In the West Asia region, the vulnerability of Ramsar Convention wetlands due to unsustainable utilization driven by water scarcity continues to grow. Here, a global surface water product generated by the European Joint Research Centre was used to assess changes in surface water in 77 wetlands listed under the Ramsar Convention over a 37-year period (1984–2021). By combining this product with a quantitative valuation model, estimates were made of the economic value of the ecosystem services provided by these wetlands, enabling the determination of the economic losses resulting from any reduction in surface water. We show that 20% (7550 km2) of permanent surface waters in Ramsar sites have disappeared or are no longer classified as permanent. Based on this, USD 106 billion of the economic value of wetlands ecosystem services have been lost. Additionally, 33% (12 100 km2) of seasonal surface waters in these wetlands have experienced a decrease in area. Iran and Iraq account for 90% of water losses, primarily in 34 wetlands (30 in Iran and 4 in Iraq). These findings underscore the urgent need for water management policies and conservation strategies in the West Asia region.

The Vulnerable marsh deer Blastocerus dichotomus, the largest native cervid in South America, is declining throughout its range as a result of the conversion of wetlands and overhunting. Estimated densities in open wetlands of several types are 0.1–6.8 individuals per km2. We undertook the first unmanned aerial vehicle (UAV) survey of the marsh deer to estimate the density of this species in a 113.6 km2 area under forestry management in the lower delta of the Paraná River, Argentina. During 6–8 August 2019, at a time of year when canopy cover is minimal, we surveyed marsh deer using Phantom 4 Pro UAVs along 94 transects totalling 127.8 km and 8.6 km2 (8.1% of the study area). The 5,506 photographs obtained were manually checked by us and by a group of 39 trained volunteers, following a standardized protocol. We detected a total of 58 marsh deer, giving an estimated density of 6.90 individuals per km2 (95% CI 5.26–8.54), which extrapolates to 559–908 individuals in our 113.6 km2 study area. As it has generally been assumed that marsh deer prefer open habitats, this relatively high estimate of density within a forestry plantation matrix is unexpected. We discuss the advantages of using UAVs to survey marsh deer and other related ungulates.

Mollusk and ostracode assemblages from the distal Old River Bed delta (ORBD) contribute to our understanding of the Lake Bonneville basin Pleistocene-Holocene transition (PHT) wetland and human presence on the ORBD (ca. 13,000–7500 cal yr BP). Located on U.S. Air Force-managed lands of the Great Salt Lake Desert (GSLD) in western Utah, USA, the area provided 30 samples from 12 localities. The biological assemblages and the potential water sources using 87Sr/86Sr analyses showed wetland expansion and contraction across the PHT, including the Younger-Dryas Chronozone (YDC). The record reflects cold, freshwater conditions, which is uncharacteristic of the Great Salt Lake Desert, after recession of Lake Bonneville. Lymnaea stagnalis jugularis, Cytherissa lacustris, and possibly Candona sp. cf. C. adunca, an endemic and extinct species only reported from Lake Bonneville, suggest cold-water environments. Between 13,000–12,400 cal yr BP, a shallow lake formed, referred to as the Old River Bed delta lake, fed by Lake Gunnison, as shown by 87Sr/86Sr ratios of 0.71024–0.71063 in mollusk fossils collected at the ORBD, characteristic of the Sevier basin. These findings add paleoenvironmental context to the long-term use of the ORBD by humans in constantly changing wetland habitats between 13,000–9500 cal yr BP.

Invasive species negatively impact vegetation communities. Invasive European common reed [Phragmites australis (Cav.) Trin. ex Steud. ssp. australis] is rapidly spreading throughout North American wetlands. As such, the suppression of P. australis populations is a goal of many managers, as its removal should provide an opportunity to restore native vegetation communities. In Ontario, managers applied a glyphosate-based herbicide to more than 400 ha of P. australis in ecologically significant coastal marshes, representing the first time this tool was used over standing water to suppress an invasive species in Canada. Using a before–after–control–impact monitoring design, we evaluated the efficacy of glyphosate-based herbicide at removing P. australis along a water-depth gradient and assessed the recovery of the vegetation community for 2 yr after treatment in relation to reference conditions. We found that herbicide suppressed more than 99% of P. australis 1 yr after treatment and worked effectively along the entire water-depth gradient (10 to 48 cm). However, the post-treatment vegetation community remains distinctive from reference marsh 2 yr after treatment. In many plots where P. australis was removed, nonnative European frog-bit (Hydrocharis morsus-ranae L.) is now dominant, likely aided by high lake-water levels.

