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Metacommunity ecology provides a basis for understanding how ecological communities are assembled. Metacommunity theory can be applied to assess the effects of anthropogenic disturbance on freshwater communities. However, few studies have examined how species-specific responses to environmental covariates can generate broader patterns in freshwater metacommunities. I determined occupancy patterns in an amphibian metacommunity to identify important predictors of reproduction at wetland sites. I conducted surveys at 49 wetlands for tadpoles with fish traps and dip netting in an urbanising region in southeastern Australia. The larvae of seven frog species were detected. There were negative relationships between the probabilities of reproduction at a site and the relative abundance of the eastern mosquitofish (Gambusia holbrooki) and wetland electrical conductivity. There was a positive relationship between tadpole occupancy and the proportion of accessible habitat within 1000 m of a site, a measure of the combined effects of roads and habitat amount. These results highlight the negative effect of predatory Gambusia on frog communities and illustrate the importance of the species-sorting and mass-effect perspectives of metacommunity theory at multiple spatial scales. Habitat restoration projects for amphibians should remove exotic fish or prevent their establishment in managed wetlands and maintain habitat connectivity to facilitate dispersal.

Understanding habitat use and reproductive biology of invasive species is essential to predicting invasions, designing early detection programs, and developing management plans. The rudd (Scardinius erythrophthalmus; Linnaeus, 1758) is an omnivorous fish native to Europe and western Asia that has been translocated to several countries in western Europe, New Zealand, North America, and Africa. However, little is known about early life history of rudd, particularly in invaded ecosystems, limiting our ability to predict invasions and create early detection and control programs. The upper Niagara River has the most abundant population of rudd in North America and has been the focus of several ecological investigations. Our study identified critical nursery habitats by determining which nearshore habitat factors were most strongly associated with presence of age-0 rudd. We found that emergent vegetation was the most important habitat characteristic associated with the presence of age-0 rudd. When emergent vegetation was not present, rudd were more likely to be present at sites with abundant submerged aquatic vegetation. Additionally, the odds of rudd presence decreased as distance to the nearest wetland increased. These findings can be used to create habitat-driven predictive models of rudd invasion and guide early detection programs for rudd outside their native range.

Constructed wetlands may compensate to some degree for the impact of the loss of natural wetlands on aquatic biodiversity. However, information is lacking on the relative value of artificial wetlands and comparable natural wetlands for freshwater turtles. I contrasted the population structure, diet and body growth of Australian eastern long-necked turtles (Chelodina longicollis) in artificial and natural ponds in farmland settings. Turtle populations in the artificial ponds had a more even distribution of body size, and a much larger proportion of young individuals, than those in the natural ponds, suggesting that the artificial ponds were important recruitment sites. Diet differed little between the two types of ponds, being greatly dominated by aquatic insects in both cases. However, body growth of juvenile turtles was on average more rapid in the artificial ponds, possibly because they were generally permanent, unlike the natural ponds. These findings suggest that artificial farm ponds are valuable habitats for C. longicollis, which may foster population recruitment that counters the effects of introduced nest predators and road mortality.

Bolboschoenus planiculmis is a key wetland plant in the semi-arid regions of Songnen Plain, China, providing food and habitat for the endangered Siberian crane. B. planiculmis wetlands are being degraded by water shortages caused by anthropogenic activities and climate changes. However, the vegetation dynamics under hydrological fluctuations have been rarely reported. We conducted a two-year field investigation in B. planiculmis wetlands to determine the vegetation response to water level changes, and a comparative control experiment to examine the restoration effect of supplemental water on degraded community. We found that the community biomass was positively related with water depth under natural conditions, whereas plant diversity and richness were negatively related. The population density, biomass, and root/shoot ratio of B. planiculmis exhibited quadratic relationships with water depth. The optimum ecological threshold of water depth determining B. planiculmis populations was 11.2–36.1 cm. The control experiment demonstrated that water depth at 0–10 cm during the early growing season and 10–25 cm at later growing stages can enhance the dominance of B. planiculmis and help it outcompete other macrophyte species. Understanding the water requirement cycles of B. planiculmis is valuable for guiding water management plans for the rehabilitation of degraded natural wetlands.

