Macrophyte Diversity Research Articles

Species Diversity and Distribution of Macrophytes in Different Wetland Ecosystems

Wetlands are vital and dynamic components of the global ecosystem, providing a wide range of ecosystem services such as water control and biodiversity. During 2015–2019, plant diversity and distribution of wetlands were studied in forty areas of the Mardan division, Khyber Pakhtunkhwa, Pakistan. A total of 282 vascular wetland plant species were identified, divided into 192 genera and 73 families. Poaceae, with 41 species, is the most diverse family of wetland plants, followed by Asteraceae, with 26 species. In the present study, wetland plants are classified based on the Cook classification system. It is interesting to note that all the life forms were present in the study area except Plankton. Helophyte life form was represented by the highest number of plants with 177 plants and 62.5 percent of total wetland plants, followed by Tenagophyte with 42 plant species (14.8%) and Hyperhydate with 27 plant species (9.5%). Based on the distribution pattern of 282 species in 40 wetland sites, the most common plant species found was Euphorbia helioscopia, recorded from 36 locations, followed by Cynodon dactylon which was found in 32 locations. In Mardan division, the Gulshan Abad Khuwar had the highest number of species occurrences (83 species) accounting for 32% of all species, followed by Alo Khwar (59 species, 23%) and Hathian Khwar (50 species, 19%). The current work presents a comprehensive and field-based detailed survey of wetland plant distribution in this region, filling knowledge gaps in the Himalayas in particular, and having broader implications for wetland management policy and practice. Unfortunately, wetlands of the research area are facing high pressure due to an increase in human population, overgrazing, deforestation, construction of buildings and roads. The filling up of these water bodies is resulting in the loss of hydrophytic species diversity. Therefore, these wetlands need proper attention and effective protection from anthropogenic disturbances.

Diversity of Marine and Brackish Macrophytes in the Port-Cros National Park (Provence, France, Mediterranean Sea): Taxa and Research Effort over Space and Time

The terrestrial and marine Port-Cros National (PCNP) was established in 1963; it was then made up only of the Archipelago of Port-Cros. Since 2012, it has been extended to include a vast land and sea area, including not only islands but also part of the mainland, the new PCNP (N-PCNP); the marine core area and the adjacent marine area cover approximately 120,000 ha and extend over 63 km as the crow flies, from east to west. Taxon richness is just one descriptor of biodiversity among others (e.g., functional and ecosystem diversity), and is far from being the most reliable one; however, it deserves to be taken into consideration, provided that certain prerequisites are met, because it constitutes a convenient measure of, e.g., the research effort and the diversity of habitats. The number of reported macrophyte taxa amounts to 502: 73 green algae, 316 red algae, 104 brown algae and 9 magnoliophyta and other taxa. Two new combinations are proposed: Ericaria brachycarpa var. claudiae and Gongolaria montagnei var. compressa. This gamma species diversity is far from being exceptionally high, but rather is within the norm for the Mediterranean, if we take into account the size of the area considered. The number of reported taxa per site is highly heterogeneous throughout the N-PCNP area; it is, as expected, correlated with the number of studies per site. The research effort peaked in the 1970–1980s, and then irregularly declined, which may seem surprising in this era of biodiversity launched at the 1992 Rio Summit. The exceptionally extensive database available, covering more than a century, provides the basis for a critical analysis of the concept of biodiversity, as proclaimed by the general public and the ‘greens’, which can be naive or biased, and of the concept of ‘heritage value species’, which the authors of this article consider to be a ‘toxic concept’, as opposed to ‘ordinary biodiversity’, which enables ecosystem functioning. However, this database, straddling both areas highly impacted by humans (coastal development, tourist resorts) and areas that are effectively protected, does not highlight obvious changes over time.

