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At least 649 records · Page 36Linked to original sources
USGS2008

The effect of fixative on total length of small-bodied stream fishes

Longnose dace (Rhinichthys cataractae), red shiner (Cyprinella lutrensis), and green sunfish (Lepomis cyanellus) were fixed in 5% and 10% formalin and 70% and 95% ethyl alcohol to determine fixative effects on total length (TL). Total length reduced over the first 24h for all species (P<0.0001) but then stabilized. Longnose dace and green sunfish TL reduction was less for 5% formalin than for either 70% or 95% ethanol (both P<0.0001), whereas the fixative solution had no effect on red shiner TL (P=0.347). A greater percentage of change in TL was observed in green sunfish and red shiner than in longnose dace, suggesting that body form (compressiform vs. fusiform) may affect shrinkage rate among adult stream fishes.

Journal of Freshwater Ecology↗
USGS2008

Habitat features affect bluehead sucker, flannelmouth sucker, and roundtail chub across a headwater tributary system in the Colorado River Basin

We assessed the distributions of three species of conservation concern, bluehead sucker (Catostomus discobolus), flannelmouth sucker (Catostomus latipinnis), and roundtail chub (Gila robusta), relative to habitat features across a headwater tributary system of the Colorado River basin in Wyoming. We studied the upper Muddy Creek watershed, Carbon County, portions of which experience intermittent flows during late summer and early fall. Fish and habitat were sampled from 57 randomly-selected, 200-m reaches and 416 habitat units (i.e., pools, glides, or runs) during the summer and fall of 2003 and 2004. Among reaches, the occurrences of adults and juveniles of all three species were positively related to mean wetted width and the surface area of pool habitat, and the occurrences of adult bluehead sucker and roundtail chub were also positively related to the abundance of rock substrate. Only juvenile bluehead sucker appeared to be negatively influenced by the proportion of a reach that was dry at the time of sampling. Within individual pools, glides, and runs, the occurrences of adults and juveniles of all three species were positively related to surface area and maximum depth, and occurrences of bluehead sucker and flannelmouth sucker juveniles were more probable in pools than in glides or runs.

Journal of Freshwater Ecology↗
USGS1997

Late summer and fall use of stream margins by young-of year brown trout in a high-elevation stream

We determined the relative abundance of young-of-year (YOY) brown trout (Salmo trutta) from late summer to fall during day and night in stream margin habitats of Douglas Creek, Wyoming. No significant differences in relative abundance were observed from August 14 through October 26. Few YOY brown trout were observed during the day over the entire sampling period, but significantly greater numbers were seen at night. Within stream margins, YOY brown trout of 36-75 mm total length primarily resided in concealment cover among interstices of cobbie during the day and emerged at night. Because no significant change in relative abundance was observed throughout the study period, we conclude that a shift to winter habitat did not occur up until three days prior to ice formation when the diurnal range in water temperature was 2.5-7.5??C.

Journal of Freshwater Ecology↗
USGS1998

Foraging characteristics of larval bluegill sunfish and larval longear sunfish in the Kanawha River, West Virginia

We determined spatial and temporal foraging characteristics of larval bluegill sunfish (Lepomis macrochirus) and longear sunfish (Lepomis megalotis) in the upper Kanawha River, West Virginia during the summer of 1989. Stomach contents were examined among habitat types (i.e., main channel, main-channel border, and shoreline habitats) and depth (surface, middle, and bottom). Diet of larval bluegill sunfish was dominated by Chironomidae, temporally and spatially. Chironomidae dominated larval longear sunfish diet in main channel and main-channel border collections from all three depths. However, along the shoreline, larval longear sunfish diet was dominated by Cladocera.

