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Gary L. Larson

Publications and source records attributed to Gary L. Larson.

35 records · Page 2Linked to original sources
USGS1998

Phytoplankton assemblages in high-elevation lakes in the northern Cascade Mountains, Washington State, USA

Phytoplankton assemblages in high-elevation lakes of North Cascades National Park Service Complex were studied during the open-water period in 1989. Collectively, 93 taxa were identified in 55 samples from 51 lakes. Based on cell densities, cyanobacteria had the highest relative abundance (36.7 %), followed by chlorophytes (29.8 %), and chrysophytes (19.6 %). Aphanocapsa delicatissima had the highest proportional abundance (14.0 %). Only 15.1 % percent of the taxa occurred in more than 20 samples. Phytoplankton cell densities increased following a gradient of increasing lake-water temperature, alkalinity, and concentration of total Kjeldahl-N with decreasing lake elevation. Chrysophytes and cyanobacteria were quantitatively (relative abundance) the most important taxa in alpine and subalpine lakes, whereas cyanobacteria had the highest relative abundances in high-forest and low-forest lakes. Chlorophytes had their highest relative abundance in high-forest lakes. Although low in relative abundance, diatoms and dinoflagellates were most abundant in alpine lakes. An ordination by correspondence analysis indicated that most alpine, subalpine, and high-forest lakes had similar floras. Although a few subalpine lakes exhibited deviations from this pattern, the main differences in phytoplankton composition were found in a group of low-forest and high-forest lakes. Canonical correspondence analysis (CCA) provided evidence that the distribution of samples and taxa in ordination space was correlated with a gradient of decreasing lake elevation and increasing water temperature, alkalinity, and concentration of nitrogen. When CCA was used to examine relationships among phytoplankton taxa and vegetation zones, a continuous distribution of taxa was found from the low-forest zone to the subalpine zone, with a large number of taxa occurring primarily in the subalpine and high-forest zones. Three phytoplankton taxa occurred primarily in alpine lakes, whereas five taxa co-occurred in alpine, subalpine, and high forest zones. Collectively, lake elevation and associated changes in water quality and concentrations of nutrients, especially nitrogen, appeared to be the primary physical and chemical factors influencing the taxonomic structures of phytoplankton assemblages.

Washington↗
USGS1998

Variability of Secchi disk readings in an exceptionally clear and deep caldera lake

SUMMARY: The Peromyscus leucopus on a 17-acre study area were live-trapped, marked, and released over a seven-day period. On the three following nights intensive snap-trapping was done on the central acre of the study plot. The animals caught by snap traps in the central acre represented the population of the central acre and several surrounding acres. By the currently accepted methods of interpreting snap-trap data, the population per acre would be considered to be 23 adults. The live-trap data show that the true population was between six and seven adults per acre. Modern methods of live-trapping are shown to be valid for population studies. Two methods are presented for the conversion of live-trap data into per acre figures. Errors involved in the current use of snap-trap data are discussed and snap-trap methods are shown to be invalid for determining actual population numbers. It should be practical to use a snap-trap quadrant technique to obtain a relative measure or index figure for small mammal populations.

Archiv fur Hydrobiologie↗
USGS1997

Influence of basin-scale physical variables on life history characteristics of cutthroat trout in Yellowstone Lake

Individual spawning populations of Yellowstone cutthroat trout Oncorhynchus clarki bouvieri differ in life history characteristics associated with broad spatial and temporal environmental patterns, but relationships between specific life history characteristics of Yellowstone cutthroat trout and physical aspects of the environment are poorly understood. We examined basin-scale physical characteristics of tributary drainages and subbasins of Yellowstone Lake in relation to timing (peak and duration) of lacustrine–adfluvial Yellowstone cutthroat trout spawning migrations and mean length of cutthroat trout spawners in 27 tributaries to the lake. Stream drainages varied along gradients that can be described by mean aspect, mean elevation, and drainage and stream size. Approximately two-thirds of the variation in the timing of the peak of the annual cutthroat trout spawning migrations and average length of spawners was explained by third-order polynomial regressions with mean aspect and basin area as predictor variables. Because most cutthroat trout ascend tributaries soon after peak runoff, it appears that the influence of basin-scale physical variables on the date of the migration peak is manifested by the pattern of stream discharge. Spawner length does not seem to be a direct function of stream size in the Yellowstone Lake watershed, and aspect of the tributary basin seems to have a greater influence on the body length of cutthroat trout spawners than does stream size. Mechanisms that explain how the interaction of basin-scale physical variables influence spawner length were not investigated directly; however, we found evidence of distinct aggregations of cutthroat trout that are related to physical and limnological characteristics of the lake subbasins, and there is some indication that lake residence may be related to tributary location.

