A summary of biological investigations concerning the Great Salt Lake, Utah (1861-1973)

The early stages in the history of biological investigation of the Great Salt Lake involved the identification and establishment of taxonomic relationships of the indigenous flora and fauna. A result of advancements in systematic biology is that many of the earlier names of organisms have been placed in synonomy. Recent interest in the lake has centered on biological productivity and interactions of components of the ecosystem. The creation of two ecologically distinct lakes by the construction of a railroad causeway has further enhanced the biological complexity of what was originally believed to be a lifeless body of brine.       

Autumnal migration of Eared Grebes ( Podiceps nigricollis ) through southwestern Wyoming: a key to assessing the size of the North American population

In autumn the vast majority of the North American population of Eared Grebes ( Podiceps nigricollis ) congregates for several months at Great Salt Lake, Utah, and Mono Lake, California. Because the lakes are so large, it has not been possible to monitor grebe migration with sufficient accuracy to determine when peak numbers are reached. To clarify migration phenology, we analyzed data from 2 isolated wetland areas in southwestern Wyoming where grebes land en route between breeding areas in the interior and Great Salt Lake. Occasional birds, probably nonbreeders or failed breeders, begin moving southward as early as mid-June. Migration of postbreeding birds starts in late July, peaks in late August and September, and is largely completed by the end of October, with very small numbers arriving into November. The pattern of migration and number of birds encountered varied annually, but 95% of the migration was usually completed by 15 October. As a result, censuses at the major staging lake made on or after 15 October but before the grebes depart for wintering areas can be used to study trends in size of the North American population.     

Biology of Red-necked Phalaropes ( Phalaropus lobatus ) at the western edge of the Great Basin in fall migration

Large numbers of Red-necked Phalaropes migrate overland across the Great Basin in fall, occurring commonly at highly saline lakes. Migrants occur at Mono Lake, California, from mid-July to mid-October. The earliest migrants are adult females, followed several weeks later by adult males, and finally by juveniles. Adults make up ca 75% of the population, with males outnumbering females by 5:4. From 1980 through 1984 an estimated 52,000–65,000 birds passed through the area each year, except in 1983, when only 36,000 were recorded. The low number might be attributable to high mortality on oceanic wintering grounds in the Southern Hemisphere in 1982 associated with the severe El Ni&#241o. At Mono Lake the phalaropes concentrate near the shore and feed almost exclusively on brine flies. The migrants neither gain much weight nor accomplish much molt during their sojourn, which suggests that the average stay is only a few days. Some aspects of the molt pattern differ from those reported elsewhere.     

Phytoplankton in a high-elevation lake, Colorado Front Range: application to lake acidification

The purpose of this research was to evaluate the status of phytoplankton in Lake Albion in the Green Lakes valley, Colorado Front Range, with respect to lake acidification. The research was conducted during the inventory phase of the Long-Term Ecological Research program of the University of Colorado at the Niwot Ridge/Green Lakes valley site. Lake Albion is a small subalpine lake on the terminal end of the Green Lakes valley (13 ha, mean depth 6 m, and surface pH 6.51). Net plankton were collected six times during June-August 1984. Ancillary data on nutrients, temperature, chlorophyll a , and Secchi disc transparency were also obtained. Diatoms were identified and assigned to categories based upon their known tolerances to hydrogen ion concentration. The diatom flora was composed mostly of alkaliphilic or species indifferent to hydrogen ion concentration, a characteristic Lake Albion shares with other Front Range lakes. The diatom flora and water chemistry of Lake Albion are compared to other high-elevation lakes.     

Nearctic stonefly genera as indicators of ecological parameters (Plecoptera: Insecta)

Selected stonefly genera found in North America are classified as to their occurrence in: cold lotic, warm lotic, or lentic habitats. Most genera occur only in the cold lotic, but several occur both in cold and warm lotic systems. Few are found exclusively in warm lotic habitats and almost none in lentic. Lake or true lentic inhabits are found to usually be cold lotic species which have adapted to life in the wave-washed shores of cold mountain lakes. Even though data at the specific level would be even more useful, especially where different faunal regions are involved, stoneflies are probably the best insect indicators of aquatic environmental quality at the generic level.     

