Article

A salt lake under stress: Relationships among birds, water levels, and invertebrates at a Great Basin saline lake

February 2018
Biological Conservation 220

DOI:10.1016/j.biocon.2018.02.003

Authors:

Nathan R. Senner

University of Massachusetts Amherst

S Trent Seager

Sustainable Northwest

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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.

Functional Wetland Loss Drives Emerging Risks to Waterbird Migration Networks

Article

Full-text available

Mar 2022

Migratory waterbirds (i.e., shorebirds, wading birds, and waterfowl) rely on a diffuse continental network of wetland habitats to support annual life cycle needs. Emerging threats of climate and land-use change raise new concerns over the sustainability of these habitat networks as water scarcity triggers cascading ecological effects impacting wetland habitat availability. Here we use important waterbird regions in Oregon and California, United States, as a model system to examine patterns of landscape change impacting wetland habitat networks in western North America. Wetland hydrology and flooded agricultural habitats were monitored monthly from 1988 to 2020 using satellite imagery to quantify the timing and duration of inundation—a key delimiter of habitat niche values associated with waterbird use. Trends were binned by management practice and wetland hydroperiods (semi-permanent, seasonal, and temporary) to identify differences in their climate and land-use change sensitivity. Wetland results were assessed using 33 waterbird species to detect non-linear effects of network change across a diversity of life cycle and habitat needs. Pervasive loss of semi-permanent wetlands was an indicator of systemic functional decline. Shortened hydroperiods caused by excessive drying transitioned semi-permanent wetlands to seasonal and temporary hydrologies—a process that in part counterbalanced concurrent seasonal and temporary wetland losses. Expansion of seasonal and temporary wetlands associated with closed-basin lakes offset wetland declines on other public and private lands, including wildlife refuges. Diving ducks, black terns, and grebes exhibited the most significant risk of habitat decline due to semi-permanent wetland loss that overlapped important migration, breeding, molting, and wintering periods. Shorebirds and dabbling ducks were beneficiaries of stable agricultural practices and top-down processes of functional wetland declines that operated collectively to maintain habitat needs. Outcomes from this work provide a novel perspective of wetland ecosystem change affecting waterbirds and their migration networks. Understanding the complexity of these relationships will become increasingly important as water scarcity continues to restructure the timing and availability of wetland resources.

Assessing the contemporary status of Nebraska’s eastern saline wetlands by using a machine learning algorithm on the Google Earth Engine cloud computing platform

Article

Full-text available

Mar 2022
ENVIRON MONIT ASSESS

Nebraska’s eastern saline wetlands are globally unique and highly vulnerable inland salt marsh ecosystems. This research aims to evaluate the status of the saline wetlands in eastern Nebraska to discover the conditions of saline wetland hydrology, hydrophytes, and hydraulic soil. The research adopts machine learning and Google Earth Engine to classify Sentinel-2 imagery for water and vegetation classification and the National Agriculture Imagery Program imagery for salinity conditions. Six machine learning models are applied in water, soil, and vegetation detection in the study area. The optimal model (linear kernel SVM) generates an overall accuracy of 99.95% for water classification. For saline vegetation classification, the optimal model is the gradient tree boost with an overall accuracy of 94.07%. The overall accuracy values of saline soil classification using the optimal model (linear kernel SVM) varied among different years. The results of this study show the possibility of an observation approach for continuously monitoring Nebraska’s eastern saline wetlands. The water classification results show that the saline wetlands in this area all have a similar temporal water cover pattern within each year. For saline vegetation, the peak season in this area is between June and July. The years 2019 (19.00%) and 2018 (17.69%) had higher saline vegetation cover rates than 2017 (10.54%). The saline soil classification shows that the saline soil area is highly variable in response to changes in the water and vegetation conditions. The research findings provide solid scientific evidence for conservation decision-making in these saline wetland areas.

Functional wetland loss drives emerging risks to waterbird migration networks

Preprint

Full-text available

Jan 2022

Migratory waterbirds (i.e., shorebirds, wading birds, and waterfowl) are particularly vulnerable to climate and land-use change. Life history strategies supported by an interdependent network of diffuse geographic regions can expose waterbird populations to multiple independent risks throughout their range. Emerging bottlenecks raise concerns over sustainability of continental wetland networks as water scarcity triggers ecological effects misaligned with waterbird habitat needs. Here we use important wetland regions in Oregon and California, USA, as a model system to examine impacts of these changes on waterbird migration networks in western North America. We monitored wetland hydrology and flooded agricultural habitats monthly from 1988 to 2020 using satellite imagery to quantify the timing and duration of inundation (a key delimiter of habitat niche values associated with waterbird use). Trends were binned by management practice and wetland hydroperiods (semi-permanent, seasonal, and temporary) to identify differences in their climate and land-use change sensitivity. Wetland results were assessed using 33 waterbird species to detect nonlinear effects of network change across a diversity of life cycle and habitat needs. Pervasive loss of semi-permanent wetlands was an indicator of systemic functional decline driven by cascading top-down effects of shifting ecosystem water balance. Shortened hydroperiods caused by excessive drying transitioned semi-permanent wetlands to seasonal and temporary hydrologies, a process that in part counterbalanced concurrent seasonal and temporary wetland losses. Expansion of seasonal and temporary wetlands associated with closed basin lakes offset wetland declines on other public and private lands, including wildlife refuges. Diving ducks, black terns, and grebes exhibited the most significant risk of habitat decline due to semi-permanent wetland loss that overlapped important migration, breeding, molting, and wintering periods. Shorebirds and dabbling ducks were beneficiaries of stable agricultural practices and top-down processes of functional wetland declines that operated collectively to maintain habitat needs. Outcomes from this work provide a novel perspective of wetland ecosystem change affecting waterbirds and their migration networks. Understanding the complexity of these relationships will become increasingly important as water scarcity continues to restructure the timing and availability of wetland resources.

Aquatic Invertebrate Community Resilience and Recovery in Response to a Supra-Seasonal Drought in an Ecologically Important Naturally Saline Lake

Article

Full-text available

Mar 2021

Climate induced drought is a prominent threat to natural saline aquatic ecosystems by modifying their hydrology and salinity, which impacts the biodiversity of these ecosystems. Lake Nyamithi is a naturally saline lake in South Africa that experienced the effects of a two-year supra-seasonal drought (2015–2016). This study aimed to determine potential effects of the drought and accompanying increased salinity (between 9.8 and 11.5 g L−1) on aquatic invertebrate communities of Lake Nyamithi, and assess their potential recovery following the drought. Aquatic invertebrates and water were collected for biodiversity and chemical assessments during predrought conditions (2014), the peak of the drought (2016) and after the site had received water (2017). Taxon richness was considerably reduced during the peak of the drought as many biota could not tolerate the increased salinity. Ecological resilience and recovery was evident in the lake since numerous biota (re)colonized the lake promptly after the site received water and salinity decreased (<8 g L−1). By the end of 2017, invertebrate biodiversity exceeded that of predrought conditions. Although some biota may be able to temporarily cope with extreme weather conditions, frequent or prolonged periods of drought and increased salinity pose a threat to naturally saline lakes such as Nyamithi and dilution with fresh water is vital for the persistence of species diversity and ecological integrity.

Climate-Altered Wetlands Challenge Waterbird Use and Migratory Connectivity in Arid Landscapes

Article

Full-text available

Mar 2019

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.

The drying of Lake Urmia and its consequences for waterbird assemblages

Article

May 2024

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.

Climate change and lithium mining influence flamingo abundance in the Lithium Triangle

Article

Full-text available

Mar 2022

The development of technologies to slow climate change has been identified as a global imperative. Nonetheless, such 'green' technologies can potentially have negative impacts on biodiversity. We explored how climate change and the mining of lithium for green technologies influence surface water availability, primary productivity and the abundance of three threatened and economically important flamingo species in the 'Lithium Triangle' of the Chilean Andes. We combined climate and primary productivity data with remotely sensed measures of surface water levels and a 30-year dataset on flamingo abundance using structural equation modelling. We found that, regionally, flamingo abundance fluctuated dramatically from year-to-year in response to variation in surface water levels and primary productivity but did not exhibit any temporal trends. Locally, in the Salar de Atacama-where lithium mining is focused-we found that mining was negatively correlated with the abundance of two of the three flamingo species. These results suggest continued increases in lithium mining and declines in surface water could soon have dramatic effects on flamingo abundance across their range. Efforts to slow the expansion of mining and the impacts of climate change are, therefore, urgently needed to benefit local biodiversity and the local human economy that depends on it.

Impact of dredging and opening of the sea mouth into the Pulicat lake at Rayadoruvu village of Vakadu Mandal, on the habitat of Pulicat Bird Sanctuary, Andhra Pradesh Final Report

Technical Report

Full-text available

Sep 2019

Impact of dredging and opening of the sea mouth into the Pulicat lake at Rayadoruvu village of Vakadu Mandal, on the habitat of Pulicat Bird Sanctuary, Andhra Pradesh.

Twenty-one Year Trends for Shorebirds, Waterfowl, and Other Waterbirds at Great Salt Lake, Utah

Preprint

Full-text available

May 2021

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 presumed to be high-quality habitat for migratory shorebirds, waterfowl, and other waterbirds at Great Salt Lake and associated wetlands. As expected for high-quality habitats, 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. Despite stable or positive aggregate trends, negative trends did occur in some individual survey units. Foraging, 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.

Development of a gold nanomaterial enabled colorimetric sensor method for the analysis of sodium chloride in seawater

Article

Nov 2019

In this study, a simple and practical gold nanoparticle enabled colorimetric sensor technique was developed for the detection of sodium chloride. The synthesis of gold nanoparticles was based on the chemical reduction of gold (III) chloride trihydrate using tri-sodium citrate that also served as a capping agent thus, protecting the particles against aggregation. UV–vis spectra and transmission electron microscopy were used to characterise the synthesized citrate capped gold nanoparticles. The colorimetric response of sodium chloride was performed by the gold nanoparticle sensor, based on the property of localized surface plasmon resonance. The interaction between sodium ions, chloride and tri-sodium citrate causes rapid aggregation of the gold nanoparticles conjugates, resulting in color conversion from wine red to blue which is clearly visible by the naked eye. Thereby, we propose the use of gold nanoparticles as colorimetric sensors, as they cause a color change when interacting with sodium chloride which is recognized easily by naked eye with high selectivity. The detection limit of the sensor calculated by the linear relationship of localised surface plasmon resonance for sodium chloride was found to be 1.18 parts per thousand and the lowest quantified amount was 3.57 parts per thousand, making the developed sensor to be highly sensitive. The practical applicability of the gold nanoparticles was also verified by the detection of sodium chloride in estuary and seawater samples.

ATLAS-Humedales Costeros-FINAL-ULS-MMA (1)

Book

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Aug 2024

Marcela Cristina Robles Iriarte

Effects of drought-induced stress on nematode communities in aquatic and terrestrial habitats of the Nebraska Sandhills

Article

Full-text available

Feb 2024

Introduction Global change events (e.g., worsening drought) are increasing environmental stress in a variety of terrestrial and aquatic habitats. The degree to which communities in soils and sediments are driven by temporal environmental changes across multiple habitat types from the same region is not clear. Methods We used nematodes, a common bioindicator of soil and sediment health, to determine how community diversity and composition are altered by rising alkalinity across lakes, shorelines, and prairies in the western Nebraska Sandhills. We sampled these three habitats from five lake basins spanning an alkalinity gradient (pH 7–11) across three years (2019, 2020, 2021). During our sampling, the Sandhills experienced a range of drought intensities, with 2019 being a wet year, followed by severe drought in 2020, and abnormally dry/moderate drought in 2021. To determine if diversity and composition of nematodes responded to increased alkalinity and drought-induced stress we used different modelling approaches, including Random Forest and pairwise comparisons. Results and discussion Overall, nematode diversity in lakes was most affected by increasing alkalinity over time, whereas in shorelines and prairies diversity was most reliant on bacterial diversity and potential nematode-nematode interactions. In comparison to shorelines and prairies, community composition in lakes was the least variable and consistently driven by pH and lake water levels. In contrast, compositions in the shorelines and prairies were more variable and explained at varying degrees by pH, year, lake basin, and climate-associated variables. In addition, relative abundance and compositional nature of select copious taxa were highly unpredictable, indicating potential instability in these habitats. Future research is necessary to address the ecologic stability of the Sandhills and determine where conservation efforts are most needed.

