Wetland Macrophytes Research Articles

Macrophyte species composition and abundance of hydrogeologically connected wetlands in upper Abbay river basin, Ethiopia

Macrophytes are key components of aquatic ecosystems including wetlands that have considerable ecological importance. The role of macrophytes is closely linked to their structural attributes like species composition and abundance. Therefore, this study aimed to assess macrophyte species composition, abundance and diversity of six hydrogeologically connected wetlands in the upper Abbay River basin, Ethiopia. The studied wetlands (Gudera, Geray, Zindib, Kurt Bahir, Infranz and Wonjeta) are found in west Gojjam administrative zone, Amhara region, Ethiopia. Two cross-sectional surveys were conducted at the end of September 2021 and February 2022. Quadrat sampling technique was employed to collect macrophyte samples following protocols for sampling aquatic macrophytes in freshwater wetlands. A total of 41 species of macrophytes belonging to 16 families were identified across the wetlands. The wetlands were dominated by emergent macrophytes, with the Poaceae and Cyperaceae families being particularly abundant. The physicochemical water quality status, water level fluctuations and level of human interventions might be the reason for the variation in the macrophytes composition, abundance and diversity across the wetlands. The low macrophyte diversity index value and the presence of pollution-tolerant taxa such as Pistia stratiotes and Azolla africana indicate an overall ecological degradation of the wetlands. Therefore, this study highlights the potential role of macrophyte monitoring to identify anthropogenic pollution. Application of appropriate land use planning and the development of macrophyte based multimetric indices are recommended for their sustainable management.

Macrophyte Diversity and Ecosystem Services in Wetlands of Eastern Ranchi: A Multi-site Analysis of Abundance, Frequency, and Importance Value Index Patterns

Macrophytes, visible aquatic and semi-aquatic plants, are integral components of wetland ecosystems, playing crucial roles in maintaining biodiversity, providing ecosystem services, and ensuring ecological stability. This research examines the distribution, abundance, frequency, diversity, and ecosystem services of macrophytes in several wetlands (W1-W7) located in the eastern part of Ranchi district, Jharkhand, India. The study sites include Bundu Lake, Hindalco Pond, Choga Bada Talab, Raja Bandh, Kita Uparbandh, Tamar Bada Talab, and Rukka Dam. A quantitative assessment using quadrat sampling and phytosociological methods was conducted from September 2022 to March 2023 to ensure accurate data collection and analysis. The study documented 78 macrophyte species belonging to 33 families and 58 genera. Emergent macrophytes were found to be the dominant life form, constituting 69% of the recorded species. Several species demonstrated high frequency and abundance across multiple study sites, including Pontederia crassipes Mart., Alternanthera philoxeroides (Mart) Griseb., Hydrilla verticillata (L.f.) Royle, Ipomoea aquaticaForssk., and Nymphoides hydrophyllum (Lour.) kuntze. To assess the diversity and ecological characteristics of the macrophyte communities, various diversity indices were calculated. These included the Shannon-Wiener index, Simpson's index, Margalef index, and Pielou's Evenness index. The results of these analyses revealed high levels of macrophyte diversity and evenness within the studied wetlands. Twenty-one macrophytes were identified as key species and nine species as rare species based on their IVI (Importance Value Index) scores. The key species were found to provide essential ecosystem services, including erosion control, water quality improvement, nutrient cycling, carbon sequestration, and habitat provision for other organisms. This research contributes significantly to our understanding of macrophyte diversity patterns and traits-based ecosystem services in wetland ecosystems. The findings of this study have important implications for the development and implementation of effective conservation strategies for these vital wetland ecosystems in the eastern Ranchi (W1- W7).

Sediment accretion and nutrient enrichment enhance the growth and vegetative propagation of Phalaris arundinacea growing within a Carex thunbergii stand.