Journal of Freshwater Ecology↗
USGS2002

Effect of deer exclusion by fencing on abundance of Amblyomma americanum (Acari: Ixodidae) on Fire Island, New York, USA

The effects of deer exclusion on northern populations of lone star ticks, Amblyomma americanum , were tested at the Lighthouse Tract, Fire Island, NY, USA, where densities of this species have increased recently. Game fencing was erected to exclude deer from two sites of roughly one ha each, and populations of nymphal and adult A. americanum within were compared with those at control sites outside the exclosures. Percent control of nymphs within vs. outside the exclosures averaged 48.4% in the four years post-treatment, compared to pretreatment values. Percent control varied markedly in different years, suggesting that factors in addition to deer densities had strong effects on population densities of A. americanum . Exclosures of this size did not control adult A. americanum . Effects of deer exclusion in this recently expanded northern population of A. americanum were similar to those that have been reported for southern populations of this species.

Journal of Vector Ecology↗
USGS2006

Relative persistence and dispersal of age-0 and age-1 largemouth bass stocked into two Ohio River embayments

In October of 1998 the West Virginia Division of Natural Resources stocked age-0 [mean total length (MTL) = 178 mm] and age-1 (MTL = 273 mm) hatchery-reared largemouth bass into two embayments of the Ohio River. Stocked fish were fitted with both an anchor tag and a visible implant elastomer mark. A multifaceted sampling approach was undertaken to (1) evaluate the persistence of stocked largemouth bass, (2) estimate fidelity of stocked largemouth bass to release sites, and (3) compare return rates of the two age classes. Although stocked largemouth bass comprised the majority (81%) of all bass captured in electrofishing surveys of the stocked embayments during fall 1998, catches declined rapidly during winter 1998, and by spring and summer 1999 stocked largemouth bass were virtually absent from electrofishing surveys. Creel surveys indicated no catch of stocked largemouth bass in the release sites after winter 1998. Electrofishing surveys, creel surveys, and angler call-ins all suggested stocked fish did not persist and either moved out of the stocked embayments or died. The results suggest that stocking advanced-size largemouth bass into these embayments only provided a limited and short-term enhancement of the fishery in those areas.

Journal of Freshwater Ecology↗
USGS2008

Use of an annular chamber for testing thermal preference of westslope cutthroat trout and rainbow trout

Remaining populations of westslope cutthroat trout (Oncorhynchus clarkii lewisi) in western North America are primarily confined to cold headwaters whereas nonnative rainbow trout (Oncorhynchus mykiss) predominate in warmer, lower elevation stream sections historically occupied by westslope cutthroat trout. We tested whether differing thermal preferences could account for the spatial segregation observed in the field. Thermal preferences of age-1 westslope cutthroat trout and rainbow trout (125 to 150 mm total length) were assessed in the laboratory using a modified annular preference chamber at acclimation temperatures of 10, 12, 14, and 16??C Final preferred temperature of westslope cutthroat trout (14.9??C) was similar to that of rainbow trout (14.8??C) when tested in a thermal gradient of 11-17??C The high degree of overlap in thermal preference indicates the two species have similar thermal niches and a high potential for competition. We suggest several modifications to the annular preference chamber to improve performance in future studies.

Journal of Freshwater Ecology↗
USGS2009

Influence of diet of double-crested cormorants on thiamine, lead, and mineral contents of their eggs

Throughout much of the Great Lakes basin, reproduction of several fish species is impaired by deficiency of thiamine in their eggs, an effect attributed to consumption of thiaminase-containing forage species, primarily alewife ( Alosa pseudoharengus ). Because the double-crested cormorant ( Phalacrocorax auritus ) nesting on islands in Lake Ontario is known to consume considerable amounts of alewife, we examined cormorant food habits and measured thiamine content in eggs collected in 1999 from six separate nests of cormorants from colonies near Lake Ontario and contrasted them with food habits and eggs of cormorants from Oneida Lake where the alewife is rare. Thiamine concentrations in eggs varied between 4.31 and 11.24 nmoles/g with no significant ( P >0.18) difference between mean concentrations for Lake Ontario and Oneida Lake (8.08 vs 8.36 nmoles/g) even though alewife comprised approximately 65 vs 0 % of their diets, respectively. Consumption of other thiaminase-containing species was minor in both lakes. Therefore, consumption of alewife and other thiaminase containing fishes by cormorants on Lake Ontario did not appear to significantly impair the levels of thiamine in their eggs. However, we found that the concentration of thiamine in eggs (T; nmoles/g) was inversely related ( P <0.02) to lead (Pb) concentration (µg/g) according to the equation: T = -3.142 Pb + 16.25. This relationship may reflect the known ability of thiamine to chelate lead and increase its excretion.

