Article

The drying of Lake Urmia and its consequences for waterbird assemblages

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

The hypersaline Lake Urmia, located in Iran, has undergone a significant reduction in size and is currently facing the risk of desiccation. The decrease in water levels, coupled with elevated salinity levels, has initiated ecological degradation, leading to a substantial decline in the region’s waterbird population. This study employs breakpoint analysis to determine the year when the drought event affecting the lake commenced. Additionally, canonical correspondence analysis (CCA) is utilised to elucidate the interaction between environmental parameters and the waterbird assemblages in Lake Urmia over the period 1970–2018. Our investigation identifies the year 2000 as the initiation of the water crisis in Lake Urmia, synchronously coinciding with the decline in the waterbird populations. This finding highlights a significant connection between the majority of waterbird species and the axes of CCA, intricately linked with water availability within Lake Urmia. This revelation underscores the pivotal role of fluctuations in water levels in shaping the dynamics of the lake’s waterbird assemblages. Furthermore, our observations emphasise the importance of even minor improvements in hydrological conditions of the lake, resulting in substantial positive impacts on waterbird populations.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Existing studies have demonstrated that water level fluctuations are a key factor influencing waterbirds' use of wetland habitats, playing a crucial role in forming suitable habitats [25][26][27][28]. The dynamics of rising and falling water levels significantly drive the fluctuation in waterbird populations within the region, which, in turn, has a profound impact on species diversity [29][30][31]. However, a single water level snapshot from remote sensing data reflects the habitat conditions on that specific day. ...
Article
Full-text available
The landscape of the Poyang Lake wetland is significantly influenced by changes in water levels, impacting the distribution of habitats for migratory birds. While long-term effects of water level variations have been extensively studied, short-term impacts on Siberian crane habitats and their ecological vulnerability remain poorly understood. This study utilized 35 years (1987–2022) of Landsat remote sensing data and daily water level records from Poyang Lake to examine the effects of short-term water level fluctuations on the spatial distribution and ecological vulnerability of Siberian crane habitats. The geographic detector method was employed to quantify the explanatory power and interaction effects of factors, including short-term water level fluctuations, on ecological vulnerability. The findings reveal significant differences in the habitats of wintering Siberian cranes across various water level intervals and short-term fluctuation patterns. Short-term water level fluctuations can result in the largest suitable wintering habitat area for Siberian cranes, reaching 1856.41 km² in this study. These habitats are highly sensitive to short-term water level changes, with rising and falling trends potentially leading to habitat loss. Oscillating water levels in the short term create broader and more concentrated habitats. Notably, fluctuations at low water levels support the sustainability and stability of crane habitats. Furthermore, short-term water level trends and nature reserves play a critical role in maintaining habitat ecological vulnerability; well-managed and protected nature reserves exhibit significant explanatory power, both in single-factor analysis and in their interaction with other environmental factors. Specifically, these protected areas show explanatory power exceeding the 20% threshold for both water level fluctuations and ranges, highlighting the crucial role of anthropogenic management in mitigating ecological vulnerability. This study emphasizes the necessity of scientifically informed regulation of short-term water level fluctuations to protect Siberian crane habitats and provides a strong scientific basis for decision-making support.
... This decline has negatively impacted the lake's appeal to tourists and its ecological functions, aesthetic value, and therapeutic properties. Moreover, climate change has increased the frequency of adverse weather events such as dust storms, floods, lightning strikes, and storms, posing risks to tourists' and tourism enterprises' safety, property, and well-being (Shariati & Hemami, 2024;Shirmohammadi et al., 2024). ...
Article
Full-text available
Climate change poses significant challenges to the tourism industry, making understanding the factors influencing businesses' adaptive responses crucial. This research investigates the complex interplay of social discourse, belief systems, perceived costs, risk perceptions, response efficacy, and self-efficacy in shaping tourism professionals' adaptive and maladaptive behaviors. Focusing on businesses near Iran's Lake Urmia, the study employs the model of private proactive adaptation to climate change on a sample of 320 tourism businesses. The findings highlight the positive impact of climate change-related discussions on perceptions and behaviors, the critical role of strongly held beliefs, and the barriers posed by perceived costs. Risk perception emerges as a central driver of decision-making, emphasizing the importance of raising risk awareness. The study also reveals how response efficacy and self-efficacy impact adaptive behavior, while maladaptation presents a significant challenge. These insights are valuable for developing strategies to enhance tourism resilience to climate change in vulnerable destinations.
Article
Full-text available
In September 2024, following two rare storms, Lake Iriqui in southern Morocco experienced a remarkable revival after five decades of desiccation. Historically, the lake played an important role as one of the largest water bodies before the Sahara Desert, serving as a critical stopover in migratory routes for various bird species. Two field missions documented this event: the first confirmed the lake's reappearance, while the second recorded the resurgence of the ecosystem and the return of migratory birds, last observed in the lake in 1968. The lake's surface water extent, which had been completely dry, expanded dramatically, reaching over 80 km 2 after the first storm and subsequently increasing to approximately 146 km 2 following the second. This event has drawn considerable attention from international and national media. The revival was monitored using satellite imagery from Landsat 8 and 9 and Sentinel-2A, processed through Google Earth Engine (GEE), with the Normalized Difference Water Index (NDWI) applied to detect water presence. A time-series analysis revealed significant changes in the lake's surface water extent following the rainfall. This study emphasizes the need for proactive support to preserve Lake Iriqui, aligning with sustainable development goals: SDG 15 (Life on Land) and SDG 8 (Decent Work and Economic Growth). These goals highlight the importance of sustainable water resource management, biodiversity conservation, and eco-tourism initiatives to benefit local communities.
Article
Full-text available
Globally, bird populations are experiencing a significant decline due to disruptions caused by human activities. The Chahakhoor International Wetland, as one of the important bird areas, is located in Chaharmahal and Bakhtiari Province. In this study, we evaluated the habitat quality of Chahakhoor over an 11-year period using the InVEST model. Land use and land cover maps for 2013, obtained from the Forests and Ranges Organization, and for 2024 were prepared using Landsat 9 image classification, employing a supervised method and the random forest algorithm. The results showed that habitat quality for waterbirds in this wetland declined by approximately 20% from 2013 to 2024. Additionally, changes in land use and land cover indicated reductions in water resources, dense vegetation, and average pasture land, while areas allocated for villages, cities, roads, and agriculture increased. Overall, our findings suggest that the decline in the abundance of many surveyed waterbird species in Chahakhoor Wetland is likely associated with the decline in the habitat quality over the 11-year period. This highlights the urgent need for conservation initiatives aimed at restoring and protecting this wetland, which supports bird populations.
Article
Full-text available
the southeastern part of the country, in the territory of the Danube Delta Biosphere Reserve and its surroundings, especially over the lacunar complex. The first two flocks (with a total of 116 birds) appeared in May but the numbers increased gathering adults, immatures and juveniles. The highest number of flamingos recorded was 265, but the flock was not stable, usually splitting, moving or disappearing temporarily, dealing also with anthropogenic disturbances. One individual was ringed, what allowed us to state it was born in the south of France. Although some adult birds displayed rituals and behaviour characteristic for breeding, we did not find any colony or nesting place and the timing of the observations does not support a successful breeding attempt. It is quite plausible that most of these birds come from other colonies, most likely those on Lake Tuz, in Turkey, where this year an ecological tragedy caused the loss of the entire generation of chicks. Here we hypothesize that they might have nested in other unknown colonies outside the borders of Romania. In conclusion, we cannot confirm the breeding of flamingos in the studied area and we reaffirm the vagrant character of the species as non-nesting summer guests.