The decrease of the water level in Mediterranean wetlands due to global warming allows UVR to reach the sediment microbial community. Macrophyte meadows, through their structure and compounds contribution, exert influence on this community. Our goal was to establish how the sediment microbial community of a wetland is harmed by UVR, and how the macrophytes mitigate such effects. We performed a field factorial experiment (UVR and macrophytes as factors) in a Mediterranean wetland. The abundance and composition of the sediment microbial community (bacteria, Archaea, microalgae and cyanobacteria) and sediment stoichiometry in superficial and sub-superficial layers were analysed. The microbial community was altered even by the small doses of UVR of the Mediterranean coastal wetlands by decreasing the periphyton abundance, including bacteria involved in C and N metabolism. Submerged macrophytes favoured the periphytic biofilm and increased sub-superficial carbon and nitrogen amounts, by promoting bacteria involved in their cycles. The shade exerted by the meadows minimized the UVR effects, driving to a community similar to that of the UVR-filtered environment. Therefore, macrophytes, through different mechanisms, can mitigate the harmful effects of UVR in sediment communities. Thus, the conservation of macrophyte meadows in highly vulnerable wetlands becomes crucial in a global change context.

Identifying the character and importance of invertebrates in thawing wetlands is useful, since they are the main food resource for migratory waterfowl during spring. We investigated aquatic invertebrate composition in the spring-thaw and compared it with the summer in wetlands of the Sanjiang Plain, China. NMDS analysis showed that the composition of aquatic invertebrates in the spring-thaw is significantly different from in summer. Aquatic invertebrate diversity (including Shannon–Wiener index; Margalef’s species richness; Pielou’s evenness) was lower in the spring-thaw, and Network analyses indicated that it was a simpler community. Indicator species were different between spring-thaw and summer. The scraper functional feeding group (i.e., snails) dominated both seasons, but especially in the spring-thaw. Snails and other invertebrates such as asellid crustaceans abounded in spring, are rich in both calcium and protein, making them to be an especially important food source for migratory waterfowl. Therefore, the spring-thaw should be a focus when assessing aquatic invertebrate function for waterfowl production.

Changes in dissolved oxygen (DO) within aquatic ecosystems integrate dynamic biological, physical, and chemical processes that control the rate of ecosystem metabolism. Aquatic ecosystem metabolism can be characterized by the diel change in DO changes over time and is expressed as the net aquatic productivity (NAP) based on the balance of gross primary productivity (GPP) and ecosystem respiration (ER). This study investigated aquatic metabolism of dominant emergent and submerged aquatic vegetation (EAV and SAV, respectively) within two treatment flow-ways of Stormwater Treatment Area 2 (STA-2) in the Everglades ecosystem. This study hypothesizes that aquatic metabolism will differ between aquatic vegetation communities with SAV communities having a greater GPP and ER rate than EAV communities driven by biophysical, hydrodynamic, and biogeochemical differences between systems. Aquatic metabolism observed in this study varied spatially (along flow-ways) and temporally (diel to days) controlled by different factors related to biological, physical, and chemical processes. This study suggests that ecosystem metabolism is controlled differently across flow-ways with varying levels of response to loading/transport and water quality resulting in differences in organic matter accumulation, C turnover, and P cycling. The relationship between GPP and TP concentrations could be an indicator of P-removal efficiency and ecosystem function.