Sediment accretion (burial) and nutrient enrichment may exert a synergistic influence on the growth and distribution of macrophytes in floodplain wetlands; however, this phenomenon has rarely been examined. In this study, we investigated the effects of sediment accretion and nutrient enrichment on the growth and vegetative propagation of Phalaris arundinacea within a Carex thunbergii stand (one P. arundinacea ramet within 25 C. thunbergii ramets) using a factorial sediment burial (0, 3, and 6 cm) and nutrient addition (low, medium, and high) experimental design. High sediment burial (6 cm) without nutrient addition decreased the aboveground and total biomass of C. thunbergii but did not affect P. arundinacea, indicating that P. arundinacea is more tolerant to sediment burial than C. thunbergii. Moderate sediment burial (3 cm) with nutrient addition enhanced the aboveground and total biomass of P. arundinacea but did not affect C. thunbergii, indicating that P. arundinacea may gain a growth advantage over C. thunbergii under moderate sedimentation. High sediment burial with nutrient addition increased the number of rhizomes and ramets produced by P. arundinacea but did not affect C. thunbergii, indicating that the relative abundance of P. arundinacea may increase within the Carex community under high sedimentation conditions. Based on these results, it can be concluded that an increased sedimentation rate facilitates the invasion of P. arundinacea into Carex grasslands, and this invasion is further enhanced by nutrient enrichment. Therefore, management measures should be taken to reduce the sediment load and nutrient input to prevent Carex grasslands invasion by P. arundinacea and maintain the ecological function of floodplain wetlands.

Assessment of the Potential Phytotoxicity of Chlorpyrifos in the Wetland Macrophyte Bidens laevis (L.).

Chlorpyrifos (CPF) has been used worldwide, but its possible negative effects on macrophytes have been scarcely studied. The main goal of the present work was to assess the potential phytotoxic effects of CPF on different stages (seed and seedling) of the wetland macrophyte Bidens laevis. During the germination of seeds, stimulation of radicle growth at low concentrations of CPF (10µg/L) and inhibition of its elongation at 80µg/L CPF were observed. In seedlings, concentrations ≤ 160µg/L CPF did not exhibit adverse effects on growth after 7 days of exposure, despite the decrease of photosynthetic pigments and carotenoids observed at 40µg/L CPF compared to the control. Environmentally relevant concentrations of CPF altered neither oxidative stress biomarkers nor pigment contents in seedlings exposed for 48h, suggesting CPF would be non-toxic to B. laevis in natural scenarios.

Enhancing nitrate removal from small wetlands via regulating bacterial-algal symbiosis with macrophyte coverage

With increasing land resource constraints, wetlands, as ecological hotspots, are expected to enhance biogeochemical processes to mitigate nitrogen (N) pollution, particularly nitrate-nitrogen (NO3−-N). However, the interactions among bacteria, algae, and macrophytes in wetlands, which are crucial for N removal, remain largely unknown. This study explored how macrophyte coverage influences bacterial-algal interactions, shifting from mutualism to inhibition, thereby affecting N removal. Moderate coverage enhanced NO3−-N and total nitrogen (TN) removal (P < 0.05), which was correlated with increased microbial abundance (P < 0.05). This may have resulted from moderate algal photosynthesis, reduced physiological stress, and the expansion of ecological niches for microbes. Insufficient coverage promoted algal growth (chlorophyll-a > 31.8 μg·L−1), leading to increased competition for substrates and elevated pH, which further inhibited bacterial activity. Excessive coverage also inhibited bacterial activity by reducing illumination and oxidation-reduction potential. Consequently, insufficient and excessive coverage decreased N removal efficiencies by 2.7–15.7 % (NO3−-N) and 3.7–11.1 % (TN) while increasing methane emission potential by 1.4–6.9 times compared with moderate coverage. These findings offer insights into solving NO3−-N contamination using near-natural methods and balancing the ecological and practical considerations for small wetlands.