Journal of Freshwater Ecology↗
USGS2008

Diel diet composition and feeding activity of round goby in the nearshore region of Lake Ontario

Expansion of the invasive round goby Apollonia melanostoma (=Neogobius melanostomus) throughout the Great Lakes drainage has created considerable concern among fisheries management agencies. These concerns have led to several studies on the biology and impact of the goby in the basin. However, little information exists on diel patterns in food consumption of the round goby. We examined the diets of 300 round gobies collected during crepuscular, diurnal, and nocturnal periods in Lake Ontario. There was little variation in the diel diet composition of the goby, as chironomid larvae were the major prey consumed during each period. Feeding intensity of the round goby was significantly (P<0.05) greater at night than during crepuscular or diurnal periods.

Journal of Freshwater Ecology↗
USGS2008

Influence of summer water-level variability on St. Lawrence River-wetland fish assemblages

Water-level and associated variability are substantial influences on wetland and shallow aquatic communities. The Akwesasne Wetland Complex is an extensive St. Lawrence River system affected by water regulation. The responses of fish assemblages to short-term summer water-level variation were examined throughout this section of the St. Lawrence River and its tributaries. An influence of water-level variability was detected on abundance of three common species [bluntnose minnow (Pimephales notatus), rock bass (Amboplites rupestris), and white sucker (Catastomus commersonii)] and explained 30-44% of variation. This influence has implications for water regulation and natural resource management, and a larger scope evaluation may reveal more extensive effects.

Journal of Freshwater Ecology↗
USGS2008

Diel variation in near-shore great lakes fish assemblages and implications for assessment sampling and coastal management

I compared fish assemblages captured in three different microhabitats (shoreline, pelagic near-shore, and benthic near-shore) during day and night fishing in different protection (inside bay or tributary vs. outside in Lake Ontario proper) and turbidity regimes of four near-shore areas of Lake Ontario. The effects of diel movement and availability to gear were clearly evident. Fish assemblages were consistently and significantly more diverse at night than during the day, with nighttime assemblages often being supersets of daytime assemblages. Evidence for a turbidity effect was much weaker than the effects of nocturnal movements and changes in availability to the gear associated with darkness. Nighttime sampling is more likely to capture the full array of species in near-shore areas of the Great Lakes than daytime sampling.

Journal of Freshwater Ecology↗
USGS2010

Survival of foul-hooked largemouth bass (Micropterus salmoides)

We conducted a field experiment to determine the survival rate of foul-hooked (hooked external to the oral cavity) largemouth bass (Micropterus salmoides) caught and released by recreational anglers. Of 42 largemouth bass caught with hard-plastic baits containing three treble hooks, 15 were hooked only within the mouth and 27 had at least one hook penetrating the external surface of the fish (i.e., foul-hooked). There was no difference in survival of mouth-hooked (100%), foul-hooked (100%), or control (100%) largemouth bass.

Journal of Freshwater Ecology↗
USGS1996

The contribution of wetlands to stream nitrogen load in the Loch Vale Watershed, Colorado, USA

We explored the difference between the concentrations of different N forms and other chemical properties between stream water and riparian zone wetland soil water in the Loch Vale Watershed which is located on the eastern slope of the Continental Divide in Rocky Mountain National Park, Colorado, USA. The nitrate N concentration in stream water were significantly higher than in soil water of the three wetlands, while no significant difference appeared in ammonium N. The pH values were higher and conductivity values were lower in stream water than in wetland soil water. However, significant difference also appeared between nitrate N concentrations, pH and conductivity values in the water sampled from different positions of streams. The stream tributary water had higher nitrate N concentrations, higher pH and higher conducitity values. We also conducted experiments to compare the difference between the productivity, total N concentrations in biomass and soil of upper layers. At the end, we concluded that the wetlands distributed along the streams in Loch Vale Watershed had little effect on the nitrogen load of the stream water there.