Annotated inventory of invertebrate populations of an alpine lake and stream chain in Colorado

Benthic macroinvertebrates were collected during the ice-free season (1 July-20 October) over a five-year period from a chain of alpine lakes and intervening streams in the Green Lakes Valley (3,347-3,615 m) in Boulder County, Colorado. A list of taxa was developed for 1981 and 1982, with taxonomic additions for 1983- 1985 and comments on community structure, seasonal and elevational changes in species abundance, and noteworthy occurrences. A total of 111 taxa was collected, of which 84% occurred in streams, 58% being exclusively lotic. Dipterans composed 73-81% of total abundance in streams. The littoral benthic zone of lakes was predominantly trichopterans and dipterans, 44-60% and 24-39%, respectively. Numerically important organisms in various lakes and streams were chironomids, simuliids (particularly Metacnephia ), oligochaetes, and the bivalve Pisidium casertanum . An isolated lake and its outlet stream, with unique characteristics, were the sole locations of Gammarus lacustris (Amphipoda) and Glossiphonia complanata (Hirudinea). Manipulated lowering of a lake along the main drainage exposed abundant and luxuriant colonies of the bryozoan Fredericella sultana . This organism was found on 43% of all rocks sampled, a preponderance heretofore unknown for this, or any, ectoproct in alpine or arctic lakes.     

Environmental characteristics and benthic invertebrate assemblages in Colorado mountain lakes

Twenty-two high-elevation lakes (> 3000 m) in Rocky Mountain National Park and Indian Peaks Wilderness Area, Colorado, were surveyed during summer 1998 to explore relationships among benthic invertebrates, water chemistry (particularly nitrate concentrations), and other environmental variables. Water samples were collected from the deepest portion of each lake and analyzed for ions and other water chemistry parameters. Benthic invertebrates were collected from the littoral zone using both a sweep net and Hess sampler. Physical and geographical measurements were derived from maps. Relationships among benthic invertebrate assemblages and environmental variables were examined using canonical correspondence analysis, and the importance of sampling methodology and taxonomic resolution on these relationships was evaluated. Choice of sampling methodology strongly influenced the outcome of statistical analyses, whereas taxonomic resolution did not. Presence/absence of benthic invertebrate taxa among the study lakes was best explained by elevation and presence of fish. Relative abundance and density of benthic invertebrate taxa were more strongly influenced by sampling date and water chemistry. Nitrate (NO 3- ) concentration, potentially on the rise due to regional nitrogen deposition, was unrelated to benthic invertebrate distribution regardless of sampling method or taxonomic resolution.     

Observations on the ecology and trophic status of Lake Tahoe (Nevada and California, USA) based on the algae from three independent surveys (1965-1985)

Numerous physical, chemical, and biological criteria evidently confirm that Lake Tahoe is oligotrophic. However, detailed examination of the ecology and trophic status status of algae (mostly diatoms) from Lake Tahoe taken from three independent, long-term sampling programs aided in interpretation of plankton and periphyton algal communities by spectral analysis (supported by computerized data synthesis) and "ultra-oligotraphic" lakes over the world from which future studies may reveal algal communities that may be described as more mesotrophic and/or eutrophic than oligotrophic. Lake Tahoe probably is not as oligotrophic as is generally believed, and the indicator algae in it are not as accurate as is generally believed.     

