Wetland Species Research Articles

Factors Influencing Wood Stork Prey Biomass in Roadside Created Wetlands

Infrastructure associated with a growing human population has disrupted hydrologic patterns and impacted wetland species such as Mycteria americana (Wood Stork). However, storks are commonly observed foraging along roadways in created wetlands and nesting in urban environments, suggesting that these areas may provide novel foraging habitat. We sampled both permanently inundated and ephemeral created wetlands to determine which hydrologic, vegetative, and physical attributes are associated with high stork prey biomass. Factors influencing stork prey biomass differed between permanently inundated and ephemeral created wetlands. Landscape-level vegetation and the physical properties of a wetland were more influential in permanently inundated ponds and canals whereas local-scale vegetation and hydrologic conditions were most influential in ephemeral ponds and swales. Furthermore, aquatic fauna biomass in permanently inundated created wetlands was 9x greater than in natural wetlands, and aquatic fauna biomass was even greater in the urban landscape. These findings suggest that created wetlands may serve as additional foraging habitat for Wood Storks. As natural wetlands continue to be lost and managed for human purposes, created wetlands should be considered in conservation plans and future management decisions for Wood Storks and other wading birds given their ability to produce wading bird prey.

Geographic Variation in Survival and Growth of Atlantic White-Cedar (Chamaecyparis Thyoides [L.] B.S.P.): Implications for Artificial Regeneration of a Declining Species

Abstract Atlantic white-cedar (Chamaecyparis thyoides [L.] B.S.P.; AWC), a wetland tree species native to the eastern United States, is declining rangewide. This decline has stimulated interest in restoring AWC in parts of its range. However, restoration could benefit from more research on this species, especially that focus on where to source seedlings for artificial reforestation. This study presents results out to years 18–20 from a southern New Jersey common garden established in the early 2000s as part of the first rangewide provenance planting of AWC. The goal of this research was to expand our understanding of intraspecific variation in AWC linked to the geographic origin of genetic sources. Results indicated that genotype performance was linked to their geographic origin and that local sources were among the top performers when taking all metrics into consideration (e.g., survival, height, basal area). Top-performing provenances were sourced within plus or minus two decimal degrees latitude of the planting site. Although local sources remain suitable for artificial regeneration of this species in southern New Jersey, nearby southern sources could be deployed to achieve out-planting success and conservation of this imperiled species in a warming climate. We hope this work will inform AWC restoration efforts and bring visibility to this declining wetland species.

Habitat seasonal competition and coexistence of typical wetland species in the Yellow Sea-Bohai Gulf Natural Heritage Site

The Natural Heritage Site of the Coast of Yellow Sea-Bohai Gulf of China plays a prominent role in the conservation of global biodiversity. However, with the increase in the number of species inhabiting here, the problem of competition in the habitat space of species within the heritage site has gradually emerged, which has become an important bottleneck restricting the sustainable development of the heritage site. Therefore, this study selected the typical wetland wildlife in this area, red crowned crane (Grus japonensis) and Chinese water deer (Hydropotes inermis), as the study objects. This study used their continuous GPS tracking data to reveal the seasonal laws of habitat selection and suitability of two typical wetland species, and analyze their spatial competition and coexistence relationship. The study results showed that the distribution of home range of the crane and the deer in spring and summer was significantly larger than that in autumn and winter. The area of the sub and most suitable area of the deer in spring was larger than that of the crane. In autumn and winter, the area of the sub and most suitable areas for the deer was small, while the area of the most suitable area for the crane was more than 50 hm2. Except in spring, the two species kept a certain distance from each other in other seasons, and their habitat selection was stable. The optimal threshold range of the crane for D_ree variable was 0–202 m in spring and 0–1200 m in summer and autumn. The deer was affected by vegetation factors in the four seasons. The threshold range of D_ree variable in spring, autumn and winter was 0–80 m, the suitable vegetation height of the deer was 2.31–2.92 m. Finally, this study proposed a refined management pattern of habitat with multiple species coexist.