Linking carbon storage with land use dynamics in a coastal Ramsar wetland

Coastal wetland ecosystems make an important contribution to the global carbon pool, yet their extent is declining due to aquaculture-related land use changes. We conducted an extensive investigation into the carbon stock and area coverage of macrophytes in a tropical coastal Ramsar wetland, Kolleru in Andhra Pradesh, India. A total of 72 quadrats of size 1 × 1 m2 were laid in the wetland, 19 species of macrophytes were collected and analyzed for carbon content using a CNHS analyzer. To assess changes in the wetland macrophytes, Normalized Difference Vegetation Index (NDVI) was estimated using Landsat time series data from 1975 to 2023. The importance value index (IVI) of macrophytes scored highest for the Ipomoea aquatica (41.4) and the lowest for Ottelia alismoides (1.9). Non-metric multidimensional scaling (NMDS) significantly (r = 0.1905, p = 0.0361) revealed a clear separation of macrophytes in ordination space. ANOVA indicated highly significant (p < 0.0001) variations in the carbon content of aboveground and belowground components of macrophytes. Among the different macrophytes, the highest carbon content was found in Phragmites karka (0.6 g. g−1) and the lowest was recorded in Utricularia stellaris (0.2 g. g−1). On an average, emergents in the Kolleru wetland sequester 1525 ± 181 g C m−2 yr−1, rooted floating species sequester 858 ± 101 g C m−2 yr−1, submerged macrophytes sequester 480 ± 60 g C m−2 yr−1, and free-floating macrophytes sequester 221 ± 90 g C m−2 yr−1. Land cover mapping revealed a decrease in spread of aquatic vegetation from 225.2 km2 in 1975 to 100.6 km2 in 2023. Although macrophytes are vital carbon sinks, the wetland conversion into fishponds has resulted in a loss of 55.3 % of carbon storage. Therefore, immediate restoration of macrophyte cover is vital for the proper functioning of carbon sequestration and mitigation of climate change impacts.

Submerged macrophytes enhance carbon emission (CO2 and CH4) from the freshwater wetland in Keibul Lamjao National Park, Manipur, India

Worldwide, the exacerbation of global warming has accelerated the growth of submerged macrophytes in wetlands, thereby substantiating the supply of labile substrates for carbon (CH4 and CO2) emissions. Nevertheless, limited studies have been conducted on carbon emission from tropical wetlands with submerged macrophytes. In the current study an attempt has been made to reveal the role of submerged macrophytes in influencing carbon flux from a natural wetland in the Indo-Burma Biodiversity hotspots. The submerged macrophytes colonising the shallow freshwater wetland of Keibul Lamjao comprise of Hydrilla verticillata, Ceratophyllum demersum, and Potamogeton crispus, with primary productivity at community level ranging between 20.72 and 152.53 g m-2 d-1 (mean, 95.6 ± 54.66 g m-2 d-1). This study gives a comparative analysis of the carbon gases (CH4 and CO2) emission in two distinct zones of the wetland: areas with profuse submerged macrophytic growth and water free of macrophytes. The mean CO2 and CH4 emissions from the zone with submerged macrophytes were 8362.64 ± 2935.57 and 227.90 ± 73.50 mg m-2 d-1, respectively, compared to 5558.07 ± 1222.05 and 149.72 ± 20.44 mg m-2 d-1 from those without macrophytes. The CO2 and CH4 emissions peak during the summer and wane in the following seasons, with minimum emissions occurring during the winter. It is apparent from the results that the generation of the gases in the wetland was temperature dependent, plus the macrophytic detritus availability. The carbon emissions were significantly correlated with the physicochemical properties of the water and the lake bottom sediment. A significantly positive correlation between carbon emission and dissolved organic carbon (DOC) and organic matter (OM) was established in the zone with macrophytes, thereby revealing that the growth of submerged macrophytes in the wetland enhances atmospheric carbon emissions.