ECOLOGICAL IMPACTS OF ECOHYDROLOGICAL INTERVENTION ON THE WETLANDS ALONG THE SOUTHEASTERN SHORE OF LAKE TANA, ETHIOPIA

Lake Tana watershed wetlands have critical functions of nutrient and sediment retention, biodiversity and hydrological functions. Although ecohydrological solutions have been proposed, a comprehensive study on the impacts of ecohydrology intervention in relation to biological aspects is limited. Information regarding the ecological impacts of ecohydrology based intervention approach in the wetland ecosystem plays an indispensable role in increasing biodiversity and improves water quality. Thus, the aim of this study was to investigate the impacts of ecohydrological intervention in relation to macrophytes, phytoplankton and zooplankton of the wetlands in Lake Tana shore. Quantitative characteristics of macrophytes and plankton sampling were conducted using transect and quadrat method along vegetation and water depth gradients. The biological data were measured on each fixed sampling point. Macrophytes, phytoplankton and zooplankton were significantly different (p<0.05) across the sampling sites. Low disturbed wetland supports higher abundance and diversity of macrophytes, phytoplankton and zooplankton than moderately and highly disturbed wetlands. Overall results of the study confirmed that biological abundance and diversity were associated with the level of disturbance of wetlands. Therefore, emphasis should be given to the factors which may lead to the degradation of wetland resources within and its catchment. Immediate ecohydrology based intervention approaches should be implemented to conserve and minimize further degradation of wetlands along the shore of Lake Tana.

A Study on Aquatic Macrophytes Diversity of Lake Kharungpat, Manipur, India

Aquatic macrophytes are considered as an important component of the aquatic ecosystem not only as food source for aquatic invertebrates, but also act as an efficient accumulator of heavy metals. The infestation of freshwater bodies by aquatic weeds influences water management in waterways, rivers, reservoirs and canals which interfere with the use of water, or in some way constitute a nuisance to man or hazard to human welfare, or growing on a water body where it is not desired.The present study was conducted during September, 2019 to August, 2020 in lake Kharungpat of Manipur which is situated towards the southern lowlands of the central valley of Manipur in the Kakching district. Five numbers sampling Site namely Site 1 (Longitude 93º 92' E and Latitude 24º 58' N), Site 2 (Longitude 93º 91' E and Latitude 24º 56' N), Site 3 (Longitude 93º 93' E and Latitude 24º 54' N), Site 4 (Longitude 93º 96' E and Latitude 25º 55' N) and Site 5 (Longitude 93º 96' E and Latitude 24º 58' N) were selected to make the study statistically sound. A total of 26 aquatic macrophytes were identified from lake Kharungpat during 2019-2020. The identified aquatic macrophytes comprised of 26 species belonging to 23 genera, 15 families and 11 orders. Phragmites karka species was the most dominant aquatic macrophytes of the lake in case of species occurrence and percentage contribution, alone contributing 81 percent to the total macrophytes vegetation during the study period. The overall total infestation percentage of macrophytes was recorded maximum (76.67 percent) in the month December, 2019 and March, 2020 with minimum 41.39 percent in the month August, 2020.The Simpson index, Shannon index and Evenness richness index value ranged between 0.7398 to 0.9386, 1.712 to 2.956 and

Aquatic Macrophytes in Southern Amazonia, Brazil: Richness, Endemism, and Comparative Floristics

Southern Amazonia harbors a wide diversity of aquatic macrophyte species because of its diverse wetland habitats and location in the Amazon-Cerrado transition zone, which spans the two largest biogeographic domains in South America. We investigated the taxonomic diversity of aquatic macrophytes in the region with a focus on endemism, species richness, and life forms. We present new records of aquatic macrophyte species and compare our results with other Brazilian phytogeographic domains. We found a high number of species of aquatic macrophytes for the southern Amazon region, comparable to extensive inventories in southern, northeastern, and northern regions of Brazil. We recorded 709 species of aquatic macrophytes in 313 genera and 97 families, which includes 90 species endemic to Brazil and five species endemic to the Brazilian Amazonia. The macrophyte species list of southern Amazonia showed < 25% similarity to inventories in Amazonia and Cerrado. This high diversity of aquatic macrophytes in southern Amazonia, with endemic species and others with restricted ranges, emphasizes the need for conserving these wetlands and vegetation types.