Article
Full-text available
The present paper aims to highlight the impact of the partial or total drying of the Nuntași and Tuzla lakes (from the Danube Delta Biosphere Reserve) as a result of intense drought phenomena on groups of waterfowl that are encountered in this region. Our analysis combined satellite remote sensing techniques with bird observations that were made monthly during the analyzed period, corroborated with the meteorological context of the time interval that was taken into account. The results of the satellite image processing show a partial drying in 2013 and a total drying in 2020 of the Nuntași and Tuzla lakes, which were caused by both natural factors (drought) and anthropogenic factors (inadequate management of the area—e.g.,: communication channels with surrounding lakes are clogged). These situations have led to repercussions for groups of birds, which behave differently depending on their ecology. Pelicans and swans are the most affected birds, they leave the area in the absence of water, whereas gulls and terns are not affected by the decrease in the water surface, they even increase their numbers in such conditions. Our study also shows that from 2010 to 2020 the largest numbers of birds (total numbers of birds), with the exception of pelicans, were recorded in 2013 and 2020, more precisely in the years when the water surface decreased considerably. Another important feature of this paper involves highlighting how fragile an ecosystem can be in the context of climate change, but also how important it is to involve human society in maintaining the adequate conditions for an ecosystem that is part of one of the most important biodiversity hotspots on the planet, the Danube Delta Biosphere Reserve.
Article
Full-text available
Study Region Lake Urmia, Iran. Study focus There is widespread interest in restoring drying saline lakes. At Iran’s hypersaline Lake Urmia, managers have sought a uniform target lake level of 1274.1 m above sea level to lower salinity below 263 g L⁻¹ and recover Artemia to sufficient densities to support flamingos. We suggest that addressing a broader range of objectives will allow more flexibility for managing the lake. We define eight restoration objectives to lower salinity, sustain Artemia and flamingo populations, separate islands from each other and the mainland, reduce lakebed dust, maintain commercially valuable ions, and improve recreational access from resort beaches. We use 40 years of experimental, field, satellite, and model data to relate each objective to lake level. We describe variations through time and associated uncertainties for meeting each objective. New hydrological insights We show that:1) Lake variations prevent setting a precise target restoration level; 2) The current target may not sufficiently lower salinity to recover Artemia to sufficient densities to support flamingos; 3) Restoration objectives do not converge to a single lake level; tradeoffs are murky; 4) Lake Urmia managers should focus on multiple ecosystem services and track how they are met as lake level varies over time; and 5) As information about the lake improves, managers should adapt their management strategies to meet the most attainable objectives.
Chapter
Full-text available
Utah’s Great Salt Lake (GSL) is so saline that the only invertebrates that survive in the open water are brine fly larvae and brine shrimp. In the absence of competition from other invertebrates, they are incredibly abundant. Only a few avian species can take advantage of their abundance because a bird cannot eat them without also ingesting salt. Moreover, brine shrimp and brine flies are so tiny that only a few avian species can consume the massive number of brine shrimp and brine flies required to meet a bird’s nutritional needs. For example, eared grebes need to consume 28,000 adult brine shrimp each day to survive. To achieve this, an eared grebe has to spend 7 h daily foraging and needs to harvest one shrimp per second during foraging.
Technical Report
Full-text available
The report presents trends in sulphate, nitrate, chloride, base cations, ANC (acid neutralising capacity), pH and DOC at circa 500 ICP Waters sites in Europe and North America for the period 1990-2016. Time series were analysed for trends in annual median values, annual extreme values and change points, that indicate years with sudden changes in trend or level. Also provided is a brief overview of possible implications of land use change for recovery of acidified surface waters.
Article
Full-text available
Migrating waterbirds moving between upper and lower latitudinal breeding and wintering grounds rely on a limited network of endorheic lakes and wetlands when crossing arid continental interiors. Recent drying of global endorheic water stores raises concerns over deteriorating migratory pathways, yet few studies have considered these effects at the scale of continental flyways. Here, we investigate the resiliency of waterbird migration networks across western North America by reconstructing long‐term patterns (1984‐2018) of terminal lake and wetland surface water area in 26 endorheic watersheds. Findings were partitioned regionally by snowmelt‐ and monsoon‐driven hydrologies and combined with climate and human water‐use data to determine their importance in predicting surface water trends. Nonlinear patterns of lake and wetland drying were apparent along latitudinal flyway gradients. Pervasive surface water declines were prevalent in northern snowmelt watersheds (lakes ‐27%, wetlands ‐47%) while largely stable in monsoonal watersheds to the south (lakes ‐13%, wetlands +8%). Monsoonal watersheds represented a smaller proportion of total lake and wetland area, but their distribution and frequency of change within highly arid regions of the continental flyway increased their value to migratory waterbirds. Irrigated agriculture and increasing evaporative demands were the most important drivers of surface water declines. Underlying agricultural and wetland relationships however were more complex. Approximately seven percent of irrigated lands linked to flood irrigation and water storage practices supported 61% of all wetland inundation in snowmelt watersheds. In monsoonal watersheds, small earthen dams meant to capture surface runoff for livestock watering, were a major component of wetland resources (67%) that supported networks of isolated wetlands surrounding endorheic lakes. Ecological trends and human impacts identified herein underscore the importance of assessing flyway scale change as our model depictions likely reflect new and emerging bottlenecks to continental migration.
Article
Full-text available
The present study was aimed to determine the effect of some environmental factors such as water features and vegetation cover on the distribution and habitat use of herons over different seasons of the bird's life (breeding, passage and wintering) in Tonga Lake (North East Algeria) from March 2017 to February 2018. We used remote sensing techniques to study the environmental factors variations, we adopted the normalized difference vegetation index (NDVI) to give an estimate of vegetation cover and we used the normalized difference water index (NDWI) to study the water features. In our study, we determine that the abundance and richness of herons species is largely influenced by the water features and vegetation cover. The seasonal variations in the amount of these environmental factors are known to affect the availability of various food items for herons. Eight species of herons were identified during the study period. Pearson's Correlation Coefficient was used to examine the effect of NDVI and NDWI on the distribution of herons. The results showed that the NDVI was significantly positively correlated with richness and abundance of herons respectively (r=0.728, p<0.05) (r=0.651, p<0.05), wherease the NDWI was significantly negatively correlated with the richness and abundance of herons (r=-0.65, p<0.05) (r=-0.69, p<0.05) respectively.
Preprint
Full-text available
s Wetlands play a crucial role in the biosphere and provide numerous services. They performed multiple functions such as groundwater recharge, water purification, conservation of biological resources, act as a carbon sink and habitat of amphibians and birds. A Ramsar site- the Sambhar Lake is one of the largest inland saline wetland present in the arid region of Rajasthan, India has unique habitat suitability for the winter avifauna migrants like flamingoes and falcons. The occurrence of suitable climatic conditions and food availability like brine shrimps (Artemia salina) attracts flocks of migratory birds. From the last three decades, Sambhar Lake has been continuously facing degradation due to anthropogenic activities, which disturb Lake’s natural ecology and existence. These cause disturbances in habitat suitability of migratory birds in the Sambhar Lake, which leads to a reduction of population density of migratory birds. Therefore, this study aimed to assess the degradation and vulnerability of Sambhar Lake and the habitat suitability of migratory birds using Maxent Habitat Suitability model. This model provides a platform to integrate the bird’s occurrence data with the bioclimatic variables using remote sensing and Geographical Information System, and provides bird’s habitat suitability as well as predicts future bird’s occurrence scenarios. Landsat-5 and Sentinel-2 imagery for the year 1996 and 2019 respectively were used in this study. Four indicators such as LULC NDWI, MSI and SABI depicts the environmental condition of the Sambhar Lake. Output form Maxent model reveals that the Sambhar lake area with increasing anthropogenic activities has become unsuitable for flamingos. A remarkable loss of breeding sites of animal, particularly avian fauna (flamingos) is seen in the recent years due to different types of threats posed on the Ramsar site. Increase in Salt crust and Vegetation area from 36.8055 to 123.837 Sq. Km. and 26.5347 to 36.857 Sq. Km. respectively have taken place. While a decrease in saline water area from 88.8309 to 19.3256 Sq. Km has been observed, within the vicinity of Sambhar Lake as clearly shown through LULC map. The future prediction of the distribution of species in the region for the year 2050 shows that the most suitable regions will be near to Jhapok and nearby waters of Salt Lake City as the drains from the city opens in the lake where the flamingoes get Algae in the form of food. Active steps are needed for the lake conservation to reduce the risks of migratory bird’s population.
