Chapter

American White Pelicans of Gunnison Island, Great Salt Lake, Utah

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Abstract

Great Salt Lake (GSL) is recognized as a site of “Hemispheric Importance” for shorebirds by the Western Hemisphere Shorebird Reserve Network. An estimated ten million birds visit GSL every year for breeding, staging, and for some species, as a wintering destination. American white pelicans (Pelecanus erythrorhynchos) rely on GSL for both breeding and foraging habitat. Surveys conducted by the Utah Division of Wildlife Resources (UDWR) during mid-September 1997 estimated over 85,000 pelicans using GSL wetlands for foraging and loafing. Gunnison Island, situated in the northwestern section of GSL, is home to one of the largest breeding colonies of American white pelicans in North America. Aerial counts completed by the UDWR have shown up to 20,000 breeding pelicans on the island. Naturally protected by water and the island’s remoteness, pelicans have been able to breed and raise their young free from predation and disturbance from red fox (Vulpes vulpes), coyote (Canis latrans), and humans. Lower water availability and threats of increasing pressure on water resources in recent years has caused increased attention to, preparation for, and response to losses of aquatic habitat. The population of American white pelicans in Utah has remained stable over time, but the potential effects of local and regional stressors on pelicans and their habitat are poorly understood. Recent research provides an eye into the lives of American white pelicans in Utah and to the broader watershed and flyway dynamics.

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... The Gunnison Island pelican breeding colony (Gunnison Island State Wildlife Management Area, Box Elder County, Utah, US; Figure 1) is among the largest pelican colonies in western North America. At a peak count of approximately 20,000 breeding individuals, this population likely acts as a primary contributor to the western metapopulation of this species (Kijowski et al., 2020), and is therefore important to the metapopulation's persistence. Pelicans nest in small, dense subcolonies on benchlands around the island. ...
... We developed a set of environmental drivers hypothesized to influence pelican population dynamics (see Table 1 for full description of hypotheses). We hypothesized that local water levels may drive colony abundance by influencing the availability of wetland foraging habitat and by facilitating predator access to colony habitat, especially in low water years (Anderson, 1991;Kijowski et al., 2020). Extremely high water levels may also reduce available foraging area by making water too deep for pelicans to forage in (Anderson, 1991). ...
... U.S. Geological Survey, 2023). We derived a "land bridge presence" indicator (an index of whether terrestrial predators have access to the island; J. Neill, UDWR, written communication, 2016; Baskin & Turner, 2006;Kijowski et al., 2020) in years when Great Salt Lake water levels were below 1278.5 m (measured in meters above sea level). We calculated mean minimum temperatures during April-July from monthly minimum temperature summaries collected at the Salt Lake City International Airport weather station (https://w2.weather.gov/climate/ ...
Article
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Shrinking saline lakes provide irreplaceable habitat for waterbird species globally. Disentangling the effects of wetland habitat loss from other drivers of waterbird population dynamics is critical for protecting these species in the face of unprecedented changes to saline lake ecosystems, ideally through decision‐making frameworks that identify effective management options and their potential outcomes. Here, we develop a framework to assess the effects of hypothesized population drivers and identify potential future outcomes of plausible management scenarios on a saline lake‐reliant waterbird species. We use 36 years of monitoring data to quantify the effects of environmental conditions on the population size of a regionally important breeding colony of American white pelicans (Pelecanus erythrorhynchos) at Great Salt Lake, Utah, US, then forecast colony abundance under various management scenarios. We found that low lake levels, which allow terrestrial predators access to the colony, are probable drivers of recent colony declines. Without local management efforts, we predicted colony abundance could likely decline approximately 37.3% by 2040, although recent colony observations suggest population declines may be more extreme than predicted. Results from our population projection scenarios suggested that proactive approaches to preventing predator colony access and reversing saline lake declines are crucial for the persistence of the Great Salt Lake pelican colony. Increasing wetland habitat and preventing predator access to the colony together provided the most effective protection, increasing abundance 145.4% above projections where no management actions are taken, according to our population projection scenarios. Given the importance of water levels to the persistence of island‐nesting colonial species, proactive approaches to reversing saline lake declines could likely benefit pelicans as well as other avian species reliant on these unique ecosystems.
... The American White Pelican (AWPE) is the most commonly trapped animal at the Rozel Tar Seeps during our study in 2018. Gunnison Island in GSL, 19 km from Rozel Point, is the location of one of the world's largest breeding populations of AWPE (Kijowski et al. 2020). These enormous birds, about a meter tall, spend their spring and summer, from March to September on the island nesting. ...
... In 2018, we began documenting the pelicans observed entrapped in the seeps and recording those that have been marked by the Utah Division of Wildlife Resources (Kijowski et al. 2020). To date, we have documented 42 pelicans entrapped in the tar seeps, 31 of them in one seep ( Fig. 15.8). ...
... It is important to note that pelican mortality is not restricted to the tar seeps but also occurs in the lake shoreline area outside of the tar seeps. Scattered bones of pelicans can be found on the beach outside the petroleum area covered (USGS 2019; Kijowski et al. 2020), but the degree of disarticulation has made it difficult to determine the number of individuals, and none of these individuals represented by bones retained wing tags, with the exception of a few recently deceased individuals and decay had not yet started. In these soils, wing tags can be easily separated from the animal following the decomposition of soft tissues, unlike birds in the tar seeps where the adhesive nature of the tar often holds the tag in place next to the bird. ...
Chapter
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Great Salt Lake (GSL), Utah, is the largest lake in the Great Basin and one of the primary migratory stops for many species of birds in North America. Located at Rozel Point, on the north arm of the lake, are natural tar seeps that have formed on the former lake bed resulting from the migration of oil to the surface along fault lines. Once the petroleum reaches the surface of the ground, usually at low pressure, it then spreads out from the seep. The resulting tar seeps are numerous and vary in size. During warm weather, the surface of the Rozel Point tar is sufficiently sticky, and it can lead to entrapment of animals.
... The world's second largest colony of American White Pelicans is on GSL's Gunnison Island. An average of 11,000 pelicans nest there (Paul and Manning 2002;Hoven 2017;Kijowski et al. 2020). During most years, this colony is surrounded by water and is safe from mammalian predators. ...
... During most years, this colony is surrounded by water and is safe from mammalian predators. In recent years, however, water levels in Gunnison Bay have dropped to the point that this island was connected to the mainland, and coyotes (Canis latrans) have gained access to the island (Kijowski et al. 2020). ...
... The world's second largest colony of American White Pelicans is on GSL's Gunnison Island. An average of 11,000 pelicans nest there (Paul and Manning 2002;Hoven 2017;Kijowski et al. 2020). During most years, this colony is surrounded by water and is safe from mammalian predators. ...
... During most years, this colony is surrounded by water and is safe from mammalian predators. In recent years, however, water levels in Gunnison Bay have dropped to the point that this island was connected to the mainland, and coyotes (Canis latrans) have gained access to the island (Kijowski et al. 2020). ...
Article
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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.
... Another taxon routinely detected with HPAIv before our model predicted arrival was the American white pelican (Pelecanus erythrorhynchos). This was particularly evident in the PF, where pelicans are known to perform longitudinal migrations to California from Utah (where HPAIv was detected in spring [60], in the summer months before fall waterfowl migration south to California. Detections in these groups (resident waterfowl/captive birds and pelicans) also preceded detections in commercial facilities, indicating that they may have been better indicators than migratory waterfowl of HPAIv spread to commercial facilities in this region in 2022. ...
Article
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Understanding timing and distribution of virus spread is critical to global commercial and wildlife biosecurity management. A highly pathogenic avian influenza virus (HPAIv) global panzootic, affecting ~600 bird and mammal species globally and over 83 million birds across North America (December 2023), poses a serious global threat to animals and public health. We combined a large, long-term waterfowl GPS tracking dataset (16 species) with on-ground disease surveillance data (county-level HPAIv detections) to create a novel empirical model that evaluated spatiotemporal exposure and predicted future spread and potential arrival of HPAIv via GPS tracked migratory waterfowl through 2022. Our model was effective for wild waterfowl, but predictions lagged HPAIv detections in poultry facilities and among some highly impacted nonmigratory species. Our results offer critical advance warning for applied biosecurity management and planning and demonstrate the importance and utility of extensive multispecies tracking to highlight potential high-risk disease spread locations and more effectively manage outbreaks.