Acoustic telemetry is an important tool for assessing the behavioural ecology of aquatic animals, but the performance of receivers can vary spatially and temporally according to changes in environmental gradients. Studies testing detection efficiency and/ or detection range are, therefore, important for data interpretation, although the most thorough range-testing approaches are often costly or impractical, such as the use of fixed sentinel tags. Here, stationary tag data (from study animals that had either died or expelled their tags) provided a substitute for the long-term monitoring of receiver performance in a wetland environment and was complemented by periodic boat-based range testing, with testing of the effects of environmental variables (water temperature, conductivity, transparency, precipitation, wind speed, acoustic noise) on detection efficiency (DE) and detection range (DR). Stationary tag DE was highly variable temporally, the most influential factors being water temperature and precipitation. Transparency was a strong predictor of DR and was dependent on chlorophyll concentration (a surrogate measure of algal density). These results highlight the value of stationary tag data in assessments of acoustic receiver performance. The high seasonal variability in DE and DR emphasises the need for long-term receiver monitoring to enable robust conclusions to be drawn from telemetry data.

Soil moisture remarkably influences soil organic carbon (SOC) decomposition and is one of the key variables in ecological models influencing changes in soil carbon (C) storage. However, the mechanisms determining the impact of soil moisture on SOC decomposition in coastal wetlands are poorly understood. We collected and incubated soil samples from a coastal wetland of the Yellow River Delta, China, to investigate the response of SOC decomposition (the sum of CO2–C and CH4–C) to soil moisture. Soil samples were incubated at 20%, 60%, 100%, 140% and 180% water holding capacity (WHC), respectively. Compared to drought condition (20% WHC), moist (60% and 100% WHC) and flooding (140% and 180% WHC) conditions were observed with significantly higher SOC decomposition, explained by increased soil microbial biomass and altered soil physical parameters (pH and electronic conductivity (EC)). Excluding the effect of drought, we found decreased SOC decomposition with increased microbial biomass in flooding conditions compared to moist conditions. Structural equation modeling analysis showed that SOC decomposition and soil C storage were associated with changes in soil environment and soil microbial biomass resulted from soil moisture variation. This study highlights the importance of soil moisture in soil carbon dynamics, which is enlightening for the evaluation of soil C cycling with a decline of soil moisture under a warmer climate in coastal wetlands.

Global warming-related changes to freshwater ecosystems in Arctic and Subarctic regions have been magnified by nutrient input from increasing waterfowl populations. To gain insight into how these changes might affect ecosystem function, we conducted a mesocosm experiment in the Subarctic by enriching N and P (1 ×, 10 ×, and 20 × treatments) and increasing mean water temperatures ≤ 3°C. We measured responses of two species of larval amphibians, periphyton, and phytoplankton. Wood frog (Rana sylvatica) larvae developed quicker (odds ratio [OR] for 1°C increase = 0.903, 95% CI 0.892–0.912) and were more likely to metamorphose (OR 1.076, 95% CI 0.022–14.73) in warmer waters. Boreal chorus frogs (Pseudacris maculata) also developed quicker with warmer temperatures (OR 0.880, 95% CI 0.860–0.900), despite a non-significant trend toward reduced survival (OR 0.853, 95% CI 0.696–1.039). Periphyton and phytoplankton concentrations increased with nutrient additions, as did size of wood frog metamorphs. Periphyton and phytoplankton did not vary with temperature, but periphyton was limited by tadpole abundance. Our results highlight the potential for non-linear responses to ecosystem change, with species-specific consumer and ecosystem responses that depend on the magnitude of changes.

Lake water levels can be managed in shallow lakes in order to improve water quality and promote aquatic vegetation that presumably benefits waterbirds. We aimed to understand whether waterbird abundance and species richness during fall migrations were positively influenced by managed lake water levels at 32 shallow lakes over 10 years. We conducted annual waterbird surveys that counted 6 million birds and repeatedly measured several in-lake habitat variables. Lakes with water level management had lower water depths, greater water quality and clarity, more submerged aquatic vegetation (SAV), and more wild rice (Zizania palustris L.) compared to unmanaged lakes. Redundancy analysis and regressions revealed that the waterbird community and several waterbird species were positively correlated to water level management and SAV; however, waterbirds were apparently responding principally to abundant SAV regardless of water depth or management. Two presented case studies of turbid-state lakes also highlighted that water level management rehabilitated lake habitat and waterbird use for a few years. We concluded that water level management can be an effective tool for increasing SAV and migrating waterbirds, but noted that large bird communities can also occur on unmanaged, deeper wetlands with existing SAV coverage of > 80%.