Article
Full-text available
A recent article reviewed data on Great Salt Lake (Utah) and concluded falsely that climate changes, especially local warming and extreme precipitation events, are primarily responsible for lake elevation changes. Indeed climatically influenced variation of net inflows contribute to huge swings in the elevation of Great Salt Lake (GSL) and other endorheic lakes. Although droughts and wet cycles have caused lake elevation changes of over 4.5 m, they have not caused a significant long-term change in the GSL stage. This recent article also suggests that a 1.4 • C rise in air temperature and concomitant increase in the lake's evaporative loss is an important reason for the lake's decline. However, we calculate that a 1.4 • C rise may have caused only a 0.1 m decrease in lake level. However, since 1847, the lake has declined 3.6 m and the lake area has decreased by ≈50%, despite no significant change in precipitation (p = 0.52) and a slight increase, albeit insignificant, in river flows above irrigation diversions (p = 0.085). In contrast, persistent water extraction for agriculture and other uses beginning in 1847 now decrease water flows below diversions by 39%. Estimates of consumptive water use primarily for irrigated agriculture in the GSL watershed suggest that approximately 85% (2500 km 2) of the reduced lake area can be attributed to human water consumption. The recent article's failure to calculate a water budget for the lake that included extensive water withdrawals misled the author to focus instead on climate change as a causal factor for the decline. Stable stream flows in GSL's headwaters, inadequate temperature increase to explain the extent of its observed desiccation, stable long-term precipitation, and the magnitude of increased water consumption from GSL together demonstrate conclusively that climatic factors are secondary to human alterations to GSL and its watershed. Climatization, in which primarily non-climatic processes are falsely attributed to climatic factors, is a threat to the credibility of hydrological science. Despite a recent suggestion to the contrary, pressure to support Earth's rising human population-in the form of increasing consumption of water in water-limited regions, primarily to support irrigated agriculture-remains the leading driver of desiccation of inland waters within Earth's water-limited regions.
Article
Full-text available
The surfaces of saline lakes are shrinking at a threatening rate worldwide. Likewise, the Uchhali complex (formed by three saltwater lakes located in the Salt Range, Pakistan) that serves as a major regional source of water for humans and as a habitat for water birds must be monitored. With this objective in mind, we conducted a study coupling hydrochemistry and stable isotope compositions (δ 37 Cl, δ 18 O and δD) in order to characterize its hydrochemical properties and the main processes controlling them. Results showed that the Uchhali complex salinity has dramatically increased compared to other similar lakes in the world. While the Uchhali (UL) and Khabbeki (KL) lakes present a sodium-chloride hydrofacies, the Jahlar (JL) is of a sodium-bicarbonate type. Hydrochemistry parameters indicate that the weathering of surrounding rocks is the major vector for the increase of total dissolved solids in the water. On the other hand, the observed enrichment in heavy isotopes of the water stable isotope compositions implies that the different lakes are undergoing a long history of intense evaporation. The study of the corresponding δ 37 Cl isotope compositions supports the conclusion that evaporation, along with weathering, are the main driving processes. Besides climate effects that result in the decrease of annual precipitation and the increase of evaporation, water consumption for domestic purposes (household and agriculture) aggravates the rise of the lakes' salinity.
Article
Full-text available
Llista de control d’ocells aquàtics de l’oasi de Wadi Djedi (Ziban, Algèria) Aquest treball documenta per primera vegada la comunitat d’avifauna de l’oasi de Wadi Djedi, a Ziban, regió situada al sud-est d’Algèria. Presentem els resultats obtinguts a partir dels recomptes mensuals d’ocells aquàtics fets des del setembre de 2013 fins al setembre de 2016. En aquesta zona humida es van registrar un total de 36 espècies d’ocells aquàtics corresponents a 11 famílies. La família Anatidea, amb 11 espècies, és la més representada. Entre el conjunt d’espècies, 18 són hivernants, nou migrants, vuit espècies criadores residents com ara l’ànec canyella Tadorna furruginea i el corriol camanegre Charadrius alexandrines i una espècie, la cigonya blanca, criadora migratòria. D’altra banda, dues espècies, el xarxet marbrenc Marmaronetta angustirostris i el morell xocolater Aythya nyroca, estan incloses a la categoria VU de la Llista Roja d’espècies amenaçades de la Unió Internacional per a la Conservació de la Natura (UICN). Dades publicades a GBIF (Doi:10.15470/6m0dyq)
Article
Full-text available
Wetlands in arid landscapes provide critical habitat for millions of migratory waterbirds across the world and throughout their annual cycle. the scope and scale of understanding avian use of these wetlands in conjunction with changes in climate are daunting yet critical to address lest we lose continent-wide migratory pathways. Here, we assess changes in waterbird use of North America's Pacific Flyway in the Great Basin by examining water availability and climate trends over the past 100 years. We found recent (1980-2015) climate warming has significantly reduced the amount and shifted seasonality of water flowing into wetlands. Further, we found remarkable changes in waterbird species composition over time. We propose that a reduced hydroperiod and lower water quality from reduction in water level and flow limits sites used by waterbirds. These factors reduce chick survivorship as they cannot metabolize saline water, which makes suitable freshwater conditions a limiting resource. Collectively, climate-induced changes in Great Basin wetlands suggest a major shift in freshwater ecosystems, resulting in degradation of a continental migratory route. This work illustrates the importance of examining multi-scale changes in critical regional resources to understand their impact across a hemispheric flyway and provides a model to examine other flyways.
Article
Full-text available
Changing weather patterns, droughts and competing water demands are dramatically altering the landscape and creating conditions conducive to the production of wind-blown dust and dust storms. In California, such factors are leading to the rapid shrinking of the Salton Sea, a 345 mile2 land-locked "sea" situated near the southeastern rural border region known as the Imperial Valley. The region is anticipated to experience a dramatic increase in wind-blown dust and existing studies suggest a significant impact on the health and quality of life for nearby residents of this predominantly low-income, Mexican-American community. The discussion calls attention to the public health dimensions of the Salton Sea crisis. We know little about the possible long-term health effects of exposure to mobilized lakebed sediments or the numerous toxic contaminants that may become respirable on entrained particles. We draw on existing epidemiological literature of other known sources of wind-blown dust, such as desert dust storms, and related health effects to begin to understand the potential public health impact of wind-blown dust exposure. The increased production of wind-blown dust and environmental exposures to such non-combustion related sources of particulate matter are a growing health threat, due in part to drought coupled with increasing pressures on limited water resources. Recent population-based studies have linked dust storms with cardiovascular mortality, asthma hospitalization and decrease in pulmonary function in both adults and children. A growing number of studies provide evidence of the acute health effects of wind-blown dust exposures among children, which with repeated insults have the potential to influence respiratory health over time. The shrinking of the Salton Sea illustrates a public health and environmental justice crisis that requires action and attention to protect the health and well-being of local communities.
Article
Full-text available
A viewpoint of a temporal trend with an extremely changing point analysis is proposed to analyze and characterize the so-called current declines of the world’s saline lakes. A temporal trend of a hydrological or climate variable is statistically tested by regressing it against time; if the regression is statistically significant, an ascending or declining trend exists. The extremely changing points can be found out by using the mean of a variable, adding or subtracting two times of its standard deviation (SD) for extremely high values and extremely low values, respectively. Applying the temporal trend method to the Great Salt Lake’s (GSL) relationship between its surface levels and precipitation/temperature in the last century, we conclude that climate changes, especially local warming and extreme weather including both precipitation and temperature, drive the dynamics (increases and declines) of the GSL surface levels.