... The Great Salt Lake (GSL) is the largest terminal saline lake in the Western Hemisphere and the largest inland body of water along the Pacific flyway, a major pathway for migratory birds in the Americas (Cohenour and Thompson 1966;Kijowski et al. 2020). In addition, the lake is surrounded by approximately 145,000 ha of wetlands, many of which are waterfowl impoundments that are hydrologically managed to support submerged aquatic vegetation, an important food source for the 4-6 million waterfowl and other migratory birds that frequent the region (Downard and Endter-Wada 2013;Downard et al. 2014). ...
Article
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Wetland impoundments are constructed for recreational and conservational purposes. Here, the water level can be carefully controlled, producing ideal conditions for aquatic plant growth to support migratory birds or other management goals. These wetlands also perform a critical function of nutrient assimilation, with the capability to protect downstream waters from eutrophication. Understanding how the structural characteristics of wetlands are related to this functional capacity within shallow impoundments will help inform management practices to improve overall wetland function. We characterized 18 waterfowl impoundments surrounding the Great Salt Lake, Utah, USA. Wetland assimilation of nitrogen (N) and phosphorus (P) was estimated at each wetland by controlled nutrient addition within mesocosms. In addition, wetland condition was assessed using a multimetric index (MMI), an indicator of the biological quality of the wetlands. We found that N assimilation was inversely correlated with water depth and positively correlated with soil % clay and total iron. Phosphorus assimilation was related to dissolved oxygen, aluminum, and N and P concentrations within the water column and soil. Nutrient assimilation did not differ among wetlands rated as poor, fair, and good by the MMI.
... Gunnison Island and the receding hypersaline water of Great Salt Lake's North Arm. With the island connected to the mainland, predators can access the island's colony of American white pelicans, which is one of the largest in the world105 . Photo: EcoFlight. ...
Technical Report
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Great Salt Lake is facing unprecedented danger. Without a dramatic increase in water flow to the lake in 2023 and 2024, its disappearance could cause immense damage to Utah's public health, environment, and economy. This briefing provides background and recommends emergency measures. The choices we make over the next few months will affect our state and ecosystems throughout the West for decades to come. We thank all those already working on solutions, and we thank you for considering this information.
... For both Great Salt Lake and Lake Urmia, the breaches in the existing transportation causeways could be closed or narrowed, allowing the southern portions of each lake to fill and function ecologically, but at the expense of all or some of the northern regions. In Great Salt Lake, closing the causeway would dry the north arm and connect Gunnison Island with the mainland, exposing one of the largest nesting colonies of White Pelicans (Pelecanus erythrorhynchos) in North America to predators, and their valuable habitat would likely be lost [100]. Additionally, the multi-million-dollar potash extraction industry there could not function. ...
Article
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Many saline lakes throughout the world are shrinking due to overexploitation of water in their drainage basins. Among them are two of the world’s largest saline lakes, the U.S.A.’s Great Salt Lake, and Iran’s Lake Urmia. Here we provide a comparative analysis of the desiccation of these two lakes that provides insights on management decisions that may help save them and that are relevant to saline lake management worldwide. Great Salt Lake and Lake Urmia were once remarkably similar in size, depth, salinity, and geographic setting. High rates of population growth in both basins have fueled a demand for irrigated agriculture and other uses. In the Great Salt Lake basin, this development began in the late 1800’s and is continuing. The lake’s volume has decreased by 67%, with 75% of the loss driven by water development and 25% by a millennial drought which may portend the start of global climate change impacts. This has greatly increased salinities to 180 g·L−1 stressing the invertebrates in the lake on which birds depend. Only 1% of people in the basin are employed in agriculture; thus, reducing the demand for irrigation development. Population densities in the Urmia basin are double those of the Great Salt Lake basin, and 28% of people are employed in agriculture. These demographics have led to a rapid increase in reservoir construction since 2000 and the subsequent loss of 87% of Lake Urmia’s volume. The water development of Lake Urmia was later, but much faster than that of Great Salt Lake, causing Urmia’s salinity to increase from 190 to over 350 g·L−1 in just 20 years, with subsequent severe ecological decline. Dust storms from the exposed lakebeds of both systems threaten the health of the surrounding populations. To save these lakes and others will require: (1) transparent and collaborative involvement with local interest groups; (2) shifts away from an agricultural-based economy to one based on manufacturing and services; (3) consideration of the diverse ecosystem services of the lakes including mineral extraction, recreation, bird habitats in surrounding wetlands, and dust control.
... Together with Artemia, these invertebrates represent keystone species of North and South American saline lakes and constitute an important food resource for millions of avian migrators (Herbst, 1999;Marden et al., 2020;Red on et al., 2020). Great Salt Lake, the largest body of water on the Pacific flyway, hosts 338 migratory bird species, including shorebirds (Sorenson et al., 2020) and pelagic birds (Conover & Bell, 2020;Kijowski et al., 2020). In recent years, Nearctic-Neotropical migratory bird species have shown the greatest reduction in their populations, but intra-Nearctic migrants also have declined in abundance (Kirby et al., 2008). ...
Article
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When it comes to the investigation of key ecosystems in the world, we often omit salt from the ecological recipe. In fact, despite occupying almost half of the volume of inland waters and providing crucial services to humanity and nature, inland saline ecosystems are often overlooked in discussions regarding the preservation of global aquatic resources of our planet. As a result, our knowledge of the biological and geochemical dynamics shaping these environments remains incomplete and we are hesitant in framing effective protective strategies against the increasing natural and anthropogenic threats faced by such habitats. Hypersaline lakes, water bodies where the concentration of salt exceeds 35 g/l, occur mainly in arid and semiarid areas resulting from hydrological imbalances triggering the accumulation of salts over time. Often considered the ‘exotic siblings’ within the family of inland waters, these ecosystems host some of the most extremophile communities worldwide and provide essential habitats for waterbirds and many other organisms in already water-stressed regions. These systems are often highlighted as natural laboratories, ideal for addressing central ecological questions due to their relatively low complexity and simple food web structures. However, recent studies on the biogeochemical mechanisms framing hypersaline communities have challenged this archetype, arguing that newly discovered highly diverse communities are characterised by specific trophic interactions shaped by high levels of specialisation. The main goal of this review is to explore our current understanding of the ecological dynamics of hypersaline ecosystems by addressing four main research questions: (i) why are hypersaline lakes unique from a biological and geochemical perspective; (ii) which biota inhabit these ecosystems and how have they adapted to the high salt conditions; (iii) how do we protect biodiversity from increasing natural and anthropogenic threats; and (iv) which scientific tools will help us preserve hypersaline ecosystems in the future? First, we focus on the ecological characterisation of hypersaline ecosystems, illustrate hydrogeochemical dynamics regulating such environments, and outline key ecoregions supporting hypersaline systems across the globe. Second, we depict the diversity and functional aspects of key taxa found in hypersaline lakes, from microorganisms to plants, invertebrates, waterbirds and upper trophic levels. Next, we describe ecosystem services and discuss possible conservation guidelines. Finally, we outline how cutting-edge technologies can provide new insights into the study of hypersaline ecology. Overall, this review sheds further light onto these understudied ecosystems, largely unrecognised as important sources of unique biological and functional diversity. We provide perspectives for key future research avenues, and advocate that the conservation of hypersaline lakes should not be taken with ‘a grain of salt’.
... Shallow, wadeable water separates the island from the mainland at about 4,197 feet and a land-bridge forms when lake levels drops below about 4,193 feet (UDNR FFSL, 2013). Great Salt Lake level has consistently been lower than 4,197 feet since 2012 (Fig. 2), threatening one of the largest White Pelican rookeries in North America (Kijowski et al. 2020). ...