Environmental interaction in summer algal communities of Utah Lake

Utah Lake is a shallow eutrophic lake in central Utah. It is characterized by high nutrient and silt loads and by large algal blooms in late summer and early fall. Phytoplankton samples and environmental data were taken from June through August 1974. Phytoplankton species were identified and then quantified in a Palmer counting cell. Environmental continuum theory was employed to describe algal succession, and regression analysis was used to discover interactions between algal communities and the environment. Phytoplankton communities in June were characterized by high species diversity. As the lake environment became stressed in late summer due to higher turbidity, nutrient levels, pH, and available inorganic carbon species diversity decreased. By August, the phytoplankton flora was composed essentially of only two species, Ceratium hirundinella and Aphanizomenon flos - aquae.     

Pollen evidence of historical forest disturbance on the Wasatch Plateau, Utah

Environmental indicators from lake sediments provide excellent opportunities to improve understanding of forest disturbance processes and corresponding changes in forest composition. Our research provides a methodology for assessing recent, historic, and prehistoric disturbances using lacustrine sediment records. We collected sediment cores from Blue Lake, a small subalpine lake on the Wasatch Plateau in central Utah. These cores record environmental changes caused by both spruce beetle ( Dendroctonus rufipennis Kirby) and human (logging and livestock grazing) modification. We observed deteriorated insect remains in the lake sediments. These remains correspond temporally with a historic spruce beetle outbreak, though alkaline conditions in the lake water may have inhibited preservation of bark beetle remains. Pollen data reveal that despite the unprecedented level of mortality among Engelmann spruce ( Picea engelmannii Parry ex Engelm.) resulting from the spruce beetle epidemic, logging activities subsequent to Euro-American settlement appear to be the most severe disturbance to the Blue Lake watershed over the last 750 years.     

Ovoviviparity in carabid beetles of the genus Pseudomorpha (Insecta: Coleoptera)

Ovoviviparity is reported for the first time in the ground beetle family Carabidae. Eclosed larvae and fully developed embryos are found within the expanded lateral oviducts, bursa copulatrix and vagina of the putative myrmecophiles Pseudomorpha angustata and P. hubbardi. Eclosed larvae do not appear to be active while held inside the female prior to larviposition. Maximum larval numbers occur from mid-July to early September in these Arizona species, implying that larviposition is timed to coincide with summer rains. Larviposition is hypothesized as a means to eliminate egg mortality due to predation by ant hosts.     

Lakeward and downstream movements of age-0 arctic grayling ( Thymallus arcticus ) originating between a lake and a waterfall

Arctic grayling in Deer Lake, Montana spawn only in the 350-m segment of outlet stream between the lake and a waterfall. The purpose of this study was to examine consequences of and possible adaptations by this population to spawning above the falls, by determining the extent of loss over the falls of age-0 young, the daily and seasonal patterns of such losses, and the seasonal pattern of movement upstream into the lake by the remaining young. We measured fish movements during 1989 and 1990 with traps placed at the outlet and at the falls, from fry swimup in July until October or November. Young went over the falls predominantly as newly swimming fry at night. In 1989 about 5000-9000 were lost downstream, representing an estimated 4-7% or less of young produced. Most young thus appear adapted to maintaining their position above the falls. A few started entering the lake in August and September, but only 95 in 1989 and 23 in 1990 had done so by the time observations were ended by the onset of wintery conditions. Most movement into the lake appeared to occur sometime during the six to seven months of annual ice cover. This extended period of stream residence contrasts with early lakeward movements reported for other inlet-spawning, lacustrine grayling populations and may be an adaptation for avoiding predation by large conspecifics in Deer Lake.     

The reproductive ecology of the Tahoe sucker, Catostomus tahoensis, in Pyramid Lake, Nevada

The Tahoe sucker spawns in Pyramid Lake from April to August at lake temperatures of 11.7 to 22.7 C. The spawning population is comprised of a large lake spawning group and a numerically smaller river running group. The river running group is smaller in length and was not considered during this study. The sex ratio of sampled suckers significantly favored the females. This is the result of the longer life of females and greater mortality of males during spawning.   Pyramid Lake Tahoe suckers reach sexual maturity at two to three years of age; however, those in Lake Tahoe do not mature until four or five years of age. The size at sexual maturity is different in both populations, which suggests that size or rate of growth rather than age determines sexual maturity.   The fecundity of Tahoe suckers is positively correlated with fork length, weight, and age. Additional analysis showed that a better correlation occurred between fish size (either length or net weight) and total ovary weight. We believe that fish size is primarily correlated with total reproductive tissue produced and secondarily with fecundity. A comparison of the Pyramid Lake population and the Lake Tahoe population demonstrated that size, not age, is the most important determinant of Tahoe sucker fecundity.     