Disentangling responses of aquatic and terrestrial invertebrates to drying in saline streams and shallow lakes

Article

Full-text available

Apr 2024
AQUAT SCI

In inland aquatic ecosystems, drying and salinity can co-occur as natural stressors, affecting aquatic invertebrate communities. Despite recent appreciation of the importance of temporary waterbodies for terrestrial invertebrates, knowledge about the effects of drying on dynamics of aquatic and terrestrial invertebrate communities is scarce, especially in saline ecosystems. This study analyzed structural and compositional responses of both communities to the coupled effects of drying and salinity in two streams and two shallow lakes in Spain, during three hydrological phases: wet, contraction, and dry. In the two studied saline streams, the contraction phase presented the highest aquatic and terrestrial abundance and richness, and the main compositional changes were mainly due, to an increase in aquatic lentic taxa (e.g., Coleoptera), and Araneae and Formicidae as terrestrial taxa. In shallow lakes, which presented highly variable salinity conditions, the highest abundance and diversity values were found at the wet phase for aquatic invertebrates and at the dry phase for terrestrial invertebrates. Compositional invertebrate community changes were due to a decrease in Rotifera and Anostraca (aquatic taxa) in the contraction phase for aquatic communities, and to an increase of Araneae, Coleoptera, and Formicidae (terrestrial taxa) at the dry phase for the terrestrial. Our study evidences the significant effect of drying on both aquatic and terrestrial invertebrates communities in natural inland saline waters and the need to integrate aquatic and terrestrial perspectives to study temporary inland waters.

Developmental and reproductive costs of osmoregulation to an aquatic insect that is a key food resource to shorebirds at salt lakes threatened by rising salinity and desiccation

Article

Full-text available

Mar 2023

David B. Herbst

Saline lakes worldwide are undergoing drying, and as lake levels fall and areas contract, salinities increase. There is a critical need for data on salinity impacts to guide conservation for recovery of the aquatic productivity that supports migratory and breeding birds that depend on these habitats. Brine flies are key sources of food to these birds and are adapted for life in saline waters owing to their capacity for osmotic regulation. The sublethal effects on growth, development and reproduction were determined in experiments and field observations with the alkali fly Cirrula hians from alkaline lakes of differing salinity. The cost of osmoregulation to fitness from rising salinity was exhibited in slower growth rates of larvae, smaller size at maturity of pupae, reduced adult emergence success, and lower fecundity. The results identify a salinity management range of 25 to 100 g L⁻¹ that would optimize life history traits and productivity of this insect as a food source for birds.

Intensified Warming and Aridity Accelerate Terminal Lake Desiccation in the Great Basin of the Western United States

Article

Full-text available

Jan 2023

Terminal lakes in the Great Basin (GB) of the western US host critical wildlife habitat and food for migrating birds and can be associated with serious human health and economic consequences when they desiccate. Water levels have declined dramatically in the last 100+ years due to diversion of inflows, drought and climate change. Satellite‐derived environmental science data records (ESDRs) from the MODerate‐resolution Imaging Spectroradiometer (MODIS) (snow cover, evapotranspiration (ET) and land surface temperature (LST)), enable a unique approach to evaluate the effects of aridification on terminal lakes and to study their individual vulnerabilities. Surface and air temperatures in the GB are rising dramatically, with a sharp rise in the rate of increase observed beginning around 2011, while the number of days of snow cover is declining especially in the western mountainous part of the GB as exemplified in Mono Basin, California. Rising temperatures coincide with fewer days of snow cover, a decrease of inflow to the lakes and greater evaporation of water from the lakes. MODIS ESDRs show strong and statistically significant increasing surface temperature (LST) in the GB, a reduction in the number of days of snow cover, and mixed results in ET. ET declined slightly in the more arid parts of the GB due to greater moisture restrictions to evaporation from extended drought, while ET increased in the more‐vegetated, wetter, mountainous northeastern parts as temperatures have risen. Severe and costly ecological, human health and economic consequences are expected if the lakes continue to decline as predicted.

Challenges and solutions to biodiversity conservation in arid lands Arid ecosystems Threats and challenges Strategy Human well-beings in arid lands

Article

Oct 2022
SCI TOTAL ENVIRON

Biodiversity in arid-lands is very sensitive to some forms of perturbation and very slow to recover. • Arid-lands are vulnerable to agriculture such as grazing of cattle and irrigation, which need certification standards to ensure best practice and reduce impact. • Combined efforts of researchers, practitioners, policymakers, and local communities are needed to adopt a socio-ecological approach. The strategic goals of the United Nations and the Aichi Targets for biodiversity conservation have not been met. Instead , biodiversity has continued to rapidly decrease, especially in developing countries. Setting a new global biodiversity framework requires clarifying future priorities and strategies to bridge challenges and provide representative solutions. Hyper-arid, arid, and semi-arid lands (herein, arid lands) form about one third of the Earth's terrestrial Science of the Total Environment 857 (2023) 159695 ⁎ Corresponding authors. surface. Arid lands contain unique biological and cultural diversity, and biodiversity loss in arid lands can have a disproportionate impact on these ecosystems due to low redundancy and a high risk of trophic cascades. They contain unique biological and cultural diversity and host many endemic species, including wild relatives of key crop plants. Yet extensive agriculture, unsustainable use, and global climate change are causing an irrecoverable damage to arid lands, with far-reaching consequences to the species, groundwater resources, ecosystem productivity, and ultimately the commu-nities' dependant on these systems. However, adequate research and effective policies to protect arid land biodiversity and sustainability are lacking because a large proportion of arid areas are in developing countries, and the unique diversity in these systems is frequently overlooked. Developing new priorities for global arid lands and mechanisms to prevent unsustainable development must become part of public discourse and form the basis for conservation efforts. The current situation demands the combined efforts of researchers, practitioners, policymakers, and local communities to adopt a socio-ecological approach for achieving sustainable development (SDGs) in arid lands. Applying these initiatives globally is imperative to conserve arid lands biodiversity and the critical ecological services they provide for future generations. This perspective provides a framework for conserving biodiversity in arid lands for all stakeholders that will have a tangible impact on sustainable development, nature, and human well-being. Contents

Challenges and solutions to biodiversity conservation in arid lands

Article

Oct 2022
SCI TOTAL ENVIRON

The strategic goals of the United Nations and the Aichi Targets for biodiversity conservation have not been met. Instead, biodiversity has continued to rapidly decrease, especially in developing countries. Setting a new global biodiversity framework requires clarifying future priorities and strategies to bridge challenges and provide representative solutions. Hyper-arid, arid, and semi-arid lands (herein, arid lands) form about one third of the Earth's terrestrial surface. Arid lands contain unique biological and cultural diversity, and biodiversity loss in arid lands can have a disproportionate impact on these ecosystems due to low redundancy and a high risk of trophic cascades. They contain unique biological and cultural diversity and host many endemic species, including wild relatives of key crop plants. Yet extensive agriculture, unsustainable use, and global climate change are causing an irrecoverable damage to arid lands, with far-reaching consequences to the species, ground-water resources, ecosystem productivity, and ultimately the communities' dependant on these systems. However, adequate research and effective policies to protect arid land biodiversity and sustainability are lacking because a large proportion of arid areas are in developing countries, and the unique diversity in these systems is frequently overlooked. Developing new priorities for global arid lands and mechanisms to prevent unsustainable development must become part of public discourse and form the basis for conservation efforts. The current situation demands the combined efforts of researchers, practitioners, policymakers, and local communities to adopt a socio-ecological approach for achieving sustainable development (SDGs) in arid lands. Applying these initiatives globally is imperative to conserve arid lands biodiversity and the critical ecological services they provide for future generations. This perspective provides a framework for conserving biodiversity in arid lands for all stakeholders that will have a tangible impact on sustainable development, nature, and human well-being.

Coordinated phalarope surveys at western North American staging sites, 2019-2021

Technical Report

Full-text available

Sep 2021

To investigate phalarope population trends and conservation status, we conducted coordinated monitoring of western North American staging areas of historical importance to phalaropes: Great Salt Lake (Utah), Mono Lake (California), Lake Abert (Oregon), Owens Lake (California), south San Francisco Bay (California), and Chaplin Lake (Saskatchewan).

Waterbird guilds predict environmental attributes of inland saline aquatic ecosystems on multi-spatial scales

Article

Full-text available

Sep 2022
SCI TOTAL ENVIRON

Inland saline waters in Central Asia constitute an important part of steppe ecosystems, providing considerable ecological functions and ecosystem services. Here we aim to present a multi-spatial scale analysis of nutrient cycling and transport waterbird guilds, and the environmental attributes of saline-soda aquatic ecosystems in Kazakhstan. The density, biomass, and diversity of waterbird guilds was determined in the case of three nutrient cycling and transport guilds: a) net-importer (IM), b) importer-exporter (IMEX): c) net-exporter (EX), according to the Boros's guild classification method, and for several traditional feeding guilds: carnivorous, herbivorous, invertebrate eater, omnivorous and piscivorous. Our results revealed that waterbird guilds, as predictors represented by the complete waterbird community, are in close relationship with several (N = 12) environmental attributes of inland saline waters through complex trophic linkages of waterbird populations on multi-spatial scales. The density and the biomass of the IM and IMEX guilds are strongly and positively correlated (i) with the productivity metrics of habitats (e.g., CHL, GPP), indicating their trophic position, and (ii) with water depth. We found significant correlations among guild density, biomass diversity and environmental attributes on multi-spatial scales for IMEX and EX. Our results revealed that IMEX predicts the surrounding environment of aquatic habitats, whereas EX species are substantial environmental predictors of aquatic ecosystems. However, the diversity metric had valid models only with EX. The herbivorous and omnivorous guilds, that feed chiefly on plant materials consist mainly of IMEX and EX duck species, which were positively related to grassland coverage and the shoreline development index. As a methodological result, here we present a novel approach, the guild transport index, which has more robust relationships with environmental attributes than individual guilds, thus it provides a complex evaluation of the nutrient cycling by birds between aquatic and terrestrial environments on multi-spatial scales.

Some Water Quality Properties of Acı Lake and Meke Lake (Konya/ Turkey)

Article

Full-text available

Feb 2021

Living beings need water to sustain their lives. Usage, conservation and management of water supplies are therefore extremely important. Researches on the investigation of the water quality properties of aquatic ecosystems are frequently carried out. The purpose of this study is to determine water quality characteristics of Acı Lake and Meke Lake. The lakes are located in Konya Province, Karapınar District and they are important habitats for birds and other species. In this study, some physical and inorganic parameters were examined in Acı Lake and Meke Lake at July 2014, October 2014 and January 2015. During the study, water samples were taken seasonally from the stations in the lakes. Results were compared with water pollution control regulation (SKKY) and water intended for human consumption standards (TS-266). According to Pearson Correlation Index (PCI) analysis, physical and inorganic parameters relationships were determined. About the measurement results of the physical and inorganic parameters, temperature values at July 2014 in two lakes, electrical conductivity values for all measurements in two lakes, dissolved oxygen and oxygen saturation values at July 2014 and October 2014 in Meke Lake and color values for all measurements in Meke Lake exceeded the limit values specified in the regulations, values other than these were found within the limit values of the regulation. According to PCI results, physical and inorganic parameters showed positive and negative correlation with each other in Acı Lake and Meke Lake.

Corrigendum to: Biology and conservation of the unique and diverse halophilic macroinvertebrates of Australian salt lakes

Article

Oct 2021

This study synthesises information on the biology of the unique and diverse halophilic macroinvertebrates of Australian salt lakes, focusing on gastropods and crustaceans. This information is needed to evaluate and manage the threats posed to these invertebrates by increased periods of drought and secondary salinisation. Most of these species are endemic to Australian salt lakes, and some have adapted to extreme conditions (e.g. salinities >100gL^–1 and pH <5). This study identifies key general findings regarding the taxonomy, ecology and life histories of these invertebrates, such as that many ‘new’ species have been uncovered in the past 20 years, with more likely to come. The study also identifies critical knowledge gaps, such as the need to elucidate the abiotic and biological drivers of the field distributions of species, including why some species are widespread and common whereas other congeneric species are rare or have narrow distributions. Those species that are either restricted to low salinity environments or survive dry periods as aestivating adults (as opposed to desiccation-resistant eggs) are probably the most vulnerable to increasing salinisation and drought. Future work should prioritise the development of a sound taxonomy for all groups, because this is needed to underpin all other biological research.