Organisms living in intermittent wetlands present adaptations to cope with the inundation-desiccation process. Microcrustaceans are commonly found in intermittent wetlands because they present reproductive strategies able to synchronize with the hydroperiod. To know the dynamic of the microcrustaceans, that inhabit these wetlands of the subtropical coastal plain, which predominate the Pampas biome in Brazil, we analyzed the influence of hydration time and temperature on the hatching of microcrustaceans, comparing in situ and ex situ approaches. We followed hatching 34 days after in situ flooding and tested three temperatures (10, 15, and 20°C) 30 days after laboratory flooding. In both approaches, we classified the hydration time as the beginning, middle, and end of the hydroperiod. We recorded a total of 41 taxa distributed in Cladocera (26 taxa), Ostracoda (8), Copepoda (3), Anostraca (1), and Conchostraca (1). We observed that in situ hydration time was the most important factor for hatching. Ex situ hydration time was also important, but the increase in temperature positively affected the hatching of organisms. We also found that in both approaches, the beginning of hydration time is the most important period for the hatching of microcrustaceans.

Freshwater meiofauna occupies a central role in stream food webs, not always as intermediary but also as top consumers. Consequently, the meiofauna's transient dynamical patterns and turnover are vital to understand its contribution to the overall production and energy flow within benthic freshwater systems. Here, we revise the current methodological procedures used to estimate production in benthic meiofauna, and compare their biomass and production data (a) to other benthic taxa, (b) in different habitats and systems, and (c) at the species level. Given the phyla diversity and when including temporary meiofauna (i.e. small insect larvae), care must be taken in selecting a production method and/or relying on published generation times. A handful of studies demonstrate that meiofaunal production values are well within the range displayed by macrofauna. We show that temperature-adjusted production and biomass of meiofaunal species from lakes, wetlands, and streams display a positive linear relationship with an exponent around 0.9, whereby biomass explains 90% of the variation in production. Further studies on meiofauna production should test the validity of our proposed allometric model for stream ecosystems and, thus, its possible generality.

Fertiliser use in agriculture increases the non-point pollution of waters with nitrogen (N) and phosphorus (P). Wetland buffer zones (WBZs) are wetland ecosystems between agricultural lands and water bodies that protect surface waters from non-point source pollution. We assessed how vegetation harvesting within WBZs impacts their N and P removal efficiency, nutrient uptake by plants and their biomass quality. We surveyed vegetation of a spontaneously rewetted fen along a small river in Poland, and analysed plant biomass, its nutrient contents and nutrient-leaching potential and the water chemistry. Total N removal reached 34–92% and total P removal 17–63%. N removal was positively related to the initial N concentration, regardless of mowing status. We found a high N removal efficiency (92%) in the harvested site. Vegetation of mown sites differed from that of unmown sites by a higher water-leached carbon and P contents in the biomass. We found that vegetation harvesting may stimulate the overall N removal, but may increase potential biomass decomposability, which eases the recycling of plant-incorporated nutrients back to WBZ. Thus, mowing should always be followed by the removal of biomass. Neglecting already mown WBZs may temporarily lower their nutrient removal efficiency due to potentially faster decomposition of plant biomass.

This study investigated macroinvertebrate assemblage composition in relation to the cover of aquatic macrophytes (Schoenoplectus decipiens) for a set of 13 temporary depressional wetlands occurring within a semi-arid environment (Eastern Cape Karoo, South Africa). We hypothesised that invertebrate abundance and taxonomic richness would be higher in wetlands containing aquatic macrophytes than in those lacking them. It was expected that a positive relationship between vegetation cover categories (sparse, moderate and extensive) and invertebrate richness and abundance would be observed. In contrast to expectations, the macroinvertebrate assemblage was not significantly different across the three investigated categories. Non-parametric permutational MANOVA results indicated that the presence/absence of vegetation and wetland surface area had a significant effect on macroinvertebrate assemblage composition. Multivariate regressions (distance-based redundancy analysis) indicated that surface area, dissolved inorganic nitrogen and pelagic chlorophyll a concentration explained significant variation in macroinvertebrate assemblage composition in these wetlands. Overall, the presence or absence of vegetation appears to play a role in structuring the macroinvertebrate assemblages, but no convincing evidence was found for an effect of the vegetation cover gradient (sparse vs moderate vs extensive) on macroinvertebrate assemblages in these temporary wetlands.