Sedimentary DNA identifies modern and past macrophyte diversity and its environmental drivers in high‐latitude and high‐elevation lakes in Siberia and China

AbstractArctic and alpine aquatic ecosystems are changing rapidly under recent global warming, threatening water resources by diminishing trophic status and changing biotic composition. Macrophytes play a key role in the ecology of freshwaters and we need to improve our understanding of long‐term macrophytes diversity and environmental change so far limited by the sporadic presence of macrofossils in sediments. In our study, we applied metabarcoding using the trnL P6 loop marker to retrieve macrophyte richness and composition from 179 surface‐sediment samples from arctic Siberian and alpine Chinese lakes and three representative lake cores. The surface‐sediment dataset suggests that macrophyte richness and composition are mostly affected by temperature and conductivity, with highest richness when mean July temperatures are higher than 12°C and conductivity ranges between 40 and 400 μS cm−1. Compositional turnover during the Late Pleistocene/Holocene is minor in Siberian cores and characterized by a less rich, but stable emergent macrophyte community. Richness decreases during the Last Glacial Maximum and rises during wetter and warmer climate in the Late‐glacial and Mid‐Holocene. In contrast, we detect a pronounced change from emergent to submerged taxa at 14 ka in the Tibetan alpine core, which can be explained by increasing temperature and conductivity due to glacial runoff and evaporation. Our study provides evidence for the suitability of the trnL marker to recover modern and past macrophyte diversity and its applicability for the response of macrophyte diversity to lake‐hydrochemical and climate variability predicting contrasting macrophyte changes in arctic and alpine lakes under intensified warming and human impact.

High abundance of a single taxon (amphipods) predicts aquatic macrophyte biodiversity in prairie wetlands

Conservation programs often aim to protect the abundance of individual species and biodiversity simultaneously. We quantified relations between amphipod densities and aquatic macrophyte (large plants and algae) diversity to test a hypothesis that biodiversity can support high abundance of a single taxonomic group. Amphipods (Gammarus lacustris and Hyalella azteca) are key forage for waterfowl and are declining in the Prairie Pothole Region of North America. We sampled a large gradient of amphipod densities (0–7050 amphipods/m3) in 49 semi-permanent wetlands, and 50% of the study wetlands had high amphipod densities (> 500 amphipods/m3). Generalized linear models revealed G. lacustris and H. azteca densities increased exponentially with macrophyte diversity indices. Further, H. azteca densities were greatest at moderate levels of submersed vegetation biomass. Community analyses showed both amphipod species were positively associated with diverse macrophyte assemblages and negatively associated with high coverage of cattails (Typha spp.), a taxon that creates monotypic stands, as well as bladderwort (Utricularia spp.), a carnivorous plant. Our results indicate that amphipods could be used as an umbrella species for protecting diverse macrophyte communities in semi-permanent and permanent wetlands of North America’s Prairie Pothole Region.

Abundance, diversity and distribution of Macrophytes in lotic wetlands: A case study on Sironga and Kapkatet Wetlands, Kenya

Wetland macrophytes provide important ecological and social-economic values. However, the recent increase in anthropogenic influences has compromised the ecological integrity of most lotic wetlands, which has ultimately threatened their structure and functioning, causing degradation and loss of macrophytes. This study was aimed at assessing the biodiversity, distribution and abundance of macrophytes in Sironga and Kapkatet wetlands with respect to various anthropogenic activities. Sampling was conducted for a period of six months, covering both dry and wet seasons from February – July 2019. Macrophytes were identified using identification keys and diversity indices such as the Shannon-Wiener, Simpson’s, and Species evenness were used to determine macrophyte diversities. The numbers of different macrophytes species was enumerated from five randomly sampled line transects along the water ways and another fifteen also randomly distributed on the wetlands on a monthly basis. There were three main lifeforms of aquatic macrophytes found in both Sironga and Kapaktet wetlands namely, emerged, submerged and floating, which were dominated by Centella asciatica and Cyperus sp. and the floating macrophytes, Potamogeton schwenfurthii dominated Kapaktet wetland. The study found that macrophyte distribution, abundance and biodiversity were highly affected by predominant economic activities resulting to wetland conversion, nutrient influxes and unsustainable exploitation of macrophytes. We recommend a further study focusing on effects of sedimentation resulting from unsustainable agricultural practices on water quality and macrophytes diversity, distribution and abundance, the effects of changing land-use practices and how different environmental agencies can be involved in the advocacy, conservation and management of the riverine wetlands.