Biology and conservation of the unique and diverse halophilic macroinvertebrates of Australian salt lakes

Article

Full-text available

Jul 2021

This study synthesises information on the biology of the unique and diverse halophilic macroinvertebrates of Australian salt lakes, focusing on gastropods and crustaceans. This information is needed to evaluate and manage the threats posed to these invertebrates by increased periods of drought and secondary salinisation. Most of these species are endemic to Australian salt lakes, and some have adapted to extreme conditions (e.g. salinities >100 g L-1 and pH <5). This study identifies key general findings regarding the taxonomy, ecology and life histories of these invertebrates, such as that many 'new' species have been uncovered in the past 20 years, with more likely to come. The study also identifies critical knowledge gaps, such as the need to elucidate the abiotic and biological drivers of the field distributions of species, including why some species are widespread and common whereas other congeneric species are rare or have narrow distributions. Those species that are either restricted to low salinity environments or survive dry periods as aestivating adults (as opposed to desiccation-resistant eggs) are probably the most vulnerable to increasing salinisation and drought. Future work should prioritise the development of a sound taxonomy for all groups, because this is needed to underpin all other biological research.

Does salinity have an influence on the diversity and structure of the wintering waterbirds of the Saharan wetlands in Algeria?

Article

Full-text available

May 2021

Influeix la salinitat en la diversitat i l’estructura dels ocells aquàtics hivernants als aiguamolls del Sàhara, a Algèria? Durant el període 2017-2019 es van registrar 42 espècies d’ocells aquàtics hivernants al complex d’aiguamolls de la vall d’Oued Righ, al Sàhara algerià. Les diferències de salinitat expliquen les variacions en la riquesa d’espècies i en la distribució dels ocells aquàtics als diversos aiguamolls estudiats. Els ambients oligohalins (0,5-5 ‰) i mesohalins (5-18 ‰), representats pel llac Aiata, el llac Sidi Khelil i l’Oued Kherouf, són els més favorables per als anàtids, excepte el gènere Tadorna, que és present als punts d’estudi euhalins (30-40 ‰) i hiperhalins (> 40 ‰). El flamenc rosat Phoenicopterus roseus i la gavina de bec prim Chroicocephalus genei es distingeixen per ser presents a les zones més holomorfes del complex com ara Chott Merouane. Dades publicades a GBIF (Doi: 10.15470/6fqd0h)

Wetland Conservation: Challenges Related to Water Law and Farm Policy

Article

Full-text available

Jun 2021

Water is essential for wetland function and sustaining migratory networks for wetland wildlife across broad landscapes. Groundwater declines and surface flow reductions that impact aquatic and wetland organisms are common in the western U.S. and increasingly in the eastern U.S. Agriculture is the largest consumptive water use in the U.S. and understanding economic incentives of water-use practices and the legal context of water rights is foundational to identifying meaningful water solutions that benefit all sectors of society. In this paper, we provide a brief overview of water rights in the U.S. and synthesize the literature to provide a broad overview of how federal farm policy influences water-use decisions. We conclude that the ultimate cause of many water-use conflicts is an inefficient farm economy that is driven by several proximate factors, of which outdated water laws and subsidies that encourage increased water use are among the most important. Development of multi-scale water budgets to assess project impacts and by working more intensively at local watershed and aquifer scales may improve conservation efforts. Finally, detailed analyses to understand the impacts of specific federal policies on agricultural water use may enhance water conservation efforts, facilitate long-term food and water security, and provide greater protection for wetland and aquatic resources.

Coordinated phalarope surveys at western North American staging sites, 2019-2020

Technical Report

Full-text available

Mar 2021

Given saline lake habitat is threatened worldwide by water diversion and climate change, there is an urgent need to better understand phalarope population and trends. We conducted coordinated monitoring of western North American staging areas of historical importance to phalaropes: Great Salt Lake (Utah), Mono Lake (California), Lake Abert (Oregon), Owens Lake (California), south San Francisco Bay (California), and Chaplin Lake (Saskatchewan). We conducted surveys at each site during week-long “survey windows,” from mid-July to mid-September, 2019 and 2020, with the goal of at least one survey per site per window. Methods were standardized within sites but varied across sites, including plane-based, boat-based, and land-based surveys. We report results from Great Salt Lake, Mono Lake, and Lake Abert in 2019 and for all surveyed sites in 2020.

Simulation of Lake Water Volume in Ungauged Terminal Lake Basin Based on Multi-Source Remote Sensing

Article

Full-text available

Feb 2021

Obtaining the water volume of small-and medium-sized lakes in enclosed watersheds with scarce data is a global focus of research. River flow into a lake is an important factor affecting the water volume. However, most river flow measurement methods involve long cycles, low efficiency , and transdisciplinary expertise, making rapid assessments in ungauged basins impossible. This paper proposes a remote sensing flow estimation method based on multi-source remote sensing data, which quickly assesses river flow and provides important input data for lake water volume simulation. The cross-section flow was estimated by extracting the river width. The calculated results were consistent with the measured data, with accuracy greater than 90%. The results compared with daily data measured at hydrological stations, and the Nash coefficient was greater than 0.9. Additionally, the simulation method for lake area, water volume, and water level was constructed using river inflow input data, greatly reducing the parameters required by the conventional lake water volume simulation method. Based on the remote sensing discharge estimation method, we quickly and conveniently obtained changes in river flow into the lake, simulated lake water volume, and provided the basis for water resource management in terminal lake basins with scarce data.

Spatiotemporal Variation of Siberian Crane Habitats and the Response to Water Level in Poyang Lake Wetland, China

Article

Full-text available

Jan 2021

The Poyang Lake wetland in China is the largest wintering destination for Siberian cranes worldwide. Understanding the spatiotemporal characteristics of crane habitats is of great importance for ecological environment governance and biodiversity protection. The shallow water, grassland, and soft mudflat regions of the Poyang Lake wetland are ideal habitats for wintering Siberian cranes. Based on Landsat Thematic Mapper (TM), Enhanced Thematic Mapper Plus (ETM+), and Operational Land Imager (OLI) remote sensing images, habitat areas were extracted and associated with various water levels taken on multiple dates. Landscape metrics were applied to describe the spatial structural characteristics of the crane habitats, and spatial statistics are used to explore the cold and hot spots of their distribution. Moreover, three indicators including sustainability, stability, and variety were applied to evaluate the vulnerability of the crane habitats under different hydrological conditions. Our findings indicate: (a) The main crane habitats exhibit a gradual decreasing degree of fragmentation in time, an obvious uncertainty of shape complexity and a relatively stable connectivity. (b) The crane habitats have a consistent spatial pattern of highly aggregated distributions associated with various water levels. (c) The hot spots of the habitats formed multiple “sheet” belts centered on the “Lake Enclosed in Autumn” regions, while the cold spots indicate a spatial pattern of axial distributions. (d) The majority of the hot spots of the habitats were distributed in sub-lakes found in the southeast part of the Poyang Lake watershed and the Nanjishan and Wucheng nature reserves, while the cold spots were mainly distributed in the main channels of the basins of Poyang Lake. (e) The sustainable habitats were mainly distributed in the “Lake Enclosed in Autumn” regions and intensively aggregated in two national nature reserves. (f) Under conditions of extremely low to average water levels (5.3–11.46 m), an increase of water level causes a decrease of the stability and variety of the crane habitats and weakens the aggregation structure.

Great Salt Lake Biology A Terminal Lake in a Time of Change

Chapter

Full-text available

Jan 2020

Michael R. Conover

Conserving Freshwater Biodiversity in an African Subtropical Wetland: South Africa’s Lower Phongolo River and Floodplain

Chapter

Full-text available

Oct 2020

Freshwater biodiversity is under constant threat from a range of anthropogenic stressors. Using South Africa’s Phongolo River and floodplain (PRF) as a study case, the aim of this chapter is to provide an overview of the conservation and management of freshwater biodiversity in a highly diverse subtropical ecosystem. The PRF is the largest floodplain system in South Africa which is severely threatened by irregularly controlled flood releases from a large upstream dam, prolonged drought, deteriorating water quality, organic pollutants and the increasing dependence of the local communities. Based on a decade of survey of the PRF conducted from 2010 to 2020, this chapter highlights the current diversity of aquatic organisms (invertebrates, fishes, frogs and their parasitic fauna), followed by an overview of their biological and physical stressors. The current challenges in the management of the aquatic biodiversity of this region and a way forward to conservation strategies are also addressed in this chapter.

Freshwater Biome of the World

Chapter

Jan 2020

Of the Earth's three major biomes or realms, freshwater is the smallest, dwarfed in size and extent by terrestrial and marine realms. It has also been the most exposed to human exploitation, resulting in higher declines of biodiversity compared to other realms, primarily because of human reliance on fresh water and invasive species. Major sub-biomes in the freshwater realm can be grouped into seven categories: rivers and streams, lakes (salt, freshwater, oases and springs), palustrine wetlands (swamps, marshes, and floodplains), transitional waters (including estuarine and coastal lagoons), brackish tidal systems (deltas, intertidal forests, saltmarshes), subterranean water bodies and artificial wetlands (dams, rice paddies, aquaculture, canals and channels). A range of key freshwater characteristics, including the hydrological regime, water quality, and influences from terrestrial and marine drivers, form unique ecosystems around the world, providing for diverse species but ones which share many functional traits, reflected in convergent evolution. Direct or indirect appropriation of water resources (consumption, agriculture, and hydro-electricity) and disposal of waste water has devastated many of the world's freshwater ecosystems. Their protection demands identification of sustainable and cost-effective management of hydrological regimes and inflows, including protection and restoration of flows for the environment as well as management of invasive species, stopping habitat destruction and pollution.

Climate and human water use diminish wetland networks supporting continental waterbird migration

Article

Full-text available

Jan 2020

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.

Determinación del riesgo de los impactos del Cambio Climático en las costas de Chile. HUMEDALES

Technical Report

Full-text available

Jan 2020

Patricio Winckler

Volumen 6: Vulnerabilidad en humedales, en “Determinación del riesgo de los impactos del Cambio Climático en las costas de Chile”