Diversion of river waters to adjacent estuaries may occur during wetland restoration, navigation channel development, or storms. We proposed that diversions of nitrogen- and phosphorus-enriched waters from the river to estuarine waters would result in increased phytoplankton biomass and shifts to noxious or harmful algal blooms. We tested this hypothesis by conducting four seasonal microcosm experiments in which Mississippi River water was mixed at different volume ratios with ambient estuarine waters of three lakes in the upper Barataria Basin, Louisiana, USA. These lakes included two brackish lakes that were in the path of diverted Mississippi River water, and a freshwater lake that was not. The results from the 3- to 8-day experiments yielded a predictable increase in phytoplankton biomass related to nutrient additions from Mississippi River water. The subsequent decreases in the dissolved nitrate + nitrite, soluble reactive phosphorus, and silicate concentrations explained 76 to 86% of the increase in chlorophyll a concentrations in the microcosms. Our experiments showed that cyanobacteria can successfully compete with diatoms for N and P resources even under non-limiting Si conditions and that toxic cyanobacteria densities can increase to bloom levels with increased Mississippi River water inputs to ambient waters in the microcosms. Diversions of Mississippi River into adjacent estuarine waters should be considered in relation to expected and, possibly, unexpected changes in phytoplankton communities to the receiving waters and coastal ecosystems.

Predicting the potential distribution of invaders is informative for pre-emptive policy or management decisions and identifying suitable areas for establishment of new populations. Temporal projection of potential distributions is complicated by the magnitude and pace of changing climate, which could alter suitability under future conditions. The wetland invader, Butomus umbellatus is widespread in the northern US and southern Canada, but potential for invasion into new areas is unknown. We used environmental niche modeling to address our hypotheses for B. umbellatus: (1) a climatic niche shift has occurred between native and invasive ranges, (2) suitable areas in the invaded range have been colonized, and (3) climate suitability is likely to change in future climates. Environmental niche is highly conserved and stable (0.761) between ranges of B. umbellatus. Ensemble forecast revealed that nearly 60% of the invaded range is climatically suitable, including large areas in both the southern US and Alaska. Under future climates, there is a net decrease of suitable area, although two of three global circulation models predict range expansion of this species across gas emission scenarios. Given that the area is already invaded or at risk for future invasion, development of geographically adaptable long-term management strategies is prudent.

The global offtake of wild animals is valued at US$400 billion annually and supports the livelihoods of 15% of the global population. Wetlands are amongst the most important ecosystems globally, but offtake may represent a substantial pressure. This study assessed the availability of information and evaluated the offtake of wild animals from wetlands by focussing on fish and waterbirds. A literature search identified 2726 studies on wetland offtake. Scoping of these resulted in 82 studies that contained quantitative information on fish or waterbird offtake. Fishing offtake statistics for inland waters are collated nationally by some governments, but other sources of information are few. Reporting of fish offtake for species or across scales was constrained by insufficient detail, even in relatively well-documented countries such as Bangladesh. Although government hunting statistics from Europe and North America were available, there was little waterbird data from less economically developed countries. The case of Canada indicated that the species richness and composition of waterbirds taken varied between indigenous subsistence and recreational hunting communities. Hidden (unquantified) offtake, of both fish and waterbirds, hinders obtaining precise data for offtake, which may threaten the conservation of species and the sustainability of wetland ecosystems.