Evaluation of the evapotranspiration rate of lacustrine wetland macrophytes in Lake Tana, Ethiopia

This study quantified the total evapotranspiration (ET) flux of three major types of macrophytes that cover lacustrine fringe wetlands in Lake Tana, Ethiopia during the dry season, April and May, 2022. This study was conducted to understand lacustrine wetland macrophytes' ET rates and provide an important guideline for designing their conservation and restoration plans. To assess ET rates during the peak dry season, three macrophytes of lacustrine wetlands in Lake Tana were chosen: Eichhornia crassipes (water hyacinth), Cyperus papyrus, and Echinochloa stagnina. Three replicate lysimeters for each of the three treatment types (macrophytes) and one control type (open water) were applied to measure ET. To calculate reference evapotranspiration (ETo), FAO's ETo Calculator Version 3.2 was applied. All statistical analyses were carried out using R software. The results of ET rates from wetland macrophytes (9.05mm/day) were considered to be significantly higher than open water evaporation (5.90mm/day). There was a significant difference in mean ET among the macrophytes [F (3, 488) = 194.6, p < 2e-16 ***]. In this study, crop coefficient (Kc1) (1.99 ± 0.65) referenced to FAO Penman–Monteith ETo is greater than Kc2 (1.58 ± 0.59) referenced to open water evaporation (Eow). In terms of wetland macrophyte type, E. crassipes had the maximum mean Kc values (Kc1 = 2.51±0.70 and Kc2 = 2.02±0.67). E. stagnina had the minimum mean Kc values (Kc1 = 1.52±0.32 and Kc2 = 1.19±0.24). Except for open water which strongly correlated with sunshine hours (r = 0.61) and solar radiation (r = 0.60), the correlation among daily ET values and meteorological variables was found to be weak. The result of our research indicated that the presence of floating macrophytes of E. crassipes will increase the ET flux during the dry season more than emergent macrophytes and open water surfaces. Our findings could provide an important guideline for designing conservation and restoration plans for C. papyrus and E. stagnina to reverse the spread of E. crassipes and maintaining lacustrine fringe wetlands for fish breeding ground and sediment control.

Contrasting two urban wetland parks created for improving habitat and downstream water quality

This paper describes the ecology and management of two flow-through created wetlands that, in turn, defined 30 years of research by Bill Mitsch, 20 years in Columbus, Ohio (1992–2012) and 10 years in Naples, Florida (2012−2022). The Olentangy River Wetland Research Park was built in several stages from 1993 through 2010. The first stage was the creation of dual 1-ha kidney-shaped wetlands primarily fed by pumped Olentangy River water. A pattern of inflow that depended on river stage was maintained for 17 years. The two experimental wetlands were established by planting one of the wetlands with a variety of wetland macrophytes and leaving the second wetland unplanted to ultimately determine whether human introduction of wetland plants matter in the long run. In addition to maintaining data collection for hydrology, water quality, and other functions, these wetlands and several others constructed on the 20-ha floodplain site were heavily used as was the mesocosm compound, mostly for short-term (2 to 3 year) experiments by graduate students.Another 20-ha created wetland complex, called Freedom Park Wetlands, was constructed in 2007–2008 in Naples, Florida, at an abandoned citrus grove, to seasonally treat urban stormwater runoff. During that wet season, the design calls for an average water detention time of 18 days. The wetland system included a 1.9-ha deepwater pond for temporary storage of the urban stormwater pulses from what is mostly an urban watershed, followed by 2.7 ha of shallower vegetated wetland ponds designed to sequentially improve water quality. Within each wetland, there are three deep-water cells and two shallow-water cells. The water eventually exits the treatment wetlands via a rectangular and travels diffusely through a restored bottomland forest to the Gordon River and ultimately toward Naples Bay and the Gulf of Mexico. During our tenure at Florida Gulf Coast University's (FGCU) Everglades Wetland Research Park, Freedom Park was a venue with active mesocosm experiments in a constructed mesocosm compound. Several of these mesocosm experiments were the subjects of master's theses from FGCU and doctoral dissertations from our partner, University of South Florida. Our students also contributed to the local environmental communities by giving tours of the Freedom Park wetlands and our mesocosm research.

