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At least 631 records · Page 35Linked to original sources
USGS2023

Expansive, positive changes to fish habitat diversity following the formation of a valley plug in a degraded desert river

Widespread hydrologic alterations have simplified in-stream habitats in rivers globally, driving population declines and extirpations of many native fishes. Here, we examine how rapid geomorphic change in a historically degraded desert river has influenced habitat diversification and ecosystem persistence. In 2010, a large reach of the degraded and simplified lower San Rafael River (SRR), Utah, was impacted by the formation of a valley plug and began to shift from a homogenous, single-thread channel to a complex, multi-threaded riverscape. We combined field measurements and drone-collected imagery to document changes in fish habitat due to the valley plug. Our results demonstrate that in 2021, the affected reach was more diverse than any other stream reach along the SRR, containing 641% more diverse habitat (e.g., pools, riffles, and backwaters) than what was measured in 2015. The plug reach also retained water for periods beyond what was expected during seasonal drying, with the total extent of inundation within the riverscape increasing by over 2800%. Since the formation of the valley plug, riparian habitat has increased by 230% and channel networks have expanded to more than 50 distinct channels throughout the zone of influence. Our results provide evidence of successful self-restoration in a formerly highly degraded reach of desert river, and encourage new methods of desert river restoration. We aim to inform the use of large-scale, disruptive restoration actions like intentional channel occlusions, with the goal of mitigating the impacts of simplification and increasing habitat persistence in the face of exacerbated aridity in the desert Southwest.

Utah↗
USGS1997

Jonah field, Sublette County, Wyoming: Gas production from overpressured Upper Cretaceous Lance sandstones of the Green River basin

Jonah field, located in the northwestern Green River basin, Wyoming, produces gas from overpressured fluvial channel sandstones of the Upper Cretaceous Lance Formation. Reservoirs exist in isolated and amalgamated channel facies 10-100 ft (3-30 m) thick and 150-4000 ft (45-1210 m) wide, deposited by meandering and braided streams. Compositional and paleocurrent studies indicate these streams flowed eastward and had their source area in highlands associated with the Wyoming-Idaho thrust belt to the west. Productive sandstones at Jonah have been divided into five pay intervals, only one of which (Jonah interval) displays continuity across most of the field. Porosities in clean, productive sandstones range from 8 to 12%, with core permeabilities of .01-0.9 md (millidarcys) and in-situ permeabilities as low as 3-20 µ d (microdarcys), as determined by pressure buildup analyses. Structurally, the field is bounded by faults that have partly controlled the level of overpressuring. This level is 2500 ft (758 m) higher at Jonah field than in surrounding parts of the basin, extending to the top part of the Lance Formation. The field was discovered in 1975, but only in the 1990s did the area become fully commercial, due to improvements in fracture stimulation techniques. Recent advances in this area have further increased recoverable reserves and serve as a potential example for future development of tight gas sands elsewhere in the Rocky Mountain region.

Wyoming↗
USGS1970

Reconnaissance of the Pigeon River, a cold-water river in the northcentral part of Michigan's southern peninsula

The cold-water streams of the northern states provide unique recreational values to the American people (wilderness or semi-wilderness atmosphere, fast-water canoeing, and trout fishing), but the expanding recreational needs must be balanced against the growing demand of water for public and industrial supplies, for irrigation, and for the dilution of sewage and other wastes. In order to make intelligent decisions regarding use and management of the water resource for recreation and other demands, an analysis of the hydrologic factors related to recreational values is essential. The Pigeon River is one of Michigan's outstanding trout streams and is the favorite of a large number of anglers who return year after year. Camping is also popular and is usually, but not always, associated with fishing. Boating is very rare on the Pigeon because of numerous portages around log jams. Cabin-living and resorting are relatively minor on this river as yet, but much of the private river front may be developed in future years. The Pigeon is located in the north-central part of the southern peninsula of Michigan (see index map). Headwaters are a few miles northeast of Gaylord, and the mouth is at Mullet Lake, a few miles northeast of Indian River. Interstate Highway 75 roughly parallels the river about 5 to 10 miles to the west. Exits from this highway at Gaylord, Vanderbilt, Wolverine, and Indian River, provide easy access to the Pigeon. The recreational value of the river depends on the streamflow characteristics, quality of water, and character of stream channel, and bed and banks. The purpose of this atlas is to describe these characteristics, and to show how they relate to recreational uses. Most of the information presented here was obtained from a field reconnaissance in June, 1966, and from basic records of the U.S. Geological Survey's Water Resources Division. The area of field study is limited to the channel, bed, and banks of the main stem of the Pigeon from source to mouth. The study was made in cooperation with the Michigan Geological Survey, Gerald E. Eddy, Chief. Advice and assistance were also obtained from other sections of the Michigan Conservation Department. Sheet 1 of this atlas presents information on streamflow characteristics and water quality. Sheet 2 describes the physical characteristics of the stream channel, and bed and banks, and shows how these physical characteristics relate to streamflow, water quality, and recreational use.