While dissolved organic matter (DOM) is an important indicator of water quality, land use and land cover (LULC) of watersheds define the source, quality, and quantity of DOM delivered to a waterbody. This study examined the influence of various LULC classes in the spatial distribution of DOM in 41 lakes across the state of Mississippi. To scale the influence of LULC classes on DOM distribution, we have classified 41 lakes into five clusters based on DOM compositions determined by parallel factor analysis. Four major DOM compositions including terrestrial humic-like (C1), microbial humic-like (C2), soil-derived humic-like (C3), and tryptophan-like or tyrosine like (C4) components were identified. Higher amounts of terrestrial humic-like and soil-derived humic-like DOM compositions were observed in lakes within watersheds dominated by forested, barren, wetlands, or agricultural areas with exposed unconsolidated soil. Higher amounts of microbial humic-like composition were observed in lakes surrounded by hay/pasture, rangeland, and urbanized areas. Additionally, protein-like DOM and ammonia were more enriched in larger lakes, indicating the influences of photochemical reactions. High amounts of forested areas and higher concentrations of terrestrial humic-like DOM composition were identified in all lakes suggesting forested areas in the watershed as the principal source of DOM in Mississippi lakes.

Mangrove forest encroachment into coastal marsh habitats has been described in subtropical regions worldwide in recent decades. To better understand how soil processes may influence vegetation change, we studied soil surface elevation change, accretion rates, and soil subsurface change across a coastal salinity gradient in Florida, USA, an area with documented mangrove encroachment into saline marshes. Our aim was to identify if variations in the soil variables studied exist and to document any associated vegetation shifts. We used surface elevation tables and marker horizons to document the soil variables over 5 years in a mangrove-to-marsh transition zone or ecotone. Study sites were located in three marsh types (brackish, salt, and transition) and in riverine mangrove forests. Mangrove forest sites had significantly higher accretion rates than marsh sites and were the only locations where elevation gain occurred. Significant loss in surface elevation occurred at transition and salt marsh sites. Transition marshes, which had a significantly higher rate of shallow subsidence compared to other wetland types, appear to be most vulnerable to submergence or to a shift to mangrove forest. Submergence can result in herbaceous vegetation mortality and conversion to open water, with severe implications to the quantity and quality of wetland services provided.

Simplification of communities is a common consequence of anthropogenic modification. However, the prevalence and mechanisms of biotic homogenization among wetland systems require further examination. Biota of wetlands in the North American Prairie Pothole Region are adapted to high spatial and temporal variability in ponded-water duration and salinity. Recent climate change, however, has resulted in decreased hydrologic variability. Land-use changes have exacerbated this loss of variability. We used aquatic-macroinvertebrate data from 16 prairie-pothole wetlands sampled between 1992 and 2015 to explore homogenization of wetland communities. Macroinvertebrate communities of small wetlands that continued to cycle between wet and dry phases experienced greater turnover and supported unique taxa compared to larger wetlands that shifted towards less dynamic permanently ponded, lake-like regimes. Temporal turnover in beta-diversity was lowest in these permanently ponded wetlands. Additionally, wetlands that shifted to permanently ponded regimes also experienced a shift from palustrine to lacustrine communities. While increased pond permanence can increase species and overall beta-diversity in local areas previously lacking lake communities, homogenization of wetland communities at a larger, landscape scale can result in an overall loss of biodiversity as the diverse communities of many wetland systems become increasingly similar to those of lakes.

Water-level fluctuations are common abiotic stresses influencing growth and physiological processes of wetland plants. Nonetheless, little is known about plant eco-physiological responses and growth strategy under multi-hydrological processes. Carex schmidtii was grown under the conditions with interaction of initial water-level depth (DW) and water-level amplitude (AW). Dynamics of plant eco-physiological traits and growth strategy were investigated continuously during the entire growth stages. Results indicated that leaf morphology was significantly affected by DW and lasted time, and leaf width was sensitive to AW. The SLA and LDMC of C. schmidtii varied significantly at different lased time, and their relationships indicated the trade-off in leaves between matter production and nutrient conservation. Increasing DW inhibited matter production of C. schmidtii in early growth stage, but increased nutrient conservation in late growth stage. However, increasing AW contributed to both increase of matter production and nutrient conservation of C. schmidtii. The photosynthetic pigments of C. schmidtii are relatively sensitive to DW, AW and their interaction. Slowing down water-level fluctuations and appropriate water management in the key growth stage will assist with the adaption of Carex schmidtii. The findings provide invaluable supporting information for the management and conservation of C. schmidtii tussock wetlands.