Population structure and ecological effects of the crayfish Pacifastacus leniusculus in Castle Lake, California

The recent appearance of the ""California crayfish,"" Pacifastacus leniusculus , in Castle Lake, California, and interest in its potential impacts on the lake ecosystem provided motivation for a study of the population structure and habitat use of this species and its effects on aquatic macrophytes. Mark-recapture studies indicated that the total number of adult (3 + yr or older) crayfish in the lake was ca 10,100 individuals, yielding an estimate of lakewide crayfish density in preferred crayfish habitats of 0.13 adults m -2 . Using mean body mass of individuals, we estimated that ambient biomass density was 5.9 g m -2 . Length-weight relationships determined for captured individuals were sex dependent, with males having greater body mass for a given carapace length. Length-frequency and weight-frequency diagrams indicated that P. leniusculus reaches larger sizes in Castle Lake than do populations of P. leniusculus in ultraoligotrophic Lake Tahoe. Population-wide, males were significantly larger in both carapace length and body mass than females. We also examined sex dependence of interhabitat differences in crayfish body size by comparing animals trapped in rocky areas with those from areas with macrophytes and soft sediments. No significant differences in overall body size were found between habitats, but a significant habitat-sex interaction term occurred because the sex-dependent size differences were more pronounced in sediment than in rocky areas. Exclosure and enclosure experiments indicated that crayfish had large but differential impacts on Castle Lake macrophyte species, as the abundance of two of the dominant species ( Chara sp., Potamogeton richardsonii ) declined in the presence of crayfish and, in one case, increased in exclosures. These effects occurred via both consumptive and nonconsumptive mechanisms. These studies indicate that and expanding population of P. leniusculus in Castle Lake may be producing sizable impacts on the littoral zone habitat.     

Spawning chronology and larval emergence of June sucker ( Chasmistes liorus )

June sucker ( Chasmistes liorus ) spawned in the Provo River, Utah, over a 2-wk period in early June during both 1987 and 1988. Emergent larvae emigrated from the river to Utah Lake over a 2- to 3-wk period. Drift into the lake peaked between 1200 and 0400. During daylight hours, emergent larvae tended to occur in pools. Peak emergence of larval drift was approximately 1.2 larvae/m 3 during late June in 1987 and 1988. Recruitment failure of June sucker is not due to reproductive failure.     

Utah Chub ( Gila atraria ) from the latest Pleistocene Gilbert Shoreline, West of Corrine, Utah

A bulk sampling of gastropods collected near Great Salt Lake, Utah, Revealed several fish bones of Gila atraria (Girard). The early date of this find, coupled with the relationship of the Gilbert lake transgression and successive regression of approximately 11,000 years B.P., reveals a death assemblage induced by a series of saline inundations into the freshwater paludal environment.     

Observations on Double-crested Cormorants ( Phalacrocorax auritus ) at sportfishing waters in southwestern Utah

