonstrate well usefulness of this technology e.g. in an additional treatment step, because the mentioned groups of micropollutants are removed with comparable or even higher effectivity, than it is in case of conventional wastewater treatment plants.

Treatment of Combined Dairy and Domestic Wastewater with Constructed Wetland System in Sicily (Italy). Pollutant Removal Efficiency and Effect of Vegetation

Dairy wastewater (DWW) contains large amounts of mineral and organic compounds, which can accumulate in soil and water causing serious environmental pollution. A constructed wetland (CW) is a sustainable technology for the treatment of DWW in small-medium sized farms. This paper reports a two-year study on the performance of a pilot-scale horizontal subsurface flow system for DWW treatment in Sicily (Italy). The CW system covered a total surface area of 100 m2 and treated approximately 6 m3 per day of wastewater produced by a small dairy farm, subsequent to biological treatment. Removal efficiency (RE) of the system was calculated. The biomass production of two emergent macrophytes was determined and the effect of plant growth on organic pollutant RE was recorded. All DWW parameters showed significant differences between inlet and outlet. For BOD5 and COD, RE values were 76.00% and 62.00%, respectively. RE for total nitrogen (50.70%) was lower than that of organic compounds. RE levels of microbiological parameters were found to be higher than 80.00%. Giant reed produced greater biomass than umbrella sedge. A seasonal variation in RE of organic pollutants was recorded due to plant growth rate Our findings highlight the efficient use of a CW system for DWW treatment in dairy-cattle farms.