Preprint
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Utah's Great Salt Lake covers 5500 km 2 (2100 mi 2) at its unimpacted elevation and is the eighth largest saline lake in the world. Its highly productive food web supports millions of migratory birds and the economic value of the lake is estimate at 1.5billionin2019U.S.dollars.Droughtsandwetcycleshavecausedhugefluctuationsinlakelevel,areaandsalinities,andthisvariationhasmaskedanthropogenicimpacts.Recentwork,however,hasdeterminedthatconsumptivewaterusesinthewatershedhavedepletedinflowsbyapproximately391.5 billion in 2019 U.S. dollars. Droughts and wet cycles have caused huge fluctuations in lake level, area and salinities, and this variation has masked anthropogenic impacts. Recent work, however, has determined that consumptive water uses in the watershed have depleted inflows by approximately 39%, with 63% used by agriculture, 11% by cities, 13% by solar ponds, and 13% by other uses. This has lowered the lake by 3.4 m, decreased its area by 51%, and reduced its volume by 64%. Projected water development of the lake's primary tributary could lower the lake approximately 1.5 m more. Climate change, to date, has not noticeably influenced lake level. Per-capita water use in Utah is the second highest in the nation and is 2.6-fold higher than other semi-arid nations. Potential solutions exist to reduce consumptive water uses and stabilize or increase Great Salt Lake water level. Water conservation is likely the most economical solution, with permanently mandated water cutbacks costing 14-96 million (5to5 to 32 per person). Water conservation paired with water markets reduce costs further, costing between 2to2 to 16 per person. Descriptions of potential solutions to reduce consumptive water uses and stabilize Great Salt lake level are a starting point to encourage discussion. Strategies have yet to be prioritized or thoroughly evaluated. Quantifying water diversions from rivers that feed Great Salt Lake and consumptive water uses will allow Utahns to make de-fensible decisions to manage water resources and the lake's biology for long term ecological, recreational, and economic benefit.
Chapter
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The elevation of Great Salt Lake has fallen to historic lows in recent years, exposing once submerged microbialites along the lake’s shores. Although prior studies have attempted to map microbialite locations, this has proved challenging, with mapped microbialite areas limited to accessible shoreline locations or via indirect sonographic evidence. Meanwhile, the importance of Great Salt Lake’s microbialites to the lake’s food chain has made quantifying the extent of microbialites exposed versus submerged at different lake elevations critical to lake management decisions. Low lake levels combined with seasonal high-water clarity have enabled microbialite reefs to be spotted in aerial and satellite imagery, even in deeper areas of the lake. In this study, satellite images were used to identify and map microbialite reef areas in Great Salt Lake and along its dry shores. In the south arm, submerged microbialites were easily recognized as dark green reefs against a light-colored benthic background (primarily ooid sand). Stationary microbialite mounds were distinguished from rip-up clasts or other dark-colored mobile material by comparing potential microbialite regions across several high-visibility timepoints. In this way, we identified 649 km2 (251 mi2) of putative microbialite reef area: 288 km2 (111 mi2) in the north arm, 360 km2 (139 mi2) in the south arm, of which 375 km2 (145 mi2) was mapped at a high degree of confidence. We also produced geospatial shapefiles of these areas. This map, combined with currently available lake bathymetric data, permits the estimation of the extent of microbialite reef exposed vs. submerged in various parts of the lake at different lake elevations. At the end of fall 2022, when lake level dipped to 1276.7 masl (4188.5 ft-asl) in elevation, we estimate that ~40% of the south arm microbialite reef area was exposed.
Chapter
Great Salt Lake (GSL) covers 5500 km² (2100 mi²) at its unimpacted elevation and is the eighth largest saline lake in the world. Its highly productive food web supports millions of migratory birds and the economic value of the lake is estimated at 1.5billionUSdollarsin2019.Droughtsandwetcycleshavecausedhugefluctuationsinlakelevel,area,andsalinities,andthisvariationhasmaskedanthropogenicimpacts.Recentwork,however,hasdeterminedthatconsumptivewaterusesinthewatershedhavedepletedinflowsbyapproximately391.5 billion US dollars in 2019. Droughts and wet cycles have caused huge fluctuations in lake level, area, and salinities, and this variation has masked anthropogenic impacts. Recent work, however, has determined that consumptive water uses in the watershed have depleted inflows by approximately 39%, with 63% used by agriculture, 11% by cities, 13% by solar ponds, and 13% by other uses. This has lowered the lake by 3.4 m, decreased its area by 51%, and reduced its volume by 64% as of 2019. Projected water development of the lake’s primary tributary could lower the lake approximately 1.5 m more. Climate change, to date, has not noticeably influenced lake level. Per capita water use in Utah is the second highest in the nation and is 2.6-fold higher than other semiarid nations. Potential solutions exist to reduce consumptive water uses and stabilize or increase the GSL water level. Water conservation is likely the most economical solution, with permanently mandated water cutbacks costing 14–96 million (532perperson).Waterconservationpairedwithwatermarketsreducecostsfurther,costingbetween5–32 per person). Water conservation paired with water markets reduce costs further, costing between 2 and $16 per person. Descriptions of potential solutions to reduce consumptive water uses and stabilize GSL level are a starting point to encourage discussion. Strategies have yet to be prioritized or thoroughly evaluated. Quantifying water diversions from rivers that feed GSL and consumptive water uses will allow Utahns to make defensible decisions to manage water resources and the lake’s biology for long-term ecological, recreational, and economic benefit.
Chapter
Terminal lakes are highly susceptible to climate change impacts since water that enters through precipitation, runoff, and groundwater must be balanced with water that leaves through evaporation. A change in this equation can lead to a decline in elevation, which can be tragic for the ecosystem, particularly if the closed basin is shallow. Great Salt Lake faces many threats that will impact the volume of water in the depression of the Bonneville Basin where it resides. If the lake’s level declines, salinity increases, and wetlands are altered. Salinity is a driver of microbial diversity and, as this foundation of the ecosystem is altered, so will be the rest of the food web, affecting large numbers of avian migrators along the Pacific and Central fly-ways. Human population growth and water diversions for agriculture have put a strain on Great Salt Lake, resulting in a terminal lake whose trajectory is downward in surface area. How might anthropogenic climate change impact this scenario? Alterations in temperature can influence the timing of snowmelt and change evapotranspiration. As temperatures increase and droughts persist, climate change will amplify the decline in lake elevation, creating more dust from the exposed lakebed. Dust blowing into inhabited valleys will worsen air quality with particulates and may be laden with the pollutants collected by the lake. Early melting of the snowpack in the Wasatch Mountains due to higher temperatures would be further impacted as airborne dust from the dry shorelines is deposited during storms and can reduce the albedo of snow, altering groundwater recharge of the watershed. The current status of Great Salt Lake, with no water rights of its own and increasing pressures for water use upstream, does not bode well for the survival of this critical ecosystem given climate change predictions for the southwestern United States.
Chapter
Every year millions of shorebirds representing 42 species congregate on Great Salt Lake (GSL). It is one of the largest concentrations of shorebirds on Earth, and yet, compared to waterfowl and colonial nesting species at GSL, they have received relatively little attention. Some shorebirds nest and rear young, but many more use the lake as a fueling stopover during migration with some departing flights lasting thousands of nonstop kilometers. Three ecological parameters determine whether or not any given location is suitable shorebird habitat: water depth, type and extent of vegetation, and type of food items available. Although shorebirds are opportunistic, each species shows a preferential niche along the intersection of these parameters, which do not form distinct units but lie along overlapping continuums. We explain these continuums and describe how, in each specific shorebird habitat, salinity is a driver for both vegetation and macroinvertebrates, the primary food source. Playas and mudflats are important components of shorebird habitat, but the characteristics that define these features in the landscape have been mired in confusion. We clarify these major components of the GSL ecosystem. Finally, we provide species accounts for each of the 42 species of shorebird while at GSL, detailing status, abundance, range, and timing of arrival and departure and ecological preferences.