Ecosystem Services and Disservices of Bay-Delta Primary Producers: How Plants and Algae Affect Ecosystems and Respond to Management of the Estuary and Its Watershed

The Sacramento–San Joaquin Delta (Delta) is a case-study of the Anthropocene “great accelerations,” with exponentially increasing temperatures and sea level over time, leading to rapid change in other ecosystem components. In nearly all these interconnected changes and across scales, primary producers play a major role, with diverse effects that mitigate or exacerbate rapid change induced by climate or other human-driven perturbations. Through this anthropocentric lens, primary producers can be viewed as performing numerous ecosystem services—which ultimately benefit humans—as well as ecosystem disservices, which have negative effects on human communities. For example, through carbon sequestration, wetlands can perform ecosystem services of mitigating warming at a global scale and combating relative sea-level rise at a local scale, while generating food that supports regional food webs and fisheries. On the other hand, invasive aquatic vegetation (IAV) can trap sediment before it reaches wetlands, exacerbating local subsidence and relative sea-level rise while incurring great costs to recreation, fishing, and agencies tasked with its control. Effectively managing these ecosystem services and disservices requires understanding of how they are connected. For example, wetland restoration often creates opportunities for IAV, which may inhibit sediment deposition on the wetland and outcompete native species. As the Delta science community works toward a more integrative understanding of how different components of the Delta interact as a whole and across scales, the pervasive effects of the ecosystem services and disservices of primary producers serve as foundational knowledge. In this topically themed edition of State of Bay-Delta Science, we review these effects. Individual chapters focus on the historical ecology of the primary productivity of aquatic vegetation, the ecology and control of invasive aquatic vegetation, harmful algal blooms, carbon sequestration and subsidence reversal by wetlands, and remote sensing methods for quantifying the ecosystem services and disservices of Delta primary producers.

Occurrenceand characteristics of microplastics in benthic species from mangrove wetlands of Hainan, South China

Microplastics (MPs) are emerging contaminants that pose a global threat to the environment. Mangrove ecosystems, which contribute to biogeochemical cycles, are vulnerable to various anthropogenic disturbances and chemical pollutants. In this study, the abundance and the characteristics of MPs were investigated in 10 species of benthic organisms, including crabs, bivalves, and snails, from seven typical mangrove distribution areas, with a total of 15 sampling sites in Hainan, South China. The abundance of MPs in each sampling site ranged between 0.83 ± 1.32 and 12.00 ± 0.00 items/individual, with an average of 3.90 ± 3.31 items/individual, while the abundance of MPs varied between 0.17 and 2.00 items/individual for the different species. Fibers (80.13%) were the most abundant MPs, most of the MPs were brown (37.18%) or blue (26.64%), and more than 80% were small-sized plastic (<2 mm). Raman analysis showed that polypropylene (94.44%) was the most dominant type of polymer. In addition, crabs (with an average abundance of 1.10 ± 0.59 items/individual) showed a higher potential for accumulating MPs than the other species investigated in the present study. This study shows that MPs are widely distributed throughout benthic species in the mangrove wetlands of Hainan.

Bison influences on composition and diversity of riparian plant communities in Yellowstone National Park