Article
Full-text available
Under climate warming, migratory birds should align reproduction dates with advancing plant and arthropod phenology. To arrive on the breeding grounds earlier, migrants may speed up spring migration by curtailing the time spent enroute , possibly at the cost of decreased survival rates. Based on a decades-long series of observations along an entire flyway, we show that when refuelling time is limited, variation in food abundance in the spring staging area affects fitness. Bar-tailed godwits migrating from West Africa to the Siberian Arctic reduce refuelling time at their European staging site and thus maintain a close match between breeding and tundra phenology. Annual survival probability decreases with shorter refuelling times, but correlates positively with refuelling rate, which in turn is correlated with food abundance in the staging area. This chain of effects implies that conditions in the temperate zone determine the ability of godwits to cope with climate-related changes in the Arctic.
Article
Full-text available
The timing of muscle activity is a commonly applied analytic method to understand how the nervous system controls movement. This study systematically evaluates six classes of standard and statistical algorithms to determine muscle onset in both experimental surface electromyography (EMG) and simulated EMG with a known onset time. Eighteen participants had EMG collected from the biceps brachii and vastus lateralis while performing a biceps curl or knee extension, respectively. Three established methods and three statistical methods for EMG onset were evaluated. Linear envelope, Teager-Kaiser energy operator + linear envelope and sample entropy were the established methods evaluated while general time series mean/variance, sequential and batch processing of parametric and nonparametric tools, and Bayesian changepoint analysis were the statistical techniques used. Visual EMG onset (experimental data) and objective EMG onset (simulated data) were compared with algorithmic EMG onset via root mean square error and linear regression models for stepwise elimination of inferior algorithms. The top algorithms for both data types were analyzed for their mean agreement with the gold standard onset and evaluation of 95% confidence intervals. The top algorithms were all Bayesian changepoint analysis iterations where the parameter of the prior (p0) was zero. The best performing Bayesian algorithms were p0 = 0 and a posterior probability for onset determination at 60–90%. While existing algorithms performed reasonably, the Bayesian changepoint analysis methodology provides greater reliability and accuracy when determining the singular onset of EMG activity in a time series. Further research is needed to determine if this class of algorithms perform equally well when the time series has multiple bursts of muscle activity.
Article
Full-text available
Lake Urmia in northwest Iran, once one of the largest hypersaline lakes in the world, has shrunk by almost 90% in area and 80% in volume during the last four decades. To improve the understanding of regional differences in water availability throughout the region and to refine the existing information on precipitation variability, this study investigated the spatial pattern of precipitation for the Lake Urmia basin. Daily rainfall time series from 122 precipitation stations with different record lengths were used to extract 15 statistical descriptors comprising 25th percentile, 75th percentile, and coefficient of variation for annual and seasonal total precipitation. Principal component analysis in association with cluster analysis identified three main homogeneous precipitation groups in the lake basin. The first sub-region (group 1) includes stations located in the center and southeast; the second sub-region (group 2) covers mostly northern and northeastern part of the basin, and the third sub-region (group 3) covers the western and southern edges of the basin. Results of principal component (PC) and clustering analyses showed that seasonal precipitation variation is the most important feature controlling the spatial pattern of precipitation in the lake basin. The 25th and 75th percentiles of winter and autumn are the most important variables controlling the spatial pattern of the first rotated principal component explaining about 32% of the total variance. Summer and spring precipitation variations are the most important variables in the second and third rotated principal components, respectively. Seasonal variation in precipitation amount and seasonality are explained by topography and influenced by the lake and westerly winds that are related to the strength of the North Atlantic Oscillation. Despite using incomplete time series with different lengths, the identified sub-regions are physically meaningful.
Article
Full-text available
Combined physiological and behavioural responses to salt loads during development have rarely been studied in air-breathing vertebrates able to inhabit hypersaline habitats, but they may be of particular importance in understanding, for example, the differences among species in patterns of habitat use or ontogenetic diet switches. Here, we compared the physiological and behavioural responses of self-feeding precocial chicks developed in contrasting levels of water salinity. The model species was the Black-winged Stilt (Himantopus himantopus) a precocial shorebird that breeds in a range of habitats from freshwater to hypersaline wetlands. Specifically, we compared resting metabolic rate (RMR), heat shock proteins (Hsp70), plasma ions, hematocrit, body mass, body size, growth rate and head-shaking behaviour of captive-reared Black-winged Stilt fledglings developed under fresh (0 ‰), saline (20 ‰), and hypersaline (60 ‰) water. Contrary to expectations, none of the physiological and morphological variables measured differed significantly among treatments. Likewise, the RMR of wild and captive-reared fledglings was similar. Surprisingly, the saltgland mass of wild fledglings from freshwater and those from hypersaline habitats was also similar. However, head-shaking, a behavioural response associated to minimize salt intake and to expel the secretions of salt glands, differed according to salinity source: head-shaking rate increased with increasing salinity. The results of this study support the key role of behavioural osmoregulation in avoiding salt stress during development.
Article
Full-text available
Saline lakes provide a prey-rich, predator-free environment for birds to utilize during migration and stopover periods. The Great Salt Lake (GSL), Utah is the largest salt lake in North America and is utilized by millions of migratory birds. It also is host to multiple commercial endeavors. Proposed expansion of commercial use of the GSL would result in increased impounded area and water extraction for mineral production, which may increase the GSL's salinity and negatively impact invertebrate abundance. I review previous literature and synthesize diets of avian species utilizing the GSL to determine the importance of each invertebrate species, including brine shrimp (Artemia franciscana) and brine flies (Ephydra spp.), and clarify the anthropogenic impacts on food sources and avian populations. Species considered are eared grebes (Podiceps nigricollis), northern shovelers (Anas clypeata), green-winged teals (Anas crecca), common goldeneyes (Bucephala clangula), American avocets (Recurvirostra americana), black-necked stilts (Himantopus mexicanus), Wilson's phalaropes (Phalaropus tricolor), red-necked phalaropes (Phalaropus lobatus), and California gulls (Larus californicus). Brine shrimp and brine fly adults are consumed by all species considered. Alterations in prey abundance due to increased salinity may alter the ability of the GSL to support large avian populations.
Article
Full-text available
Our study conducted from August 2007 to May 2011 in the main wetlands of the Oued Righ complex (Eastern Sahara of Algeria) aimed to study the habitat use and distribution pattern of the Ruddy Shelduck Tadorna ferruginea. As the species was recorded breeding at most sites of the wetland complex, it was given the resident breeder status, which differs from the one it had previously. The maximum number of Ruddy Shelducks (284 individuals) was recorded each year during the winter season (second half of December). The Ruddy Shelduck (60% of population) shows preference for shallow middle-sized salt ponds with a high proportion of open water (e.g. Chott Tindla and Chott Sidi Slimane). No interannual variations were observed in habitat use; moreover, seasonal variations in the use of shallow salt pond habitat may be the outcome of hot and dry climate of this arid region.
Article
Full-text available
Saline lakes change in size and salinity because of natural climate variability and especially from inflow diversions, which threaten life in these waters. We conducted a microcosm experiment in 12 L containers using organisms from the Great Salt Lake to determine how salinities ranging from 10 to 275 g·L⁻¹ influenced the ecosystem. After 30 days, brine shrimp (Artemia franciscana) were nearly absent in salinities of 10 g·L⁻¹ (where fish survived) and >225 g·L⁻¹. As salinities increased from 75 to 225 g·L⁻¹, final masses decreased 60% and their total biomass decreased fourfold. Copepod and rotifer biomasses were negligible at salinities >50 g·L⁻¹. Brine fly (Ephydra gracilis) final biomass decreased 45% as salinity increased from 50 to 250 g·L⁻¹. When Artemia and other grazers were abundant, phytoplankton chlorophyll levels were near 4.0 μg·L⁻¹, but when grazing rates declined at higher salinities, phytoplankton chlorophyll increased to 130 μg·L⁻¹. Mean periphyton chlorophyll levels showed the reverse pattern. Denitrification decreased total N concentrations during the experiment, resulting in final N:P ratios indicative of algal nitrogen limitation. The microcosm experiment demonstrated the strong influence of salinity on the entire ecosystem and highlighted the need for careful management of salt lakes to maintain appropriate salinities.