Wyoming↗
USGS1996

Development of a 10-year limnological study of Crater Lake, Crater Lake National Park, Oregon, USA

This paper summarizes the development of a limnological study of Crater Lake conducted between 1983 and 1992. The program was mandated by Congress in the fall of 1982 after a panel of limnologists found the lake data base (1896–1981) to be inadequate to determine if the phytoplankton community had changed and if the lake was decreasing in clarity as suggested from independent studies between 1978 and 1981. Congress authorized and directed the Secretary of the Interior to promptly instigate studies and investigations as to the status and trends of changes of water quality and to immediately implement such actions as necessary to assure the retention of the lake's natural pristine water quality. Program goals were to develop a detailed data base and an understanding of physical, chemical, and biological characteristics and processes of the lake. Ecological relationships among trophic levels and environmental conditions were stressed to evaluate the hypothesis that the lake had changed in water quality and clarity.

Journal of Lake and Reservoir Management↗
USGS1996

Temperature, water chemistry, and optical properties of Crater Lake

Water temperature, water chemistry, and optical properties of Crater Lake were studied from 1983 to 1991. In winter and spring, wind energy and convection mixed the water column to a depth of 200 to 250 m. The lake was thermally stratified in summer and early fall; however, the epilimnion was only 5 to 20 m thick, and most of the 589 m deep water column was a cold hypolimnion. The lake was slightly basic, with moderate alkalinity and conductivity. The water column was oxygenated, although slight decreases in dissolved oxygen concentration were noticed near the lake bottom in late summer and early fall. Phosphorus and nitrogen concentrations were low. Orthophosphorus-P concentrations increased slightly with increased lake depth, whereas nitrate-N was below detection limits in the upper 200 m of the water column and then increased with increased lake depth. Secchi disk clarity typically varied from the high-20-m to low-30-m range. The depth of 1 % surface incident light (425–655 nm) in July and August typically ranged between 80 and 100 m. The results also indicated that water temperature, water chemistry, and optical properties of the lake between 1983 and 1991 were consistent with those observed between 1896 and 1982.

Journal of Lake and Reservoir Management↗
USGS1996

Chemical solute mass balance of Crater Lake, Oregon

Crater Lake covers the floor of the caldera at the top of Mount Mazama. Surrounded by steep walls, the water surface of the lake occupies 78 percent of the catchment basin. No major rivers empty into the lake, and there is no surface outlet Based on a chemical solute mass balance model, mass inputs of major solute chemical components (Na, Ca, K, Mg, SO 4 , Cl, Si, and HCO 3 ) from atmospheric deposition and caldera springs do not equal the mass output in seepage from the lake. One or more previously unquantified sources must be present in the lake or watershed system to account for the calculated deficits of mass inputs which range from 50 to 90 percent of mass outputs. A hydrothermal source, with a flow rate of approximately 6 percent of me seepage rate and chemical composition similar to saline fluids found in isolated pockets on the bottom of Crater Lake and to hydrothermal springs in die Cascade Mountain Range, could account for the calculated input mass deficits for major solute chemical components. Atmospheric bulk deposition (wet plus dry) may account for up to 90 percent of nitrogen and 30 percent of phosphorus inputs to Crater Lake. A net removal of nutrients from the lake water column occurs through internal processes, most likely burial of cellular debris in sediments.

Journal of Lake and Reservoir Management↗
USGS1996

Taxonomic structure and productivity of phytoplankton assemblages in Crater Lake, Oregon

Interactions among physical, chemical, and biological components and processes in Crater Lake result in a complex and dynamic ecosystem. In winter and spring, wind energy mixes the lake to a depth of about 200 m. During this period, episodic sinking of cold water below the depth of 200 m produces an upwelling of nutrient-rich water from the deep lake, a process that has a strong influence on the concentrations of nutrients available to phytoplankton in the euphotic zone. Patterns of upwelling are variable from year to year, and physical data indicate that water from the deep lake is completely mixed with surface water every 1–4 years. Phytoplankton cell biovolume and total chlorophyll are distributed uniformly to the depth of 200 m in winter and spring, at which time maximum rates of primary production occur in the upper 60 m of the water column. The onset of thermal stratification in July is associated with development of a chlorophyll maximum at depths between 100 and 140 m and a downward shift of the primary production maximum to depths between 60 and 100 m. Thermal stratification also is accompanied by a stratified distribution of phytoplankton populations that is characterized by assemblages with low species diversity and high dominance in the epilimnion and assemblages with higher diversity and lower dominance in the metalimnion and upper hypolimnion. Therefore, the thermal properties of the upper 200 m of Crater Lake, and associated changes in light and nutrients with increasing depth, are closely related to structural and functional attributes of phytoplankton assemblages in the water column.