AbstractRiparian zones are among the most biologically diverse ecosystems in the Intermountain West, USA, and provide valuable ecosystem services, including high rates of biotic productivity, nutrient processing, and carbon storage. Thus, their sustainability is a high priority for land managers. Large ungulates affect composition and structure of riparian/stream ecosystems through herbivory and physical effects, via trailing and trampling. Bison (Bison bison) in Yellowstone National Park (YNP) have been characterized as “ecosystem engineers” because of their demonstrated effects on phenology, aboveground productivity of grasses, and woody vegetation structure. Bison have greatly increased in numbers during the last two decades and spend large periods of time in the broad open floodplains of the Northern Range of the Park, where they are hypothesized to have multiple effects on plant species composition and diversity. We sampled indicators of bison use as well as riparian vegetation composition, diversity, and structure along eight headwater streams within YNP's Northern Range. Total fecal density ranged from 333 to 1833 fecal chips and/or piles/ha, stubble heights ranged from 7 to 49 cm, and streambank disturbance ranged from 9% to 62%. High levels of bison use were positively correlated with exotic species dominance and negatively correlated with species richness, native species diversity, willow (Salix spp.) cover, and wetland species dominance. At three sites, the intensity of bison use exceeded recommended utilization thresholds to avoid degradation of streams and riparian zones on public lands. The influences of large herbivores, principally bison, on vegetation composition and structure suggest the cumulative effects of the current densities on the Northern Range are contributing to biotic impoverishment, representing the loss of ecosystem services that are provided by native riparian plant communities. In addition, contemporary levels of bison use may be exacerbating climate change effects as observed through ungulate‐related shifts in composition toward plant assemblages adapted to warmer and drier conditions. However, the resilience of native riparian vegetation suggests that sites currently heavily utilized by bison would have the potential for recovery with a reduction in pressure by this herbivore.

Mapping groundwater discharge seeps by thermal UAS imaging on a wetland restoration site

One of the key metrics for the effectiveness of wetland restoration is whether a restored wetland behaves hydrologically like a natural wetland. Restoration is designed to increase the water residence time on the surface of the site in order to capture and process nutrients, mitigate the impact of local flooding and drought, and provide a habitat for wetland species abundance and biodiversity. Quantifying the change in groundwater presence at the wetland’s surface will inform future freshwater wetland restorations across New England. The ability to produce a comprehensive map of the locations of groundwater discharge over a large area has the potential to provide insight into restoration practice, its success, and its effects on individual seeps over time. Identification, mapping, and measurement of groundwater discharge sites have long been a challenge, but new methodologies are developing with the advances in unmanned aerial systems (UAS). This study uses a UAS-mounted thermal infrared camera to map groundwater seeps on a 25-ha (62-acre) site in Plymouth, Massachusetts, before and after it underwent restoration to a freshwater wetland. Using the thermal map, we located and quantified the spatial extent that of groundwater seeps pre-restoration and the changes after restoration. The location and size of these seeps show that existing groundwater seeps remained immobile through restoration, but their surface expression grew, indicating that restoration removed barriers to surface expression and successfully increased residence time. This analysis using a thermal camera-enabled UAS allows for a temporal comparison over large spatial scales and provides insight into restoration impacts to groundwater expression on the surface of post-agricultural wetland sites.

DNA barcoding detects resurrected taxon Giuris laglaizei (Sauvage 1880) in Sulawesi, Indonesia: Bolano Sau Lake payangka phylogeny, phenotypic characters and implications for Giuris spp. conservation

Background: The freshwater ichthyofauna of Wallacea is diverse and understudied. A baseline survey of Bolano Sau Lake in Parigi Moutong District, Central Sulawesi Province, Indonesia in 2019 found an eleotrid goby (local name payangka) with characters conforming to the genus Giuris, long considered monophyletic as G. margaritacea/G. margaritaceus but recently found to comprise at least eight species. This study focused on the molecular (DNA barcoding) identification and phenotypic characters of the payangka. Methods: Payangka samples were collected from August to December 2019 in collaboration with local fishermen, weighed and measured, and preserved in 75% ethanol. Length, weight, sex (n=111) and 17 morphometric characters/six meristic counts (n=42) were recorded. DNA barcoding was performed on a fin clipping preserved in 96% ethanol. Homologous nucleotide sequences were obtained from public (GenBank and BOLD) databases, analysis conducted in MEGA X, and phylogenetic trees edited in the Interactive Tree of Life (iToL). Results: Within the deeply divided Giuris clade, the payangka sequence resolved into a sub-clade identified as Giuris laglaizei (Sauvage 1880), a recently resurrected taxon, based on a sequence provided by Philippe Keith. The length-weight relationship (L = 0.0087∙W3.162) indicated mildly allometric positive growth. Size distribution differed significantly between male and female fish with significantly larger mean size of males (13.56 cm) than females (11.62 cm). The meristic formula was: D VI-I,8 A I,8 P 13 V I,5 C15. Phylogenetic analysis indicated four Giuris species in wetlands around Tomini Bay and five in Sulawesi. Conclusions: This first record of G. laglaizei in Indonesia advances knowledge of Wallacean and Indo-Pacific Gobiiformes biogeography and highlights the need for a revision of the conservation status of the taxa currently grouped under Giuris margaritacea/G. margaritaceus in the IUCN Red List and FishBase databases. The data will inform biodiversity and fisheries management at local and regional levels.