Article
Full-text available
Great Salt Lake (Utah, USA) is one of the world's largest hypersaline lakes, supporting many of the western U.S.'s migratory waterbirds. This unique ecosystem is threatened, but it and other large hypersaline lakes are not well understood. The ecosystem consists of two weakly linked food webs: one phytoplankton-based, the other organic particle/benthic algae-based. Seventeen years of data on the phytoplankton-based food web are presented: abundances of nutrients (N and P), phytoplankton (Chlorophyta, Bacillariophyta, Cyanophyta), brine shrimp (Artemia franciscana), corixids (Trichocorixa verticalis), and Eared Grebes (Podiceps nigricollis). Abundances of less common species, as well as brine fly larvae (Ephydra cinerea and hians) from the organic particle/benthic algae-based food web are also presented. Abiotic parameters were monitored: lake elevation, temperature, salinity, PAR, light penetration, and DO. We use these data to test hypotheses about the phytoplankton-based food web and its weak linkage with the organic particle/benthic algae-based food web via structural equation modeling. Counter to common perceptions, the phytoplankton-based food web is not limited by high salinity, but principally through phytoplankton production, which is limited by N and grazing by brine shrimp. Annual N abundance is highly variable and depends on lake volume, complex mixing given thermo-and chemo-clines, and recycling by brine shrimp. Brine shrimp are food-limited, and predation by corixids and Eared Grebes does not depress their numbers. Eared Grebe numbers appear to be limited by brine shrimp abundance. Finally, there is little interaction of brine fly larvae with brine shrimp through competition, or with corixids or grebes through predation, indicating that the lake's two food webs are weakly connected. Results are used to examine some general concepts regarding food web structure and dynamics, as well as the lake's future given expected anthropogenic impacts.
Article
Full-text available
This paper analyzes climate variability and change in the Urmia Lake Basin, northwest of Iran. Annual average of the following data time series has been analyzed by statistical methods: dry bulb temperature, maximum and minimum temperature, precipitation, and number of rainy and snowy days. We have also used mean monthly temper-ature and precipitation data for analysis of drought spells for the period 1964–2005 to find out whether fluctuations in the lake level are attributable to natural drought. Our results indicate that mean precipitation has decreased by 9.2 % and the average maximum temperature has increased by 0.8°C over these four decades. The seasonal changes are particularly visible in winter and spring. Results of the Palmer Drought Severity Index show that on average, drought episodes have hit the Urmia Lake Basin every 5 years and most of them reached severe levels, but recent droughts have become more intense and last longer.
Article
Full-text available
We conducted 14 bird surveys in the Melincu saline lake from 1992 to 2002 (7 in winter and 7 in summer), and we detected 223,643 individuals belonging to 71 species from 17 families. The more abundant species were Fulica leucoptera, Larus maculipennis, Phoenicopterus chilensis, Plegadis chihi, Anas platalea, Himantopus mexicanus, and Rollandia rolland. Bird abundance was similar in winter and summer, whereas species composition differed between seasons. We recorded 65 species in summer and 59 in winter. P. chilensis and A. sibilatrix were more abundant in winter, whereas Ajaia ajaja, Phalacrocorax olivaceus, Ardea ibis, Sterna nilotica, Egretta thula, Mycteria americana, Charadrius collaris, A. versicolor, Calidris fuscicollis, and Ciconia maguari were more abundant in summer. Bird abundance in each survey was positively associated with the lake level. In summer surveys, the highest variation in species composition through the years was associated with water level fluctuations. Shorebirds predominated in those years with lower level, whereas the species that fed mainly on plants or vertebrates predominated in years with higher levels. Those species that fed on invertebrates (not shorebirds) and those that fed on invertebrates and plants predominated in years with intermediate level. The omnivorous species predominated in years of lower level. There were differences among transects in the proportion of different trophic groups. Short-term studies that do not take into account the particular dynamic of these systems may lead to erroneous generalisations. Thus, the long-term information of this study may be useful for management and conservation of species and system.
Article
Full-text available
The demand for water to support irrigated agriculture has led to the demise of wetlands and their associated wildlife for decades. This thirst for water is so pervasive that many wetlands considered to be hemispheric reserves for waterbirds have been heavily affected; for example, the California and Nevada wetlands in North America, the Macquarie Marshes in Australia, and the Aral Sea in central Asia. These and other major wetlands have lost most of their historic supplies of water and some have also experienced serious impacts from contaminated subsurface irrigation drainage. Now mere shadows of what they once were in terms of biodiversity and wildlife production, many of the so-called 'wetlands of international importance' are no longer the key conservation strongholds they were in the past. The conflict between irrigated agriculture and wildlife conservation has reached a critical point on a global scale. Not only has local wildlife suffered, including the extinction of highly insular species, but a ripple effect has impacted migratory birds worldwide. Human societies reliant on wetlands for their livelihoods are also bearing the cost. Ironically, most of the degradation of these key wetlands occurred during a period of time when public environmental awareness and scientific assertion of the need for wildlife conservation was at an all-time high. However, designation of certain wetlands as 'reserves for wildlife' by international review boards has not slowed their continued degradation. To reverse this trend, land and water managers and policy makers must assess the true economic costs of wetland loss and, depending on the outcome of the assessment, use the information as a basis for establishing legally enforceable water rights that protect wetlands from agricultural development.
Article
Full-text available
The use of water for agricultural production in water scarcity regions requires innovative and sustainable research, and an appropriate transfer of technologies. This paper discusses some of these aspects, mainly relative to on-farm irrigation management including the use of treated wastewater and saline waters. First, the paper proposes some concepts relative to water scarcity, concerning aridity, drought, desertification and water shortage, as well as policies to cope with these water stressed regimes. Conceptual approaches on irrigation performances, water use and water savings are reviewed in a wide perspective. This is followed by a discussion of supply management to cope with water scarcity, giving particular attention to the use of wastewater and low-quality waters, including the respective impacts on health and the environment as water scarcity is requiring that waters of inferior quality be increasingly used for irrigation. The paper then focuses on demand management, starting with aspects relating to the improvement of irrigation methods and the respective performances, mainly the distribution uniformity (DU) as a fundamental tool to reduce the demand for water at the farm level, and to control the negative environmental impacts of over-irrigation, including salt stressed areas. Discussions are supported by recent research results. The suitability of irrigation methods for using treated wastewaters and saline waters is analysed. Supplemental irrigation (SI) and deficit irrigation strategies are also discussed, including limitations on the applicability of related practices. The paper also identifies the need to adopt emerging technologies for water management as well as to develop appropriate methodologies for the analysis of social, economic, and environmental benefits of improved irrigation management.
Article
Full-text available
Barry and Hartigan (1993) propose a Bayesian analysis for change point problems. We provide a brief summary of selected work on change point problems, both preceding and following Barry and Hartigan. We outline Barry and Hartigan's approach and offer a new R package, pkgbcp (Erdman and Emerson 2007), implementing their analysis. We discuss two frequentist alternatives to the Bayesian analysis, the recursive circular binary segmentation algorithm (Olshen and Venkatraman 2004) and the dynamic programming algorithm of (Bai and Perron 2003). We illustrate the application of bcp with economic and microarray data from the literature.