Michigan↗
USGS2015

Surface-water quality in agricultural watersheds of the North Carolina Coastal Plain associated with concentrated animal feeding operations

The effects of concentrated animal feeding operations (CAFOs) on water quality were investigated at 54 agricultural stream sites throughout the North Carolina Coastal Plain during 2012 and 2013. Three general watershed land-use types were examined during the study, including 18 background watersheds with no active CAFOs (BK sites), 18 watersheds with one or more active swine CAFOs but no poultry CAFOs (SW sites), and 18 watersheds with at least one active swine CAFO and one active dry-litter poultry CAFO (SP sites). The watershed drainage areas for these 54 stream sites ranged from 1.2 to 17.5 square miles. Conventional fertilizers used for crop production are the primary source of nutrients at the BK sites. Animal-waste manures represent an additional source of nutrients at the SW and SP study sites. Land cover, soil drainage, and CAFO attributes were compiled for each watershed. Water-quality field measurements were made and samples were collected at the 54 primary sites during 6 bimonthly sampling periods from June 2012 to April 2013. An additional 23 secondary sites were sampled once during April 2013 to provide supplemental data at stream locations directly adjacent or in close proximity to swine CAFOs and (or) background agricultural areas within 9 of the primary watersheds. The watershed drainage areas for the 23 secondary sites ranged from 0.2 to 8.9 square miles. Water temperature, specific conductance, dissolved-oxygen concentration, and pH were measured directly in the streams. Water samples were analyzed for major ions, nutrients, and stable isotopes, including delta hydrogen-2 (δ 2 H) and delta oxygen-18 (δ 18 O) of water and delta nitrogen-15 (δ 15 N) and δ 18 O of dissolved nitrate plus nitrite. Most of the water-quality properties and constituents varied significantly among the six sampling periods, changing both seasonally and in response to hydrologic conditions. The differences noted among the sampling periods indicate that the interactions between seasonal climatic differences, streamflow conditions, and instream biotic and abiotic processes are complex and their integrated effects can have varying degrees of influence on individual nutrients. Water-quality differences were noted for the SW and SP land-use groups relative to the BK group. Median values of specific conductance, several major ions (magnesium, sodium, potassium, and chloride), and nitrogen fractions (ammonia plus organic nitrogen, ammonia, nitrate plus nitrite, total nitrogen, and δ 15 N of nitrate plus nitrite) were higher for the SW and SP groups compared to the BK group. No significant differences in water temperature, dissolved oxygen, calcium, total organic nitrogen, orthophosphate, total phosphorus, or δ 18 O of nitrate plus nitrite were noted among the land-use groups. When compared on the basis of land-use type, there was an overall measurable effect of CAFO waste manures on stream water quality for the SW and SP watershed groups. Some individual sites within the SW and SP groups showed no measurable CAFO effects on water quality despite having CAFOs present upstream. An evaluation of sodium plus potassium concentrations coupled with δ 15 N values of nitrate plus nitrite proved valuable for distinguishing which SW and SP sites had a water-quality signature indicative of CAFO waste manures. Sites with CAFO manure effects were characterized by higher sodium plus potassium concentrations (commonly between 11 and 33 milligrams per liter) and δ 15 N values of nitrate plus nitrite (commonly between 11 and 26 parts per thousand) relative to sites reflecting background agricultural conditions, which commonly had sodium plus potassium concentrations between 6 and 14 milligrams per liter and δ 15 N values of nitrate plus nitrite between 6 and 15 parts per thousand. On the basis of the results of this study, land applications of waste manure at swine CAFOs influenced ion and nutrient chemistry in many of the North Carolina Coastal Plain streams that were studied. A classification tree model was developed to examine relations of watershed environmental attributes among the study sites with and without CAFO manure effects. Model results indicated that variations in swine barn density, percentage of wetlands, and total acres available for applying swine-waste manures had an important influence on those watersheds where CAFO effects on water quality were either evident or mitigated. Measurable effects of CAFO waste manures on stream water quality were most evident in those SW and SP watersheds having lower percentages of wetlands combined with higher swine barn densities and (or) higher total acres available for applying waste manure at the swine CAFOs. Stream water quality was similar to background agricultural conditions in SW and SP watersheds with lower swine barn densities coupled with higher percentages of wetlands or lower acres available for swine manure applications. The model provides a useful tool for exploring and identifying similar, unmonitored watersheds in the North Carolina Coastal Plain with potential CAFO manure influences on water quality that might warrant further examination.