Journal of Lake and Reservoir Management↗
USGS1996

Zooplankton assemblages in Crater Lake, Oregon, USA

The zooplankton community in Crater Lake was comprised of 11 rotifer species and 2 species of cladocerans. Most zooplankton taxa were distributed in winter and spring from the lake surface to a depth of about 200 m, the maximum depth of mixing of lake waters by wind energy. The distribution of zooplankton species was partitioned in the water column to a depth of 200 m during summer and fall, which corresponded to the period when the lake was thermally stratified. At that time of year, zooplankton density in die upper 20 m of the water column was very low, whereas highest densities were found in the depth interval between 80 and 120 m. Closely related or competing species were found in different portions of the water column. Daphnia pulicaria the largest cladoceran species, was cyclic in abundance, and its density corresponded to patterns of lake productivity and fish predation. When D. pulicaria was abundant, abundances of rotifers and Bosmina longirostris declined and changes in the vertical distribution of Bosmina were observed. Relationships between variations in Secchi disk clarity and zooplankton abundances in the upper 40 m of the water column were not obvious.

Lake and Reservoir Management↗
USGS1996

Ecology of kokanee salmon (Oncorhynchus nerka) and rainbow trout (Oncorhynchus mykiss) in Crater Lake, Oregon

Originally barren of fish, Crater Lake was stocked with approximately 1.8 million salmonids from 1888 to 1941. Rainbow trout ( Oncorhynchus mykiss ) and kokanee salmon ( O. nerka ) now inhabit the lake. This study was conducted from 1986 to 1991 to document and compare kokanee salmon and rainbow trout ecology in the lake to better evaluate the ecological implications of the presence of these non-native fish. Kokanee salmon exhibited cyclic patterns in population age structure, condition, abundance, and biomass from 1986 to 1991. One dominant year class of relatively low abundance and high condition was present from 1986 to 1987. Multiple year classes with increasing abundance and decreasing condition were present from 1989 through 1991. Rainbow trout maintained a diverse population structure throughout the study with a trend toward a relative increase of older age classes and larger fish. Vertical and horizontal migrations of kokanee salmon occurred within and between the nearshore and offshore zones of the lake. Rainbow trout were located along the edge of the lake. Kokanee salmon fed primarily offshore on zooplankton and small-bodied insects. Kokanee salmon cropped the Daphnia population and altered the zooplankton community structure during the study period. Rainbow trout fed nearshore on large-bodied vertebrates and invertebrates. Introduced fish in Crater Lake exhibited the potential to impact limnetic and benthic community structure and nutrient flux within and between these communities.

Oregon↗
USGS1996

Overview of the limnology of Crater Lake

Crater Lake occupies the collapsed caldera of volcanic Mount Mazama in Crater Lake National Park, Oregon. It is the deepest lake (589 m) in the United States and the 7th deepest lake in the world. The water column mixes to a depth of about 200 m in winter and spring from wind energy and cooling. The deep lake is mixed in winter and early spring each year when relatively cold water near the surface sinks and exchanges positions with water in the deep basins of the lake. The lake becomes thermally stratified in summer and early fall. The metalimnion extends to a depth of about 100 m; thus most of the water column is a cold hypolimnion. Secchi disk clarity measurements typically are in the upper-20-m range to the low-30-m range in summer and early fall. Concentrations of nutrients are low, although conductivity is relatively high owing to the inflow of hydrothermal fluids. Total chlorophyll is low in concentration, but typically maximal at a depth of 120 m during periods of thermal stratification. Primary production also is low, with the maximum levels occurring between the depth of 40 and 80 m. Phytoplankton taxa are spatially segregated from each other within the water column to a depth of 200 m in summer and early fall. The same generalization applies to the zooplankton taxa. Water level, clarity, concentrations of total chlorophyll, primary production, and abundances of zooplankton and introduced kokanee salmon exhibit long-term fluctuations. Based primarily on a recent 10-year study of the lake, the lake is considered to be pristine, except for the consequences of fish introductions.