Environment and time drive the links between the species richness and ecosystem multifunctionality from multitrophic freshwater mesocosms

Understanding the link between biodiversity and ecosystem functioning is imperative for ecosystem-based management. The role of multitrophic diversity in sustaining multifunctionality remains unclear, especially in highly diverse aquatic ecosystems. We performed a species-addition experiment consisting of one, two, three, and five species in simulated multitrophic ecosystems to evaluate biodiversity and ecosystem functioning relationships within and across trophic levels. Our results showed that there are positive species richness–productivity relationships within and across trophic levels. We found significant negative correlations between species richness and the cumulative variation of total phosphorus, and between species richness and ecosystem multifunctionality across trophic levels. Also, we found that the relationships between ecosystem multifunctionality and species richness within and across the trophic levels are mediated by a combination of environmental factors, including water temperature, dissolved oxygen, pH, irradiance, and time, rather than by species richness. Our results imply that species richness–ecosystem functioning relationships vary for different ecological functions; the individual ecosystem functions selected and the way multifunctionality calculated are critical when examining links between biodiversity and ecosystem multifunctionality. Our study highlights that multitrophic richness, such as for consumers, is crucial for driving ecosystem multifunctionality. Furthermore, our study implies that management practices for restoring the diversity of aquatic macrophytes in wetlands should consider not only macrophyte richness but also different functional groups and life-forms.

Effects of Soil pH on the Growth and Cadmium Accumulation in Polygonum hydropiper (L.) in Low and Moderately Cadmium-Contaminated Paddy Soil

Wetland macrophytes have advantages when used in the remediation of cadmium (Cd)-contaminated paddy fields because they can adapt to overly wet soil environments; however, only a few studies have tested the efficiency of macrophytes in Cd phytoremediation. In this study, we investigated the effect of soil pH (pHs of 5, 6, and 7) on the accumulation and translocation of Cd by Polygonum hydropiper (L.) in low and moderately Cd-contaminated paddy soil (0.56 and 0.92 mg/kg, respectively). Our results indicated that Cd accumulation in stems and roots, as well as subcellular distribution in P. hydropiper, was affected by soil pH, with significant interactions between the soil pH and Cd level. At low soil Cd levels, stem and root Cd contents were higher at a soil pH value of 6. In addition, with higher soil pH values, the proportion of Cd distributed in the cell wall increased, whereas that distributed in the organelles decreased. The Cd content in the roots and stems of P. hydropiper significantly decreased with the increase in soil pH in the moderate Cd-contaminated soil. In addition, with higher soil pH values, the proportion of Cd distributed in the cell wall decreased, whereas that distributed in the organelles increased. The translocation factor (TF) of P. hydropiper was higher than one in all treatments, indicating that it can effectively transport root-absorbed Cd to the aboveground shoots. Based on the relatively high bioconcentration factor and TF, P. hydropiper has the potential to remediate Cd-polluted paddy soil. Furthermore, the remediation efficiency of P. hydropiper can be enhanced by adjusting the pH as per the soil-Cd pollution.

Sustainable Bioconversion of Wetland Plant Biomass for Pleurotus ostreatus var. florida Cultivation: Studies on Proximate and Biochemical Characterization

The abundant biomass growth of aquatic macrophytes in wetlands is one of the major concerns affecting their residing biota. Moreover, the biomass degenerates within the wetlands, thereby causing a remixing of nutrients and emission of greenhouse gases. Therefore, it is crucial to find sustainable methods to utilize the biomass of aquatic macrophytes devoid of environmental concerns. The present study investigates the utilization of the biomass of three aquatic macrophytes, including the lake sedge (CL: Carex lacustris Willd.), water hyacinth (EC: Eichhornia crassipes Mart. Solms), and sacred lotus (NL: Nelumbo nucifera Gaertn.) to produce oyster (Pleurotus ostreatus var. florida) mushrooms. For this purpose, different combinations of wheat straw (WS: as control) and macrophyte’s biomass (WH) such as control (100% WH), CL50 (50% WH + 50% CL), CL100 (100% CL), EC50 (50% WH + 50% EC), EC100 (100% EC), NL50 (50% WH + 50% NL), and NL100 (100% NL) were used for P. florida cultivation under controlled laboratory conditions. The results showed that all selected combinations of wheat straw and macrophyte biomass supported the spawning and growth of P. florida. In particular, the maximum significant (p &lt; 0.05) growth, yield, bioefficiency, proximate, and biochemical parameters were reported using the WH substrate followed by CL, NL, and EC biomass, which corresponds to the reduction efficiency of the substrate parameters. Therefore, the findings of this study reveal that the biomass of selected aquatic macrophytes can be effectively utilized for sustainable mushroom cultivation while minimizing the risk associated with their self-degeneration.