The non-native charophyte Nitellopsis obtusa (starry stonewort) influences shifts in macrophyte diversity and community structure in lakes across a geologically heterogeneous landscape

The non-native charophyte Nitellopsis obtusa (starry stonewort) influences shifts in macrophyte diversity and community structure in lakes across a geologically heterogeneous landscape

Long-term analysis of aquatic macrophyte diversity and structure in the Paraguay river ecological corridor, Brazilian Pantanal wetland

Spatial and temporal variation in limnological variables, as well as local changes in the hydrological pattern, may affect inundation hydrology and alter biotic interactions and functional diversity of aquatic macrophyte communities in the Pantanal. The objectives of this research in the floodplain along the Paraguay River were to: 1) examine changes in the diversity of aquatic macrophyte communities over a ten-year period based on surveys taken in 2008 and 2018; and 2) evaluate the possible indirect relation of changes in rainfall patterns, which in turn affect lateral hydrological connectivity and limnological variables that directly affect the composition and productivity of the aquatic macrophyte community. Comparison of data taken in 2008 and 2018 revealed a change in the timing and a reduction in the number of rainy days. These changes in rainfall patterns coincided with limnological changes, including increases in transparency, pH, dissolved oxygen, ammonium, nitrate, total nitrogen, orthophosphate, and total phosphorus, as well as decreases in water temperature and connectivity. Species richness of aquatic macrophyte communities in three ecological zones of the Paraguay River floodplain increased between 2008 and 2018, with increases in emergent grasses, emergent non-grasses, and amphibious life forms, showing a trend that favors species that are more adapted to drought conditions. The seasonal pattern of inundation and desiccation, as well as dissolved oxygen and temperature, where correlated with macrophytes communities variations. The colonization and expansion of rooted emergent macrophytes over this period could be a response to local anthropogenic activities, hydrological trends, or may reflect interannual rainfall variability.

Macrophyte diversity and their uses with special reference to freshwater wetland ecosystem Barbilabeel of Nalbari district, Assam, India

Macrophyte diversity and their uses with special reference to freshwater wetland ecosystem Barbilabeel of Nalbari district, Assam, India

Макрофиты российской части Калининградского /Вислинского залива (бассейн Балтийского моря)

The authors study the modern composition of the macrophyte flora of the Kaliningrad Bay (The Russian part of the Vistula Lagoon), which includes 116 species: 96 species of vas­cular plants and 20 species of macroalgae. Only 39 species of macrophytes were found in 2021, i. e., 19 species of higher plants and 20 species of macroalgae. Depending on the abiotic factors in the four hydrological regions of the lagoon, the floristic diversity and distribution of macrophytes has its own characteristics. The maximum species diversity (29 species), as well as the biomass of macrophytes, are characteristic of the eastern region, characterized by mini­mal salinity values and a high level of nutrients.

Diversity and network structure of epiphytic bacterial communities on different submerged macrophytes