North Carolina↗
USGS1971

Reconnaissance of the Pere Marquette River, a cold water river in the central part of Michigan's Southern Peninsula

The cold-water streams of the northern states provide unique recreational values to the American people (wilderness or semi-wilderness atmosphere, fast-water canoeing, and trout fishing) but the expanding recreational needs must be balanced against the growing demand of water for public and industrial supplies, for irrigation, and for the dilution of sewage and other wastes. In order to make intelligent decisions regarding use and management of the water resource for recreation and other demands, an analysis of the hydrologic factors related to recreational values is essential. The Pere Marquette, an outstanding river for brown and steelhead trout fishing, is also a popular canoe trail. Larger boats, some equipped with motors, are common in the lower reaches where the river is wide and deep. Cabins are abundant on the river near Baldwin but are relatively sparse elsewhere. The broad swampy floodplain that borders most of the river between Walhalla and Ludington apparently offers few favorable cabin sites. The Pere Marquette is located in the west-central part of the Southern Peninsula of Michigan, and flows westward from the headwaters near Chase in Lake County to the mouth at Ludington, in Mason County. The river is south of, and roughly parallel to, U.S. Highway 10 from Chase to Ludington. Access to the river is by roads leading south from U.S. 10 at Nirvana, Idlewild, Baldwin, Branch, Walhalla, Scottville, and many intermediate points. The recreational value of the river depends on the streamflow characteristics, quality of water, and character of stream channel and bed and banks. The purpose of this report is to describe these characteristics and show how they relate to recreational USGS. Most of the information presented here was obtained from a field reconnaissance in July and August, 1966, and from basic records of the U.S. Geological Survey's Water Resources Division. The area of field study is limited to the channel, bed, and banks of the Middle Branch and main stem of the Pere Marquette from source to mouth. The study was made in cooperation with the Michigan Geological Survey, Gerald E. Eddy, Chief. Advice and assistance were also obtained from other sections of the Michigan Department of Natural Resources. Sheet 1 of this atlas presents information on streamflow and quality of water. Sheet 2 describes the physical characteristics of the stream channel, and bed and banks, and shows how these characteristics relate to streamflow, water quality, and recreational use.

Michigan↗
USGS2012

Specific conductance measurements in central and western New York streams - A retrospective characterization

U.S. Geological Survey (USGS) Data Rescue Program funds were used to recover data from paper records for 139 streamgages across central and western New York State; 6,133 different streamflow measurement forms, collected between 1970-80, contained field water-quality measurements. The water-quality data were entered, reviewed, and uploaded into the USGS National Water Information System. In total, 4,285 unique site visits were added to the database. The new values represent baseline water quality from which to measure change and will lead to a comparison of water-quality change over the last 40 years and into the future. Specific conductance was one of the measured properties and represents a simple way to determine if ambient inorganic water quality has been altered by anthropogenic (road salt runoff, wastewater discharges, or natural gas development) or natural sources. The objective of this report is to describe ambient specific conductance characteristics of surface water across the central and western part of New York. This report presents median specific conductance of stream discharge for the period 1970-80 and a description of the relation between specific conductance and concentrations of total dissolved solids (TDS) retrieved from the USGS National Water Information System (NWIS) database from 1955 to present. The data descriptions provide a baseline of surface-water specific conductance data that can used for comparison to current and future measurements in New York streams.