Technical Report

Full-text available

Dec 2019

El estudio Determinación del riesgo de los impactos del Cambio Climático en las costas de Chile busca generar información de proyecciones de la amenaza, exposición, vulnerabilidad y riesgo de los sistemas humanos y naturales de la zona costera ubicados en 104 comunas de Chile continental, además de Rapa Nui y el Archipiélago Juan Fernández. El objetivo de este estudio es sentar las bases para el diseño de políticas e implementación de medidas de adaptación. El estudio se desarrolló entre octubre de 2019 y octubre de 2019 y se presenta mediante un resumen ejecutivo, 8 volúmenes temáticos y un Sistema de Información Geográfica (SIG). El equipo desarrollador consiste en 21 investigadores de 5 universidades (PUC, UV, UPLA, PUCV y UCM) y 3 centros de investigación (CCG-UC, CIGIDEN y COSTAR-UV). El estudio de amenaza se basa en el análisis histórico del oleaje y del nivel medio del mar (NMM), además de una proyección para el período 2026-2045 de estas variables y de la cota de inundación. En primer lugar, se analiza el comportamiento histórico del oleaje obtenido a partir un modelo numérico (WWIII) cada 2° de latitud (1980-2015). El análisis de clima medio del oleaje concluye que ha habido un incremento leve en la altura y el período, además de un giro al sur del oleaje, probablemente asociados a la migración al sur del Anticiclón Permanente del Pacífico Sur. El análisis de clima extremo demuestra en todo Chile se ha registrado un aumento en la cantidad de marejadas de 0.1 a 0.3 eventos más por año, dependiendo de la latitud. El estudio de NMM, basado en el análisis de 11 mareógrafos con más de 30 años de data, muestra que no existe una tendencia clara de aumento en Chile, lo que puede atribuirse a las deformaciones de la corteza producto del ciclo sísmico. En particular, en el norte existe un descenso del NMM probablemente asociado al acoplamiento de las placas tectónicas luego del terremoto de 1877. En segundo lugar, el estudio busca evaluar los cambios del oleaje (marejadas), NMM y cota de inundación entre el período histórico (1985-2004) y la proyección (2026-2045) correspondiente al escenario de emisiones RCP 8.5 del IPCC. El estudio de oleaje basa en el forzamiento del modelo WWIII mediante 6 modelos de viento en toda la cuenca del Pacífico. El modelo es calibrado y validado con registros de boyas direccionales y altimetría satelital entre 1980 y 2015. El estudio de clima medio concluye que la altura de ola y el período seguirán incrementándose levemente y el oleaje girará más al sur, también en forma moderada. Los eventos extremos, no obstante, serán más frecuentes e intensos, sobretodo en la zona central de Chile, lo que seguramente aumentará los daños en la infraestructura costera. El estudio de NMM, por su parte, se basa en 21 modelos disponibles en el CMIP5 los cuales se analizan cada 5 [km] en forma latitudinal. El estudio concluye que en todo Chile, incluidas Rapa Nui y Juan Fernández, se espera un ascenso de 0.15 a 0.18 [m], con un rango de incertidumbre del orden de ±0.1 [m] para la proyección. A fines de siglo, no obstante, el incremento sería del orden de 0.65 ±0.3 [m]. La cota de inundación, calculada a partir del oleaje, el NMM, la marea astronómica y la marea meteorológica, presenta valores de 2.5 [m] NRS en el extremo norte a 3.5 [m] NRS en el Canal Chacao para el escenario histórico y de entre 2.8 a 3.8 [m] NRS para ambos extremos. El aumento de la cota de inundación abarca desde +0.23 a +0.29 [m] en los extremos sur y norte, respectivamente. El estudio de exposición consiste en elaborar un modelo de elevación digital (DEM) en 106 comunas a partir de tres fuentes satelitales (ASTER GDEM-2, ALOS WORLD 3D y ALOS PALSAR). A partir del DEM se elabora un inventario de exposición de los sistemas humanos y naturales ubicados bajo los 10 metros sobre el nivel del mar (msnm). El inventario es generado a partir de información disponible en los servicios públicos, levantamientos en terreno y talleres efectuados en Antofagasta, Valparaíso y Concepción. Luego de un proceso de limpieza de 174.746 registros identificados inicialmente, se llega a un inventario con 18.376 entradas, separadas en 6 categorías (población, infraestructura, equipamiento, economía, sistemas naturales y otros), subdivididas a su vez en 76 tipos de entidades. La información más relevante del inventario es presentada a nivel nacional, regional y comunal. En síntesis, el inventario identifica un total de 972.623 personas habitando en los primeros 10 msnm y que en dicha área se ubican 546 caletas de pescadores, 1692 humedales, 256 campos dunares, 1172 playas, 156 lugares de interés para la biodiversidad, 1198 equipamientos (colegios, jardines infantiles, carabineros, entre otros), 171 terminales marítimos, 475 elementos de infraestructura costera y 477 asentamientos, entre otros elementos (Tabla 22, Volumen 1). A partir inventario y mediante el juicio experto, se definen 12 comunas críticas en las que se utilizan planos de borde costero del SHOA para refinar el cálculo de la vulnerabilidad. Las comunas críticas son Antofagasta, Coquimbo, Viña del Mar, Valparaíso, Pichilemu, Talcahuano, Coronel, Arauco, Puerto Saavedra, Valdivia, Rapa Nui y el Archipiélago Juan Fernández; ambas últimas que se detallan en el volumen de vulnerabilidad y riesgo en islas oceánicas. El estudio de vulnerabilidad se orienta a los sistemas humanos y naturales identificados en el estudio de exposición. Dada la gran cantidad y complejidad de categorías (6) y entidades existentes (76), el análisis se reduce a evaluar si cada objeto del inventario de exposición será o no inundado durante la proyección (2026-2045) bajo el escenario RCP 8.5. Las líneas de inundación para el período histórico y la proyección se presentan en el SIG. El estudio concluye que 589 manzanas censales, 46357 personas y 18338 viviendas pasarían a ubicarse en zonas de inundación. Lo mismo ocurriría 17 puentes, 4245 puntos de la red vial, 8 centros de distribución de energía por hidrocarburos, 1 central termoeléctrica, 2 subestaciones y 53 elementos de infraestructura sanitaria. Con respecto al equipamiento comunal, 10 edificaciones de bomberos, 7 establecimientos de salud, 49 de educación y 5 de policía se ubicarían en zonas inundables. Por último, se identifican 358 elementos asociados al turismo en dichas zonas. Adicionalmente, y en volúmenes separados, se caracteriza la vulnerabilidad (y cuando es posible el riesgo) de playas, caletas, puertos y humedales, proponiendo también medidas de adaptación específicas para estos sistemas. En el estudio de vulnerabilidad en playas se determinan los cambios en la posición de la línea litoral para 35 playas en las regiones de Antofagasta, Coquimbo, Valparaíso, O’Higgins y Biobío. Para ello se usa el software DSAS, fotografías aéreas, imágenes satelitales y levantamientos topográficos. El análisis cubre desde 39 años (La Serena) a sólo 3 años (Lebu-Tirúa), pero en 33 playas exceden los 20 años. Los resultados integrados en el SIG indican que el 9% de estas playas presenta erosión alta (mayor a 1.5 m anuales), el 71% erosión, el 11% un estado estable y solo un 9% acreción. Los casos de mayor erosión corresponden a extensos litorales arenosos, asociados a campos dunares y humedales. El estudio histórico no establece las causas que explican la erosión generalizadas, que pueden ser de origen oceanográfico, geofísico, antrópico o hidrológico. En el estudio de riesgo en playas se estima, en forma general, que aquellas playas ubicadas entre Arica y el Canal Chacao experimentarán retrocesos medios de entre 3 y 23 [m] por efecto de cambios en oleaje y nivel del mar en el escenario RCP 8.5 en el período 20262045. La tendencia es que playas largas experimenten erosión en sus extremos sur y acreción en sus extremos norte debido a un leve cambio en la dirección del oleaje. La estimación del daño económico calculado en forma específica para 6 playas en la Región de Valparaíso permite estimar una pérdida cercana a los 500 mil dólares anuales producto del riesgo de erosión causada por cambio climático. En el estudio de vulnerabilidad en puertos se analiza el impacto histórico asociado a la pérdida de disponibilidad de sitios de atraque debido a oleaje (downtime). A partir de los certificados de cierre de puerto (2015 a 2017) y una base de datos de SERVIMET (2007 a 2014) se concluye que, entre 2008 y 2017, se registraron 9097 cierres de puerto en 19 capitanías expuestas al Océano Pacífico de las cuales se contó con información. Los puertos con mayor cantidad de cierres son Arica (850), Tocopilla (802) y Quintero (761). El estudio de riesgo en puertos se evalúa el downtime operacional en 9 puertos en Chile (Arica, Iquique, Mejillones, Antofagasta, Coquimbo, Quintero, Valparaíso, San Antonio y San Vicente). El oleaje en aguas profundas se transfiere a cada puerto utilizando un modelo numérico (SWAN). Luego, el downtime, expresado en horas de cierre por año, se calcula comparando el clima del oleaje local con límites operacionales definidos en la ROM 3.1-99 (PPEE, 2000) para el período histórico (1985-2004) y la proyección (2026-2045). Se concluye que algunos puertos mejorarán y otros empeorarán su operatividad y que el clima extremo será más severo a mediados de siglo. La mejora operativa puede explicarse por el giro al sur del oleaje que mejoraría las condiciones de abrigo de puertos ubicados en el extremo sur de las bahías. En términos económicos, el análisis a nivel agregado para los 9 puertos se traduce en pérdidas de US

4,12 millones anuales y ganancias por US

6,34 millones anuales, dando como resultado unas ganancias netas de US

2,22 millones anuales como efecto del cambio climático. El aumento del NMM, sumado al incremento en la frecuencia e intensidad de las marejadas, no obstante, significará un aumento significativo del sobrepaso y del daño estructural de obras portuarias. Se proponen medidas de adaptación para mejorar las condiciones operacionales y para la gestión de la infraestructura en un contexto de clima futuro más severo que el actual. Dada su similitud operacional, el estudio de vulnerabilidad en caletas equivale al de puertos y busca mostrar que estas han experimentado numerosos cierres debido a marejadas en la última década. En el estudio de riesgo en caletas de pescadores se evalúa el downtime operacional de las 546 caletas agrupadas cada 2° de latitud para el período histórico (1985-2004) y la proyección (2026-2045), considerando los límites operacionales definidos en base a focus groups y encuestas para diferentes actividades (buzos, recolectores, embarcaciones de eslora inferior y superior a 12 m). El oleaje en aguas profundas se transfiere a la costa utilizando una metodología simplificada que rescata la física fundamental de la zona de aproximación a la costa, pero no las condiciones locales de cada caleta. El análisis concluye que un 23% de los registros pesqueros artesanales se encuentran en zonas con predicciones de aumento en downtime de pesca (19°S a 34S). Hacia el sur, las condiciones operacionales asociadas al oleaje mejorarían en la proyección. Considerando los valores de desembarque y de precios en playa del año 2017, se estima una pérdida a nivel agregado que podría fluctuar entre los US

1,3 y 7,6 millones anuales para las caletas ubicadas entre los 19°S y 34°S, dependiendo del escenario. Las pérdidas en desembarque representan alrededor de un 2-5% de capturas actuales. El estudio de vulnerabilidad de humedales presenta la distribución comunal de 1692 humedales costeros. A nivel específico y dependiendo de la disponibilidad de información y levantamientos en terreno, se identifica una tendencia general a la reducción del área de los espejos de agua (18 de 21 casos analizados) que podría explicarse por la reducción de los caudales (100% de 30 ríos analizados). Debido al incremento histórico de la frecuencia e intensidad de las marejadas extremas, los episodios de sobrepaso que aportan agua salada a los humedales podrían generar cambios en el patrón de dominancia de las especies vegetales levantadas en los humedales costeros. No obstante, los cambios identificados en los humedales podrían deberse a otros factores no estudiados como la influencia de perturbaciones naturales provenientes de la cuenca (aluviones), al efecto del pastoreo ejercido por vacas y caballos, al pisoteo de turistas y al efecto combinado de dichos factores, tsunamis y tormentas marinas.

Threatened habitat at Great Salt Lake: Importance of shallow-water and brackish habitats to Wilson’s and Red-necked phalaropes

Article

Full-text available

May 2019

Great Salt Lake (GSL) is the largest hypersaline lake in North America and is the fall staging area for a high proportion of North America’s Wilson’s Phalaropes (Phalaropus tricolor) and Red-necked Phalaropes (Phalaropus lobatus). Unfortunately, diversion of freshwater for agriculture and development has decreased the size of GSL by 48%. To assess the potential impact of a smaller GSL on phalaropes, we collected data from 2013 to 2015 from sites where large, dense flocks of phalaropes congregated and sites where there were no phalaropes. At each site, we measured the densities of invertebrates that were preyed upon by phalaropes, including larval and adult brine flies (Ephydridae), adult brine shrimp (Artemia franciscana), chironomid larvae (Chironomidae), and corixid adults (Corixidae). Abiotic characteristics measured included water depth, water salinity, water temperature, wind speed, and benthic substrate. We analyzed high-salinity sites separately from low-salinity sites because they contained different invertebrates. High-salinity sites were in Carrington and Gilbert bays and were relatively deep (mostly <2 m). At the high-salinity sites, phalaropes exhibited a preference for sites with an abundance of adult brine flies and for microbialite substrates. The low-salinity sites were in Ogden and Farmington bays and were shallow (<1 m). At low-salinity sites, large phalarope flocks were more likely to occur at sites that were shallower, less saline, and had a high biomass of benthic macroinvertebrates. Our results indicate that physical features and prey availability are both important in determining phalarope habitat use at GSL. Phalaropes prefer to use shallower parts of GSL and brackish waters. These areas will be especially impacted by decreased freshwater inflow into GSL.