Northwest Science↗
USGS1996

Distribution of nearshore macroinvertebrates in lakes of the Northern Cascade Mountains, Washington, USA

During the summer of 1949 studies were conducted at Princeton, New Jersey, to determine the effects on wildlife of DDT used in the control of Dutch elm disease. Direct mortality was determined by intensive search for dead birds after spraying. Twenty-six songbirds, one bat, and one gray squirrel were found. Of 11 dead birds from a study area of approximately 20 acres only one was an adult. Songbird populations were determined by censuses before and after spraying on a study area and on a similar unsprayed check area. The number of all breeding birds showed a 19.6 percent decrease on both the study and check areas during the week immediately following spraying. About two weeks after spraying the population in the treated area began to increase and within another week was back to prespray level. When only those species common to both sprayed and unsprayed areas are considered a population decline of 22 percent was measured in the sprayed area while the check area showed a 6 percent increase in numbers over the same period. Nestling mortality was studied in both areas. Among 18 young found on the study area during and following spraying 8 (44%) survived. Death of two broods of catbirds occurred four days after spraying. Of 21 young found on the check area 15 (71%) survived.

Archiv fur Hydrobiologie↗
USGS1995

Effects of hydrology on zooplankton communities in high-mountain ponds, Mount Rainier National Park, USA

Ten high-mountain ponds in Mount Rainier National Park, Washington State, were studied from ice-out in June through September1992 to investigate the influences of fluctuating pond volumes on zooplankton communities. All of the ponds were at maximum volume immediately after ice-out. The temporary pond with the shortest wet phase was inhabited by rotifer taxa with short generation times and a crustacean taxon with the ability to encyst as drought-resistant resting bodies at immature stages of development. Dominant zooplankton taxa in three other temporary ponds and six permanent ponds were similar. Rotifer densities typically were lower in temporary ponds relative to those in permanent ponds, although Brachionus urceolaris was abundant shortly before the temporary ponds dried. Large volume loss was associated with large declines in total abundances of crustacean populations. Daphnia rosea was not present in temporary ponds following fall recharge. In deep-permanent ponds, copepods had slower developmental rates, smaller temporal changes in total abundances of crustacean populations and two additional large-bodied crustacean taxa were present relative to the characteristics of crustacean communities in shallow-permanent ponds. Owing to their small sizes and sensitivity to environmental change, collectively ponds such as these may provide an early signal of long-term climate change in aquatic systems.

Journal of Plankton Research↗
USGS1995

Ebb and flow of encroachment by nonnative rainbow trout in a small stream in the southern Appalachian Mountains

Brook trout Salvelinus fontinalis is the native salmonid species of streams in the southern Appalachian Mountains. The present distribution of this species, once widespread from headwaters to lower reaches of large streams, is restricted to mostly headwater areas. Changes in the distribution of native brook trout in the presence ofˈ nonnative rainbow trout Oncorhynchus mykiss have been documented in Great Smoky Mountains National Park. When rainbow trout were first found in a tributary (Rock Creek) in the park in 1979, a study was begun to assess changes through time in distribution and abundance of rainbow trout in Rock Creek and to compare the brook trout and rainbow trout associations in Rock Creek with associations found in other park streams. Abundance of brook trout was low in the downstream sections of Rock Creek in 1979–1993. Brook trout abundance was highest in the steep‐gradient, pool‐dominated headwater section which was only 2 km from the confluence of Rock Creek and Cosby Creek. Rainbow trout were present in low densities in Rock Creek during the same period. Although rainbow trout were most abundant in the lower stream sections and never found in the headwater section, adult and age‐0 rainbow trout were found in the middle section in 1988. Rainbow trout were absent in the middle section in 1991, but one large adult rainbow trout was present in the section in 1992 and 1993. Floods, freshets, and periods of low stream discharge appeared to play an important role in the distribution and population structure of rainbow trout in Rock Creek. The lower portion of Rock Creek was poor trout habitat because the sections were dominated by cobble–rubble substrate and shallow riffle areas. Stream habitat appeared to be better suited for brook trout than for rainbow trout in the steep‐gradient upstream sections which were dominated by boulder‐cobble substrate and deep pools. The results of this study suggest that encroachment by rainbow trout can exhibit considerable ebb and flow in steep‐gradient tributaries in the park, and they suggest substantial evolutionary adaptation by brook trout to the hydrological conditions in the Rock Creek drainage.