Effect of soil moisture on the multi-component decomposition of wetland macrophytes

Effect of soil moisture on the multi-component decomposition of wetland macrophytes

A Study on Water Quality and Macrophyte Diversity in Three Wetlands of Sambalpur District, Odisha from Ecosystem Management Perspective

Manmade wetlands provide many services that contribute to human well-being and poverty alleviation.Some groups of people, particularly those living near wetlands, are highly dependent on these services andare directly harmed by their degradation. We assessed overall ecological condition of two lentic and onelotic wetlands present in the periphery of Sambalpur town, Odisha, India. Wetland macrophytes weresampled through 1x1m2 quadrates and water quality parameters were studied following “Guide manual:water and wastewater analysis” by CPCB and APHA (1998)”. In the phytosociological study, 43 species ofmacrophytes were recorded belonging to 20 families in the 3 study sites. Both the lentic wetlands showedhighest diversity indices in postmonsoon period with emergent plants outnumbering free floating andsubmerged plants. This indicated that the hydrodynamic forces in lentic wetlands were not enough touproot the emergent plants. The present work showed that macrophytic diversity being negatively correlatedby all most all water quality parameters studied indicating considerable anthropogenic impact on thesesystems. Further PCA biplot showed large positive loadings on component 1 by water conductivity, TSS,TDS, NO3, and BOD that caused regionalization of three wetlands namely Durgapali pond (Site I), Kanjhurinalia/ canal (Site II), and Gobindtola canal (Site III) of Sambalpur town indicating differential antropogenicimpact as per their need. The study emphasized on immediate management of these wetlands specificallythe small lotic wetlands for promoting water health.

Copper hydrophytoremediation by wetland macrophytes in semi-hydroponic and hydroponic mesocosms

High levels of trace metals such as copper (Cu) can affect water quality and induce toxic effects on living organisms in aquatic ecosystems. This research assesses the potential capacity for Cu phytofiltration by three emergent macrophytes from Cu-contaminated sediments and water containing five concentrations of Cu (0, 50, 100, 150, and 200 µM). We conducted a greenhouse study using semi-hydroponic and hydroponic experimental conditions to simulate a natural wetland system. We selected three plant types that were collected in Quebec (Canada): native Typha latifolia, and native and, exotic Phragmites australis. Under semi-hydroponic, the responses indicated an almost 3-fold higher mean root Cu-accumulation from Cu-0 to Cu-Sediment (80.3–226.1 mg kg−1) and an 8.6-fold increase (122.2–1045.5 mg kg−1) for Cu-0 to Cu-200 µM under hydroponic conditions, resulting in Cu translocation < 1 and BCF >1 under both conditions. We found an inverse correlation between increasing doses of Cu with mean aboveground and belowground biomass together with height, and root length of selected plants under hydroponic conditions. Our results indicate that these wetland macrophytes could be useful in heavy-metal removal from Cu-contaminated sediments and Cu-enriched water.

Germination niche breadth of invasive Iris pseudacorus (L.) suggests continued recruitment from seeds with global warming.