Wetlands dynamics analysis: a case study of Keoladeo National Park (India), the wintering grounds of West Siberian white crane population

Article

Full-text available

Dec 2023

The work is devoted to the study of the dynamics of the wetlands area in the Keoladeo National Park (Bharatpur province, Rajasthan, India) over the past decades in connection with changes in climatic parameters to assess the wintering conditions of the endangered West Siberian White Crane population (Leucogeranus (=Grus) leucogeranus Pallas, 1773). The article presents the results of a statistical analysis of the main meteorological parameters (average maximum and minimum temperatures of the surface layer of the atmosphere in 1971–2022, average precipitation per year and from October to March (the wintering period of West Siberian White Crane) in 1958–2021); the results of an analysis of the ratio of areas of different types of habitats according to remote sensing data in 1972–2022; the results of statistical analysis of the volume of water entering the park from the Ajahn Bund reservoir in 1980–2010. During the study period, a significant increase in the average maximum and minimum temperatures of the winter period was revealed, which, along with the absence of a significant trend towards an increase in the average amount of precipitation and an increase in the number of dry years, indicates a warming climate with an increase in its aridity. A statistically significant reduction in the area of habitats suitable for West Siberian White Crane has been established. This indicates a significant decrease in the water level in the Keoladeo wetlands, both due to increased evaporation and a significant reduction in the volume of water entering the park from the reservoir. The results of the study show that in the conditions of observed climate changes, the main regulators of the water level and the state of the ecosystem of the Keoladeo wetlands are agricultural users, whose water consumption increases with increasing aridity of the climate.

Twenty-One Year Trends for Shorebirds, Waterfowl, and Other Waterbirds at Great Salt Lake, Utah

Article

Feb 2023

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.

A Note of a Unique Inland, Saline Water Fishery: Brine Flies (Diptera: Ephydridae) of Lake Cuitzeo, Mexico

Article

Full-text available

Mar 2022

Fisheries in Cuitzeo, the second largest Mexican lake, used to take place on the permanent freshwater East and Central Basins as opposed to the temporal, saline, and initially thought barren West Basin. The 1980 fisheries collapse forced fishers to look for non-conventional fishing products elsewhere in the lake. The West Basin’s temporal, saline-alkaline, and shallow water provides exceptional habitat for ephydrids to flourish. Locally known as “pupa”, ephydrids are collected in large numbers. Although consumed since pre-Hispanic times, no other commercial fisheries of ephydrids are known worldwide. This study records the species composition and abundance of the “pupa” throughout an annual cycle in the West Basin, where fisheries occur. Two species were found: Ephydra hians and Lamproscatella muria. Ephydrids co-occurred in June and July at the end of the dry season when salinity was highest. L. muria was more abundant (954 ± 2385 ind m−2) than E. hians (94 ± 38 ind m−2). The relatively low salinity of the West Basin favoured L. muria over E. hians, which prefers higher salinities. This “pupa” fishery is still unpredictable due to the astatic nature of the lake, and hence limited economic importance to the local fishers.

Salt Lakes

Chapter

Jan 2021

Brian V. Timms

This article aims to characterize saline lakes, especially to differentiate them from freshwater lakes. They range in various modes of origin, shoreline level stability, salt load and ionic dominances. Species diversity is generally inversely proportional to salinity. While many common higher taxonomic groups of animals occur in saline lakes, those of hypersaline waters are distinctive and include brine shrimps, ostracods and rotifers. These halophilic groups employ osmotic regulation often at cost to their life cycles. Faunas vary a little between continents, but with the old landscape of Australia is most unique. Saline lakes host a much greater and scientifically interesting variety of microbial life than freshwaters; some unique lake structures include microbial mats, stromatolites and thrombolites. Saline lakes are poorly managed throughout the world. Many are being denied water inflow, directly or indirectly while changing land use inflicts secondary salinization on others. For almost all the future is bleak.

Model for calcite spherulite formation in organic, clay-rich, lacustrine carbonate shales (Barbalha Formation, Aptian, Araripe Basin, NE Brazil)

Article

Feb 2021
MAR PETROL GEOL

The formation of carbonate spherulites, recognized as part of the South-Atlantic Pre-Salt reservoir rocks, remains enigmatic. Well-chosen analogues provide insights into depositional and diagenetic conditions and the biotic versus abiotic processes that might influence or even control spherulite growth. Radial fibrous calcite spherulites of the Batateira beds in the Barbalha Formation (Aptian, Araripe, NE Brazil) formed mainly in organic and clay-rich laminite layers as nodules that grew around different nuclei, now represented by, amongst others, micrite and apatite ostracods. They vertically alternate with clays, but also carbonate laminites, which locally also contain spherulites. Characterization of the organic matter content of spherulitites (petrography, total organic carbon, vitrinite reflectance, stable isotopes) reveals TOC’s of up to 30% related to the presence of mainly oil-prone alginite next to huminite, inertinite, sporinites and zooclasts. The complex mixture of clays, dominantly autogenic mixed layered illite-montmorrilonite, which alternate with lacustrine carbonates and evaporites, is diagnostic for lakes in a semi-arid environment. The occurrence of gypsum, calcitic alveolar honeycomb spherulite textures, preferential concentration of pyrite at the spherulite-matrix contact and inward spherulite perforations suggest bacterial activity under shallow and evaporitic syn-depositional conditions. Although the Barbalha spherulites formed chemically-driven in a viscous matrix, the microbial influence, mainly as lamalginite in the clayey matrix, is undeniable. The mixed organic-silicate gel catalyzed calcite spherulite formation. The Barbalha spherulites consequently illustrate the complementary influence of clays, organic matter and evaporitic syn-sedimentary conditions.

Dependence of spatial scale in landscape associations with cause-specific predation of snowy plover nests

Article

Full-text available

Sep 2020

Understanding relationships between habitat and ecological processes often depends on the spatial scale at which the landscape is measured. A common objective in studies of avian nesting ecology is to link habitat characteristics with nest predation for generating potential conservation and management strategies aimed at increasing avian reproductive success. Yet scale dependence likely plays a considerable role in these assessments, particularly when multiple species of nest predators are present. We identified nest predators of snowy plovers, a ground-nesting shorebird, and modeled predator-specific hazard rates of nest mortality in relation to the landscape at multiple spatial scales (200 m, 500 m, 1 km, 2.5 km, and 5 km) and at the nest site. We used a Bayesian latent indicator approach for weighting the influence of habitat across spatial scales and to gain insight into the hierarchical nature of how specific predators responded to the landscape when preying upon plover nests. We did not identify a common spatial scale that best predicted nest predation by all predators, though our results indicated that unfragmented playa and marsh habitats at large spatial scales reduced nest predation by all nest predators. Land cover features including grass, shrubs, human development, and open water elicited variable responses depending on the predator group, and predator groups responded at different spatial scales. Further, the spatial configuration of nests (nest dispersion) influenced nest predation by common ravens Corvus corax and foxes (kit fox Vulpes macrotis and red fox Vulpes vulpes), suggesting that certain predators develop a search image for nests. Our results illustrate that clarifying complex relationships between nest predation and habitat characteristics requires the incorporation of predator identity and scale dependence. Thus, management and conservation plans aiming to increase avian productivity by altering or restoring habitats will likely benefit from consideration of predator-specific patterns at multiple spatial scales.

Importance of Great Salt Lake to Pelagic Birds: Eared Grebes, Phalaropes, Gulls, Ducks, and White Pelicans

Chapter

Full-text available

Jul 2020

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.

Annual Variation in Numbers of Breeding California Gulls at Mono Lake, California: the Importance of Natal Philopatry and Local and Regional Conditions

Article

Full-text available

Feb 2006

The California Gull (Larus californicus) breeding colony at Mono Lake, California, is the second largest in the world, but its size can fluctuate annually by >45%. We examined six groups of factors that potentially could affect the numbers of pairs nesting each year, including availability of nesting habitat, numbers of potential breeding gulls, environmental conditions along the Pacific coast in the preceding winter, spring conditions at the lake, food availability at the lake, and prior breeding experience. Four variables explained >80% of the variation in the numbers of breeding gulls at Mono Lake between 1987 and 2003: the potential number of four-year-old gulls returning to the lake to breed for the first time, winter coastal conditions associated with the Pacific Decadal Oscillation, density of endemic brine shrimp (Artemia monica) close to the time of egg-laying, and mean temperature in the month before egg-laying. Of the four factors the latter two, which reflect local conditions near the time of egg-laying, had the most profound direct effect on the numbers of breeding gulls. Yearly variation in the snow pack and spring runoff affects brine shrimp numbers through changes in limnological conditions, thus regional climate patterns may indirectly influence gull numbers.

Wetland salinity induces sex-dependent carry-over effects on the individual performance of a long-distance migrant

Article

Full-text available

Jul 2017

Salinization is having a major impact on wetlands and its biota worldwide. Specifically, many migratory animals that rely on wetlands are increasingly exposed to elevated salinity on their nonbreeding grounds. Experimental evidence suggests that physiological challenges associated with increasing salinity may disrupt self-maintenance processes in these species. Nonetheless, the potential role of salinity as a driver of ecological carry-over effects remains unstudied. Here, we investigated the extent to which the use of saline wetlands during winter – inferred from feather stable isotope values – induces residual effects that carry over and influence physiological traits relevant to fitness in black-tailed godwits Limosa limosa limosa on their northward migration. Overwintering males and females were segregated by wetland salinity in West Africa, with females mostly occupying freshwater wetlands. The use of these wetlands along a gradient of salinities was associated with differences in immune responsiveness to phytohaemagglutinin and sized-corrected body mass in godwits staging in southern Europe during northward migration – 3,000 km from the nonbreeding grounds – but in males only. These findings provide a window onto the processes by which wetland salinity can induce carry-over effects and can help predict how migratory species should respond to future climate-induced increases in salinity.

Rapid population decline in migratory shorebirds relying on Yellow Sea tidal mudflats as stopover sites

Article

Full-text available

Apr 2017

Migratory animals are threatened by human-induced global change. However, little is known about how stopover habitat, essential for refuelling during migration, affects the population dynamics of migratory species. Using 20 years of continent-wide citizen science data, we assess population trends of ten shorebird taxa that refuel on Yellow Sea tidal mudflats, a threatened ecosystem that has shrunk by 465% in recent decades. Seven of the taxa declined at rates of up to 8% per year. Taxa with the greatest reliance on the Yellow Sea as a stopover site showed the greatest declines, whereas those that stop primarily in other regions had slowly declining or stable populations. Decline rate was unaffected by shared evolutionary history among taxa and was not predicted by migration distance, breeding range size, non-breeding location, generation time or body size. These results suggest that changes in stopover habitat can severely limit migratory populations.

Weather and prey availability affect the timing of fall migration of Eared Grebes ( Podiceps nigricollis ) from Great Salt Lake

Article

Full-text available

Mar 2017

Great Salt Lake (GSL) is a critical migratory stopover location for Eared Grebes (Podiceps nigricollis), but the factors influencing the timing of their fall migration have not previously been investigated. We used archived Doppler radar data to visualize the nocturnal departures of Eared Grebes from GSL over 16 years, from 1999–2015. We used generalized linear models (GLMs) to examine interannual variability in the timing of migration of Eared Grebes in relation to prey availability and lake temperature, as well as variation in the nightly departure likelihoods of Eared Grebes in relation to weather. On average, Eared Grebes departed from GSL over a period of 31 days each year, with departures occurring on 17 of those days. We did not find any trend toward earlier departures over the years of the study. Departures typically began earlier in the year when densities of brine shrimp adults (Artemia franciscana) were higher than average, densities of brine shrimp cysts were lower than average, and lake temperatures were warmer than average. The span of migration departures was most strongly related to the day of first departure, with longer spans occurring in years with an earlier migration initiation day. We also found that likelihood of departure from GSL was greater on nights with high barometric pressure and low lake temperature. High barometric pressure was related to low wind speeds and low incidence of precipitation. We concluded that Eared Grebes depart when they have gained sufficient mass to successfully migrate rather than lingering at GSL for as long as possible, and that migration departure is most likely on nights with fair weather.

Recent Desiccation-Related Ecosystem Changes at Lake Abert, Oregon: A Terminal Alkaline Salt Lake

Article

Full-text available

Dec 2016

Lake Abert, a terminal alkaline salt lake in south central Oregon, has been a key staging area for migratory waterbirds along the Pacific Flyway. In 2014, the lake shrank to about 5% of its maximum size, and its salinity increased from 75 g · L–1 to 250 g · L–1. This resulted in a major ecosystem shift from one dominated at higher trophic levels by invertebrates and waterbirds to one composed primarily of hypersaline-adapted microbes. A large variety of halophilic bacteria and archaea were also detected using 16S rRNA metagenomic sequence analysis. The loss of prey and staging habitat for migratory waterbirds was especially pronounced for Eared Grebe, Red-necked Phalarope, and Wilson’s Phalarope, all of which feed on brine shrimp and alkali flies. The last time the lake was in this state was nearly a century ago during the Dust Bowl of the 1930s, which was a once-in-500-years drought. To understand the causes of the current event, we examined hydrological, climatic, and biological data. The primary cause of the event appears to have been the combined effects of upstream water diversions and lower river flows that were exacerbated by a moderate decade-long drought and elevated evaporation rates.