Mudflats are exposed for short periods after flood water drawdown. They support fast-growing annual herbs with a ruderal strategy. To optimize their recruitment success, seeds of mudflat species germinate better under fluctuating temperatures, full illumination and aerobic environments that indicate the presence of optimal (non-flooded) conditions for plant growth and development. Here, we hypothesize that prior exposure of mudflat seeds to hypoxic (flooded) environment interferes with the germination process and results in more vigorous germination once aerobic conditions are regained. To test this hypothesis, seeds of five mudflat species were incubated in both aerobic and hypoxic environments at four (14/6, 22/14, 22/22 and 30/22°C) temperature regimes, reflecting different (seasonal) conditions when drawdowns may occur. All species responded positively to four temperature regimes; however, moderate 22/14 and 22/22°C temperatures were optimum for high percentages and rates (speed) of seed germination. Since seeds of four species germinated exclusively under aerobic conditions, they were moved from hypoxic to aerobic conditions. Prior exposure of seeds to hypoxic environment facilitated high percentages, rates and synchronization of germination of Limosella aquatica, Peplis portula and Samolus valerandi seeds compared to incubation under strict aerobic conditions. However, prior exposure to hypoxic environment induced secondary dormancy in non-dormant seeds of Hypericum humifusum but broke dormancy in Lythrum hyssopifolia seeds that otherwise required cold stratification to overcome physiological dormancy. All species that have a narrow ecological niche (strictly occurring in mudflat habitats) showed positive responses to prior exposure to hypoxic environments. In contrast, H. humifusum that has a wide ecological niche (from mudflats to moist sandy grasslands) showed a negative response. We conclude that the hypoxic environment may strongly affect seed germination behaviour once the aerobic environment is regained. The most striking effect is the acceleration of the germination process and, therefore, life cycle supporting the survival in an ephemeral habitat.

This study evaluated the effectiveness of 14 herbicide treatments for purple loosestrife (Lythrum salicaria L.) control over a period of 10 yr. The study commenced in 2000/2001 at four wetland locations in Nebraska. The evaluated herbicides included: glyphosate at 2.2 and 3.4 kg ha−1; 2,4-D dimethylamine at 1.4 and 2.8 kg ae ha−1; triclopyr at 1.3 and 2.1 kg ae ha−1; imazapyr at 1.1 and 1.7 kg ae ha−1; metsulfuron at 0.042 and 0.084 ai kg ha−1; fosamine at 13.5 and 22.4 kg ai ha−1; triclopyr at 1.3 kg ae ha−1 plus 2,4-D amine at 1.4 ae kg ha−1; and metsulfuron at 0.042 kg ai ha−1 plus 2,4-D amine at 1.4 kg ae ha−1. Some treatments provided excellent control (90%) that lasted only one season, while others suppressed L. salicaria growth for multiple seasons, depending on the location and the age of L. salicaria stand. Application of higher rates of glyphosate, imazapyr, and metsulfuron consistently provided excellent control (≥90%) of L. salicaria that lasted 360 d after treatment at most locations. Application of fosamine and the lower rate of 2,4-D amine provided the least L. salicaria control at most locations. The older the L. salicaria stand, the more multiple applications of herbicides were needed to completely control L. salicaria. Generally, there were higher percentages of grasses in the 2,4-D-, triclopyr-, and metsulfuron-treated plots compared with higher percentages of broadleaf species in the glyphosate- and imazapyr-treated plots at each location.

The exotic shrub red sesbania is an increasingly problematic weed in riparian and wetland ecosystems of California. Current control methods focus on manual removal, followed by herbicide application. Although this method effectively removes mature stands, the control is temporary because the presence of a large seed bank results in rapid germination and growth of new seedlings. We measured the density of seed banks beneath stands of varying densities and evaluated the potential of tarping and inundation for control of red sesbania seed banks. As expected, the abundance of viable red sesbania seeds in the soil was significantly greater beneath high-density stands than it was beneath low-density stands. Results for inundation and tarping experiments were mixed. Sustained inundation significantly decreased survivorship of germinated seeds compared with the control, as well as causing a statistically significant reduction in germination. Seven months after tarping, during the fall/winter growing season, there was no significant effect on red sesbania seedling abundance, stump resprout abundance, or height. Germination in the laboratory was significantly reduced by extended exposure to temperatures of 60 C, although lower temperatures did not reduce germination. Red sesbania appears to be resilient to tarping as a control method, at least in the settings studied.