Wetlands in the Pleistocene Steppe-Tundra Landscapes of Beringia, Their Insects, and the Role of Aeolian Sedimentation

Analysis of the database of Beringian subfossil insect assemblages showed a relatively low role of aquatic, riparian, and wetland species of insects with hard exoskeleton in the Pleistocene communities and an increase in their proportions and taxonomic diversity in the Holocene. Aquatic insects were represented in all types of geological deposits and in some paleosols, but their proportions varied in different depositional environments. Poor representation of aquatic insects and a lack of freshwater invertebrates in the Late Pleistocene ice-rich deposits of Beringia called Siberian Yedoma or Yukon Muck attest to the predominantly aeolian origin of this phenomenon.

Responses of key root traits in the genus Oryza to soil flooding mimicked by stagnant, deoxygenated nutrient solution.

Excess water can induce flooding stress resulting in yield loss, even in wetland crops such as rice (Oryza). However, traits from species of wild Oryza have already been used to improve tolerance to abiotic stress in cultivated rice. This study aimed to establish root responses to sudden soil flooding among eight wild relatives of rice with different habitat preferences benchmarked against three genotypes of O. sativa. Plants were raised hydroponically, mimicking drained or flooded soils, to assess the plasticity of adventitious roots. Traits included were apparent permeance (PA) to O2 of the outer part of the roots, radial water loss, tissue porosity, apoplastic barriers in the exodermis, and root anatomical traits. These were analysed using a plasticity index and hierarchical clustering based on principal component analysis. For example, O. brachyantha, a wetland species, possessed very low tissue porosity compared with other wetland species, whereas dryland species O. latifolia and O. granulata exhibited significantly lower plasticity compared with wetland species and clustered in their own group. Most species clustered according to growing conditions based on PA, radial water loss, root porosity, and key anatomical traits, indicating strong anatomical and physiological responses to sudden soil flooding.

Identification of Wetland Conservation Gaps in Rapidly Urbanizing Areas: A Case Study in Zhengzhou, China

Exploring protected area (PA) siting from a biodiversity perspective is critical in mitigating human impacts on ecosystems. This paper used the MaxEnt model to predict the geographic distribution patterns of wetland species in Zhengzhou and the environmental factors affecting species’ habitat selection. Environmental variables were screened by correlation analysis to avoid affecting the prediction results due to overfitting of the model. The AUC value of the training set of the model ROC curve was above 0.8, and the prediction accuracy was high. The prediction results showed that the only nature reserve in Zhengzhou, Yellow River Wetland Nature Reserve, currently covers only 10.25% of the total area of the high suitability areas for plants and 17.54% of the high suitability habitat areas for waterfowl in the whole area of Zhengzhou. The potential suitability areas of wetland species outside the reserve can provide a basis for site selection for wetland conservation planning in Zhengzhou. It was found that the geographic distribution of wetland species in Zhengzhou is constrained by the distribution of water bodies, bioclimatic variables, land cover, and population density.