Counts of Double-crested Cormorants ( Phalacrocorax auritus ) were made at 13 reservoirs and lakes in southwestern Utah during 1989-91 to determine current abundance of that species. Food habits of cormorants were studied at three of the reservoirs in 1989. Data were also collected on trout abundance during standardized gill-netting to make comparisons between cormorant numbers and trout abundance. Cormorants were observed at all waters studied except one and were generally most numerous during the spring as they migrated through the area. Estimated cormorant abundance ranged from 0 to 34 bird-days per ha and was highest at the larger, lower-elevation reservoirs. Cormorants were summer residents at several of the larger reservoirs and nested successfully at Piute Reservoir. Trout accounted for 24-81% of the diet of cormorants, with Utah chubs constituting most of the remainder of the diet. Estimates of the annual consumption of fish by cormorants ranged from 0 to 15.8 kg per ha. The index of trout abundance was inversely related to cormorant abundance ( P < .01) at the waters studied. Cormorants apparently have increased in numbers and extended their range in southwestern Utah during the past decade. This change may be the result of factors that have led to similar changes throughout North America as well as some factors unique to Utah. Methods to mitigate the impact of predation by piscivorous birds of sportfisheries are discussed. The Utah Division of Wildlife Resources has initiated a new management plan at Minersville Reservoir that incorporates piscivorous birds into sportfish management at that reservoir.     

Observations on the reproduction and embryology of the Lahontan tui chub, Gila bicolor, in Walker Lake, Nevada

Various aspects of the reproduction and embryology of Walker Lake Lahontan tui chub, Gila bicolor , were investigated during the spring&ndash;summer period of 1976, 1977, and 1981. Tui chub were found to spawn in littoral regions of the lake beginning in late May or early June. Early in the season male chub substantially outnumbered females over the spawning grounds, with a normal 1:1 sex ratio gradually approached as the season progressed. The developmental period between fertilization to hatch-out was shortened by increases in water temperature. Selected stages of embryonic development are described from egg fertilization through post-hatch.     

Effects of turbidity on feeding rates of Lahontan cutthroat trout ( Oncorhynchus clarki henshawi ) and Lahontan redside shiner ( Richardsonius egregius )

The spawning of Lahontan cutthroat trout ( Oncorhynchus clarki henshawi ) in Summit Lake, Nevada, has reportedly declined since the early 1970s, coincident with the appearance of Lahontan redside shiner ( Richardsonius egregius ) in the lake. We investigated the relative predatory abilities of the 2 fish species foraging on live Daphnia magna in turbidity conditions commonly observed in Summit Lake. Experiments were performed under controlled light and temperature condition. In separate trials we fed trout and shiner 1 of 3 size classes of D. magna (1.7 mm, 2.2 mm, and 3.0 mm) at 6 levels of turbidity ranging from 3.5 to 25 NTU. Feeding rates for both species varied inversely with turbidity for all prey sizes. Feeding rates of shiner were greater than trout at all turbidity levels. In low turbidity (5 TNU), shiner consumed approximately 3% more prey during 2-h feeding trials. However, at high turbidity levels, the difference in feeding rates between species was proportionally higher (10%). At high turbidity levels (≥ 20 NTU) trout predation rates were relative insensitive to prey size. However, shiner continued to consume more, larger prey at the highest turbidity levels. These results indicate that Lahontan redside shiner may be superior to Lahontan cutthroat trout as zooplankton predators at high turbidity levels, and may explain the recent success of shiner in Summit Lake.     

Recent species of the Family Candonidae (Ostracoda,Crustacea) from the ancient Lake Biwa,Central Japan

Sampling of Lake Biwa between November 1997 and February 2007 has revealed a diverse Candonidae fauna consisting of 18 species. Eleven are previously undescribed species, belonging to the genera Fabaeformiscandona (nine species), Pseudocandona (one species) and Cypria (one species), and 10 of these are potentially endemic to the lake. In total there are 12 Fabaeformiscandona species in the lake belonging to two sub‐groups based on the number of setae on the mandible palp, the fabaeformis‐group (10 species) and the acuminata‐group (two species). Including the new Fabaeformiscandona species described herein, Lake Biwa is home to 19% of the approximately 62 described living species of this genus known globally. Although, the new Fabaeformiscandona species are potentially endemic, they do not show a microevolutionary pattern similar to that suggested for the Tanganyikan Cyprideis species flock.