Article
Millions of wetland-dependent birds annually depend on saline lakes and associated wetlands in the western United States. Understanding the population status and trends of birds with different life histories and habitats can guide efforts to secure water resources needed to sustain bird habitats. We used a 21-year dataset to examine population trends for 24 survey units for migratory shorebirds, waterfowl, and other waterbirds at Great Salt Lake and associated wetlands. We found stable or positive trends for 36 of 37 species or groups in fall, spring, or both seasons when considering survey units in aggregate. Stable, positive, and negative trends were observed in individual survey units. Foraging technique, migration distance, and taxonomic groupings were unrelated to trend direction. Research is needed to test whether survey units represent high-quality habitat. With declining regional water resources, stable and positive aggregate trends reinforce the importance of surveyed units at Great Salt Lake and associated wetlands to wetland-dependent birds. Ensuring continuation of stable and positive trends will require identifying environmental factors—including water quantity and quality—driving trends, and require coordinated regional management and monitoring of wetland-dependent birds.
Article
Lake Urmia, located in the North West of Iran, was once the most extensive permanent hypersaline lake in the world. Unsustainable water management in response to increasing demand together with climatic extremes have given rise to the lake's depletion during the last two decades. The Urmia Lake Restoration Program (ULRP) was established in 2013 and aims to restore the lake within a 10-year program. This study aims to monitor these restoration endeavours using spaceborne and ground-based observations. We analyzed the in-situ water level, the surface water extent, and the water volume of the lake. The water storage change of the Urmia Lake catchment is quantified using the Gravity Recovery and Climate Experiment (GRACE) and GRACE Follow-On satellite observations, which gives us a holistic view of hydrological components. Our analysis shows a positive trend of 14.5 cm/yr, 204 km²/yr, and 0.42 km³/yr in the time series of lake water level, lake water area, and water volume from 2015 to 2019 which indicates a short-lived stabilization of Lake Urmia. This has been achieved mainly due to an increase of 0.35 km³/yr in inflow from rivers to the lake, predominantly driven by anomalous precipitation events in 2016 and early 2019. However, the long-term trend from 2003 to 2019 still shows negative values of −22 cm/yr, −200 km²/yr, and −0.72 km³/yr for the water level, the surface area, and the water volume of the lake, respectively. The stabilization seems to be fragile however, since most of the increase in the water volume of the lake has spread over the large shallow southern region with high evaporation potential during hot seasons. Furthermore, due to the high correlation between the lake water level and precipitation, the recovery observed in 2016 and the first half of 2019 might not continue in case of a long drought period.
Article
Saline lakes are threatened globally and provide critical habitat for a diverse array of migratory and breeding waterbirds. The ability of large numbers of waterbirds to profitably use saline lakes is primarily dependent upon concentrations of invertebrate fauna that are only present within a narrow range of salinities. Additionally, waterbirds themselves can incur steep physiological costs as their salt loads increase, meaning that they are especially sensitive to changes in salinity. Nonetheless, relatively little is known about ecosystem function within natural saline lakes or how birds will respond to fluctuations in salinity across time, hindering efforts to maintain ecologically functional saline ecosystems. To help address this gap, we coupled data from waterbird surveys undertaken across 25 years at Lake Abert, Oregon, USA with data on lake area (a proxy for salinity) and invertebrate abundance to document how waterbird numbers changed in response to variation in lake area and the presence of their invertebrate prey. We found that as the area of Lake Abert decreased and salinity increased, both invertebrate and waterbird numbers declined, with especially high salinities associated with the presence of few waterbirds and invertebrates. However, we also found that at high lake levels and low salinities the abundance of most waterbirds and invertebrates either plateaued or declined as well. Our study reinforces physiological studies showing that both invertebrates and waterbirds can only tolerate a narrow range of salinities, and is among the first to document the effects of this tolerance range at the ecosystem level. As anthropogenic water usage increases and snowfall decreases in the coming century, Great Basin saline lakes are projected to increasingly face water shortages and high salinities. Conserving saline lake ecosystems thus requires mitigating these losses and maintaining water levels and salinities within the normal range of inter-annual variation. When conditions outside of this range occur too frequently or persist too long, they can result in dysfunctional ecosystems with deleterious consequences for the species that rely on them.
Article
Many of the world's saline lakes are shrinking at alarming rates, reducing waterbird habitat and economic benefits while threatening human health. Saline lakes are long-term basin-wide integrators of climatic conditions that shrink and grow with natural climatic variation. In contrast, water withdrawals for human use exert a sustained reduction in lake inflows and levels. Quantifying the relative contributions of natural variability and human impacts to lake inflows is needed to preserve these lakes. With a credible water balance, causes of lake decline from water diversions or climate variability can be identified and the inflow needed to maintain lake health can be defined. Without a water balance, natural variability can be an excuse for inaction. Here we describe the decline of several of the world's large saline lakes and use a water balance for Great Salt Lake (USA) to demonstrate that consumptive water use rather than long-term climate change has greatly reduced its size. The inflow needed to maintain bird habitat, support lake-related industries and prevent dust storms that threaten human health and agriculture can be identified and provides the information to evaluate the difficult tradeoffs between direct benefits of consumptive water use and ecosystem services provided by saline lakes.
Article
The Salton Sea is a terminal lake located in the deepest point of the topographically closed Salton Trough in southeastern California. It is currently the largest lake in area in the state. It was created by a flooding event along the Colorado River in 1905–1907, similar to the way historical floods over past centuries created ephemeral incarnations of ancient Lake Cahuilla in the same location. Its position at the center of today’s Imperial Valley, a hot and arid locale home to some of the most productive irrigated agricultural lands in the United States, has ensured its ongoing survival through a delicate balance between agricultural runoff, its principal form of input, and vast evaporation losses. Nevertheless, its parallel role as a recreational resource and important wildlife habitat, established over its first century of existence, is threatened by increasing salinity decreasing water quality, and reduced water allocations from the Colorado River that feeds the valley’s agriculture. The Salton Sea faces an increasingly uncertain future that will be influenced by reduced water imports from the Colorado River, demands for additional water sources to support farming and energy industries in the valley, and needs to stabilize the lake salinity, maintain recreational resources, and preserve what have become important ecosystems and wildlife habitats. © 2016, China University of Geosciences and Springer-Verlag Berlin Heidelberg.
Article
We examined the relationship between water levels and accessible habitat, and how accessible habitat influenced Dunlin (Calidris alpina) and Semipalmated Sandpiper (Calidris pusilla) numbers in managed wetlands at Pea Island (North Carolina) and Merritt Island (Florida) National Wildlife Refuges in 1998 and 1999. At Pea Island we experimentally manipulated water levels, which also allowed us to examine the effects of water level fluctuations on prey base. We examined these relationships because access to foraging habitat by shorebirds is positively related to the length of their tarsometatarsus, and in the southeastern United States, small calidrids are a numerically important component of the two million migrants using inland and managed wetlands. We confirmed the importance of shallow waters for Dunlin and Semipalmated Sandpiper-numbers increased with increasing availability of 0-4 cm habitat. At Merritt Island, Dunlin use was inversely related to variability in water depth of 0-4 cm. Minimizing the frequency and amplitude of water level fluctuations associated with single-capped culverts is necessary to improve habitat quality. After adjusting for accessibility, spring habitat requirements for Dunlin and Semipalmated Sandpiper at Pea Island were met under nearly all abundance scenarios. We identified water level targets that maximize accessible habitat at Pea Island. In contrast, winter habitat requirements for Dunlin at Merritt Island were not met except in one scenario. Seasonally low prey density contributed to the shortfall, suggesting that allocating more habitat is the primary management option. Manipulating water levels at Pea Island did not adversely affect the density of eight shorebird prey species. Estimates of accessible habitat and other parameters (e.g., turnover rates, prey biomass) are essential to set and implement realistic shorebird habitat conservation goals.