Lake Abert, OR : a terminal lake under extreme water stress

Article

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Jan 2014

Declining adult survival of New Zealand Bar-tailed Godwits during 2005–2012 despite apparent population stability

Article

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Mar 2016

Like many migratory shorebird populations using the East Asian–Australasian Flyway, Bar-tailed Godwits Limosa lapponica baueri in New Zealand have significantly declined since the mid-1990s, but census data indicate a relatively stable population since 2004. The demographic drivers of both the decline and stabilisation remain unknown. We estimated annual survival from mark–recapture data of adult godwits in New Zealand during 2005–2014. Annualadult survival declined over the study period from 0.89–0.96 in 2005–2010 to 0.83–0.84 in 2011–2012. The simultaneousdecline in annual survival found in a separate study of Bar-tailed GodwitsL. l. menzbieri in north-west Australia suggests a common effect of their high dependence on threatened migratory staging sites in the Yellow Sea; the more extreme decline in L. l. menzbieri may reflect ecological differences between the populations, such as timing and extent of use of these sites. At current apparent recruitment rates, persistent adult survival of ~0.84 would lead to a population decline of 5–6% per year in L. l. baueri. Our study implies that the demographic precursors to a population decline developed during a period of apparent population stability; this suggests that monitoring a single index of population stability is insufficient for predicting future trends.

Salt lakes: Values, threats and future

Chapter

Full-text available

Sep 2008

INTRODUCTION Two types of saline water exist on Earth, namely marine waters, including brackish zones of mixing with fresh water, and epicontinental salt lakes. This chapter addresses the values, threats and likely future of salt lakes, which are here defined as permanent or temporary bodies of water with salinities >3 g per litre and lacking any recent connection to the marine environment (i.e. athalassohaline sensu Bayly 1967). While the use of 3 g per litre to demarcate salt lakes is somewhat arbitrary, it has come into general use and is, coincidentally, the ‘calcite branch point’; that is, the salinity at which calcite is precipitated as natural waters concentrate. The false dichotomy between marine and fresh waters embodied in the titles of institutions, textbooks and conferences obscures the fact that salt lakes are widespread and represent significant aquatic resources. They occur on all continents, including Antarctica (Fig. 7.1), under a range of climatic temperature regimes from the coldest to near hottest. Locally, they may be more abundant than fresh waters and, when they are, often dominate the landscape. While they are mostly confined to semi-arid (precipitation 200–500 mm per year) and arid (25–200 mm per year) regions of the world, these regions constitute about one-third of the Earth's total land area (Williams1998 a) and inland salt waters are not greatly lower in total global volume (85 000 km 3) than freshwater lakes (105 000 km 3) (Shiklomanov 1990).

Quantifying drivers of population dynamics for a migratory bird throughout the annual cycle

Article

Full-text available

Jan 2016
Proc Biol Sci

Worldwide, migratory species are undergoing rapid declines but understanding the factors driving these declines is hindered by missing information about migratory connectivity and the lack of data to quantify environmental processes across the annual cycle. Here, we combined range-wide information about migratory connectivity with global remote-sensing data to quantify the relative importance of breeding and non-breeding environmental processes to persistent long-term population declines of a migratory songbird, the wood thrush (Hylocichla mustelina). Consistent with theoretical predictions about population limitation of migratory birds, our results suggest that habitat loss and climate have contributed to the observed declines in wood thrush breeding abundance, yet the relative importance of breeding versus non-breeding factors is population-specific. For example, high-abundance core breeding populations appear to be more limited by habitat loss, whereas low-abundance, peripheral populations appear to be limited by climate-driven seasonal interactions. Further, our analysis indicates that the relative impact of breeding habitat loss is at least three to six times greater than the impact of equivalent nonbreeding habitat loss and therefore the steepest regional declines have likely been driven by the loss of breeding habitat. These results underscore the need for population-specific conservation strategies implemented throughout the annual cycle to reverse long-term declines. © 2016 The Author(s) Published by the Royal Society. All rights reserved.

Simultaneous declines in summer survival of three shorebird species signals a flyway at risk

Article

Full-text available

Apr 2016
J APPL ECOL

1. There is increasing concern about the world’s animal migrations. With many land-use and climatological changes occurring simultaneously, pinning down the causes of large-scale conservation problems requires sophisticated and data-intensive approaches. 2. Declining shorebird numbers along the East Asian–Australasian Flyway, in combination with data on habitat loss along the Yellow Sea (where these birds refuel during long-distance migrations), indicate a flyway under threat. 3. If habitat loss at staging areas indeed leads to flyway-wide bird losses, we would predict that: (i) decreases in survival only occur during the season that birds use the Yellow Sea, and (ii) decreases in survival occur in migrants that share a reliance on the vanishing intertidal flats along the Yellow Sea, even if ecologically distinct and using different breeding grounds. 4. Monitored from 2006–2013, we analysed seasonal apparent survival patterns of three shorebird species with non-overlapping Arctic breeding areas and considerable differences in foraging ecology, but a shared use of both north-west Australian non-breeding grounds and the Yellow Sea coasts to refuel during northward and southward migrations (red knot Calidris canutus piersmai, great knot Calidris tenuirostris, bar-tailed godwit Limosa lapponica menzbieri). Distinguishing two three-month non-breeding periods and a six-month migration and breeding period, and analysing survival of the three species and the three seasons in a single model, we statistically evaluated differences at both the species and season levels. 5. Whereas apparent survival remained high in north-west Australia, during the time away from the non-breeding grounds survival in all three species began to decline in 2011, having lost 20 percentage points by 2012. By 2012 annual apparent survival had become as low as 0.�71 in bar-tailed godwits, 0.�68 in great knots and 0.�67 in red knots. In a separate analysis for red knots, no mortality occurred during the migration from Australia to China. In the summers of low summer survival, weather conditions were benign in the Arctic breeding areas. 6. We argue that rapid seashore habitat loss in the Yellow Sea is the most likely explanation of reduced summer survival, with dire (but uncertain) forecasts for the future of these flyway populations. This interpretation is consistent with recent findings of declining shorebird numbers at seemingly intact southern non-breeding sites.7. Policy implications. Due to established economic interests, governments are usually reluctant to act for conservation, unless unambiguous evidence for particular cause–effect chains is apparent. This study adds to an increasing body of evidence that habitat loss along the Yellow Sea shores explains the widespread declines in shorebird numbers along the East Asian–Australasian Flyway and threatens the long-term prospects of several long-distance migrating species. To halt further losses, the clearance of coastal intertidal habitat must stop now.

An ontogenetic perspective on individual differences

Article

Full-text available

Sep 2015
Proc Biol Sci

Phenotypic differences among individuals can arise during any stage of life. Although several distinct processes underlying individual differences have been defined and studied (e.g. parental effects, senescence), we lack an explicit, unified perspective for understanding how these processes contribute separately and synergistically to observed variation in functional traits. We propose a conceptual framework based on a developmental view of life-history variation, linking each ontogenetic stage with the types of individual differences originating during that period. In our view, the salient differences among these types are encapsulated by three key criteria: timing of onset, when fitness consequences are realized, and potential for reversibility. To fill a critical gap in this framework, we formulate a new term to refer to individual differences generated during adulthood-reversible state effects. We define these as 'reversible changes in a functional trait resulting from life-history trade-offs during adulthood that affect fitness', highlighting how the adult phenotype can be repeatedly altered in response to environmental variation. Defining individual differences in terms of trade-offs allows explicit predictions regarding when and where fitness consequences should be expected. Moreover, viewing individual differences in a developmental context highlights how different processes can work in concert to shape phenotype and fitness, and lays a foundation for research linking individual differences to ecological and evolutionary theory. © 2015 The Author(s).

Monitoring Species Richness and Abundance of Shorebirds in the Western Great Basin

Article

Full-text available

Nov 1998

Broad-scale avian surveys have been attempted within North America with mixed results. Arid regions, such as the Great Basin, are often poorly sampled because of the vastness of the region, inaccessibility of sites, and few ornithologists. In addition, extreme variability in wetland habitat conditions present special problems for conducting censuses of species inhabiting these areas. We examined these issues in assessing multi-scale shorebird (order: Charadriiformes) censuses conducted in the western Great Basin from 1992-1997. On ground surveys, we recorded 31 species of shorebirds, but were unable to accurately estimate population size. Conversely, on aerial surveys we were able to estimate regional abundance of some shorebirds, but were unable to determine species diversity. Aerial surveys of three large alkali lakes in Oregon (Goose, Summer, and Abert Lakes) revealed > 300,000 shorebirds in one year of this study, of which 67% were American Avocets (Recurvirostra americana) and 30% phalaropes (Phalaropus spp.). These lakes clearly meet Western Hemisphere Shorebird Reserve Network guidelines for designation as important shorebird sites. Based upon simulations of our monitoring effort and the magnitude and variation of numbers of American Avocets, detection of 5-10% negative declines in populations of these birds would take a minimum of 7-23 years of comparable effort. We conclude that a combination of ground and aerial surveys must be conducted at multiple sites and years and over a large region to obtain an accurate picture of the diversity, abundance, and trends of shorebirds in the western Great Basin.

Living in Environments with Contrasting Salinities: A Review of Physiological and Behavioural Responses in Waterbirds

Article

Full-text available

Dec 2014

Jorge S. Gutiérrez

During the course of their lives many vertebrates live and forage in environments characterized by different salinities and must therefore respond to changes in salt intake. This is particularly true for numerous species of migratory waterbirds, especially those that routinely commute between saltwater and freshwater wetlands throughout their annual cycle and/or within a season. These birds have evolved a suite of morphological, physiological and behavioural mechanisms to successfully maintain osmoregulatory balance. However, relatively little is known about the impacts of salinity on the distribution, physiological performance and reproductive success of waterbirds. Here I review the current knowledge of the physiological and behavioural mechanisms through which waterbirds cope with contrasting salinities and how some of the adjustments undertaken might interfere with relevant aspects of their performance. I argue that, because of their strong reliance on wetland ecosystems for foraging and breeding, waterbirds may be particularly vulnerable to climate-induced changes in salinity, especially in arid or semiarid tropical areas where increases in both temperature and salinity may affect their body condition and, ultimately, survival prospects. I conclude by offering some suggestions for future research that could take us beyond our current level of understanding of avian osmoregulation.

Limnological effects of anthropogenic desiccation of a large, saline lake, Walker Lake, Nevada

Article

Full-text available

Dec 2001

Walker Lake is a monomictic, nitrogen-limited, terminal lake located in western Nevada. It is one of only eight large (Area>100 km^2, Z_{ mean}>15 m) saline lakes of moderate salinity (3–20 g l^−1) worldwide, and one of the few to support an endemic trout fishery (Oncorhynchus clarki henshawi). As a result of anthropogenic desiccation, between 1882 and 1996 the lake's volume has dropped from 11.1 to 2.7 km^3 and salinity has increased from 2.6 to 12–13 g l^−1. This study, conducted between 1992 and 1998, examined the effects of desiccation on the limnology of the lake. Increases in salinity over the past two decades caused the extinction of two zooplankton species, Ceriodaphnia quadrangula and Acanthocyclops vernalis. Recent increases in salinity have not negatively affected the lake's dominant phytoplankton species, the filamentous blue-green algae Nodularia spumigena. In 1994 high salinity levels (14–15 g l^−1) caused a decrease in tui chub minnow populations, the main source of food for Lahontan cutthroat trout, and a subsequent decrease in the health of stocked trout. Lake shrinkage has resulted in hypolimnetic anoxia and hypolimnetic accumulation of ammonia (800–2000 g-N l^−1) and sulfide (15 mg l^−1) to levels toxic to trout. Internal loading of ammonia via hypolimnetic entrainment during summer wind mixing (170 Mg-N during a single event), vertical diffusion (225–500 Mg-N year^−1), and fall destratification (540–740 Mg-N year^−1) exceeds external nitrogen loading (15–16 g l^−1) to support trout and chub fisheries in 20 years, and in 50–60 years the lake will reach hydrologic equilibrium at a volume of 1.0 km^3 and a salinity of 34 g l^−1.