Wetland restoration with the goal of restoring natural ecosystem functioning is receiving attention worldwide. Mesopotamian marshes, which had been suffering from a water shortage since the 1970s, were reflooded in 2003, and have been assessed to be at least partly recovered from certain physical, chemical, or biological point of views. Our focus was in the phytoplankton community and through that in the aquatic food web in order to understand the recovery of the normal functioning of the marsh ecosystem. We sampled eight separate marshes that formed a continuum from a wet to a desertified area during the desiccation period. Three to five years after the reflooding, we measured the biomass, diversity and structure of the phytoplankton community and its controlling physical and chemical factors 11 times irregularly. In most cases, the dried and reflooded marshes had a less diverse phytoplankton community than the marsh that had never dried up. The community structure of the latter differed from all dried marshes and was the most divergent from the marshes that had been succumbed to desertification and were situated farthest away from the freshwater rivers. We conclude that the aquatic food web and thus the natural wetland ecosystem functioning recover more slowly than single physical or chemical factors. Cyanobacteria species abundance may be of concern from a management point of view for a long period of time.

Climate change has been associated with alterations in temperature and precipitation regimes. Increased temperatures can change the structure and function of aquatic communities through both biotic and abiotic interactions. Many warming experiments have been conducted in permanent freshwater systems, but few in temporary freshwater systems that are dependent on precipitation patterns. Temporary aquatic communities are influenced by hydro-regime characteristics such as the hydroperiod length, magnitude, frequency, and timing of inundation, which may interact with temperature changes. Here, we used mesocosms to test for the effects of warming and inundation timing on the community composition of California vernal pools. California vernal pools are temporary wetlands, which provide habitat for many endemic and endangered species during the aquatic phase. Total species abundance was higher in both warm and late inundation treatments, while higher species richness levels in late treatments were due to the rapid emergence and colonization of species compared to early treatments. Heating increased the abundance of ubiquitous passive and active dispersers, including mosquitos, but decreased the abundance of vernal pool endemic passive dispersers. We also found that significant interactive effects between warming and inundation timing led to differences in community composition. These findings suggest that vernal pool endemic passive disperser species may decline due to increased temperatures and later inundation; however, the extent of such risk will likely be influenced by species-specific life-history traits such as bet-hedging strategies. Conservation efforts should work to identify the species most at risk to a changing climate.

The green alga Micrasterias arcuata is commonly found in the periphyton of slightly acidic ponds and wet grasslands of central Brazil. We used M. arcuata complex as a model system for evaluation of the following questions: (a) Is there any relation between morphological characteristics of M. arcuata populations and ecological features of the sites? (b) Can the observed plasticity be explained by an allometric scaling relationship leading to differential distribution of the morphotypes among different habitats (ponds and wet grasslands)? (c) Is there any surface-to-volume ratio (S:V) scaling that can be explained as adaptive response to ecological characteristics of sites? A total of 50 individual semicells of M. arcuata were photographed from ten natural populations, yielding a 500 objects dataset. Individuals from ponds were morphologically different from the ones in the wet grasslands, presenting bigger cells, but also with higher S:V. The eventual surface loss usually associated to bigger sizes was compensated by more elaborated cells, yielding positive allometry of the S:V ratio scaling. Our data support the idea that such differences in cell morphology are an adaptation to environmental conditions, especially desiccation stress favoring cells with lower S:V and higher isoperimetric quotient in the wet grasslands.