New York;Pennsylvania↗
USGS2013

Estimating instream constituent loads using replicate synoptic sampling, Peru Creek, Colorado

The synoptic mass balance approach is often used to evaluate constituent mass loading in streams affected by mine drainage. Spatial profiles of constituent mass load are used to identify sources of contamination and prioritize sites for remedial action. This paper presents a field scale study in which replicate synoptic sampling campaigns are used to quantify the aggregate uncertainty in constituent load that arises from (1) laboratory analyses of constituent and tracer concentrations, (2) field sampling error, and (3) temporal variation in concentration from diel constituent cycles and/or source variation. Consideration of these factors represents an advance in the application of the synoptic mass balance approach by placing error bars on estimates of constituent load and by allowing all sources of uncertainty to be quantified in aggregate; previous applications of the approach have provided only point estimates of constituent load and considered only a subset of the possible errors. Given estimates of aggregate uncertainty, site specific data and expert judgement may be used to qualitatively assess the contributions of individual factors to uncertainty. This assessment can be used to guide the collection of additional data to reduce uncertainty. Further, error bars provided by the replicate approach can aid the investigator in the interpretation of spatial loading profiles and the subsequent identification of constituent source areas within the watershed. The replicate sampling approach is applied to Peru Creek, a stream receiving acidic, metal-rich effluent from the Pennsylvania Mine. Other sources of acidity and metals within the study reach include a wetland area adjacent to the mine and tributary inflow from Cinnamon Gulch. Analysis of data collected under low-flow conditions indicates that concentrations of Al, Cd, Cu, Fe, Mn, Pb, and Zn in Peru Creek exceed aquatic life standards. Constituent loading within the study reach is dominated by effluent from the Pennsylvania Mine, with over 50% of the Cd, Cu, Fe, Mn, and Zn loads attributable to a collapsed adit near the top of the study reach. These estimates of mass load may underestimate the effect of the Pennsylvania Mine as leakage from underground mine workings may contribute to metal loads that are currently attributed to the wetland area. This potential leakage confounds the evaluation of remedial options and additional research is needed to determine the magnitude and location of the leakage.

Colorado↗
USGS1982

Shallow subsurface temperatures and some estimates of heat flow from the Colorado Plateau of northeastern Arizona

Temperature data to depths of a few hundred meters were obtained from 29 wells in northeastern Arizona; 12 in the region surrounding the San Francisco Volcanic Field, 8 in the Black Mesa area, and 9 in the south-central Colorado Plateau which includes the White Mountains. Although there was evidence for local hydrologic disturbances in many temperature profiles, most wells provided an estimate of the conductive thermal gradient at the site. A few thermal conductivities were measured and were combined with published regional averages for the north-central part of the Colorado Plateau to produce crude estimates of regional heat flux. None of the wells was accessible below the regional aquifers. To these depths, heat flow in the area of the San Francisco Volcanic Field appears to be controlled primarily by regional lateral water movement having a significant downward vertical component of velocity. The mean heat flow of 27?5 mW^-2 is only a third to a quarter of what we would expect in this tectonic setting. The heat that is being carried laterally and downward probably is being discharged at low enthalpy and low elevation in springs and streams of the Colorado Plateau and Mogollon Rim. In the vicinity of Black Mesa, heat-flow averages about 60 mW^-2, characteristic of the 'cool interior' of the Colorado Plateau. North of the White Mountain Volcanic Field, the average heat flow is about 95 mW^-2.

Open-File Report↗
USGS1976

Chemical and bacteriological quality of water at selected sites in the San Antonio area, Texas, August 1968-January 1975

Urban development on or adjacent to the recharge zone of the Edwards aquifer is causing concern about the possible pollution of ground water in the aquifer, which is the principal source of water supply for the San Antonio area. Water-quality data for many wells and springs and for selected sites on streams that cross the recharge zone of the aquifer are being collected to provide background information and to detect any current pollution of ground water in the area. Water from the Edwards aquifer is very hard and of the calcium bicarbonate type. The concentrations of dissolved solids in samples from wells and springs ranged from about 200 to 470 mg/1 (milligrams per liter); the chloride and sulfate concentrations ranged from 6.5 to 62 mg/1 and from 0.0 to 65 mg/1, respectively. The nitrate and phosphate contents of the ground water ranged from 0.0 to 15 mg/1 and from 0.00 to 0. 37 mg/1. The concentrations of these and other constituents show that the chemical quality of water in the Edwards aquifer has not been degraded significantly by domestic, industrial, or agricultural effluents. However, variations in the number of coliforms, the concentrations of nitrate and phosphate, and the presence of fecal coliforms and fecal streptococci in samples from some wells show that fecal pollution is reaching the aquifer. Most of these wells, which are located in or just downdip from the recharge zone, are poorly sealed or inadequately cased. The areal variation in the locations of these wells indicates that pollution of ground water in the aquifer is very localized. Prllution results principally from runoff from the land surface and from effluent from septic tanks which enters the aquifer through fractures in the recharge zone or which infiltrates through the thin soil into poorly sealed or inadequately cased wells in or adjacent to the recharge zone. Trace amounts of several pesticides have been detected in samples from two wells in the San Antonio area. Field investigations showed the source of pesticides in these wells to be. surface drainage that entered the wellbores. Water-quality data collected at sites on streams that cross the recharge zone of the Edwards aquifer show the chemical composition of surface water to be very similar to that of ground water in the area. Water in most streams is very hard and of the calcium bicarbonate type. Limited data on the bacteriological quality show that coliforms were present at each of the site sampled and that fecal coliforms and fecal streptococci were present at most sites. Although the number of these bacteria varied greatly in both time and place, their density in samples from most sites were low for untreated surface water.