Population estimates of North American shorebirds, 2012

Article

Full-text available

Jan 2013

We re-assessed the population size and trend of 52 species and 75 taxa of shorebirds that occur in North America by reviewing published papers, soliciting unpublished data, and seeking the opinions of experts. New information resulted in changing population estimates for 35 of the 71 taxa that could be compared directly to the estimates published in 2006; from this comparison, 28 estimates increased and seven decreased. Almost all of the increases (88%) were the result of more comprehensive surveys being conducted or re-analyses of existing data rather than actual increases in numbers. Retaining the previous estimate was almost always due to a lack of new information. Recent trend analysis indicates that many shorebird populations have stabilized in recent years after large declines during the early 1980s and mid-1990s. Although many shorebird populations listed as threatened or endangered by the U.S. and Canadian governments have increasing population trends, none have reached recovery targets. Information on population trends remains virtually unknown for 25% of the shorebirds occurring in North America, and surveys are needed to determine the state of these populations.

Population dynamics, distribution, and growth rate of tilapia ( Oreochromis mossambicus ) in the Salton Sea, California, with notes on bairdiella ( Bairdiella icistia) and orangemouth corvina ( Cynoscion x anthulus )

Article

Full-text available

Feb 2007
HYDROBIOLOGIA

The Salton Sea is a highly saline lake that has long supported sportfishery and large populations of fish-eating birds. A study was initiated in 1999 to assess the status of orangemouth corvina (Cynoscion xanthulus), bairdiella (Bairdiella icistia) and tilapia (Oreochromis mossambicus × O. urolepis). Multimesh (50 × 2 m) gillnets were set at nine stations in 1999, ten stations in 2000 and six stations in 2002. These stations were sampled every two months in 1999, every three months in 2000 and once in 2002. O. mossambicus was the most abundant of the four species, with a maximum mean catch per unit effort (CPUE) 13.8 kg net−1 h−1 or 29.9 fish net−1 h−1 being observed at the river mouth stations in August 1999. From spring to summer, tilapia CPUE increased at nearshore and river mouth stations and decreased at pelagic stations, apparently reflecting migration away from midlake areas in response to anoxia or hypoxia caused by periodic springtime overturn events in deep waters. Tilapia catches in nearshore, river mouth and pelagic habitats were 83 and 60% males in 1999 and 2000, respectively. Tilapia catches in rivers in August 1999 averaged only 6% male. During 1999–2000, the tilapia population consisted essentially of only the 1995 and 2000 year classes. Harsh conditions at the Salton Sea have led to erratic reproduction and survival rates and unstable age structures for its resident fishes. Massive parasite infestations of fry and physiological stressors such as anoxia, high sulfide levels, high salinity and high and low temperatures are potential causes of the irregular recruitment and periodic dieoffs of tilapia. The abundance of all fish species declined over the years of study. Between 1999 and 2002, the late summer mean CPUEs for tilapia, bairdiella and orangemouth corvina at four nearshore stations dropped from 16 fish to 0.02 fish, from 4.7 fish net to 0.23 fish, and from 0.08 fish to 0.02 fish, respectively. During 2000–2003, parallel declines occurred in estimated numbers of adult fish involved in mass mortality events at the Sea. The boom-and-bust dynamics of tilapia and other fish populations in the Sea have major consequences for fish-eating bird populations, for other components of the ecosystem, and for the recreational value of the lake.

Habitat Loss and Population Decline: A Meta-Analysis of the Patch Size Effect

Article

Full-text available

Mar 1998

We evaluated the conditions under which patch size effects are important determinants of local population density for animals living in patchy landscapes. This information was used to predict when patch size effects will be expected to occur following habitat loss and fragmentation. Using meta-analysis, we quantitatively reviewed the results of 25 published studies that tested for a relationship between patch size and population density. Patch size effects were strong for edge and interior species (negative and positive patch size effects, respectively), but negligible for generalist species that use both edge and interior habitat. We found significant differences in mean patch size effects between migratory and residential species, between herbivores and carnivores, and among taxonomic groups. We found no evidence that patch size effects were related to landscape characteristics such as the proportion of landscape covered by habitat, median patch size, or the scale at which a study was conducted. However, species in the Western Hemisphere tended to have larger absolute effect sizes, and eastern species tended to be more variable in their response. For landscapes undergoing habitat loss and fragmentation, our results predict the following: (1) among generalist species that use both the edge and the interior of a habitat patch, the decline in population size associated with habitat destruction should be accounted for by pure habitat loss alone; (2) for interior species, the decline in population size associated with habitat fragmentation per se will be greater than that predicted from pure habitat loss alone; (3) for edge species, the decline in population size will be less than that predicted by pure habitat loss alone; (4) these relative effects will not be influenced by the extent of habitat loss, but they will be affected by the pattern of habitat when large or small patches are preferentially removed; and (5) as loss and fragmentation increase within a landscape, migratory species will generally suffer less of a decline in population size than resident species.

Annual Variation in Numbers of Breeding California Gulls at Mono Lake, California: the Importance of Natal Philopatry and Local and Regional Conditions

Article

Full-text available

Jan 2009

Variación Anual en el Número de Gaviotas Larus Californicus que Nidifican en el Lago Mono, California: La Importancia de la Filopatria Natal y de las Condiciones Locales y Regionales La colonia reproductiva de la gaviota Larus californicus que se encuentra en el Lago Mono, California, es la segunda más grande del mundo, pero su tamaño puede fluctuar anualmente en más del 45%. Examinamos seis grupos de factores que podrian potencialmente afectar el número de parejas que nidifican cada año, incluyendo la disponibilidad de hábitat de cria, el número de gaviotas potencialmente reproductivas, las condiciones ambientales predominantes en la costa Pacifica durante el invierno previo, las condiciones de la primavera en el lago, la disponibilidad local de alimento y la experiencia reproductiva previa. Cuatro variables explicaron más del 80% de la variación en el número de gaviotas que criaron entre 1987 y 2003: el número potencial de individuos de cuatro años de edad que regresaron al lago a reproducirse por primera vez, las condiciones asociadas con la oscilación del Pacifico, la densidad del camarón endémico Artemia monica cerca del momento de puesta de los huevos y la temperatura media del mes anterior a la puesta. Los últimos dos factores, los cuales reflejan las condiciones locales predominantes poco antes de la puesta, tuvieron el efecto directo más profundo sobre los números de individuos nidificantes. La variación anual en la cantidad de nieve acumulada y la escorrentia de la primavera afectan la abundancia de A. monica a través de cambios en las condiciones limnológicas, por lo que los patrones climáticos regionales podrian influenciar indirectamente el número de gaviotas.

Avian BMR in Marine and Non-Marine Habitats: A Test Using Shorebirds

Article

Full-text available

Jul 2012
PLOS ONE

Basal metabolic rate (BMR) is closely linked to different habitats and way of life. In birds, some studies have noted that BMR is higher in marine species compared to those inhabiting terrestrial habitats. However, the extent of such metabolic dichotomy and its underlying mechanisms are largely unknown. Migratory shorebirds (Charadriiformes) offer a particularly interesting opportunity for testing this marine-non-marine difference as they are typically divided into two broad categories in terms of their habitat occupancy outside the breeding season: 'coastal' and 'inland' shorebirds. Here, we measured BMR for 12 species of migratory shorebirds wintering in temperate inland habitats and collected additional BMR values from the literature for coastal and inland shorebirds along their migratory route to make inter- and intraspecific comparisons. We also measured the BMR of inland and coastal dunlins Calidris alpina wintering at a similar latitude to facilitate a more direct intraspecific comparison. Our interspecific analyses showed that BMR was significantly lower in inland shorebirds than in coastal shorebirds after the effects of potentially confounding climatic (latitude, temperature, solar radiation, wind conditions) and organismal (body mass, migratory status, phylogeny) factors were accounted for. This indicates that part of the variation in basal metabolism might be attributed to genotypic divergence. Intraspecific comparisons showed that the mass-specific BMR of dunlins wintering in inland freshwater habitats was 15% lower than in coastal saline habitats, suggesting that phenotypic plasticity also plays an important role in generating these metabolic differences. We propose that the absence of tidally-induced food restrictions, low salinity, and less windy microclimates associated with inland freshwater habitats may reduce the levels of energy expenditure, and hence BMR. Further research including common-garden experiments that eliminate phenotypic plasticity as a source of phenotypic variation is needed to determine to what extent these general patterns are attributable to genotypic adaptation.

Monitoring wetlands in a salinizing landscape: Case studies from the Wheatbelt region of Western Australia

Article

Full-text available

Oct 2007

Three elements of wetland biodiversity (aquatic invertebrates, waterbirds and overstorey vegetation of the wetland edge) have been monitored since 1998 at Lake Eganu and Paperbark Swamp in the Western Australian Wheatbelt to provide information about the changes occurring in wetland biodiversity in a landscape that is severely affected by dryland salinization. Changes in extent of wetland vegetation since the 1960s were examined using historical aerial photographs and waterbird use of Lake Eganu during the early 1980s was compared with recent waterbird survey results. Lake Eganu, which is within a major drainage line, started to become salinized in the mid-1960s, about 70 years after land clearing began in the catchment, and its salinity has increased an order of magnitude. The extent of wetland overstorey vegetation and the richness of freshwater aquatic invertebrates have both declined about 80%. Waterbird richness has also declined over the past 20 years, with changes in species composition. Salinization has not occurred at Paperbark Swamp, which is in a small catchment off the main drainage line, and there has been no consistent change in the biodiversity elements monitored.

Effects of salinity on the immune response of an ‘osmotic generalist’ bird

Article

Full-text available

Jul 2012
OECOLOGIA

Salt stress can suppress the immune function of fish and other aquatic animals, but such an effect has not yet been examined in air-breathing vertebrates that frequently cope with waters (and prey) of contrasting salinities. We investigated the effects of seawater salinity on the strength and cost of mounting an immune response in the dunlin Calidris alpina, a long-distance migratory shorebird that shifts seasonally from freshwater environments during the breeding season to marine environments during migration and the winter period. Phytohaemagglutinin (PHA)-induced skin swelling, basal metabolic rate (BMR), body mass, fat stores, and plasma ions were measured in dunlins acclimated to either freshwater or seawater (salinity: 0.3 and 35.0 ‰, respectively). Seawater-acclimated dunlins mounted a PHA-induced swelling response that was up to 56 % weaker than those held under freshwater conditions, despite ad libitum access to food. Freshwater-acclimated dunlins significantly increased their relative BMR 48 h after PHA injection, whereas seawater-acclimated dunlins did not. However, this differential immune and metabolic response between freshwater- and seawater-acclimated dunlins was not associated with significant changes in body mass, fat stores or plasma ions. Our results indicate that the strength of the immune response of this small-sized migratory shorebird was negatively influenced by the salinity of marine habitats. Further, these findings suggest that the reduced immune response observed under saline conditions might not be caused by an energy or nutrient limitation, and raise questions about the role of osmoregulatory hormones in the modulation of the immune system.

Estimating shorebird numbers at migration stopover sites

Article

Full-text available

Nov 2006

We describe a method for estimating the total number of shorebirds that use a migration stopover site during spring and fall migration. We combined weekly shorebird counts with parameter estimates for detection probability, sampled proportion, and length of stay on the Squaw Creek National Wildlife Refuge. Double sampling was used to determine detection probability and estimated values varied among wetland units from a low of 0.07 to a high of 0.82. The sampled proportion of most wetland units was 100% but was lower in some of the larger units. Length of stay (measured for Pectoral [Calidris melanotos] and Least Sandpipers [C. minutilla] combined) averaged 10.0 days in spring and 3.7 days in fall. Spring shorebird numbers were approximately five times greater than fall numbers on the Refuge. Annual shorebird numbers varied among years from an estimated low in 2003 of 15 734 to a high in 2002 of 69 570. Peak daily counts during study years averaged only 12% of estimated spring totals and 4% of fall totals. An estimate of shorebird numbers based on summing weekly counts, not corrected for detection probability or sampled proportion, would have been only 21% (spring) to 31% (fall) of the total number of birds. These results reveal that peak counts and nonadjusted counts can significantly underestimate the number of shorebirds that use migration stopover sites in the midcontinent of North America.