Chapter
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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.
Article
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A fishery for brine shrimp (Artemia franciscana) cysts to supply the aquaculture industry considerably expanded in the late 1980s in the Great Salt Lake, Utah, USA. With this expansion, concerns emerged in the 1990s about the fishery's sustainability, especially its impact on the abundant western North American waterbirds that use the lake and feed on brine shrimp. We track the development of management strategies using adaptive management by the Utah Division of Wildlife Resources (UDWR), which focused on the biology of the system and development of biology‐based harvesting models. The models and their rationale are presented, their success in forecasting is evaluated, and implications for managing the harvest and conserving waterbirds are examined. We view this as an interesting case study because it transpired over a short time in a relatively simple system. This permitted us to clearly track management from the onset of a harvest market, through realization that the harvest had to be managed in the absence of needed biological knowledge, to the adaptive development of management strategies as biological knowledge was accumulated. The outcome illustrates the success that harvest management can attain with careful monitoring of the resource and terminating the harvest when a necessary escapement stock is attained.
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Microbialites, organosedimentary carbonate structures, cover approximately 20% of the basin floor in the south arm of Great Salt Lake, which ranges from ~12 to 15% salinity. Photosynthetic microbial mats associated with these benthic mounds contribute biomass that supports secondary production in the ecosystem, including that of the brine shrimp, Artemia franciscana. However, the effects of predicted increases in the salinity of the lake on the productivity and composition of these mats and on A. franciscana fecundity is not well documented. In the present study, we applied molecular and microcosm‐based approaches to investigate the effects of changing salinity on (1) the primary productivity, abundance, and composition of microbialite‐associated mats of GSL, and (2) the fecundity and survivability of the secondary consumer, A. franciscana. When compared to microcosms incubated closest to the in situ measured salinity of 15.6%, the abundance of 16S rRNA gene templates increased in microcosms with lower salinities and decreased in those with higher salinities following a 7‐week incubation period. The abundance of 16S rRNA gene sequences affiliated with dominant primary producers, including the cyanobacterium Euhalothece and the diatom Navicula, increased in microcosms incubated at decreased salinity, but decreased in microcosms incubated at increased salinity. Increased salinity also decreased the rate of primary production in microcosm assays containing mats incubated for 7 weeks and decreased the number of A. franciscana cysts that hatched and survived. These results indicate that an increase in the salinity of GSL is likely to have a negative impact on the productivity of microbialite communities and the fecundity and survivability of A. franciscana. These observations suggest that a sustained increase in the salinity of GSL and the effects this has on primary and secondary production could have an upward and negative cascading effect on higher‐trophic‐level ecological compartments that depend on A. franciscana as a food source, including a number of species of migratory birds.
Article
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Halophilic archaea inhabit hypersaline ecosystems globally, and genetically similar strains have been found in locales that are geographically isolated from one another. We sought to test the hypothesis that small salt crystals harboring halophilic archaea could be carried on bird feathers and that bird migration is a driving force of these distributions. In this study, we discovered that the American White Pelicans (AWPE) at Great Salt Lake soak in the hypersaline brine and accumulate salt crystals (halite) on their feathers. We cultured halophilic archaea from AWPE feathers and halite crystals. The microorganisms isolated from the lakeshore crystals were restricted to two genera: Halorubrum and Haloarcula, however, archaea from the feathers were strictly Haloarcula. We compared partial DNA sequence of the 16S rRNA gene from our cultivars with that of similar strains in the GenBank database. To understand the biogeography of genetically similar halophilic archaea, we studied the geographical locations of the sampling sites of the closest-matched species. An analysis of the environmental factors of each site pointed to salinity as the most important factor for selection. The geography of the sites was consistent with the location of the sub-tropical jet stream where birds typically migrate, supporting the avian dispersal hypothesis.
Article
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For migratory waterbirds, the availability and quality of suitable stopover habitat can affect body condition and demographic parameters throughout the annual cycle. This study investigates the importance of the Salton Sea, a large saline lake located in the southwestern United States near the USA-Mexico border, for migrating Caspian Terns (Hydroprogne caspia) fitted with long-duration satellite telemetry tags in the northwest contiguous USA. During fall migration, 100% (n = 25) in 2014 and 98% (n = 63) in 2015 of all tagged individuals were tracked to the Salton Sea, with median durations of stay lasting 36 and 25 days, respectively. Use of the Salton Sea during subsequent spring migrations was less consistent than in fall, but still substantial, with 91% (n = 23) and 68% (n = 53) of all birds conducting brief stops there during 2015 and 2016, respectively. The future of the Salton Sea as suitable habitat for fish and piscivorous birds is uncertain due to rising salinity levels caused by reduced input flows. It is also uncertain if other wetlands in the region can serve as replacement habitat for Caspian Terns and other migratory piscivorous species should the Salton Sea cease to provide fish prey.
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Over geologic time, the water in the Bonneville basin has risen and fallen, most dramatically as freshwater Lake Bonneville lost enormous volume 15,000–13,000 years ago and became the modern day Great Salt Lake. It is likely that paleo-humans lived along the shores of this body of water as it shrunk to the present margins, and native peoples inhabited the surrounding desert and wetlands in recent times. Nineteenth century Euro-American explorers and pioneers described the geology, geography, and flora and fauna of Great Salt Lake, but their work attracted white settlers to Utah, who changed the lake immeasurably. Human intervention in the 1950s created two large sub-ecosystems, bisected by a railroad causeway. The north arm approaches ten times the salinity of sea water, while the south arm salinity is a meager four times that of the oceans. Great Salt Lake was historically referred to as sterile, leading to the nickname “America’s Dead Sea.” However, the salty brine is teaming with life, even in the hypersaline north arm. In fact, scientists have known that this lake contains a diversity of microscopic lifeforms for more than 100 years. This essay will explore the stories of the people who observed and researched the salty microbiology of Great Salt Lake, whose discoveries demonstrated the presence of bacteria, archaea, algae, and protozoa that thrive in this lake. These scientists documented the lake’s microbiology as the lake changed, with input from human waste and the creation of impounded areas. Modern work on the microbiology of Great Salt Lake has added molecular approaches and illuminated the community structures in various regions, and fungi and viruses have now been described. The exploration of Great Salt Lake by scientists describing these tiny inhabitants of the brine illuminate the larger terminal lake with its many facets, anthropomorphic challenges, and ever-changing shorelines.
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In the Southwest and Central Plains of Western North America, climate change is expected to increase drought severity in the coming decades. These regions nevertheless experienced extended Medieval-era droughts that were more persistent than any historical event, providing crucial targets in the paleoclimate record for benchmarking the severity of future drought risks. We use an empirical drought reconstruction and three soil moisture metrics from 17 state-of-the-art general circulation models to show that these models project significantly drier conditions in the later half of the 21st century compared to the 20th century and earlier paleoclimatic intervals. This desiccation is consistent across most of the models and moisture balance variables, indicating a coherent and robust drying response to warming despite the diversity of models and metrics analyzed. Notably, future drought risk will likely exceed even the driest centuries of the Medieval Climate Anomaly (1100-1300 CE) in both moderate (RCP 4.5) and high (RCP 8.5) future emissions scenarios, leading to unprecedented drought conditions during the last millennium.