Field experiments were used to assess how distance mediates the nontarget effect on crepe myrtle by two chrysomelid beetles that were introduced to the United States in 1992 for biological control of purple loosestrife. Previous laboratory tests in Germany and concurrent tests in Oregon showed that although the control organisms can feed on crepe myrtle, they cannot complete development. Therefore, we predicted that negative effects on crepe myrtle would decrease with distance from the purple loosestrife stand. To test this prediction, cohorts of both plant species were transplanted at increasing distances (0, 5, 15, 30, and 50 m) from the colonization source. We found that leaf damage inflicted by the beetles was negatively correlated with increasing distance. Damage was significantly lower at each distance for crepe myrtle plants than for purple loosestrife plants, with a mean difference of 22% and a 95% confidence interval ranging from 12 to 31%. Extensive defoliation of crepe myrtle was limited to within 30 m of the edge of the loosestrife stand. Plant yield was negatively correlated with damage: the closer plants were to the purple loosestrife stand, the greater the suppression of biomass in both plant species. However, loosestrife biomass decreased significantly more quickly than crepe myrtle biomass, with a mean difference in slopes of 0.035 and a 95% confidence interval ranging from 0.022 to 0.048. Our results suggest that release of the Galerucella beetles in North America poses little risk to crepe myrtle. Beetles can feed but cannot complete their life cycle on crepe myrtle, and damage to crepe myrtle approaches zero approximately 50 m from the beetle colonization source.

The Asian Monsoon, which brings ~80% of annual precipitation to much of the Tibetan Plateau, provides runoff to major rivers across the Asian continent. Paleoclimate records indicate summer insolation and North Atlantic paleotemperature changes forced variations in monsoon rainfall through the Holocene, resulting in hydrologic and ecologic changes in plateau watersheds. We present a record of Holocene hydrologic variability in the Yarlung Tsangpo (YT) valley of the southern Tibetan Plateau, based on sedimentology and 14C dating of organic-rich black mats’ in paleowetlands deposits, that shows changes in wetlands extent in response to changing monsoon intensity. Four sedimentary units indicate decreasing monsoon intensity since 10.4 ka BP. Wet conditions occurred at ~10.4 ka BP, ~9.6 ka BP and ~7.9–4.8 ka BP, with similar-to-modern conditions from ~4.6–2.0 ka BP, and drier-than-modern conditions from ~2.0 ka BP to present. Wetland changes correlate with monsoon intensity changes identified in nearby records, with weak monsoon intervals corresponding to desiccation and erosion of wetlands. Dating of in situ ceramic and microlithic artifacts within the wetlands indicates Epipaleolithic human occupation of the YT valley after 6.6 ka BP, supporting evidence for widespread colonization of the Tibetan Plateau in the early and mid-Holocene during warm, wet post-glacial conditions.

Available proxy records from the Florida peninsula give a varying view on hydrological changes during the late Holocene. Here we evaluate the consistency and sensitivity of local wetland records in relation to hydrological changes over the past ~ 5 ka based on pollen and diatom proxies from peat cores in Highlands Hammock State Park, central Florida. Around 5 cal ka BP, a dynamic floodplain environment is present. Subsequently, a wetland forest establishes, followed by a change to persistent wet conditions between ~ 2.5 and 2.0 ka. Long hydroperiods remain despite gradual succession and basin infilling with maximum wet conditions between ~ 1.3 and 1.0 ka. The wet phase and subsequent strong drying over the last millennium, as indicated by shifts in both pollen and diatom assemblages, can be linked to the early Medieval Warm Period and Little Ice Age, respectively, driven by regionally higher sea-surface temperatures and a temporary northward migration of the Intertropical Convergence Zone. Changes during the 20th century are the result of constructions intended to protect the Highlands Hammock State Park from wildfires. The multiple cores and proxies allow distinguishing local and regional hydrological changes. The peat records reflect relatively subtle climatic changes that are not evident from regional pollen records from lakes.