Coastal Melaleuca wetlands under future climate and sea-level rise scenarios in the Mekong Delta, Vietnam: vulnerability and conservation

Melaleuca wetland ecosystems play crucial roles in ecology and human livelihood, yet the ecosystems are vulnerable to climate change and relative sea-level rise (SLR) impacts. Documents and research on climate change and SLR impacts on coastal Melaleuca wetlands in the Mekong Delta, Vietnam, are currently limited. Therefore, the present study aimed to identify changes in habitat suitability for a coastal Melaleuca wetland species in response to different future climate change and SLR scenarios, in the West Sea of the Mekong Delta, with the aid of an ensemble species distribution model (SDM) and the Sea Level Affecting Marshes Model (SLAMM). Melaleuca species occurrence records, bioclimatic and eco-physiological variables were utilized to predict potential distribution of the species in response to current and future climate scenarios (i.e. RCP4.5 and 8.5) for the year 2070. Wetland maps for 2020, a digital elevation model (DEM) and localized site-specific parameters (i.e. historic trend of SLR, erosion, subsidence and overwash) were utilized as input data for SLAMM to simulate spatial distribution of Melaleuca/forested wetlands under the two SLR scenarios. The final habitat suitability for the Melaleuca wetland species was identified based on these two resultant datasets, climatic suitability and spatial distribution of the wetlands. Simulated results suggested mean losses in suitable habitat of 29.8% and 58.7% for stable and subsidence scenarios, respectively, for the year 2070 in comparison to the baseline scenario. SLR combined with considerable subsidence rate was suggested as one of the main drivers responsible for the habitat suitability loss. The findings obtained from the current work are useful sources for planning conservation areas for the Melaleuca wetlands, to protect and preserve the ecosystems and their important services under future climate and SLR scenarios.

Recruitment of Melaleuca quinquenervia (Myrtaceae) in the fringing forests of the Myall Lakes, NSW, Australia

Context Melaleuca quinquenervia is a widespread, keystone species of eastern Australian coastal forested wetlands. Populations of M. quinquenervia in the fringes of Myall Lakes, New South Wales, Australia exhibit low numbers of juveniles, infrequent recruitment and a dominance of mature individuals, raising concerns about stand replacement from conservation managers. In contrast, M. quinquenervia often recruits in large numbers and is highly invasive in wetlands around the world. Aims To explore factors that limit recruitment of M. quinquenervia within its native range. Methods Field deployed seed traps; soil-core sampling; a burial longevity trial and depth of emergence experiment; laboratory temperature, salinity and light germination experiments; a transplantation experiment; monitoring of field germination; and a litter/leachate experiment. Key results Low seed viability (5–26%) is offset by high canopy seed loads (250 000 to 120 million seeds per tree) released continuously throughout the year with a peak fall in summer (2000 to 5000 viable seeds per m2 per month), coinciding with optimal germination temperatures. Seedling emergence is reduced below 5 mm soil depth, there is a very low soil seedbank reserve, and germination is light-dependant. M. quinquenervia exhibited reduced germination percentage and rate as well as reduced survival of seedlings at salinities higher than 15 dS m−1 EC (electrical conductivity). The most favourable sites for seedling establishment are permanently moist with low salinity, protected from wave action via sedge vegetation, and sheltered from prevailing winds. There is an inhibitory effect of Casuarina leachate on germination. Conclusions Germination in the field is episodic, and tied to specific environmental conditions. Highest losses occur at the seedling establishment phase. Implications Future research avenues and management recommendations are provided.