Colorado↗
USGS2012

Shading decreases the abundance of the herbivorous California horn snail, Cerithidea californica

Most of the intertidal zone in estuaries of California, USA and Baja California, Mexico is covered with vascular vegetation. Shading by these vascular plants influences abiotic and biotic processes that shape benthic community assemblages. We present data on the effects of shading on the California horn snail, Cerithidea californica . This species is important because it is the most common benthic macrofaunal species in these systems and acts as an obligate intermediate host of several species of rematode parasites that infect several other species. Using observational and experimental studies, we found a negative effect of shade on the distribution and abundance of the California horn snail. We hypothesized that shading reduces the abundance of the epipelic diatoms that the snails feeds on, causing snails to leave haded areas. We observed a negative relationship between vascular plant cover, sub-canopy light levels, and snail density in Mugu Lagoon. Then we experimentally manipulated light regimes, by clipping vegetation and adding shade structures, and found higher snail densities at higher light levels. In Goleta Slough, we isolated the effect of shade from vegetation by documenting a negative relationship between the shade created by two bridges and diatom and snail densities. We also found that snails moved the greatest distances over shaded channel banks compared to unshaded channel banks. Further, we documented the effect of water depth and channel bank orientation on shading in this system. An additional effect of shading is the reduction of temperature, providing an alternative explanation for some of our results. These results broaden our knowledge of how variation in the light environment influences the ecology of estuarine ecosystems.

California↗
USGS2001

Guidelines for the field evaluation of desert tortoise health and disease

Field evaluation of free-ranging wildlife requires the systematic documentation of a variety of environmental conditions and individual parameters of health and disease, particularly in the case of rare or endangered species. In addition, defined criteria are needed for the humane salvage of ill or dying animals. The purpose of this paper is to describe, in detail, the preparation, procedures, and protocols we developed and tested for the field evaluation of wild desert tortoises ( Gopherus agassizii ). These guidelines describe: preparations for the field, including developing familiarity with tortoise behavior and ecology, and preparation of standardized data sheets; journal notes to document background data on weather conditions, temperature, rainfall, locality, and historic and recent human activities; procedures to prevent the spread of disease and parasites; data sheets for live tortoises to record tortoise identification, location, sex, body measurements and activity; health profile forms for documenting and grading physical abnormalities of tortoise posture and movements, general condition (e.g., lethargy, cachexia), external parasites, and clinical abnormalities associated with shell and upper respiratory diseases; permanent photographic records for the retrospective analysis of progression and regression of upper respiratory and eye diseases, analysis of shell lesions and evaluation of growth and age; and indications and methods for salvaging ill or dying tortoises for necropsy evaluation. These guidelines, tested on 5,000 to 20,000 tortoises over a 10 to 27 yr period, were designed to maximize acquisition of data for demographic, ecological, health and disease research projects; to reduce handling and stress of individual animals; to avoid spread of infectious disease; to promote high quality and consistent data sets; and to reduce the duration and number of field trips. The field methods are adapted for desert tortoise life cycle, behavior, anatomy, physiology, and pertinent disease; however the model is applicable to other species of reptiles. Comprehensive databases of clinical signs of disease and health are crucial to research endeavors and essential to decisions on captive release, epidemiology of disease, translocation of wild tortoises, breeding programs, and euthanasia.

Journal of Wildlife Diseases↗
USGS2024

Browsing the literature

For this edition of Browsing the Literature, we have two new papers from Rangeland Ecology & Management, a series of basic ecology papers with an international scope from journals such as the Proceedings of the National Academy of Sciences (USA), Science, and Nature, and several papers advancing our understanding of drought and carbon at global scales. Additionally, several papers on sagebrush-steppe rangelands are covered with transferable insights to other rangeland types.