PremiseUnderstanding recruitment processes of invasive species is central to conservation and management strategies. Iris pseudacorus, an emergent macrophyte, has established invasive populations across a broad global range, and reduces biodiversity in wetland ecosystems. Climate change is altering germination cues, yet studies on the invasion of wetland macrophytes often ignore germination ecology despite its importance to their establishment and spread.MethodsWe explored germination of seeds from invasive I. pseudacorus populations in California in response to seed coat presence or absence, and several environmental factors. Using experimental results in a thermal time model, we derived germination temperature thresholds.ResultsGermination of I. pseudacorus seeds did not require cold or warm stratification, and was not affected by seed coat presence or absence. Germination occurred in the dark, although germinability was two‐ to threefold times greater under light. At constant temperature, thermal time model estimates included 18.3 ± 1.8°C base germination temperature (Tb); 28.2 ± 0.5°C optimal temperature (To); and 41.0 ± 1.7°C ceiling temperature (Tc). Seeds exposed to 36.0°C achieved over 10% germination, and embryos of ungerminated seeds presented 76% viability. Overall, germinability remained relatively low at constant temperatures (≤25%) but was close to 90% under alternating daily temperatures.ConclusionsExposure to diurnally fluctuating temperatures is essential for this species to achieve high germination rates. Our study reveals that I. pseudacorus has a broad germination niche supporting its establishment in a relatively wide range of environments, including at high temperatures more frequent with climate change.

Estimating Biomass and Carbon Sequestration Capacity of Phragmites australis Using Remote Sensing and Growth Dynamics Modeling: A Case Study in Beijing Hanshiqiao Wetland Nature Reserve, China.

Estimating the biomass of Phragmites australis (Cav.) Trin. ex Steud., i.e., a common wetland macrophyte, and the associated carbon sequestration capacity has attracted increasing attention. Hanshiqiao Wetland Nature Reserve (HWNR) is a large P. australis wetland in Beijing, China, and provides an ideal case study site for such purpose in an urban setting. In this study, an existing P. australis growth dynamics model was adapted to estimate the plant biomass, which was in turn converted to the associated carbon sequestration capacity in the HWNR throughout a typical year. To account for local differences, the modeling parameters were calibrated against the above-ground biomass (AGB) of P. australis retrieved from hyperspectral images of the study site. We also analyzed the sensitivity of the modeling parameters and the influence of environmental factors, particularly the nutrient availability, on the growth dynamics and carbon sequestration capacity of P. australis. Our results show that the maximum AGB and below-ground biomass (BGB) of P. australis in the HWNR are 2.93 × 103 and 2.49 × 103 g m−2, respectively, which are higher than the reported level from nearby sites with similar latitudes, presumably due to the relatively high nutrient availability and more suitable inundation conditions in the HWNR. The annual carbon sequestration capacity of P. australis in the HWNR was estimated to be 2040.73 gC m−2 yr−1, which was also found to be highly dependent on nutrient availability, with a 50% increase (decrease) in the constant of the nutrient availability KNP, resulting in a 12% increase (23% decrease) in the annual carbon sequestration capacity. This implies that a comprehensive management of urban wetlands that often encounter eutrophication problems to synergize the effects of nutrient control and carbon sequestration is worth considering in future practices.

Removal of perfluoroalkyl acids and dynamic succession of biofilm microbial communities in the decomposition process of emergent macrophytes in wetlands