Impact assessment of Eurasian beaver reintroduction on riparian phytocenosis of the Raifa forest in Volga-Kama Nature Reserve

Statistically significant changes in microclimatic environmental factors under the influence of the activity of the European beaver in the territory of the Raifa section of the Volga-Kama Nature Reserve were revealed. The influence of the beaver reintroduction factor on the change in the moisture and illumination regimes of habitats, the richness of soils with nitrogen, the acidity and salt regime of soils has been established. In the conditions of fodder and construction activities of the beaver, an increase in the proportion of groups of aquatic, wetland and boreal plant species was noted, as well as the expansive nature of the change in their activity. There was a decrease in the activity of the distribution of ruderal species in the conditions of beaver activity. Based on phytoindication analysis, it has been shown that the reintroduction of the beaver into the water bodies of the Raifa section of the Volga-Kama Reserve is responsible for maintaining the necessary microclimatic conditions to preserve the natural boreal communities.

Metabolite profiling of leaves of three <i>Epilobium</i> species

BACKGROUND: The ability of plants to adapt to oxygen deficiency is associated with the presence of various adaptations, many of which are mediated by significant changes of metabolism. These changes allow resistant wetland plants to grow even in oxygen-deficient environment.
 AIM: The aim of the study was to carry out metabolic profiling of the leaves of the wetland species Epilobium palustre and Epilobium hirsutum, and the mesophyte species Epilobium angustifolium in order to identify the most characteristic metabolome traits of hypoxia-resistant plants.
 MATERIALS AND METHODS: Metabolite profiling was performed by GC-MS. Statistical analysis of metabolomics data was processed using R 4.2.1 Funny-Looking Kid.
 RESULTS: The resulting profile included about 360 compounds. 70 of these were identified and 50 compounds were determined to a class. Sugars (64) were the most widely represented in the obtained profiles. 16 amino and 20 carboxylic acids, lipids and secondary compounds have been identified. Significant differences were revealed between the profiles of leaf metabolomes of mesophyte E. angustifolium and hydrophytes E. hirsutum and E. palustre. The mesophyte was characterized by high levels of sugars. The metabolomes of wetland Epilobium species practically did not differ from each other and were characterized by the accumulation of amino acids, including GABA shunt intermediates, dicarboxylic acids of the Krebs cycle, and metabolites of glycolysis and lactic acid fermentation, which reflects the stimulation of anaerobic respiration, nitrogen metabolism, and alternative pathways of NAD(P)H reoxidation in wetland plants.
 CONCLUSIONS: Traits of metabolic profiles detected in hydrophyte Epilobium species can be used to assess the degree of plant resistance to oxygen deficiency.

Effects of emergent plants on soil carbon-fixation and denitrification processes in freshwater and brackish wetlands in a watershed in northern China

Plants could affect wetland ecosystem functions by influencing the carbon and nitrogen cycles driven by microorganisms. However, the underlying mechanisms associated with CO2-fixation rate (CFR) by autotrophic microbes and denitrification rate (DR) in relation to wetland emergent plants remain unclear. In this study, we conducted a field experiment to analyze the effects of emergent plants on the activities and community characteristics of CO2-fixing autotrophic bacteria and denitrifying bacteria in two types of wetlands in a lake basin: freshwater and brackish water. We found that the effects of emergent plants on CFR and DR differed between freshwater and brackish wetlands. Compared to freshwater wetland, brackish wetland exhibited higher CFR in the rhizosphere, probably due to the abundance of organic carbon conducive to facultative autotrophic bacteria. However, the lower rhizosphere DR in brackish wetland compared to that in freshwater wetland was due to the salt stress. In both freshwater and brackish wetlands, rhizosphere soil increased CFR and DR. The microbial communities associated with them were distinct from those in non-rhizosphere. Besides, neutral-based processes governed the assembly of these bacterial communities, while the rhizosphere showed more prominent dominance of niche-based processes than non-rhizosphere. Statistical analyses revealed that soil organic carbon and root exudates jointly drove the differences in the metabolic activities and composition of CO2-fixation- and denitrification-associated microbial communities between rhizosphere and non-rhizosphere. Overall, our findings suggest that the organic carbon released by plants through root exudates and plant litter is vital for promoting wetland soil carbon-fixation and denitrification and alleviating the detrimental effects of salinity on denitrification. This study provides valuable information for the conservation of CO2-fixation and nitrogen removal with suitable plant species in wetlands.