Conservation and management challenges of Saline lakes: A review of five experience briefs

Article

Full-text available

Jun 2004

Saline lakes occur throughout the world and have significant economic, ecological, biodiversity, and cultural value. In addition to the wide array of human-caused impacts they experience in common with their freshwater counterparts, they are particularly vulnerable to changing hydrologic regimes due to climate change or water diversions. We review experience briefs addressing management issues at five lakes: Aral Sea (Kazakhstan/Uzbekistan), Issyk-kul (Kyrgyz Republic), Lake Nakuru (Kenya), Lake Poopó (Bolivia), and Chilika Lake (India). The Aral Sea experience illustrates the rapidity with which desiccation may occur and highlights the worldwide threat to all salt lakes with defined surface inflows as the demand for irrigated agriculture increases. It also shows the need for trans-boundary institutional structures for the management of water resources. All five experience briefs illustrate the linkage between lakes and their watershed and the need for basin-wide management. The role of international NGOs (e. g. Ramsar Bureau, Wetlands International, Birdlife International) in fostering an appreciation of non-economic values and promoting sustainable management is of particular importance to saline lake conservation; all five lakes considered here include Ramsar sites, "Wetlands of International Importance." The importance of stakeholder involvement in management is becoming widely recognized at all levels of governance (local to international). Experiences at Chilika Lake and Lake Nakuru provide examples of the success of stakeholder involvement.

Management and conservation of San Francisco Bay salt ponds: effects of pond salinity, area, tide, and season on Pacific Flyway waterbirds

Article

Full-text available

Jan 2002

Throughout the world, coastal salt ponds provide habitat for large numbers and diversities of waterbirds. San Francisco Bay contains the most important coastal salt pond complexes for waterbirds in the United States, supporting more than a million waterbirds through the year. As an initial step in attempting to understand how the anticipated conversion of salt ponds to tidal marsh might affect the Bay's bird populations, the number of birds using salt ponds on high and low tides was counted during the winter months of 1999/00 and 2000/01. Behavior and habitat use of birds in these ponds were assessed, and the effects of tide cycle, pond salinity, and pond area on bird use were examined. We recorded 75 species of waterbirds in surveys of salt ponds in the South Bay from September 1999 to February 2001, totaling over a million bird use days on high tide. Shorebirds and dabbling ducks were the most abundant groups of birds using the salt ponds. Waterbird numbers and diversity were significantly affected by the salinity of ponds in a non-linear fashion with lower numbers and diversity on the highest salinity ponds. With the exception of ducks and Eared Grebe (Podiceps nigricollis), tide height at the Bay significantly affected bird numbers in the salt ponds with ponds at high tides having higher numbers of birds than the same ponds on low tides. Considerable numbers of birds fed in the salt ponds on high and low tides, although this varied greatly by species. Habitat use varied by tide. Management recommendations include maintaining ponds of varying salinities and depths. Restoring salt ponds to tidal marsh should proceed with caution to avoid loss of waterbird diversity and numbers in San Francisco Bay.

Salinity controls on trophic interactions among invertebrates and algae of solar evaporation ponds in the Mojave Desert and relation to shorebird foraging and selenium risk

Article

Full-text available

Jun 2006

David B. Herbst

Three saline evaporation ponds formed by wastewater from a solar energy-generating facility near Harper Dry Lake in the Mojave Desert of California, USA were compared for differences in the communities of benthic and planktonic invertebrates and algae present along with avian visitation and foraging activity. Salinity of the ponds ranged from near 90 to over 200 g L−1 total dissolved solids. During the period of study (1997–1999), the lowest salinity pond averaged 98 g L−1, the intermediate salinity pond 112 g L−1, and the high salinity pond 173 g L−1. Differences in the biological communities, abundance of invertebrates and algae, and avian foraging were examined in relation to these differences in salinity. Only three aquatic invertebrate species were present in substantial numbers, a water boatman (Trichocorixa reticulata), a brine shrimp (Artemia franciscana), and a brine fly (Ephydra gracilis). An abundance of the predator Trichocorixa under low salinity conditions appeared to reduce algae-grazing Artemia, and so released phytoplankton growth, but this was observed only in surveys later in the growth season when populations were mature and had greatest potential for efficient consumption of resources. Brine fly larvae were also fed upon by Trichocorixa and were least abundant in the low salinity pond. At highest salinities where Trichocorixa could not survive, Artemia were abundant and waters were usually clear, becoming dense with phytoplankton only during the winter dormancy of brine shrimp. Intermediate salinity levels supported some water boatmen, often coexisting with dense brine shrimp and phytoplankton populations, and the greatest dry mass of benthic brine fly larvae and pupae. The high salinity pond produced abundant but small Ephydra larvae and pupae, accompanied by reduced emergence success of adult flies. Birds appeared to forage primarily on benthic brine fly larvae and were most successful in the intermediate salinity pond, possibly because lower salinity resulted in loss of this preferred prey to water boatman predation, and high salinity produced prey of poor quality. These observations suggest that reduced salinity may at times mediate a trophic cascade within a simple food chain, where an invertebrate predator may reduce primary consumers and permit enhanced algal density, but the predation control becomes uncoupled as salinity increases. In the case of the ponds studied here, there appeared to be minimal risk associated with selenium poisoning of water birds because Se was not detected in brine fly larvae or pupae and was found only occasionally in low content in the brine shrimp and corixids and mostly in locales where few birds were found feeding.

Comparative population ecology of Ephydra hians Say (Diptera: Ephydridae) at Mono Lake (California) and Abert Lake (Oregon)

Article

Full-text available

Jan 1988

David B. Herbst

The population dynamics of Ephydra hians Say final instar larvae and pupae were compared over a two year period in rocky littoral habitats of two alkaline saline lakes in the western Great Basin. Relative abundance increased from 1983 to 1984 at Mono Lake (California), during dilution from ca. 90 to 80 g 1-1 TDS (total dissolved solids). In contrast, relative abundance decreased over the same period at Abert Lake (Oregon), accompanied by a dilution of salinity from ca. 30 to 20 g l-1 and a marked increase in the number and abundance of other benthic macroinvertebrate species. These observations are consistent with a hypothesis that proposes biotic interactions limit E. hians abundance at low salinity, and physiological stress limits abundance at high salinity. Oviposition extends from early spring to early fall. Mixed instars present throughout this period indicates multivoltine population dynamics with overlapping generations. The standing stock biomass of final instars increases exponentially in late spring and peaks in late summer or early fall. Pupae increase in proportional representation and abundance from a spring minimum to a fall maximum. The body size of adults and pupae cycle seasonally from a spring maximum to a fall minimum, and may be related to either or both food limitation, or water temperature.

The Salton Sea as critical habitat to migratory and resident waterbirds

Article

Full-text available

Jan 2002

Concern about the Salton Sea ecosystem, based on potential impacts of increasing salinity, contaminants, disease outbreaks, and large die-offs of birds, is heightened because of tremendous prior loss and degradation of wetland habitat in western North America. In 1999, we used a variety of survey methods to describe patterns of abundance of birds at the Salton Sea and in adjacent habitats. Our results further documented the great importance of the Salton Sea within the Pacific Flyway to wintering, migratory, and breeding waterbirds. Exclusive of Eared Grebes, we estimated about 187000 individual waterbirds at the Salton Sea in January, 88000 in April, 170000 in August, and 261000 in November. Additional surveys of Eared Grebes in November and December suggested the total population of all waterbirds was about 434000 to 583000 in those months, respectively. We also documented breeding by about 14000 pairs of colonial waterbirds. Waterbirds were particularly concentrated along the northern, southwestern, southern, and southeastern shorelines and river deltas. By contrast, some species of wading birds (Cattle Egret, White-faced Ibis, Sandhill Crane) and shorebirds (Mountain Plover, Whimbrel, Long-billed Curlew) were much more numerous in agricultural fields of the Imperial Valley than in wetland habitats at the Sea. Various studies indicate the Salton Sea is of regional or national importance to pelicans and cormorants, wading birds, waterfowl, shorebirds, and gulls and terns. Important taxa are the Eared Grebe, American White Pelican, Double-crested Cormorant, Cattle Egret, White-faced Ibis, Ruddy Duck, Yuma Clapper Rail, Snowy Plover, Mountain Plover, Gull-billed, Caspian, and Black terns, and Black Skimmer. Proposed restoration projects should be carefully assessed to ensure they do not have unintended impacts and are not placed where large numbers of breeding, roosting, or foraging birds concentrate. Similarly, plans to enhance opportunities for recreation or commerce at the Sea should aim to avoid or minimize disturbance to birds. Future research should focus on filling gaps in knowledge needed to effectively conserve birds at the Salton Sea.

HABITAT LOSS AND POPULATION DECLINE: A META-ANALYSIS OF THE PATCH SIZE EFFECT

Article

Mar 1998

Estimating Shorebird Numbers at Migration Stopover Sites

Article

Nov 2006

We describe a method for estimating the totalnumber of shorebirds that use a migration stopoversite during spring and fall migration. We combinedweekly shorebird counts with parameter estimatesfor detection probability, sampled proportion, andlength of stay on the Squaw Creek National WildlifeRefuge. Double sampling was used to determinedetection probability and estimated values variedamong wetland units from a low of 0.07 to a high of0.82. The sampled proportion of most wetland unitswas 100% but was lower in some of the largerunits. Length of stay (measured for Pectoral[Calidrismelanotos] and LeastSandpipers [C.minutilla] combined)averaged 10.0 days in spring and3.7 days in fall. Spring shorebird numberswere approximately five times greater than fallnumbers on the Refuge. Annual shorebird numbersvaried among years from an estimated low in 2003 of15 734 to a high in 2002 of 69 570.Peak daily counts during study years averaged only12% of estimated spring totals and 4%of fall totals. An estimate of shorebird numbersbased on summing weekly counts, not corrected fordetection probability or sampled proportion, wouldhave been only 21% (spring) to31% (fall) of the total number ofbirds. These results reveal that peak counts andnonadjusted counts can significantly underestimatethe number of shorebirds that use migrationstopover sites in the midcontinent of NorthAmerica.

Towards Reliable Bird Surveys: Accounting for Individuals Present but not Detected

Article

Jan 2002

William L. Thompson

Decline of the world's saline lakes

Article

Oct 2017
NAT GEOSCI

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.

lme4: Linear mixed-effects models using Eigen and S4

Article

Jan 2014
J STAT SOFTW

Rapid population decline in migratory shorebirds relying on Yellow Sea tidal mudflats as stopover sites

Article

May 2017

R: A Language and Environment for Statistical Computing

Article

Jan 2011

R Development Core Team

Earth: multivariate adaptive regression spline models

Article

Jan 2014

S. Milborrow

Recent desiccation of Western Great Basin Saline Lakes: Lessons from Lake Abert, Oregon, U.S.A

Article

Mar 2016

Johnnie N. Moore

Although extremely important to migrating waterfowl and shorebirds, and highly threatened globally, most saline lakes are poorly monitored. Lake Abert in the western Great Basin, USA, is an example of this neglect. Designated a critical habitat under the Western Hemisphere Shorebird Reserve Network, the lake is at near record historic low levels and ultra-high salinities that have resulted in ecosystem collapse. Determination of the direct human effects and broader climate controls on Lake Abert illustrates the broader problem of saline lake desiccation and suggests future solutions for restoration of key habitat values. A 65-year time series of lake area was constructed from Landsat images and transformed to lake volume and salinity. "Natural" (without upstream withdrawals) conditions were calculated from climate and stream flow data, and compared to measured volume and salinity. Under natural conditions the lake would have higher volume and lower salinities because annual water withdrawals account for one-third of mean lake volume. Without withdrawals, the lake would have maintained annual mean salinities mostly within the optimal range of brine shrimp and alkali fly growth. Even during the last two years of major drought, the lake would have maintained salinities well below measured values. Change in climate alone would not produce the recent low lake volumes and high salinities that have destroyed the brine shrimp and alkali fly populations and depleted shorebird use at Lake Abert. Large scale withdrawal of water for direct human use has drastically increased the imbalance between natural runoff and evaporation during periods of drought in saline lakes worldwide but could be offset by establishing an "environmental water budget" to lay a foundation for the conservation of saline lake habitats under continued threats from development and climate change.

The use of eastern Sacramento Valley vernal pools by ducks

Article

Jun 2006
CALIF FISH GAME

A salt lake under stress: Relationships among birds, water levels, and invertebrates at a Great Basin saline lake

Abstract

No full-text available