Conference Paper
We examined the relationship between water levels and accessible habitat, and how accessible habitat influenced Dunlin (Calidris alpina) and Semipalmated Sandpiper (Calidris pusilla) numbers in managed wetlands at Pea Island (North Carolina) and Merritt Island (Florida) National Wildlife Refuges in 1998 and 1999. At Pea Island we experimentally manipulated water levels, which also allowed us to examine the effects of water level fluctuations on prey base. We examined these relationships because access to foraging habitat by shorebirds is positively related to the length of their tarsometatarsus, and in the southeastern United States, small calidrids are a numerically important component of the two million migrants using inland and managed wetlands. We confirmed the importance of shallow waters for Dunlin and Semipalmated Sandpiper-numbers increased with increasing availability of 0-4 cm habitat, At Merritt Island, Dunlin use was inversely related to variability in water depth of 0-4 cm. Minimizing the frequency and amplitude of water level fluctuations associated with single-capped culverts is necessary to improve habitat quality. After adjusting for accessibility, spring habitat requirements for Dunlin and Semipalmated Sandpiper at Pea Island were met under nearly all abundance scenarios. We identified water level targets that maximize accessible habitat at Pea Island. In contrast, winter habitat requirements for Dunlin at Merritt Island were not met except in one scenario. Seasonally low prey density contributed to the shortfall, suggesting that allocating more habitat is the primary management option. Manipulating water levels at Pea Island did not adversely affect the density of eight shorebird prey species. Estimates of accessible habitat and other parameters (e.g., turnover rates, prey biomass) are essential to set and implement realistic shorebird habitat conservation goals.
Article
Published accounts of interspecific differences in habitat use by waterbirds predict that shallow wetlands should accommodate more species and greater numbers of waterbirds than deep wetlands. We evaluated this hypothesis by examining relationships between winter (January/February) waterbird use (presence/absence, density and number of species) and average depth, variation in depth and size of 25 wetlands in the northern San Joaquin Valley, California. Bird densities correlated consistently with depth. Likelihood of use increased in shallow wetlands for all nine wading birds (shorebirds and ibis); densities of three dabbling duck species and Black-necked Stilt (Himantopus mexicanus) also increased in shallow wetlands, whereas use and densities of two diving birds increased in deep wetlands. We observed no statistically significant relationship between depth and densities of two other waterbird species. The number of species of waterbird, dabbling duck, and wading bird increased in shallow wetlands, whereas the number of species of diving bird increased in deep wetlands. Wetland size and topographic variation inconsistently predicted waterbird densities, but both characteristics correlated positively with number of species. Our results provide general support for shallow flooding of wetlands to provide habitat for more species. We conclude that managers seeking to provide foraging habitat for a diverse community of wintering waterbirds should flood wetlands to average depths of 10-20 cm, where topography can provide a range of depths attractive to a large number of species. However, this prescription is region-specific and influenced by the great diversity and abundance of waterfowl and shorebirds wintering in California's Central Valley. Received 27 September 1999, accepted 23 December 1999.
Article
WC studied habitat use of shorebirds (Charadriiformes) at a wetland experiencing natural fluctuations in water levels located at Tishomingo National Wildlife Refuge in the south-central Great Plains. We describe use of macrohabitats (disturbed, deciduous, snags, and mudflat) and microbabitats (dry-land, wet-land, and water) by foraging groups (terrestrial-aquatic gleaner, small aquatic prober-gleaner, aquatic gleaner). Water level was correlated with shorebird abundance. The small aquatic prober-gleaner group comprised 85.9% of the total shorebird community. Shorebirds selected mudflat macrohabitats; (P < 0.05) and avoided disturbed, deciduous, and snags. All shorebird groups selected water microhabitat, except for the small aquatic prober-gleaner group that selected wet-land microhabitat (P < 0.05). There was a negative correlation (r(s) = -0.36, n = 58, P = 0.005) between pool level and number of shorebirds per survey. The relationship of water level and shorebird abundance may have more impact in an unmanaged wetland than managed wetlands. Tishomingo National Wildlife Refuge may be an important stopover site for small aquatic prober-gleaner species (e.g., western sandpipers, Calidris mauri) that require many stops along their migration routes.
Article
Some grow and others shrink as changing climate patterns and human demands for scarce water resources reshape the ecology of the world's salt lakes.
Article
A sequence of observations undergoes sudden changes at unknown times. We model the process by supposing that there is an underlying sequence of parameters partitioned into contiguous blocks of equal parameter values; the beginning of each block is said to be a change point. Observations are then assumed to be independent in different blocks given the sequence of parameters. In a Bayesian analysis it is necessary to give probability distributions to both the change points and the parameters. We use product partition models (Barry and Hartigan 1992), which assume that the probability of any partition is proportional to a product of prior cohesions, one for each block in the partition, and that given the blocks the parameters in different blocks have independent prior distributions. Given the observations a new product partition model holds, with posterior cohesions for the blocks and new independent block posterior distributions for parameters. The product model thus provides a convenient machinery for allowing the data to weight the partitions likely to hold; inference about particular parameters may then be made by first conditioning on the partition, and then averaging over all partitions. The parameter values may be estimated exactly in O(n3) calculations, or to an adequate approximation by Markov sampling techniques that are O(n) in the number of observations. The Markov sampling computations are thus practicable for long sequences. We compare this model with a number of alternative approaches to fitting change points and parameters when the error distribution is normal, then show that the proposed method is superior to the alternatives in detecting sharp short-lived changes in the parameters.
Article
Urmia Lake, located in a closed basin in north-west Iran, is the largest lake (5000–6000 km2) in the Middle East. It is very saline with total dissolved salts reaching 200 g/l compared with a normal seawater salinity of about 35 g/l. The construction of a causeway, which was initiated in 1979 but then abandoned until the early 2000s, is near completion and will provide road access between the western and eastern provinces. The causeway has an opening 1.25 km long and divides Urmia Lake into a northern and southern basin and restricts water exchange. The flow and salinity regimes are affected by the presence of this new causeway, and there are concerns over the well being of the Artemia population. This study investigates the effects of the construction of the causeway on flow and salinity regimes, considers remedial actions, and examines the effects of climatic variability on salinity and flow. Flow and salinity regimes were numerically simulated by using a commercially available two and three-dimensional (2D and 3D) MIKE model. The validity of the numerical model was assessed through sensitivity analysis of the model and comparing the simulated results against field measurements; the 3D model provided the higher correlation between simulated and actual data. Wind input was the main climatic and hydrologic factor influencing flow regime while river discharge, evaporation and rainfall were the key parameters affecting salinity distribution in the lake models. The 3D model was subsequently used to predict lake conditions in typical dry, wet and normal climates, to examine the environmental impacts from the new causeway, and to evaluate possible improvements that some remedial measures may provide.
Article
Salt lakes are geographically widespread, numerous and a significant part of the world's inland aquatic ecosystems. They are important natural assets with considerable aesthetic, cultural, economic, recreational, scientific, conservation and ecological values. Some features, notably the composition of the biota, uniquely distinguish them from other aquatic ecosystems. The paper reviews the nature of environmental impacts and their effects upon salt lakes. Its aims are two-fold: to draw attention to the extensive damage that salt lakes have now undergone, and to indicate the likely status of salt lakes in 2025. Salt lakes develop as the termini of inland drainage basins where hydrological inputs and outputs are balanced. These conditions occur in arid and semi-arid regions (approximately one-third of total world land area). Many human activities threaten or have already impacted salt lakes, especially surface inflow diversions, salinization and other catchment activities, mining, pollution, biological disturbances (e.g. introduction of exotic species), and anthropogenically-induced climatic and atmospheric changes. The effects of such activities are always adverse and include changes to the natural character of salt lakes, loss of biodiversity and fundamental limnological changes. The effects are geographically widespread, mostly irreversible, and degrade the values of salt lakes. Four salt lakes are discussed, namely the Aral Sea in central Asia, Mono Lake in California, USA, and Lake Eyre and Lake Cantara South, in Australia. By 2025, most natural salt lakes will have undergone some adverse change. Many permanent ones will have decreased in size and increased in salinity, and many unnatural saline water-bodies will have appeared. In certain regions, many seasonally-filled salt lakes are likely to be drier for longer periods. The extent to which episodically-filled salt lakes will change by 2025 will largely depend upon the nature of climate change in arid regions. Objective cost/benefit analyses of adversely affecting salt lakes are rare, and international bodies have not properly recognized salt lakes as important inland aquatic ecosystems. To redress this situation, there is a need to raise awareness of: (1) the values of salt lakes, (2) the nature of threats and impacts from human activities, and (3) their special management requirements. More effective management and conservation measures need to be implemented. Mono Lake provides an example of what can be achieved in the conservation of salt lakes. Its conservation was largely brought about by (1) the commitment of a non-governmental organization which recognized its non-economic values, (2) the freedom to express views, (3) a legal system which took account of non-economic values, and (4) a legislature which implemented judicial findings. The conservation of Mono Lake was difficult; the conservation of other salt lakes is likely to be even more difficult. Only international pressure from appropriate organizations will be effective for the conservation of many.