Perfluoroalkyl acids (PFAAs) are emerging contaminants that pose significant environmental and health concerns. Water–sediment–macrophyte residue systems were established to clarify the removal efficiency of PFAAs, explore possible removal pathways, and profile the dynamic succession of biofilm microbial communities in the decomposition process. These systems were fortified with 12 PFAAs at three concentration levels. Iris pseudacorus and Alisma orientale were selected as the decomposing emergent macrophytes. The removal rates in the treatments with residues of I. pseudacorus (IP) and A. orientale (AO) were 34.4% to 88.9% and 36.5% to 89.9%, respectively, which were higher than those in the control groups (CG) (30.3% to 86.9%), suggesting that decomposition could alter the removal of PFAAs. Sediment made the greatest contributions (preloaded 14.5% to 77.8% of PFAAs in IP, 14.3% to 78.2% in AO, and 27.4% to 71.9% in CG). PFAAs could also be removed by macrophyte residue sorption (0.0190% to 13.0% in IP and 0.016% to 15.6% in AO) and bioaccumulation of residual biofilm (the contributions of biofilm microbes and their extracellular polymeric substances were 0.0110% to 3.93% and 0.918% to 34.4%, respectively, in IP and 0.0141% to 4.65% and 1.49% to 34.1%, respectively, in AO). Significant correlations were observed between sediment/residue adsorption and bioaccumulation of biofilm microbes, and were significantly correlated with perfluoroalkyl chain length (p < 0.05). The dynamic succession of residual biofilm microbial communities was investigated. The largest difference was found at the preliminary stage. The most similar communities were found in AO on day 70 (with specific genera Macellibacteroides and WCHB1-32) and in IP on day 35 (with specific genera Aeromonas and Flavobacterium). This study is useful to understand the removal of PFAAs during the decomposition process, providing further assistance in removing PFAAs during the life cycle of macrophytes in wetlands.

Physico-chemical Properties of Water and Its Impactson the Species Diversity of Aquatic Plants at Disangmukh Wetland of Assam, India

Disangmukh wetlands are an agglomeration of few wetlands beside the levee region of River Brahmaputra where the tributary Disang meets the Mighty Brahmaputra. The present study examines the physic-chemical properties of water and sees the relationship between water quality and the aquatic macrophytes in the Disangmukh wetland of Assam. The samples of plants and water were collected from four sites of Disangmukh wetland namely Ronga Garh, Rongmon, Kaziranga and Longsai beel. The plant’s samples were collected using the quadrat sampling method with 1 square meter and the diversity has been calculated using the Shannon Diversity Index (SDI) (H = -?s [(Pi) x ln (Pi)]). The results show the highest SDI at Longsai beel (2.58) and it was followed by Rongmon beel (2.2), Ronga Garh beel (2.13) and Kaziranga beel (2.11). DO, ORP and TDS shows a positive correlation with plant diversity.

Investigating the efficiency of Vertical Sub-Surface Flow Constructed Wetlands in the Reduction of Faecal Indicator Bacteria and Organic matter Under Varied Sizes of Gravel Substrate Aggregates

Constructed wetlands (CWs) polish wastewater prior to discharge into aquatic receptacles. Size variabilities of substrates used in CWS may have effects on the treatment efficiencies though there is scanty information regarding this aspect in VSSF CWs. To address this knowledge gap, a laboratory scale mesocosm experiment was set up to investigate the potential of a VSSF CW to reduce organic matter and FIB using various gravel substrate aggregate sizes. This consisted of three gravel size treatment units; &lt;12.5, 12.5-18 and 18-24 mm in triplicates. 70 liters of pre-treated wastewater from the final wastewater stabilization pond (WSP) of Egerton University’s WSPs system was added to the units, allowed to settle for 6 weeks for development of biofilms, followed by periodic feeding of equal wastewater quantity on weekly basis and influent and effluent samples collected for 8 weeks for analysis. Results disclosed reduction efficiency of 95.2, 94.3 and 88.4 % for E coli in the fine, medium and coarse gravel aggregates respectively. Less than 20 % reduction efficiency was recorded for BOD5 in all gravel aggregate sizes. There was no significant variation on performance of the three gravel aggregate sizes in reduction of both FIB and BOD5 (p˃0.05). Poor performance in BOD5 reduction was related to absence of wetland macrophytes in the study. The relatively high reduction efficiency for FIB was attributed to other factors and processes such as predation, mechanical interactions, starvation, microbial interactions and natural die-offs. The study recommends assessing the combined effect of increasing the retention time, use of wetland macrophytes and incorporating various gravel aggregate sizes in order to increase the efficiency of VSSF CW in reduction of FIB and organic matter.