Estimating fractional cover of saltmarsh vegetation species in coastal wetlands in the Yellow River Delta, China using ensemble learning model

Saltmarshes in coastal wetlands provide important ecosystem services. Satellite remote sensing has been widely used for mapping and classification of saltmarsh vegetation, however, medium-spatial-resolution satellite datasets such as Landsat-series imagery may induce mixed pixel problems over saltmarsh landscapes which are spatially heterogeneous. Sub-pixel fractional cover estimation of saltmarsh vegetation at species level are required to better understand the distribution and canopy structure of saltmarsh vegetation. In this study, we presented an approach framework for estimating and mapping the fractional cover of major saltmarsh species in the Yellow River Delta, China based on time series Landsat 8 Operational Land Imager data. To solve the problem that the coastal area is frequently covered by clouds, we adopted the recently developed virtual image-based cloud removal (VICR) algorithm to reconstruct missing image values under the cloud/cloud shadows over the time series Landsat imagery. Then, we developed an ensemble learning model (ELM), which incorporates Random Forest Regression (RFR), K-Nearest Neighbor Regression (KNNR) and Gradient Boosted Regression Tree (GBRT) based on temporal-spectral features derived from the time-series cloudless images to estimate the fractional cover of major vegetation types, i.e., Phragmites australis, Suaeda salsa and the invasive species, Spartina alterniflora. High spatial resolution imagery acquired by the Unmanned Aerial Vehicle and Gaofen-6 satellites were used for reference sample collections. The results showed that our approach successfully estimated the fractional cover of each saltmarsh species (average of R-square:0.891, RMSE: 7.48%). Through four scenarios of experiments, we found that the ELM is advantageous over each individual model. When the images during key months were absent, cloud removal for the Landsat images considerably improved the estimation accuracies. In the study area, Spartina alterniflora covers the largest area (5753.97 ha), followed by Phragmites australis with spatial extent area of 4208.4 ha and Suaeda salsa of 1984.41 ha. The average fractional cover of S. alterniflora was 58.45%, that of P. australis was 51.64% and that of S.salsa was 51.64%.

Behavioural and physiological responses to experimental temperature changes in a long-billed and long-legged bird: a role for relative appendage size?

Maintaining homeothermy may be a major challenge when species are confronted with ambient temperatures beyond their thermoneutral zone. Bird species occupying open landscapes are inherently exposed to acute heat loss and heat gain, which force them to adopt a suite of behavioural and physiological strategies to maintain homeothermy. Both types of responses could be influenced by their relative bill and leg sizes, but experimental data are lacking. Here, we evaluated how variation in body postural adjustments, panting, and locomotor activity in the dunlin Calidris alpina can be explained by experimental ambient temperature and relative bill and leg sizes. Additionally, we estimated resting metabolic rate and evaporative water loss to assess potential links between both physiological traits and relative bill and leg sizes. Temperatures below the thermoneutral zone were counteracted by enhancing metabolic heat production through increased locomotor activity, while body postural adjustments were used less than expected. Within the thermoneutral zone, back rest (tucking the bill under body feathers) and unipedal (standing on one leg) were preferred by dunlins, probably as being more comfortable for resting. At temperatures above the thermoneutral zone, dunlins were inactive and increased the time of bill exposure and wet-sitting and ultimately panting when challenged with temperatures above 37 °C. Interestingly, above the thermoneutral zone, but below their body temperature, birds with relatively longer bills and legs spent more time exposing them, probably to increase dry heat transfer into the environment. Our findings also highlighted the importance of the availability of wet substrates for minimising heat stress in wetland species.Significance statementRecent correlational field studies found support for a relationship between relative bill and leg sizes and thermoregulatory behaviour in birds inhabiting open landscapes. However, experimental data are lacking, and the mechanisms underlying this relationship remain poorly understood. Here, we performed an experiment to model behavioural and physiological responses to ambient temperature change and relative bill and leg sizes in the dunlin Calidris alpina, a long-billed and long-legged shorebird. Additionally, we also examined potential links among metabolic rates, evaporative water loss and relative appendage sizes. Our findings showed a strong experimental relationship between behavioural and physiological responses and ambient temperature, as well as a link between appendage size and resting body postures. Our findings also have a conservation message by highlighting that the type of substrate available for roosting is important for minimising heat stress in wetland species.