Rangelands↗
USGS2017

Earth Stewardship: An initiative by the Ecological Society of America to foster engagement to sustain Planet Earth

The Ecological Society of America (ESA) has responded to the growing commitment among ecologists to make their science relevant to society through a series of concerted efforts, including the Sustainable Biosphere Initiative (1991), scientific assessment of ecosystem management (1996), ESA’s vision for the future (2003), Rapid Response Teams that respond to environmental crises (2005), and the Earth Stewardship Initiative (2009). During the past 25 years, ESA launched five new journals, largely reflecting the expansion of scholarship linking ecology with broader societal issues. The goal of the Earth Stewardship Initiative is to raise awareness and to explore ways for ecologists and other scientists to contribute more effectively to the sustainability of our planet. This has occurred through four approaches: (1) articulation of the stewardship concept in ESA publications and Website, (2) selection of meeting themes and symposia, (3) engagement of ESA sections in implementing the initiative, and (4) outreach beyond ecology through collaborations and demonstration projects. Collaborations include societies and groups of Earth and social scientists, practitioners and policy makers, religious and business leaders, federal agencies, and artists and writers. The Earth Stewardship Initiative is a work in progress, so next steps likely include continued nurturing of these emerging collaborations, advancing the development of sustainability and stewardship theory, improving communication of stewardship science, and identifying opportunities for scientists and civil society to take actions that move the Earth toward a more sustainable trajectory.

Book chapter↗
USGS1990

Monitoring moisture storage in trees using time domain reflectometry

Laboratory and field tests were performed to examine the feasibility of using time domain reflectometry (TDR) to monitor changes in the moisture storage of the woody parts of trees. To serve as wave guides for the TDR signal, pairs of stainless steel rods (13 cm long, 0.32 cm in diameter, and 2.5 cm separation) were driven into parallel pilot holes drilled into the woody parts of trees, and a cable testing oscilloscope was used to determine the apparent dielectric constant. A laboratory calibration test was performed on two sapwood samples, so that the relation between the volumetric water content and the apparent dielectric constant of the sapwood could be determined over a range of water contents. The resulting calibration curve for these sapwood samples was significantly different than the general calibration curve used for soils, showing a smaller change in the apparent dielectric constant for a given change in the volumetric water content than is typical for soils. The calibration curve was used to estimate the average volumetric water content to a depth of 13 cm in living trees. One field experiment was conducted on an English walnut tree ( Juglans regia ) with a diameter of 40 cm, growing in a flood-irrigated orchard on a Hanford sandy loam near Modesto, California (U.S.A.). Rods were driven into the tree at about 50 cm above the soil surface and monitored hourly for the month of August, 1988. The moisture content determined by TDR showed a gradual decrease from 0.44 to 0.42 cm 3 cm −3 over a two week period prior to flood irrigation, followed by a rapid rise to 0.47 cm 3 cm −3 over a four day period after irrigation, then again a gradual decline approaching the next irrigation. A second field experiment was made on ten evergreen and deciduous trees with diameters ranging from 30 to 120 cm, growing in the foothills of the Coast Range of central California. Rods were driven into each tree at 50 to 100 cm above the soil surface and monitored on a biweekly to monthly basis for over a year. Most trees showed an early spring maximum in moisture content determined by TDR associated with leaf growth, and a late summer minimum in moisture content associated with the end of the dry season. Moisture contents ranged from 0.20 to 0.70 cm 3 cm −3 , with an annual percentage change in moisture of 15% to 70% depending on species and environmental conditions. A final field test was performed in northern New Mexico (U.S.A.) to examine the effect of trunk freezing on TDR measurements. This test confirmed that freezing conditions were recorded as a total loss of liquid water by the TDR method. These results suggest that further TDR calibration for wood, plus some understanding of the relation between tree moisture and physiological stress could be useful to several disciplines, ranging from irrigation scheduling to watershed management to forest ecology.

California↗