Common reed (Phragmites australis) is an invasive perennial grass in aquatic and riparian environments across the United States, forming monotypic stands that displace native vegetation that provides food and cover for wildlife. Genetic variation in global populations of common reed has given rise to two invasive haplotypes, I and M, in the United States. Our objectives were to (1) determine if any differences in herbicide efficacy exist with respect to common reed haplotypes I and M and (2) screen for other labeled aquatic herbicides that may have activity on common reed haplotypes I and M, most notably imazamox and diquat. A replicated outdoor mesocosm study was conducted in 1,136-L (300-gal) tanks using haplotypes I and M of common reed. Restriction fragment length polymorphism methodologies were used to verify the identification of I and M haplotypes used in this study. Diquat at 2.2 (1.9) and 4.5 (4.0) kg ai ha−1 (lb ai ac−1), glyphosate at 2.1 (1.8) and 4.2 (3.7) kg ae ha−1 (lb ae ac−1), imazamox at 0.6 (0.5) and 1.1 (0.9) kg ai ha−1 (lb ai ac−1), imazapyr at 0.8 (0.7) and 1.7 (1.5) kg ai ha−1 (lb ai ac−1), and triclopyr at 3.4 (3.0) and 6.7 (5.9) kg ae ha−1 (lb ae ac−1) were applied to the foliage of common reed. After 12 wk, no difference (P = 0.28) in herbicide tolerance was seen between the two haplotypes with respect to biomass. The 4.2-kg ae ha−1 rate of glyphosate and the 0.8- and 1.7 kg ai ha−1 rates of imazapyr reduced common reed by > 90% at 12 wk after treatment (WAT). Imazamox at 0.6 and 1.1 kg ai ha−1, and triclopyr at 3.4 and 6.7 kg ae ha−1 reduced common reed biomass (62–86%) at 12 WAT, though regrowth occurred. Diquat did not significantly reduce biomass by 12 wk. Glyphosate and imazapyr were the only herbicides that resulted in > 90% biomass reduction and corroborate control from previous studies.

The consequences of considering ecosystem services (ES) in conservation assessment are still widely debated. The degree of success depends on the extent to which biodiversity and ES can be secured under joint conservation actions. Unlike biodiversity, ES conservation is inseparably linked to human beneficiaries. Reconciling biodiversity with ES and conservation can be particularly challenging in sparsely populated areas. This study, in a sparsely-populated region of eastern Canada, focused on freshwater wetland biodiversity and ten ES provided by wetlands. Within a given maximal total area, the results showed that planning for biodiversity underrepresented local flow ES supply by 57% and demand by 61% in conservation networks. Planning for ES alone underrepresented wetland biodiversity surrogates by an average of 34%. Considering both biodiversity and ES simultaneously, all of the biodiversity and ES targets were achieved with only a 6% mean increase in area. Achieving all conservation targets starting from a network that was primarily built for either ES or biodiversity features alone was two to five times less efficient than considering both ES and biodiversity simultaneously in conservation assessment. A better framework is required to translate these spatial synergies into effective joint conservation actions.

Appropriate legislation based on in-depth ecological evidence is essential for ecosystem conservation. Wetland areas in the Brazilian Cerrado hotspot are facing difficulties in terms of status under environmental law: only those wetlands with the palm Mauritia flexuosa (veredas) are recognized as protected. Comprehensive fieldwork in central-western Brazil (72 50-m transects) coupled with both exploratory and confirmatory analyses showed that communities with (MP) and without (MA) M. flexuosa are similar in terms of the floristics and ecology. The results demonstrate that the analysed wetlands are part of a continuum, in which a gradual replacement of species and community structure occurs without a pattern related to physiognomy. Considering such floristic and structure patterns when legally defining the ecosystem would promote a more comprehensive and realistic view of the ecosystem's characteristics and functions, and result in laws with a stronger scientific support. Conservationists should further examine the lack of consistent separation of plant community attributes between the MP and MA areas, and reconsider the scientific definition of veredas.