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Great Salt Lake (Utah, USA) is one of the world's largest hypersaline lakes, supporting many of the western U.S.'s migratory waterbirds. This unique ecosystem is threatened, but it and other large hypersaline lakes are not well understood. The ecosystem consists of two weakly linked food webs: one phytoplankton-based, the other organic particle/benthic algae-based. Seventeen years of data on the phytoplankton-based food web are presented: abundances of nutrients (N and P), phytoplankton (Chlorophyta, Bacillariophyta, Cyanophyta), brine shrimp (Artemia franciscana), corixids (Trichocorixa verticalis), and Eared Grebes (Podiceps nigricollis). Abundances of less common species, as well as brine fly larvae (Ephydra cinerea and hians) from the organic particle/benthic algae-based food web are also presented. Abiotic parameters were monitored: lake elevation, temperature, salinity, PAR, light penetration, and DO. We use these data to test hypotheses about the phytoplankton-based food web and its weak linkage with the organic particle/benthic algae-based food web via structural equation modeling. Counter to common perceptions, the phytoplankton-based food web is not limited by high salinity, but principally through phytoplankton production, which is limited by N and grazing by brine shrimp. Annual N abundance is highly variable and depends on lake volume, complex mixing given thermo-and chemo-clines, and recycling by brine shrimp. Brine shrimp are food-limited, and predation by corixids and Eared Grebes does not depress their numbers. Eared Grebe numbers appear to be limited by brine shrimp abundance. Finally, there is little interaction of brine fly larvae with brine shrimp through competition, or with corixids or grebes through predation, indicating that the lake's two food webs are weakly connected. Results are used to examine some general concepts regarding food web structure and dynamics, as well as the lake's future given expected anthropogenic impacts.
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In the past decade, severe weather and West Nile virus were major causes of chick mortality at American white pelican (Pelecanus erythrorhynchos) colonies in the northern plains of North America. At one of these colonies, Chase Lake National Wildlife Refuge in North Dakota, spring arrival by pelicans has advanced approximately 16 days over a period of 44 years (1965-2008). We examined phenology patterns of pelicans and timing of inclement weather through the 44-year period, and evaluated the consequence of earlier breeding relative to weather-related chick mortality. We found severe weather patterns to be random through time, rather than concurrently shifting with the advanced arrival of pelicans. In recent years, if nest initiations had followed the phenology patterns of 1965 (i.e., nesting initiated 16 days later), fewer chicks likely would have died from weather-related causes. That is, there would be fewer chicks exposed to severe weather during a vulnerable transition period that occurs between the stage when chicks are being brooded by adults and the stage when chicks from multiple nests become part of a thermally protective crèche.
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ABSTRACT  About 1.5-million eared grebes (Podiceps nigricollis), representing half of the North American population, stage on Utah's Great Salt Lake, USA (GSL) during autumn migration to forage on brine shrimp (Artemia franciscana). Indirectly competing with birds for brine shrimp are commercial harvesters who annually collect >1 million kg (dry wt) of shrimp cysts (i.e., hardened eggs), an amount that during some years equals up to half of all brine shrimp cysts produced annually on the GSL. No information was available regarding what impact this commercial harvest was having on eared grebes. We determined daily energy requirements of eared grebes so that regulations governing brine shrimp cyst harvest would better reflect foraging needs of grebes. We measured basal metabolic rate (BMR) of eared grebes from June 2000 to October 2000. Mean BMR of 106 adult and subadult eared grebes was 0.023 kJ/g/hour (SD = 0.004), and mean BMR of 37 juveniles was 0.024 kJ/g/hour (SD = 0.003). Resting and preening metabolic rates were 1.2 times higher than BMR, whereas diving-bout metabolic rate was 1.7 times higher than BMR. Daily energy needs of an average-sized grebe (550 g) during November were 391 kJ. Meeting this energy need requires daily consumption of 24,400 adult brine shrimp. In addition, grebes must consume 2,100–5,200 adult shrimp daily to obtain enough energy reserves to continue their migration to California, USA, and Mexico. Hence, grebes need to consume 26,500–29,600 adult brine shrimp daily while staging on GSL. To achieve this high harvest rate, grebes need adult brine shrimp densities at >380 shrimp/m3during autumn. Commercial harvest of brine shrimp cysts from GSL should be curtailed when cyst densities fall below 20,000 cysts/m3to ensure enough adult brine shrimp for grebes during the subsequent year.
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When did humans colonize the Americas? From where did they come and what routes did they take? These questions have gripped scientists for decades, but until recently answers have proven difficult to find. Current genetic evidence implies dispersal from a single Siberian population toward the Bering Land Bridge no earlier than about 30,000 years ago (and possibly after 22,000 years ago), then migration from Beringia to the Americas sometime after 16,500 years ago. The archaeological records of Siberia and Beringia generally support these findings, as do archaeological sites in North and South America dating to as early as 15,000 years ago. If this is the time of colonization, geological data from western Canada suggest that humans dispersed along the recently deglaciated Pacific coastline.
Book
Great Salt Lake is an enormous terminal lake in the western United States. It is a highly productive ecosystem, which has global significance for millions of migrating birds who rely on this critical feeding station on their journey through the American west. For the human population in the adjacent metropolitan area, this body of water provides a significant economic resource as industries, such as brine shrimp harvesting and mineral extraction, generate jobs and income for the state of Utah. In addition, the lake provides the local population with ecosystem services, especially the creation of mountain snowpack that generates water supply, and the prevention of dust that may impair air quality. As a result of climate change and water diversions for consumptive uses, terminal lakes are shrinking worldwide, and this edited volume is written in this urgent context. This is the first book ever centered on Great Salt Lake biology. Current and novel data presented here paint a comprehensive picture, building on our past understanding and adding complexity. Together, the authors explore this saline lake from the microbial diversity to the invertebrates and the birds who eat them, along a dynamic salinity gradient with unique geochemistry. Some unusual perspectives are included, including the impact of tar seeps on the lake biology and why Great Salt Lake may help us search for life on Mars. Also, we consider the role of human perceptions and our effect on the biology of the lake. The editors made an effort to involve a diversity of experts on the Great Salt Lake system, but also to include unheard voices such as scientists at state agencies or non-profit advocacy organizations. This book is a timely discussion of a terminal lake that is significant, unique, and threatened.
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The isolated north arm of Great Salt Lake, Utah, is a unique and complex environment with salinity at saturation, above 25% total salts. It is separated from the larger south arm, which experiences more freshwater input, due to a rock-filled causeway installed around 1960. Prior studies using both cultivation and molecular methods have shown that the microbial community of this part of the lake is diverse and dynamic, experiencing year-round fluctuations in salinity and temperature. The data emerging from our published studies and others have demonstrated the presence of microbial genera from all three domains of life, with the archaeal diversity being the greatest. When we cultivated approximately 50 isolates, the majority of these were genotyped as archaea, and only four cultivars belonged to the Domain bacteria. Thus, initial studies, reviewed herein, focused on understanding the diversity of the overrepresented archaea, using molecular, culture-independent methods to assess temporal diversity and significance of environmental parameters. Cultivation studies revealed details about how the stable members of the communities maintained their lifestyle using differential gene expression. But bacteria also live in this archaeal world, and they remain understudied in hypersaline systems. Therefore, we analyzed the bacterial isolates, genetically and biochemically, to reveal more information about the bacteria of the Great Salt Lake north arm. The genus Salinibacter was present throughout the year and mostly dominated the bacterial population. 16S rRNA gene sequencing of these bacterial cultivars demonstrated relationships to strains of Salinibacter, strains of Halomonas, and other uncultured deposited DNA sequences. To look at temporal diversity profiles of this bacterial minority, next-generation DNA sequencing (with semiconductor sequencing technology) was employed on DNA extracted from four water samples collected at different time points. The analysis showed that the majority of bacteria matched the genus Salinibacter, and the minority members of the microbial population were of the genera Anaeromyxobacter, Perexilibacter, Halomonas, Psychroflexus, Schlesneria, Pseudomonas, Roseovarius, Haliscomenobacter, and Vulgatibacter. Here, we discuss methods for microbial diversity studies in hypersaline aquatic systems and review the work on the microbial diversity of the north arm. We give an overview of the predominant halophilic archaea, but we present a broader picture by including new data on the underrepresented bacterial component of this fascinating community that manages a lifestyle at salt saturation.