沉水植物叶表附着大量细菌,与沉水植物构成了复杂的共生体系.叶片附着细菌是水生态的重要组成部分,能影响沉水植物自身生长和水体物质循环过程.目前,对于沉水植物多样性对植物叶片附着细菌群落的影响知之甚少.本研究比较了不同沉水植物物种多样性对浮游细菌和叶片附着细菌群落的影响,同时探究不同植物——苦草(Vallisneria natans)、穗状狐尾藻(Myriophyllum spicatum)、微齿眼子菜(Potamogeton maackianus)和黑藻(Hydrilla verticillata)叶片附着细菌的群落结构和多样性特征.结果表明,浮游细菌和叶片附着细菌的群落α多样性和β多样性具有显著差异.与单一植物物种体系相比,高植物物种多样性体系中植物叶片附着细菌群落α多样性较高.在高植物物种多样性体系中,黑藻叶片附着细菌群落的α多样性显著较高而β多样性显著较低,苦草叶片附着细菌群落的α多样性较低.沉水植物叶片附着细菌群落优势菌群属于变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes).高植物物种多样性体系中苦草的物种共现网络最具模块性.嗜甲基菌(g_Methylophilus)、红杆菌(f_Rhodobacter)、黄杆菌(g_Flavobacterium)是物种共现网络的关键物种.本文研究植物物种多样性对淡水湖泊细菌群落结构的影响,并强调宿主植物对附着细菌群落的重要选择作用,加深对细菌群落在水生植物叶片定殖机制的理解.;Epiphytic bacteria, adhering to the leaf surface of aquatic submerged macrophytes, develop a complex symbiotic relationship with submerged macrophytes. Epiphytic bacteria are an important component of the aquatic ecosystem, which can affect not only the growth of submerged macrophytes but also the nutrient cycling in aquatic ecosystems. Currently, the effect of submerged macrophyte diversity on the epiphytic bacteria communities is far from well understood. This study compared the effects of submerged macrophyte on bacterioplankton and epiphytic bacterial communities, meanwhile explored the community structure and diversity of epiphytic bacterial communities on different macrophytes-Vallisneria natans,Myriophyllum spicatum, Potamogeton maackianus andHydrilla verticillata. The results showed that the α diversity and structure of planktonic bacterial communities were significantly different from those of the epiphytic bacterial communities. With the increase of submerged macrophyte diversity, the α diversity of epiphytic bacterial communities increased slightly. In the systems with high submerged macrophyte diversity, significantly higher α diversity and lower β diversity were found for the epiphytic bacterial community on H. verticillata. Bacteroidetes and Proteobacteria were dominant phyla on the submerged macrophyte leaves. Co-occurrence network analysis revealed that the modularity value of V. natans epiphytic bacterial network was relatively high. Methylophilus, Rhodobacter andFlavobacterium were core species in the co-occurrence networks. This study demonstrated the effect of submerged macrophytes on bacterial community structure in freshwater lakes, emphasizing the importance of host-specific selection for epiphytic bacterial communities, and deepening our understanding of the mechanism of bacterial colonization on submerged macrophytes.

Improving the framework for assessment of ecological change in the Arctic: A circumpolar synthesis of freshwater biodiversity

Abstract Climate warming and subsequent landscape transformations result in rapid ecological change in Arctic freshwaters. Here we provide a synthesis of the diversity of benthic diatoms, plankton, macrophytes, macroinvertebrates, and fish in Arctic freshwaters. We developed a multi‐organism measure of α diversity to characterise circumpolar spatial patterns and their environmental correlates, and we assessed ecoregion‐level β diversity for all organism groups across the Arctic. Alpha diversity was lowest at high latitudes and elevations and where dispersal barriers exist. Diversity was positively related to temperature, and both temperature and connectivity limited diversity on high latitude islands. Beta diversity was highly variable among ecoregions for most organism groups, ranging from 0 (complete similarity) to 1 (complete dissimilarity). The high degree of dissimilarity within many ecoregions illustrates the uniqueness of many Arctic freshwater communities. Northward range expansion of freshwater taxa into Arctic regions may lead to increased competition for cold‐stenothermic and cold‐adapted species, and ultimately lead to the extinction of unique Arctic species. Societal responses to predicted impacts include: (1) actions to improve detection of changes (e.g., harmonised monitoring, remote sensing) and engagement with Arctic residents and Indigenous Peoples; and (2) actions to reduce the impact of unwanted changes (e.g., reductions of CO2 emissions, action against the spread of invasive species). Current Arctic freshwater monitoring shows large gaps in spatial coverage, while time series data are scarce. Arctic countries should develop an intensified, long‐term monitoring programme with routine reporting. Such an approach will allow detection of long‐term changes in water quality, biodiversity, and ecosystem services of Arctic freshwaters.