Article
There is likely to be an increase in the area of the globe affected by drought under enhanced greenhouse gas conditions. Therefore water management and drought policy may need to be modified accordingly. Rainfall and potential evapotranspiration (PET) are the key factors defining meteorological drought, and the development of drought projections is facilitated by global climate model (GCM) simulations. This paper assesses how well a set of GCMs can reproduce observed characteristics of historical rainfall and PET on a regional basis and explores the implications for regional drought projections if the poorer performing GCMs are omitted. Fourteen of the GCMs used in the IPCC's 4th Assesment Report are considered and their results compared with 1951–2006 observed rainfall and PET over Australia. The results indicate that some GCMs can reproduce the observed spatial patterns of both the means and variability (represented as the coefficient of variation), but most GCMs fail to reproduce the linear long-term trends. There is less clear difference between the better and poorer GCMs at a national level, but there is a clearer distinction at the regional level. The omission of the poorer GCMs leads to a clearer sign of the likely change (either increase or decrease) in future drought intensity in some regions. It also results in a decreased range of model-to-model uncertainty in some regions. It is hoped such uncertainty reduction can be useful to end users, particularly for those dealing with water management. Copyright © 2010 Royal Meteorological Society
Article
The current conservation crisis calls for research and management to be carried out on a long‐term, multi‐species basis at large spatial scales. Unfortunately, scientists, managers, and agencies often are stymied in their effort to conduct these large‐scale studies because of a lack of appropriate technology, methodology, and funding. This issue is of particular concern in wetland conservation, for which the standard landscape approach may include consideration of a large tract of land but fail to incorporate the suite of wetland sites frequently used by highly mobile organisms such as waterbirds (e.g., shorebirds, wading birds, waterfowl). Typically, these species have population dynamics that require use of multiple wetlands, but this aspect of their life history has often been ignored in planning for their conservation. We outline theoretical, empirical, modeling, and planning problems associated with this issue and suggest solutions to some current obstacles. These solutions represent a tradeoff between typical in‐depth single‐species studies and more generic multi‐species studies. They include studying within‐ and among‐season movements of waterbirds on a spatial scale appropriate to both widely dispersing and more stationary species; multi‐species censuses at multiple sites; further development and use of technology such as satellite transmitters and population‐specific molecular markers; development of spatially explicit population models that consider within‐season movements of waterbirds; and recognition from funding agencies that landscape‐level issues cannot adequately be addressed without support for these types of studies. Movimientos de Aves y Conectividad de Humedales en la Conservación del Paisaje La actual crísis en la conservación exige de investigación y manejo a desarrollarse en escalas de largo plazo, basada en multiples especies y en espacios grandes. Desafortunadamente, los científicos, manejadores y las agencias frecuentemente ven frustrados sus esfuerzos para conducir estos estudios de gran escala debido a la carencia de tecnología, metodologia y soporte económico apropiados. Este tema es de particular interés en la conservación de humedales donde la perspectiva común de paisaje pudiera considerar un área extensa de tierra pero no incorpora humedales aptos que son frecuentemente usados por organismos con alta movilidad como lo son las aves acuáticas (aves playeras o de vados, ganzos, patos). Tipicamente estas especies tienen dinámicas poblacionales que requiren del uso de multiples humedales, sin embargo, este aspecto de su historia de vida frecuentemente es ignorado en la planeación de su conservación. Resaltamos problemas teóricos, empíricos, de modelado y de planeación asociados con este tema y sugerimos soluciones para algunos obstáculos actuales. Estas soluciones representan un intercambio entre estudios a profundidad de una sola especie y estudios genéricos multiespecie. Estos últimos incluyen el estudio de movimientos de las aves acuáticas entre y dentro estaciones en una escala espacial apropriada tanto para aves de amplia dispersión y especies mas estacionarias; censos en múltiples sitios; desarrollo y uso de tecnología como los transmisores vía satélite y marcadores moleculares específicos de poblaciones; desarrollo de modelos poblacionales espacialmente explícitos que consideren movimientos de las aves acuáticas durante las estaciones y el reconocimiento de las agencias patrocinadoras de que asuntos a nivel de paisaje no podrán ser adecuadamente afrontados sin el apoyo para este tipo de estudios.
Article
Throughout the world, diverse avian populations continuously utilize wetlands. The abundance of the resources, including shoreline habitat and food, has resulted in bird species that are adapted exclusively to this habitat and others that use this habitat only during portions of their life cycle or during migration. Today, we witness many adaptations which maximize benefit from this semi-aquatic life style, including: anatomical and morphological adaptations (including rear leg placement for swimming, bone and lung modifications for diving, water resistant plumage), adapted feeding tactics, modified migratory flight paths, and life history adaptations (Weller). These adaptations have created a dependency upon wetland habitat availability for sustained population levels. The effect of birds on wetland habitat is critical for the ecosystem. They are responsible for seed dispersal of many plants, and also for the dispersal of many invertebrates. In addition to the transfer of seeds and organisms, the birds have an effect on many wetland soils through their waste products, which can serve as nutrient deposits (WB). Birds are also critical to wetlands because they draw the attention of humans to the environment. Many critical pieces of wetland legislation have resulted from the pressure of waterfowl hunters who are concerned with the decline in habitat and the potential ramifications on their recreation. They are also critical to local economies, and then residents may choose to maintain wetlands for their recreational value rather than convert them for another use. Groups such as Ducks Unlimited and Audubon are able to work on a national level to preserve wetlands. In northern Michigan, coastal marshes nurture a diversity of plants and animals. The variance in perennial Great Lakes' water levels has sustained a myriad of plant species. With the long-term cycling of low and high water levels, many changes in micro-habitat occur which result in a shift of the entire biotic community. Plants are directly affected by nutrient availability and water saturation, thus becoming good indicators of many chemical and geophysical properties of the soil in the immediate area surrounding them. Bird populations are directly affected by plant presence and by the availability of insects, invertebrates, small mammals and other birds, which makes them an indicator of the entire productivity of an ecosystem (Weller). The cycling of water levels also has effects on the macro-habitat by significantly affecting the amount of shoreline which is nesting and foraging habitat for birds and therefore the bird populations. This effect was studied through the observation of bird species diversity and abundance at several northern Michigan coastal marsh sites and was compared to historical recrods to determine if Great Lakes' water levels had an effect on bird species diversity and abundance. http://deepblue.lib.umich.edu/bitstream/2027.42/54904/1/3345.pdf
Ramsar Sites Information Service
  • Ramsar
Ramsar (1970). Ramsar Sites Information Service. Available at http://go.nature. com/2frAOR9 (accessed 4 August 2020).
Species composition and the effects of water level fluctuation on waterbird population at inmagyi wetland in myinmu township, Sagaing region
  • H Khaing
  • M M Sein
Khaing H. and Sein M.M. (2019). Species composition and the effects of water level fluctuation on waterbird population at inmagyi wetland in myinmu township, Sagaing region. Journal of the Myanmar Academy of Arts and Science 17, 283-300.
Lake Rezaiyeh: a specialised summer habitat for Shelduck and Flamingos
  • C Savage
Savage C. (1964) Lake Rezaiyeh: a specialised summer habitat for Shelduck and Flamingos. Wildfowl 15, 108-113.