Chapter
Great Salt Lake (GSL) is a hypersaline terminal lake and has varied historically in salinity from 6 to 28%. Because the lake’s salinity is much greater than in marine environments (~3.5%), salinity is often assumed to be the driving factor for GSL benthic and pelagic food webs. Certainly, many species cannot live in a hypersaline environment (e.g., fish), and the diversity of species capable of coping with hypersaline conditions is limited. However, the GSL’s benthic and pelagic food webs are adapted to these extreme saline conditions, and their dynamics (primary and secondary production, species abundances, etc.) respond in a complex fashion to the interplay of salinity, temperature, and nutrient availability. Therefore, focusing solely on salinity is not appropriate. In this chapter, we first explore historically how GSL food webs have been reported to change and found salinity to have limited impact. We next demonstrate that in recent years (1994–2018) GSL food webs varied far less with salinity than might be expected, even though salinity varied by 8.2–17.5%, because temperatures and nutrient availability covaried with salinity and showed more impacts than salinity alone. Finally, we employ the observations on the interplay of salinity, temperature, and nutrients to project how future climatic changes in the GSL watershed will affect primary producers and consumers and impact GSL food webs. These future climatic changes will have profound effects on GSL food web dynamics.
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The anostracan crustacean Artemia franciscana is the most abundant zooplankter in Great Salt Lake (GSL) and generally the only zooplankton in the largest bay (Gilbert Bay) of this hypersaline system. Colloquially referred to as brine shrimp, Artemia are crucially important organisms in GSL and provide numerous ecosystem services including the control of eutrophication in this naturally productive lake, an abundant energy supply to a large avian population along hemispheric flyways, and critical support of global aquaculture through the large-scale commercial harvest of the resting eggs (cysts) for use as live feed in shrimp and finfish production across the world. This chapter examines the GSL Artemia population and its management from multiple angles. The successful adaptive management of the Artemia resource is discussed as a model of cooperative public and private research. An extensive body of research on the biochemistry and physiology of diapause and quiescence among Artemia cysts is reviewed. Population structure and patterns of GSL Artemia are examined across annual and multi-decadal timescales using large datasets of public and private research programs. Population level responses to spatial and temporal fluctuations in salinity are evaluated. Top-down and bottom-up controls on the Artemia population are reviewed, including the influence of salinity stratification (meromixis) on nutrient distribution within the lake and new molecular evidence of benthic linkages to the Artemia population via microbialites. Finally, we provide an assessment of threats to the GSL Artemia population and a summary of management structures and initiatives in place to mitigate them.
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Great Salt Lake (GSL) covers 5500 km² (2100 mi²) at its unimpacted elevation and is the eighth largest saline lake in the world. Its highly productive food web supports millions of migratory birds and the economic value of the lake is estimated at 1.5billionUSdollarsin2019.Droughtsandwetcycleshavecausedhugefluctuationsinlakelevel,area,andsalinities,andthisvariationhasmaskedanthropogenicimpacts.Recentwork,however,hasdeterminedthatconsumptivewaterusesinthewatershedhavedepletedinflowsbyapproximately391.5 billion US dollars in 2019. Droughts and wet cycles have caused huge fluctuations in lake level, area, and salinities, and this variation has masked anthropogenic impacts. Recent work, however, has determined that consumptive water uses in the watershed have depleted inflows by approximately 39%, with 63% used by agriculture, 11% by cities, 13% by solar ponds, and 13% by other uses. This has lowered the lake by 3.4 m, decreased its area by 51%, and reduced its volume by 64% as of 2019. Projected water development of the lake’s primary tributary could lower the lake approximately 1.5 m more. Climate change, to date, has not noticeably influenced lake level. Per capita water use in Utah is the second highest in the nation and is 2.6-fold higher than other semiarid nations. Potential solutions exist to reduce consumptive water uses and stabilize or increase the GSL water level. Water conservation is likely the most economical solution, with permanently mandated water cutbacks costing 14–96 million (532perperson).Waterconservationpairedwithwatermarketsreducecostsfurther,costingbetween5–32 per person). Water conservation paired with water markets reduce costs further, costing between 2 and $16 per person. Descriptions of potential solutions to reduce consumptive water uses and stabilize GSL level are a starting point to encourage discussion. Strategies have yet to be prioritized or thoroughly evaluated. Quantifying water diversions from rivers that feed GSL and consumptive water uses will allow Utahns to make defensible decisions to manage water resources and the lake’s biology for long-term ecological, recreational, and economic benefit.
Chapter
Terminal lakes are highly susceptible to climate change impacts since water that enters through precipitation, runoff, and groundwater must be balanced with water that leaves through evaporation. A change in this equation can lead to a decline in elevation, which can be tragic for the ecosystem, particularly if the closed basin is shallow. Great Salt Lake faces many threats that will impact the volume of water in the depression of the Bonneville Basin where it resides. If the lake’s level declines, salinity increases, and wetlands are altered. Salinity is a driver of microbial diversity and, as this foundation of the ecosystem is altered, so will be the rest of the food web, affecting large numbers of avian migrators along the Pacific and Central fly-ways. Human population growth and water diversions for agriculture have put a strain on Great Salt Lake, resulting in a terminal lake whose trajectory is downward in surface area. How might anthropogenic climate change impact this scenario? Alterations in temperature can influence the timing of snowmelt and change evapotranspiration. As temperatures increase and droughts persist, climate change will amplify the decline in lake elevation, creating more dust from the exposed lakebed. Dust blowing into inhabited valleys will worsen air quality with particulates and may be laden with the pollutants collected by the lake. Early melting of the snowpack in the Wasatch Mountains due to higher temperatures would be further impacted as airborne dust from the dry shorelines is deposited during storms and can reduce the albedo of snow, altering groundwater recharge of the watershed. The current status of Great Salt Lake, with no water rights of its own and increasing pressures for water use upstream, does not bode well for the survival of this critical ecosystem given climate change predictions for the southwestern United States.
Chapter
The relationships between humans and Great Salt Lake (GSL) have always involved change and adaptation, for both humans and the lake. Humans have changed the lake in numerous ways, and the lake has changed humans, frequently in recursive processes. Further, forces external to both humans and GSL have affected both. Some key themes of change and the need for adaptation have included the elevation and related size of GSL, and humans’ attempts to manage that; technology, both lake-related and related to broader social trends; and finally, development, of population and of communities. Using sociological research findings, this chapter addresses gaps in our understanding of some of the many and drastic changes occurring with the lake, listening to people’s perceptions of and experiences with GSL and the transitions they have observed. Challenges for the future are outlined, including the complexities of needing to meet humans’ needs without further compromising the health of the lake.
Article
Many of the world's saline lakes are shrinking at alarming rates, reducing waterbird habitat and economic benefits while threatening human health. Saline lakes are long-term basin-wide integrators of climatic conditions that shrink and grow with natural climatic variation. In contrast, water withdrawals for human use exert a sustained reduction in lake inflows and levels. Quantifying the relative contributions of natural variability and human impacts to lake inflows is needed to preserve these lakes. With a credible water balance, causes of lake decline from water diversions or climate variability can be identified and the inflow needed to maintain lake health can be defined. Without a water balance, natural variability can be an excuse for inaction. Here we describe the decline of several of the world's large saline lakes and use a water balance for Great Salt Lake (USA) to demonstrate that consumptive water use rather than long-term climate change has greatly reduced its size. The inflow needed to maintain bird habitat, support lake-related industries and prevent dust storms that threaten human health and agriculture can be identified and provides the information to evaluate the difficult tradeoffs between direct benefits of consumptive water use and ecosystem services provided by saline lakes.
Article
1. Artemia is continuously swallowing its medium, whether it is hyper-, iso-, or hypotonic to the haemolymph, and taking up water from the gut lumen. 2. The osmotic pressure of the gut fluids is appreciably greater than that of the haemolymph, but in the more concentrated media is considerably below that of the medium. This indicates that considerable amounts of NaCl must be passing across the gut epithelium into the haemolymph. 3. The concentration of both sodium and chloride ions in the gut fluids is always less than that in the haemolymph, indicating that there must be an active uptake of NaCl across the gut epithelium. 4. It is considered that the gut of Artemia has become adapted as a mechanism for the active uptake of water, controlling water balance and preventing dehydration in hypertonic media. 5. The adaptations for maintaining the NaCl and the water balances in Artemia are compared to those found in the marine teleosts, and are shown to be extremely similar.