Texas↗
USGS2014

Hyporheic flow and transport processes: mechanisms, models, and biogeochemical implications

Fifty years of hyporheic zone research have shown the important role played by the hyporheic zone as an interface between groundwater and surface waters. However, it is only in the last two decades that what began as an empirical science has become a mechanistic science devoted to modeling studies of the complex fluid dynamical and biogeochemical mechanisms occurring in the hyporheic zone. These efforts have led to the picture of surface-subsurface water interactions as regulators of the form and function of fluvial ecosystems. Rather than being isolated systems, surface water bodies continuously interact with the subsurface. Exploration of hyporheic zone processes has led to a new appreciation of their wide reaching consequences for water quality and stream ecology. Modern research aims toward a unified approach, in which processes occurring in the hyporheic zone are key elements for the appreciation, management, and restoration of the whole river environment. In this unifying context, this review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hyporheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to the watershed scale. The implications of these processes for stream biogeochemistry and ecology are also discussed."

Reviews of Geophysics↗
USGS2014

Dynamic hyporheic exchange at intermediate timescales: testing the relative importance of evapotranspiration and flood pulses

Hyporheic fluxes influence ecological processes across a continuum of timescales. However, few studies have been able to characterize hyporheic fluxes and residence time distributions (RTDs) over timescales of days to years, during which evapotranspiration (ET) and seasonal flood pulses create unsteady forcing. Here we present a data-driven, particle-tracking piston model that characterizes hyporheic fluxes and RTDs based on measured vertical head differences. We used the model to test the relative influence of ET and seasonal flood pulses in the Everglades (FL, USA), in a manner applicable to other low-energy floodplains or broad, shallow streams. We found that over the multiyear timescale, flood pulses that drive relatively deep (∼1 m) flow paths had the dominant influence on hyporheic fluxes and residence times but that ET effects were discernible at shorter timescales (weeks to months) as a break in RTDs. Cumulative RTDs on either side of the break were generally well represented by lognormal functions, except for when ET was strong and none of the standard distributions applied to the shorter timescale. At the monthly timescale, ET increased hyporheic fluxes by 1–2 orders of magnitude; it also decreased 6 year mean residence times by 53–87%. Long, slow flow paths driven by flood pulses increased 6 year hyporheic fluxes by another 1–2 orders of magnitude, to a level comparable to that induced over the short term by shear flow in streams. Results suggest that models of intermediate-timescale processes should include at least two-storage zones with different RTDs, and that supporting field data collection occur over 3–4 years.

Florida↗
USGS1970

Comparative hydrogeology: An example of its use

As a start toward needed classifications of hydrogeologic settings, a type of setting is described. The setting includes areas where soluble materials are exposed to considerable recharge from precipitation and where both the topographic relief and permeability are inappreciable. Typical areas of this setting are (1) the Black Belt of the Coastal Plain of Alabama and Mississippi, underlain by chalk of the Selma Group, and (2) a 25-sq-mi area near Harrisburg, Cabarrus County, North Carolina, underlain by gabbro in the Piedmont province. Hydrologic conditions that may be inferred and that are easily discernible from this type of setting include: excessive evapotranspiration, low water-table gradient, water table near land surface, thin soils, ground-water movement being almost inappreciable, and the zone of movement being almost limited to a thin zone that includes the contact between the soil and rock, inappreciable ground-water discharge to streams leading, in turn, to a low base flow in streams, low drainage density, and subsurface water relatively high in dissolved mineral matter. Evaluation of the hydrogeologic setting described leads inductively into the undeveloped field of comparative hydrology, which represents a quick useful means of discerning the significance of processes and principles in particular environments. The setting reveals the significance of solution by subsurface water in developing some plains. Comparative hydrology, using the described setting and typical karst settings as examples, allows an advanced analysis of some pertinent factors.

