Charles Yackulic is a research statistician with the Southwest Biological Science Center.
Science and Products
The Impacts of Climate Change and Water Supply Management on Fish in the Colorado River
Rainbow Trout Abundance and Movement in the Colorado River in Grand Canyon
Uncovering the Base of the Food Web: Primary Production Dynamics in the Colorado River
Population Dynamics of Endangered Humpback Chub in Grand Canyon
Understanding Factors Influencing Rainbow Trout Growth in the Colorado River
Continental-scale overview of stream primary productivity, its links to water quality, and consequences for aquatic carbon biogeochemistry
Brown trout movement data in Glen and Grand Canyons, Arizona, USA
Proximal and distal factors associated with the decline in secondary invertebrate prey production in the Colorado River, Glen Canyon, Arizona.
Gross primary production estimates and associated light, sediment, and water quality data from the Colorado River below Glen Canyon Dam
Rainbow trout diet and invertebrate drift data from 2012-2015 for the Colorado River, Grand Canyon, Arizona
Humpback Chub (Gila cypha) capture history data (2009-2017), and code for mark-recapture analysis and stochastic matrix projections, Colorado River and Little Colorado River, Arizona
Water temperature models, data and code for the Colorado, Green, San Juan, Yampa, and White rivers in the Colorado River basin
Marginalizing Bayesian population models - data for examples in the Grand Canyon region, southeastern Arizona, western Oregon USA - 1990-2015
Bioeconomic model population data, Grand Canyon, Arizona, USA
Northern spotted owl data and analysis code, Cascade Range, Pacific Northwest, USA
Metabolism estimates for 356 U.S. rivers (2007-2017)
Southern Pacific Pond Turtle Data, Elizabeth Lake, Los Angeles County, California, USA
Spatial distribution and risk analysis data for diamond-backed terrapins relative to crab trapping, Savannah Coastal Refuge Complex, USA
Long-term monitoring in transition: Resolving spatial mismatch and integrating multistate occupancy data
Impeding access to tributary spawning habitat and releasing experimental fall-timed floods increases brown trout immigration into a dam's tailwater
Drought related changes in water quality surpass effects of experimental flows on trout growth downstream of Lake Powell reservoir
The hydroclimate niche: A tool for predicting and managing riparian plant community responses to streamflow seasonality
The Colorado River – The science-policy interface
Dry forest decline is driven by both declining recruitment and increasing mortality in response to warm, dry conditions
Quantifying flow and nonflow management impacts on an endangered fish by integrating data, research, and expert opinion
Little bugs, big data, and Colorado River adaptive management: Preliminary findings from the ongoing bug flow experiment at Glen Canyon Dam
Exploring metapopulation-scale suppression alternatives for a global invader in a river network experiencing climate change
Range-wide sources of variation in reproductive rates of northern spotted owls
Experimental reductions in sub-daily flow fluctuations increased gross primary productivity for 425 river kilometers downstream
Water storage decisions and consumptive use may constrain ecosystem management under severe sustained drought
Colorado River Basin Projects
The Colorado River Basin Actionable and Strategic Integrated Science and Technology Team has created an interactive map of USGS projects to highlight the integrated science currently conducted within the Colorado River Basin. These projects are not all inclusive of the work conducted by the USGS within the CRB, but highlight the broad range of integrated science currently conducted.
Science and Products
- Science
The Impacts of Climate Change and Water Supply Management on Fish in the Colorado River
The Colorado River and its major tributaries provide a crucial water supply for more than 40 million people in the American Southwest and in California. This water supply is primarily used in irrigated agriculture but also provides essential drinking water to many large metropolitan areas. Hydropower is also produced at many of the large dams on the river. River flows have declined during the pastRainbow Trout Abundance and Movement in the Colorado River in Grand Canyon
Just below Glen Canyon Dam on the Colorado River is a very popular Blue Ribbon trout fishery known for its rainbow trout. However, approximately 78 miles downstream, near were the Little Colorado River flows into the Colorado River, is a population of endangered humpback chub. The introduced rainbow trout can negatively affect native humpback chub by competing with them for food (immature black...Uncovering the Base of the Food Web: Primary Production Dynamics in the Colorado River
Algae, phytoplankton, and rooted macrophytes represent the base of many aquatic food webs and are known as primary producers. Through photosynthesis, these organisms convert sunlight energy into chemical energy (i.e., carbon) that in turn fuels the growth of animals such as macroinvertebrates and fish. This project uses high frequency measurements of dissolved oxygen, which is a by-product of...Population Dynamics of Endangered Humpback Chub in Grand Canyon
The federally endangered humpback chub is a native fish of the Colorado River. Despite the environmental changes to the river following the construction of Glen Canyon Dam, humpback chub persists alongside nonnative species, including rainbow trout. The pre-dam Colorado River experienced seasonal variation in temperature and discharge. Seasonal flooding resulted in sediments carried downstream...Understanding Factors Influencing Rainbow Trout Growth in the Colorado River
Rainbow trout is a desirable sport fish that has been introduced in many locations around the world. Although introductions of rainbow trout and other nonnative fishes provide recreational fishing opportunities, they also pose threats to native fish populations. The Glen Canyon Dam Adaptive Management Program has tasked scientists and managers with identifying management options that allow rainbow...Continental-scale overview of stream primary productivity, its links to water quality, and consequences for aquatic carbon biogeochemistry
Streams and rivers have a limited spatial extent, but are increasingly recognized as key components of regional biogeochemical cycles. The collective metabolic processing of organisms, known as ecosystem metabolism, is centrally important to nutrient cycling and carbon fluxes in these environments, but is poorly integrated into emerging biogeochemical concepts. This line of inquiry lags behind oth - Data
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Brown trout movement data in Glen and Grand Canyons, Arizona, USA
These data were compiled to test hypotheses regarding drivers of movement of brown trout. Objectives of our study were to test whether the degree of movement varied in response to placement of a weir in Bright Angel Creek, fall timed flooding events, or simply seasonal changes. These data represent summarized capture histories of brown trout in terms of states based on physical locations, data onProximal and distal factors associated with the decline in secondary invertebrate prey production in the Colorado River, Glen Canyon, Arizona.