Article
We evaluated the impact of predation on juvenile steelhead Oncorhynchus mykiss and yearling and subyearling Chinook Salmon O. tshawytscha by piscivorous waterbirds from 11 different breeding colonies in the Columbia River basin during 2012 and 2014. Fish were tagged with both acoustic tags and PIT tags and were tracked via a network of hydrophone arrays to estimate total smolt mortality (1 – survival) at various spatial and temporal scales during out-migration. Recoveries of PIT tags on bird colonies, coupled with the last known detections of live fish passing hydrophone arrays, were used to estimate the impact of avian predation relative to total smolt mortality. Results indicated that avian predation was a substantial source of steelhead mortality, with predation probability (proportion of available fish consumed by birds) ranging from 0.06 to 0.28 for fish traveling through the lower Snake River and the lower and middle Columbia River. Predation probability estimates ranged from 0.03 to 0.09 for available tagged yearling Chinook Salmon and from 0.01 to 0.05 for subyearlings. Smolt predation by gulls Larus spp. was concentrated near hydroelectric dams, while predation by Caspian terns Hydroprogne caspia was concentrated within reservoirs. No concentrated areas of predation were identified for double-crested cormorants Phalacrocorax auritus or American white pelicans Pelecanus erythrorhynchos. Comparisons of total smolt mortality relative to mortality from colonial waterbirds indicated that avian predation was one of the greatest sources of mortality for steelhead and yearling Chinook Salmon during out-migration. In contrast, avian predation on subyearling Chinook Salmon was generally low and constituted a minor component of total mortality. Our results demonstrate that acoustic and PIT tag technologies can be combined to quantify where and when smolt mortality occurs and the fraction of mortality that is due to colonial waterbird predation relative to non-avian mortality sources.Received November 4, 2015; accepted February 1, 2016
Article
Predicting lake level fluctuations of the Great Salt Lake (GSL) in Utah – the largest terminal salt-water lake in the Western Hemisphere – is critical from many perspectives. The GSL integrates both climate and hydrological variations within the region and is particularly sensitive to low-frequency climate cycles. Since most hydroclimate variable records cover less than a century, forecasting the predominant yet under-represented decadal variability of the GSL level with such relatively short instrumental record poses a challenge. To overcome data limitations, this study assesses two options: (1) developing a model using the observational GSL elevation record of 137 years to predict itself; (2) incorporating the recently reconstructed GSL elevation that utilized 576 years’ worth of tree-ring records into the predictive model. It was found that the statistical models that combined the tree-ring reconstructed data with the observed data outperformed those that did not, in terms of reducing the root mean squared errors. Such predictive models can serve as a means towards practical water risk management.
Article
Since Darling' s (1938) early observations of gulls, many studies have focused on spatial and temporal patterns of reproduction in seabird colonies. Reproductive success of birds differs among colonies at different sites (Hunt 1972, Harris 1973), among hab-itats within a colony (Brown 1967, Nettle-ship 1972), between nests positioned cen-trally or peripherally in a colony (Patterson 1965, Coulson 1966, Tenaza 1971, Dexhei-mer and Southern 1974), with the relative timing of breeding (Patterson 1965, Ver-meer 1970, Parsons 1975, Hunt and Hunt 1976), and between successive seasons (Fordham 1970). At traditional nesting sites, nests of White Pelicans (Pelecanus erythrorhynchos) are grouped into many spatially and temporally separate colonies (Hall 1925, Low et al. 1950, Behle 1958). Since many colonies oc-cur on a single island, climatic factors influ-encing reproduction affect all birds similar-ly. At Gunnison Island, Utah, food is equally available to pelicans from different colonies (see discussion by Orians 1961) at the limited foraging areas along the eastern shore of Great Salt Lake (Behle 1958). Pat-terns of reproductive success in pelicans at Gunnison Island, show basic aspects of the colony-nesting habit better than at many other places. In 1973 and 1974 I studied co-lonial nesting of White Pelicans at Gunni-son Island. I report here the spatial and tem-poral distribution of their nesting efforts, how the distribution was established, and variations in reproductive success. STUDY AREA AND METHODS Gunnison Island lies in the northwest arm of Great Salt Lake about 12 km from the western shoreline (Knopf 1974). The island, 1.6 km long, reaches a maximum width of 0.8 km and rises 85 m above lake level. Its 66 ha include a series of large hills with connecting ridges that separate four low, sandy areas. Vegetation is typ-ical of the cold desert community (Oosting 1956). Prominent forms include Bromus tectorum, Atriplex spp., Sarcobatus vermiculatus, Suaeda intermedia, Bassia hyssopifolia, Salsola kali, Opuntia fragilis, and Chrysothamnus spp. As many as 6,600 pelicans nest on the flatter, lower elevations of the island each sea-son. Behle (1958) provided details of the study area and its historical use by White Pelicans. Male pelicans are larger than females (Palmer 1962), and I was able to visually distinguish the sexes (as verified during copulations) by differences in bill lengths. In addition, pelicans undergo a presupple-mental molt during incubation (Knopf 1975a). The re-sulting supplemental plumage of the crown varies greatly among individuals as does the structure of the maxillary "horn." I was able to recognize individuals by using these features. I surveyed pelican colonies weekly from 1 April to 31 July in 1973 and 1974, using binoculars, from higher elevations of the island. (A colony was defined after Penny [1968] as a geographically continuous group of breeding birds with contiguous territories.) During surveys I recorded reproductive stage and total num-ber of nests for each colony. For each new colony I noted date of establishment and spatial location rela-tive to nature of substrate, angle and direction of ground slope, associated vegetation, and proximity of other colonies. I measured distance-to-nearest-neigh-bor (nest rim to nest rim) for individual nests after chicks fledged. To aid in the description of how colonies were formed, I observed individual (n = 25) and paired (n = 42) birds for 30-min periods. I supplemented these ob-servations with telephoto, time-lapse photography of localized aggregations of courting birds. I surveyed contents of pelican nests periodically us-ing a 20X spotting scope from vantage points over-looking colonies. I recorded numbers of eggs and chicks as pelicans stood to stretch. turn the eggs, or feed a chick. I observed nests in specific colonies daily to define incidence of egg and chick mortality and in-ternest synchronization of hatching. I photographed each pelican colony weekly at dis-tances of 30 to 60 m from a hill or cliff above a colony. With these photographs I prepared weekly histories of each colony and determined the timing and location of nest abandonments. I also used photographs to census numbers of young surviving the nestling period in larg-er colonies. Late in the nestling period (21-28 days of age), I banded 300 pelican chicks in 1973 and 699 chicks in 1974. Plastic leg bands of different colors were applied to 64 of those chicks to aid in recognition of individuals after the nestling period. After all chicks fledged, I searched the island for banded chicks that died during the postnestling, prefledging (4-12 weeks of age) pe-riod.