Five Year Analyses of Vegetation Response to Restoration using Rock Detention Structures in Southeastern Arizona, United States

Rock detention structures (RDS) are used in restoration of riparian areas around the world. The purpose of this study was to analyze the effect of RDS installation on vegetation in terms of species abundance and composition. We present the results from 5 years of annual vegetation sampling which focused on short term non-woody vegetation response within the riparian channel at 3 restoration sites across southeastern Arizona. We examined the potential ways that RDS can preserve native species, encourage wetland species, and/or introduce nonnative species using a Control-Impact-Paired-Series study design. Species composition and frequency were measured within quadrats and zones on an annual basis. Multivariate bootstrap analyses were performed, including Bray-Curtis dissimilarity index and non-metric multidimensional scaling ordination. We found that response to RDS was variable and could be related to the level of degradation or proximity to groundwater. The non-degraded site did not show a response to RDS and the severely degraded site showed a slight increase in vegetation frequency, but the moderately degraded site experienced a significant increase. At the moderately degraded site, located between two historic ciénegas (desert wetlands), species composition shifted and nonnative species invaded, dominating the vegetation increase at this location. At the severely degraded site, pre-existing wetland species frequency increased in response to the installation of RDS. These findings extend the understanding of RDS effects on vegetation, provide scenarios to help land and water resource managers understand potential outcomes, and can assist in optimizing success for restoration projects.

Hydrogen peroxide pretreatment assisted phytoremediation of sodium dodecyl sulfate by Juncus acutus L

BackgroundSodium Dodecyl Sulfate (SDS) an anionic surfactant pollutant has emerged as a serious hazard to the aquatic and terrestrial environment. Due to physical and chemical methodological difficulties for SDS removal, phytoremediation techniques are efficient alternative strategies to tackle such adversities. Juncus acutus L. (J. acutus) is a pioneer wetland species that has been recently exploited for phytoremediation purposes. To our knowledge, the role of exogenous hydrogen peroxide (H2O2), in improving the phytoextraction of SDS has not been examined yet. In this study, pretreatment foliar spray of H2O2 (15 mM) combined with two levels of SDS (50 and 100 ppm) in water culture was evaluated to remove SDS contamination and add value to the phytoremediation process.ResultsThe outcomes revealed that J. acutus has considerable translocation and bioaccumulation abilities for SDS and can be utilized as an appropriate hyperaccumulator in SDS-contaminated sites. However, the involvement of H2O2 extended phytoremediation capacity and successive removal of SDS. H2O2 significantly assisted in increasing SDS remediation via more accumulation in J. acutus tissues by 29.9 and 112.4% and decreasing SDS concentration in culture media by 33.3 and 27.3% at 50 and 100 ppm SDS, respectively. Bioaccumulation factor (BCF) increased by 13.8 and 13.2%, while translocation factor (TCF) positively maximized by 82.4 and 76.2% by H2O2 application at 50 and 100 ppm SDS, respectively. H2O2 pretreatment could drive the decline in biochemical attributes in SDS-affected plants by modulating stress tolerance indices, pigments, water relations, proline content, enzymatic activities, and further, reduced oxidative stress in terms of electrolyte leakage, cellular H2O2, malondialdehyde (MDA) accumulation.ConclusionsH2O2 could play a potential role in maximizing phytoremediation capacity of SDS by J. acutus in polluted sites.