Species diversity of macrophytes in Jagadishpur Reservoir, Kapilvastu District, Nepal

The present research was conducted for quantitative study and diversity analyses of aquatic macrophytes dwelling littoral zone of Jagadishpur reservoir, Kapilvastu district in three seasons, as winter (December), summer (April), and rainy (August). Altogether 58 species of macrophytes were recorded in study site, of which highest number of species (54) was occupied by angiosperms followed by three species of pteridophytes and one species of alga. These macrophytes varied in different morphological groups, viz., emergent, submerged, and rooted-floating leaf type. Maximum number of species were represented by emergents (39) followed by rooted-floating leaf type (12) and submerged (7) macrophytes. There was distinct seasonal variation in the distribution of macrophytes: based on importance value index, Nelumbo nucifera (IVI = 22.87), Scripus sp. (IVI = 28.01), Ipomoea carnea (IVI = 24.67) and Typha angustifolia (IVI = 29.01) were dominant in the winter; Nelumbo nucifera (IVI = 20.05), Cynodon dactylon (IVI = 20.07) and Ipomoea carnea (IVI = 21.17) were dominant in the summer and Nelumbo nucifera (IVI = 23.8) and Scripus sp. (IVI =25.56) were dominant in the rainy season. The highest species diversity (H’) of macrophytes was observed during summer (3.451), followed by rainy season (3.135) and winter (3.008). The luxuriant growth of aquatic macrophytes evidenced the highly productive nature of the lake, while the dominance of emergents among the growth forms indicates the encroachment of littoral vegetation, indicating a successional trend toward marsh meadow.

Macrophyte diversity in rivers and streams of the Vologda Region and several other regions of Russia.

BackgroundThe data paper contains the authors’ materials on the diversity of macrophytes, macroscopic plants regardless of their taxonomic position, in rivers and streams of East European Russia and Western Siberia. These data, collected on 247 rivers and 32 streams in 13 administrative regions of the Russian Federation, were provided as an occurrence dataset presented in the form of GBIF-mediated data. The main portion of the data was obtained in water objects of the Vologda Region (5201 occurrences). In addition, occurrences from the Arkhangelsk Region (347 occurrences), Khanty-Mansi Autonomous Okrug (159), Yaroslavl Region (132), Novgorod Region (97), Kostroma Region (41), Republic of Karelia (31), Sverdlovsk Region (29), Komi Republic (28), Orenburg Region (26), Chelyabinsk Region (22), Voronezh Region (22) and Tyumen Region (18) were given. The studies were carried out mainly in the southern and middle taiga and, to a lesser extent, in the northern taiga and the forest-steppe. The analysed watercourses belong to five drainage basins: the Azov Sea, the Baltic Sea, the White Sea, the Caspian Sea and the Kara Sea. The dataset contains materials on the diversity of Plantae (6094 occurrences) and Chromista (59 occurrences). This paper, in a standardised form, summarises mostly unpublished materials on the biodiversity of lotic ecosystems.New informationThe paper summarises the data obtained in long-term studies of phytodiversity in a range of rivers and streams of East European Russia and, fragmentarily, Western Siberia. A total of 6153 occurrences were included in the dataset. According to the GBIF taxonomic backbone, the dataset comprises 292 taxa, including 280 lower-rank taxa (species, subspecies, varieties) and 12 taxa identified to the genus level. All the occurrences are published openly through the Global Biodiversity Information Facility (GBIF) for the first time. Most of the data were stored in field diaries and, thus, by adding the data in GBIF, we believe that other researchers could benefit from it.