Article
INTEREST has steadily mounted in the precarious plight of the gregarious, colony-nesting, White Pelicans, Pelecanus erythrorhynchus, which in the United States in 1932 numbered somewhere in the neigh- borhood of 30,000 birds in seven large and about 50 small breeding colonies (Thompson, 1932). In the perpetuation of a bird with so few "baskets" for its eggs, the success of each colony is highly im- portant. Because of the remoteness and inaccessibility of the colonies nesting on the islands of Great Salt Lake, opportunities for study by orni- thologists have been limited to short visits during the past 35 years. Juvenile pelicans have been banded as a part of the activities of the ornithologists. Studies of life history, present status and economic importance, picture-taking for educational films, and sight-seeing have largely motivated the parties which have visited the islands during the last few years. These present studies have been made
Article
1. The uptake of silver ions by Artemia has been investigated. The staining is localized to the first ten pairs of branchiae. There is no staining of the eleventh pair or of any other part of the animal. The uptake of silver is due to a purely passive precipitation of AgCl within the thickness of the branchial cuticle. 2. The effects of KMnO4 and methylene-blue solutions have also been studied. Their effect is localized to the epithelium under the cuticle of the first ten pairs of branchiae. 3. It is concluded that all these staining reactions demonstrate that the cuticle over the first ten pairs of branchiae is the only part of the external cuticle that is appreciably permeable. 4. Animals whose branchial epithelium has been damaged by a brief exposure to saturated KMnO4 solution have lost the ability to osmo-regulate. They are closely isotonic with their medium, and the range of external concentration tolerated is much restricted. 5. This isotonicity is not due simply to increased permeability, but is due to specific destruction of the mechanism normally excreting NaCl in hypertonic media. 6. Correlation of the physiological effects of KMnO4 treatment with the sharp localization of damage, and the evidence for localized permeability indicates that the epithelium of the first ten pairs of branchiae is the site of active NaCl excretion in hypertonic media, and probably of active uptake from hypotonic media. 7. The ontogeny of this mechanism is traced. In nauplii the dorsal organ is apparently concerned in NaCl excretion. When the branchiae develop the dorsal organ degenerates.
Article
Digital Hydrographic Maps were developed by means of a geographic information system in order to predict how nesting islands for the American White Pelican (Pelecanus erythrorhynchos) are likely to become land-bridged under variable water levels on Clear Lake Reservoir, California. As a management tool, the maps can be matched to water surface elevation changes forecasted by the U.S. Bureau of Reclamation every year. This graphic method has allowed Klamath Basin National Wildlife Refuge managers to set up electrified fences at Clear Lake Reservoir in advance of the nesting season, successfully protecting nesting colonies on two recent occasions. Digital Hydrographic Maps were also used to match historic hydrographic records for Clear Lake Reservoir to examine past lake conditions and changes in nesting island locations, particularly when nesting failures had occurred. Modifications to existing nesting islands are suggested, so as to create more stable nesting habitat.
Article
Comments on the American White Pelican (Pelecanus erythrorhynchos) in North America languished until Peter Ogden reported trapping one during his 1825 expedition to Utah. Brief accounts of the American White Pelican by ornithologists continued through the 1940s. In subsequent decades, scientific studies uncovered greater details of the species' biology and natural history, although documenting numbers has been difficult and tentative. Estimates of numbers of adults began at 30,000 in 1933, increased to over 100,000 by 1985, and by 1995 the total number of birds, then also including non-breeders, was estimated to be around 400,000. Beginning in the 1880s, their feeding and nesting sites were degraded by engineered water diversions and drainage of wetlands for agriculture. At the same time, pelicans were shot and clubbed, and eggs and young were intentionally destroyed largely because the birds were thought to compete with humans for fish. After the 1960s, hundreds of pelicans died yearly due to the ingestion of insecticides such as toxaphene, endrin, and dieldrin. As recently as winter 1998-99, 800 American White Pelicans died in Florida from poisoning by insecticides that were resuspended from flooded agricultural soils. In 1996 a disease pandemic at Salton Sea, California, killed over 7,500 pelicans in just several months. American White Pelicans have adapted to much persecution by simply moving. Overall, I do not believe that unusual mortalities have threatened their abundance.
Article
American white pelicans (Pelecanus erythrorhynchos) are colonial-nesting birds and their breeding sites are concentrated in a few small areas, making this species especially vulnerable to factors that can influence productivity, such as disease, disturbance, predation, weather events and loss of nesting habitat. Nearly half of the American white pelican population breeds at four colonies in the northern plains: Chase Lake National Wildlife Refuge (NWR) in North Dakota, Bitter Lake (Waubay NWR) in South Dakota, Medicine Lake NWR in Montana, and Marsh Lake in Minnesota. Thus, sustained productivity at these colonies is crucial to the health of the entire species. During the latter half of the 2002 and 2003 breeding seasons, unusually high mortality of pelican chicks was observed at these colonies. West Nile virus (WNv) was identified as one source of these losses. In 2004–2007 we monitored three major colonies in the northern plains to assess mortality of chicks during the late breeding season. We documented severe weather events, disturbance, and WNv as factors contributing to chick mortality. Before WNv arrived in the region in 2002, chick mortality after mid-July was ⩽4%, and then jumped to as high as 44% in the years since WNv arrived. WNv kills older chicks that are no longer vulnerable to other common mortality factors (e.g., severe weather, gull predation) and typically would have survived to fledge; thus WNv appears to be an additive mortality factor. Persistence of lower productivity at American white pelican colonies in the northern plains might reduce the adult breeding population of this species in the region.
Article
Lake Bonneville occupied a series of connected topographically-closed structural basins in the eastern Great Basin from about 30 ka to 12 ka. The following synthesis of Lake Bonneville history is based on a critical evaluation of the stratigraphic and geomorphic contexts of 83 radiocarbon ages of a variety of samples, including wood, charcoal, dispersed organic matter, mollusk shells, and tufa. The lake began to rise from levels close to average Holocene levels after about 28 ka. By 22 ka it had transgressed approximately 100 m; between 22 and 20 ka it regressed about 45 m in the Stansbury oscillation and the Stansbury shoreline was formed. Transgression after 20 ka proceeded in two phases—a rapid phase from 20 to 18 ka, and a slower phase from 18 to 15 ka. The lake overflowed intermittently at its highest level (the Bonneville shoreline) from about 15 to 14.5 ka, then catastrophically dropped 100 m during the Bonneville Flood to the level of the Provo shoreline, which it occupied until about 14 ka. Subsequent closed-basin regression was rapid and complete by 12 ka, and was followed by a modest transgression to form the Gilbert shoreline between 10.9 and 10.3 ka. The Lake Bonneville record is an accurate proxy of the changing water balance in the Bonneville basin during the late Pleistocene, although the nature of the climatic changes during this period are still uncertain.
Article
Benthic organisms and substrates in Great Salt Lake, Utah, were sampled to measure selenium concentrations of prey organisms of the birds that utilize the lake for nesting and during migrations. The sampling was focused on stromatolite biostromes, as these solid reef-like structures cover approximately 23% of the oxic benthic area of the lake and are the principal habitat for brine fly (Ephydra cinerea) larvae and pupae. Samples were taken at depths of 1-5 m along two transects in Gilbert Bay were salinities ranged from 116-126 g 1-1...
Article
Levels of organochlorine pesticides and mercury residues found in the White Pelican, Pelicanus erythrorhynchos, in southern Idaho are reported. Twelve white pelicans were collected and autopsied to obtain specimens for mercury analysis. They were collected along the Snake River about three miles downstream from the American Falls Reservoir. An additional bird was tested for organochlorine pesticides. This bird was found dead in the Lake Lowell region of Idaho at about the same time the other birds were collected. Analysis was made on each organ tissue separately and the results reported on a wet weight basis. The highest levels of mercury were found in the liver tissues, the highest mercury level being 32.80 ppm and the lowest level in the particular tissue 2.33 ppm. The organochlorine residues were so high in the single bird studied for these pesticides as to possibly account for its death. (MU)
Pelicans versus fishes in Pyramid Lake
  • E R Hall
  • ER Hall
Hall ER (1925) Pelicans versus fishes in Pyramid Lake. Condor 27(4):147-160
Geologic setting of Great Salt Lake
  • R E Cohenour
  • K C Thompson
  • RE Cohenour
Cohenour RE, Thompson KC (1966) Geologic setting of Great Salt Lake. In: The Great Salt Lake: guidebook to geology of Utah, vol 20. Utah Geological Society, Salt Lake City, UT, pp 35-46
Sanctuaries of the bird islands of Great Salt Lake
  • J W Sugden
  • JW Sugden
Sugden JW (1936) Sanctuaries of the bird islands of Great Salt Lake. Auk 53(3):288-294