The authors rewrite the character of Early Mesolithic settlement in Europe with their new research at one of its most famous sites. The picture of small mobile pioneering groups colonising new land is thrown into contention: far from being a small hunter-gatherer camp, Star Carr in 9000 cal BC extended for nearly 2ha and involved the construction of an estimated 30m of lakeside waterfront and at least one post-built house. With some justice, they suspect that the ‘small groups’ of Early Mesolithic Europe may have their rationale in the small excavations of archaeologists.

Many mires of high conservation value occur in Bulgaria. These mires acted as refugia during the dry phases of ice ages and therefore contain a high number of rare and disjunct species. The mires harbour specific ecotypes and genotypes of plants and animals, and thus provide an opportunity to test biogeographical hypotheses, and they also contain important information about the history of European mires. In this study we ranked all known mire and spring complexes in Bulgaria according to the occurrence of rare and threatened plant and mollusc species. This analysis shows a conspicuous concentration of rare species at several sites, and no correspondence between the importance of individual mires for biodiversity and their legal protection. Of the 10 mire complexes of highest priority only one is effectively protected. The remaining unprotected mires have either been destroyed or are threatened by ongoing development. Having joined the European Union, Bulgaria has built a Natura 2000 network that could provide an opportunity for mire conservation. However, destruction of mire habitats proceeds faster than the approval of Natura 2000 sites. There is thus a possibility that unique Bulgarian mires will be lost before the Natura 2000 system begins to perform its role. Only effective and timely protection of the mire remnants, together with appropriate management, will ensure the future of these unique habitats.

Wetlands in India supply crucial human and animal needs such as drinking water, protein production, fodder, water purification, wildlife habitat, and flood storage. Increased appreciation of uses and threats is essential to protect wetlands where justified. Three quarters of India's population is rural, it places great demands on India's wetlands and losses continue to occur. This paper is based on extensive discussions with natural resource managers, government employees, farmers, academicians, and resource users at dozens of sites in India, as well as an extensive literature search. Twelve important kinds of wetland loss are identified and mechanisms believed to be causing them discussed: (1) agricultural conversion, (2) direct deforestation, (3) hydrologie alteration, (4) inundation, (5) defoliation, (6) altered upper watersheds, (7) accumulative water demands, (8) water quality degradation, (9) wetland consolidation, (10) global climate change, (11) ground-water depletion, (12) exotic species and biodiversity. Wetland understanding, management, and Public awareness in India must continue growing if wetland resources are to remain functional.

We have studied a number of related processes of the nitrogen cycle in a Brazilian floodplain lake to identify the major pools and pathways over a short time period. The study was centred on the littoral zone dominated by the floating plant Eichhornia azurea, which has a large epiphyte algal community of which heterocystous cyanobacteria were the major components. The water column was continuously undersaturated with oxygen although some elevated values (to 60% saturation) were recorded in the macrophyte beds in the afternoon. Marked diel temperature changes were documented. NH4-N dominated the dissolved N component in the water with maximal values (60 mg m−3) at lowest O2, concentrations early in the morning. Nitrogen fixation (acetylene reduction) of the epiphyte community showed marked diel changes with daily values of 5 mg N fixed m−2 day−1 (based on 3:1 C2H4:N2 ratio). Macrophyte NH4-N uptake rates (in situ incubations) were 93 mg N m−2 day−1. The activities of nitrifying bacteria could not be detected with the nitrapyrin block on dark CO2 fixation but denitrification (acetylene block technique) was recorded in the sediments when enhanced with NO-3. The major pathways of aquatic nitrogen involved macrophyte uptake and sediment release of NH4-N.

Lac Alaotra is Madagascar's largest lake and a recognized wetland of international importance under the Ramsar Convention. It supports several Critically Endangered species, including the Alaotran gentle lemur Hapalemur alaotrensis. A principal threat facing the remaining Alaotran wetland is anthropogenic burning of the vegetation during the dry season; a practice now officially banned. A number of reasons have been given to explain this but to date no attempt has been made to investigate the principal motivations for the burning. We present the results of semi-structured interviews (n = 27) and questionnaires (n = 122) in a lakeside town. Seventy-eight percent of interviewees stated wetland burning was performed only or mainly to gather an introduced fish, the Asian snakehead Channa maculata, which buries into the underlying substrate during the dry season. Sixty-eight percent of questionnaire respondents provided a similar explanation. These data provide valuable insights into the reasons for the ongoing burning and should inform the management actions that are required to protect this globally important wetland.