Alabama, Mississippi, North Carolina↗
USGS1985

Map showing abundance and distribution of copper in oxide residues of stream-sediment samples, Medford 1 degree by 2 degrees Quadrangle, Oregon-California

Stream-sediment sampling in the Medford 1 o x 2 o quadrangle was undertaken to provide to aid in assessment of the mineral resource potential of the quadrangle. This map presents data on the abundance and distribution of copper in the oxide residues (oxalic-acid leachates) of stream sediments and in the minus-0.18-mm sieve fraction of selected stream sediments collected in the quadrangle.

Oregon↗
USGS1985

Map showing abundance and distribution of arsenic in oxide residues of stream-sediment samples, Medford 1 degree by 2 degrees Quadrangle, Oregon-California

Stream-sediment sampling in the Medford 1 o x 2 o quadrangle was undertaken to provide to aid in assessment of the mineral resource potential of the quadrangle. This map presents data on the abundance and distribution of copper in the oxide residues (oxalic-acid leachates) of stream sediments and in the minus-0.18-mm sieve fraction of selected stream sediments collected in the quadrangle.

Oregon↗
USGS2010

Environmental flow studies of the Fort Collins Science Center— Cherry Creek, Arizona

At the request of the U.S. Forest Service, an instream flow assessment was conducted at Cherry Creek, Ariz., to investigate habitat for native and introduced fish species and to describe the beneficial use of a possible instream flow water right. The U.S. Geological Survey (USGS) Fort Collins Science Center performed an intensive field study of two sections of Cherry Creek in September 2008 to provide base data for hydrodynamic simulation of the flow conditions in the stream. The USGS Arizona Cooperative Fish and Wildlife Research Unit, at the University of Arizona School of Natural Resources, conducted a survey of the habitat requirements of the resident fish species in Cherry Creek and provided the habitat suitability criteria used in this study. The habitat suitability criteria were combined with hydrodynamic simulation results to quantify fish habitat for the full range of daily flow experienced in the creek and to produce maps of habitat occurrence for those flows. The flow record at the Cherry Creek stream gage was used to generate habitat response values over time. The long-term habitat response was incorporated into an Excel (Registered) spreadsheet to allow evaluation of habitat occurrence with and without an instream water right under different hypothetical water withdrawal scenarios. The spreadsheet displays information about the time sequence of habitat events, the duration of critical events, and habitat retention.

Arizona↗
USGS2024

Quantifying the relative importance of biotic and abiotic factors in landscape-based models of stream fish distributions

Lotic fish species distributions are frequently predicted using remotely sensed habitat variables that characterize the adjacent landscape and serve as proxies for instream habitat. Recent advancements in statistical methodology, however, allow for leveraging fish assemblage data when predicting distributions. This is important because assemblage composition likely provides better information about instream habitat compared to landscape-derived metrics and therefore may improve predictions. To better understand the value of using multi-species fish data in species distribution modeling, we fit two conditional random fields (CRF) models to quantify the relative importance of fish assemblage co-occurrence, landscape-derived habitat variables, and interactions between these two predictor groups (i.e., effects of co-occurrence could be context-dependent) at over 1200 stream catchments in Pennsylvania, USA. We first compared predictive performance of CRF models against traditionally used single-species logistic regressions (generalized linear models; GLMs) and found that inclusion of fish assemblage data often improved predictive performance. The multi-species CRF models performed significantly better at predicting occurrence for 63% of species with an average percent increase in AUC of 25% compared to GLMs. Furthermore, the CRF identified species co-occurrences as more informative, and thus relatively more important, at predicting occurrence than the other effect types. The CRF also suggested that allowing these biotic effects to be context-dependent was important for predicting occurrence of many species. These findings illustrate the value of fish assemblage data for landscape-scale species distribution modeling and leveraging this information can improve predictions and inferences to help inform the management and conservation of freshwater fishes.

Pennsylvania↗