North Carolina, Tennessee↗
USGS1994

Integrating limnological characteristics of high mountain lakes into the landscape of a natural area

A general conceptual watershed-lake model of the complex interactions among climatic conditions, watershed location and characteristics, lake morphology, and fish predation was used to evaluate limnological characteristics of high mountain lakes. Our main hypothesis was that decreasing elevation in mountainous terrain corresponds to an increase in diversity of watershed size and lake area, depth, temperature, nutrient concentrations, and productivity. A second hypothesis was that watershed location and aspect relative to climatic gradients within mountainous terrain influences the limnological characteristics of the lakes. We evaluated these hypotheses by examining watershed location, aspect and size; lake morphology; water quality; and phytoplankton and zooplankton community characteristics among high mountain forest and subalpine lakes in Mount Rainier National Park. Although many of the comparisons between all forest and subalpine lakes were statistically insignificant, the results revealed trends that were consistent with our hypotheses. The forest lake group included more lakes with larger watersheds, larger surface areas, greater depths, higher concentrations of nutrients, and higher algal biovolumes than did the group of subalpine lakes. Deep lakes, which were mostly of the forest lake type, exhibited thermal stratification and relatively high values of some of the water-quality variables near the lake bottoms. However, the highest near-surface water temperatures and phytoplankton densities and the taxonomic structures of the phytoplankton and zooplankton assemblages were more closely related to geographical location, which corresponded to a west-east climate gradient in the park, than to lake type. Some crustacean and rotifer taxa, however, were limited in distribution by lake type. Fish predation did not appear to play an important role in the structure of the crustacean zooplankton communities at the genus level with the exception of Mowich Lake, where crustacean taxa were absent from the zooplankton community. This was the only lake inhabited by a true zooplanktivourous species of fish.

Environmental Management↗
USGS1994

Life-history organization of Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri) in Yellowstone Lake

Life-history organization of the cutthroat trout (Oncorhynchus clarki) may be viewed at various levels, including species, subspecies, metapopulation, population, or individual. Each level varies in spatial scale and temporal persistence, and components at each level continually change with changes in environment. Cutthroat trout are widely distributed throughout the western United States, occurring in such diverse environments as coastal rivers of the Pacific Northwest and interior streams of the Great Basin. During its evolution the species has organized into 14 subspecies with many different life-history characteristics and habitat requirements. Within subspecies, organization is equally complex. For example, life-history traits, such as average size and age, migration strategy, and migration timing, vary among individual spawning populations of Yellowstone cutthroat trout (Oncorhynchus clarki bouvieri) in tributary streams of Yellowstone Lake. Understanding the effects of human perturbations on life-history organization is critical for management of the cutthroat trout and other polytypic salmonid species. Loss of diversity at any hierarchical level jeopardizes the long-term ability of the species to adapt to changing environments, and it may also lead to increased fluctuations in abundance and yield and increase the risk of extinction.

Canadian Journal of Fisheries and Aquatic Sciences↗
USGS1994

Vertical distribution of a deep-water moss and associated epiphytes in Crater Lake, Oregon

A one-person submersible was used to examine the vertical distribution of the deep-water moss Drepanocladus aduncus (Hedw.) Warnst in Crater Lake (Oregon). Living specimens were found attached to sediment and rocks at depths between 25 m and 140 m. Dense beds of the moss were observed at depths between 30 m and 80 m, a region that corresponded roughly to the zone of maximum primary production by phytoplankton. The moss population supported a diverse assemblage of epiphytic algae, of which the most abundant genera included Cladophora,Oedogonium, Rhizoclonium, Tribonema, Vaucheria, and the diatoms Cocconeis, Cymbella, Epithemia, Fragilaria, Gomphonema, Melosira, Navicula, and Synedra. Chemical and physical data supported the hypothesis that the lower limit of distribution of the moss is determined by light limitation, whereas the upper limit is related to the availability of nutrients, particularly nitrate-nitrogen and trace elements. Deep-water videotapes of the moss population indicated that D. aduncus with its epiphytic algae was abundant enough in regions associated with the metalimnion and upper hypolimnion to have a potential influence on the nutrient dynamics of the Crater Lake ecosystem. Although the maximum depth at which living bryophytes occur in Crater Lake is similar to that found for Lake Tahoe, conditions in Lake Tahoe allow the growth and survival of a much more diverse assemblage of bryophytes and charophytes than is present in Crater Lake.

Northwest Science↗