Invertebrates are crucially important components of wetland ecosystems. Their assemblages have been well described for wetlands in many parts of the world, but not for Asia. We sampled macroinvertebrates from 39 freshwater wetlands across Northeastern China. Wetland characteristics included permanent and temporary hydroperiods, and floodplain and palustrine settings. We determined which taxa dominated wetlands of the region, and assessed patterns of dissimilarity among this set of wetlands. We then contrasted the 39 wetlands from Northeastern China, with a previously published data set of macroinvertebrate assemblages from 447 freshwater wetlands worldwide, to frame the macroinvertebrate assemblages in Northeastern China wetlands to other wetlands from across the globe. Our data set is the only comprehensive description of aquatic macroinvertebrates from freshwater wetlands in China, and one of the few known data sets for the continent of Asia. We found that macroinvertebrate taxonomic composition in wetlands from Northeastern China shared many similarities in assemblage to wetlands from other cool, moist climates in North America and Europe. Northeastern China wetlands had some unique characteristics, most notably an unusual preponderance of non-pulmonate snail families. The prevalence of these snails makes wetlands of Northeastern China ecologically unique from wetlands elsewhere, with consequences for management and assessment.

Studies about beta diversity and environmental heterogeneity have shown that the strength of the environmental filtering effect may decrease with the increasing scale. These empirical results have related eutrophic aquatic environments to higher values of beta diversity, but never to dissimilarity of species and functional traits of periphytic algae. We tested the hypotheses that periphytic algae have higher dissimilarity of both species and functional traits in eutrophic environments, and that these dissimilarities are related to environmental dissimilarity. To this end, we used richness, density, and four functional traits of periphytic algae and local limnological data from wetlands in the Brazilian savanna (Cerrado). We analyzed the beta diversity and the relationship of species and functional dissimilarities with the environmental dissimilarity and geographic distances. Our hypothesis was confirmed for functional traits dissimilarity and for the importance of the environmental dissimilarity for both species and functional beta diversity. The cultural eutrophication led to a functional homogenization in urban wetlands, which indicates the establishment of species with similar ecological requirements, and consequently, similar ‘roles’ in the ecosystem, and also that sensitive species may have been replaced by tolerant species, leading to declining biodiversity.

The Neotropical otter, Lontra longicaudis, is an opportunistic species usually found in freshwater habitats; however, it has also been recorded in environments with marine influence (e.g., islands and estuaries). Thus, we hypothesized that the isotopic niche of the Neotropical otter is wider in a coastal island (Santa Catarina Island—SC) and in a river basin composed of a series of lagoons and an estuary (Tramandai River Basin—RS) than in a wetland (Taim Wetland—RS) due a greater occurrence of the species in the marine environment of the former areas. In order to test this hypothesis, the stable isotope ratios of carbon and nitrogen in otter samples from different regions were analyzed. Long-term isotopic niche of otters was wider in Santa Catarina Island, followed by Taim Wetland, and Lagunar System of Tramandai. Therefore, we conclude that otters from Santa Catarina Island and Taim Wetland use both freshwater and marine environments as foraging areas. The sampled otters of the Lagunar System of Tramandai, on the other hand, used predominantly freshwater environments to forage. The differences found among the otters from different regions are probably related to a variety of factors, such as landscape characteristics, sampling and prey availability.

The presence of shallow lakes (SL) is typical of large floodplains with wetland landscapes. By taking into account the dynamic behavior of SL, multitemporal remote sensing data can be used to delineate and monitor water extent and SL cover types. The aim of this study was to analyze the spatial and temporal patterns of SL coverages related to flood pulses in the Lower Parana River floodplain. SL were delineated with a frequency analysis over a 1987–2015 time series of the Normalized Difference Vegetation Index derived from Landsat 5-TM and 8-OLI data. A total of 303 SL were identified (22% of the study area). Most of the SL were small, only eight were larger than 1.5 km2 (66% of the total SL area). Five dominant SL cover types were identified by using multitemporal Landsat data. The dynamics of these cover types were analyzed along seven flood pulses and we described six typical temporal patterns that repeated and characterized most of the SL areas. Vegetation quickly recovered after floods, except for extreme floods related to the occurrence of El Nino-Southern Oscillation events. The historical Landsat data turn out to be valuable tools for the reconstructions of historical processes in floodplains of large rivers.