Variabilidad estructural de la comunidad de macrófitas en un gradiente pluviométrico en la provincia de Chubut

Mallines are Patagonian wetlands characterized by permanent waterlogging on its soils, sustaining small shallow lakes that hosts a vast biodiversity. In these ecosystems, aquatic plants (i.e. macrophytes) develop different life forms adapted to humid conditions, allowing them to regulate the physical and chemical conditions of the mallín. A distinctive characteristic of Patagonia is the exponential west-east decrease in rainfall, which generates three biozones: forest, ecotone and steppe. These biozones have been typified using landform plants, but whether macrophytes assemblages are related to each biozone or not has not been evaluated yet. The aim of this work is to compare the attributes of the macrophyte and wetlands landform plants community in each biozone. During the 2013-2014 austral Summer, 20 shallow lakes were sampled in the west province of Chubut, assessing macrophyte richness and physical and chemical water variables. Macrophytes were classified according to their life forms, origin, and its diversity was calculated. A total of 62 taxa were determined, most of them corresponding to the Cyperaceae, Poaceae and Ranunculaceae families. The steppe exhibited alkaline pH values, and higher conductivity and soluble reactive phosphorus (SRP) than the ecotone and the forest. High SRP values favored the abundance of macrophytes and macroalgae. However, three sites were eutrophic, exhibiting high chlorophyll a and total phosphorus values. Those sites showed higher abundances of macroalgae and emerging macrophytes. The sampled shallow lakes would act as reservoirs of macrophyte diversity at both local and regional scales. Thus, understanding the relationships among macrophytes and environmental variables could be useful for the mallines biodiversity conservation plans.

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.

Determining macrophyte species richness and dark diversity sources – A novel approach to improve the biodiversity estimation based on species traits

Biodiversity measures deliver valuable ecological information by reflecting a range of ecosystem processes. However, the accuracy of environmental assessment based on species patterns may often be affected by insufficient survey details. The comprehensive evaluation of plant taxa richness in rivers requires an extensive sampling effort. The use of Hill numbers and Chao estimators improves species diversity assessment based on a feasible number of samples. The aim of this work was to identify macrophyte groups, associated with various species traits, which are rich in species, as well as those whose detection is particularly difficult as it requires an exceptional sampling effort (sources of dark diversity). Analyses were performed with the use of Hill numbers and Chao estimators. It was shown that the field identification of all estimated macrophytes is particularly difficult for low trophy indicators and generally submerged plants, as well as for small-leaved species. A field survey encompassing the full (expected) macrophyte diversity encountered within a river is easiest to perform in the case of free-floating plants and large-leaved macrophytes, as well as for species with high trophic tolerance. The study proved that ecological assessment of rivers based on a small number of sampling units may lead to incorrect diversity estimates. Conversely, the estimation of diversity patterns at the level of the Shannon and Simpson indices does not require extensive sampling, and the extrapolation approach is not needed. The effectiveness of diversity assessment in fluvial ecosystems can be increased by extrapolation of gray diversity which can be considered in planning of monitoring programs. Moreover even estimated dark diversity bight be already efficient to identify ecological pattern and when comparing biodiversity across regions and ecosystems.

Regional macrophyte diversity is shaped by accumulative effects across waterbody types in southern China

Studies on aquatic biodiversity in different waterbody types have attracted significant attention worldwide to achieve the goal of freshwater conservation. Different freshwater habitats can help maintain regional biodiversity by directly supporting aquatic plants and forming networks to promote aquatic dispersal across regions. However, few studies have conducted large-scale comparisons of macrophyte diversity among different waterbody types in China due to a lack of a national macrophyte dataset. Here, we compared species richness, species composition, beta diversity, and its components among ponds, ditches, disturbed ponds, lakes, rivers, and reservoirs in southern China. We found that macrophyte species composition overlapped in the different waterbody types, indicating similar regional species pools. Species composition was best explained by temperature, elevation, and flow velocity. For species richness, ponds supported the highest number of species, followed by lakes, ditches, rivers, and reservoirs, with disturbed ponds showing the lowest diversity. For beta diversity, the relatively low turnover and high nestedness in the lakes indicated high dispersal of macrophyte species throughout these water bodies or suggested that human disturbance in lakes may lead to a more uniform chemical environment and thus regional macrophyte community. This study emphasized the importance of maintaining the diversity of different waterbody types in the landscape and determining the most threatened freshwater habitats. Moreover, small water bodies (e.g., ponds) contribute more to the regional macrophyte species pool than permanent water bodies (e.g., lakes) due to their relatively high biodiversity value. Their stable hydrological environment may help maintain rare and uncommon species that do not appear in other waterbody types.