Using a bioenergetic model, demographic data for the Rainbow Trout (Oncorhynchus mykiss) population were compiled and used to estimate total prey consumption in the Colorado River, Glen Canyon , AZ. Additionally, other data including invertebrate diet, drift, and benthic measurements were used to make generalized estimates of daily production rates for the most common benthic invertebrate taxa. ThGross primary production estimates and associated light, sediment, and water quality data from the Colorado River below Glen Canyon Dam
These data were compiled to model the effects of flow regime and bed grain size distributions on rates of gross primary production (GPP) in the Colorado River below Glen Canyon Dam, AZ, USA. The objectives of our study were to quantify daily and weekly scale effects of an experimental flow regime on GPP in the Colorado River. The experimental flow was conducted at Glen Canyon Dam from May-August iRainbow trout diet and invertebrate drift data from 2012-2015 for the Colorado River, Grand Canyon, Arizona
These data were compiled to explore the foraging ecology of Rainbow Trout (Oncorhynchus mykiss) in the Colorado River, Grand Canyon, Arizona. These data represent samples characterizing the availability of drifting invertebrate prey (hereafter, drift) and use of these invertebrate prey by rainbow trout determined by gut samples (hereafter, diets). Drift and diet sampling occurred in five distinctHumpback Chub (Gila cypha) capture history data (2009-2017), and code for mark-recapture analysis and stochastic matrix projections, Colorado River and Little Colorado River, Arizona
These data represent capture histories for humpback chub (Gila cypha) that spawn in the Little Colorado River (LCR) from 2009-2017. Capture histories pertain to size class (<150mm total length [TL], 150-199mm TL, 200-249mm TL, and >250mm TL) and spatial location (the juvenile chub monitoring [JCM] reach in the Colorado River [63.4-65.0 river miles downstream of Lees Ferry],Water temperature models, data and code for the Colorado, Green, San Juan, Yampa, and White rivers in the Colorado River basin
These data were compiled for a manuscript in which 1) we develop a water temperature model for the major river segments and tributaries of the Colorado River basin, including the Colorado, Green, Yampa, White, and San Juan rivers; 2) we link modeled water temperature to fish population data to predict the probability native and nonnative species will be common in the future in a warming climate; aMarginalizing Bayesian population models - data for examples in the Grand Canyon region, southeastern Arizona, western Oregon USA - 1990-2015
These data were compiled here to fit various versions of Bayesian population models and compare their performance, primarily the time required to make inferences using different softwares and versions of code. The humpback chub data were collected by US Geological Survey and US Fish and Wildlife service in the Colorado and Little Colorado Rivers from April 2009 to October 2017. Adult fish were capBioeconomic model population data, Grand Canyon, Arizona, USA
These data were estimated for use in the bioecomomic model simulation of the rainbow trout population in the Colorado River in Marble Canyon. The initial rainbow trout abundance is a vector (RBT_intN) representing the population of rainbow trout within each river segment (151 mile long sergments) along the mainstem of the Colorado River from Lees Ferry to 151 river miles downstream. The movement mNorthern spotted owl data and analysis code, Cascade Range, Pacific Northwest, USA
These data were compiled to allow examination of northern spotted owl territorial occupancy dynamics, especially with regards to the roles played by habitat and competition with barred owl in past and future dynamics. Data are estimates of parameters derived from previous modelling of northern spotted owl territorial occupancy dynamics. These data were collected as part of monitoring of northern sMetabolism estimates for 356 U.S. rivers (2007-2017)
This data release provides modeled estimates of gross primary productivity, ecosystem respiration, and gas exchange coefficients for 356 streams and rivers across the United States. The release also includes the model input data and alternative input data, model fit and diagnostic information, spatial data for the modeled sites (catchment boundaries and site point locations), and potential predictSouthern Pacific Pond Turtle Data, Elizabeth Lake, Los Angeles County, California, USA
These data were compiled to study the effects of severe drought and a concurrent large wildfire on a large population of southern Pacific pond turtles living in a rapidly drying lake. The study was done in collaboration with biologists from Ecorp Consulting in Santa Ana, California with funding from the Desert Tortoise Council. Data were collected in August and September of 2014. This worksheet coSpatial distribution and risk analysis data for diamond-backed terrapins relative to crab trapping, Savannah Coastal Refuge Complex, USA
There were five objects for compiling these data: 1) to conduct a systematic inventory of diamond-backed terrapins (Malaclemys terrapin) using headcount surveys on four National Wildlife Refuges (Harris Neck, Blackbeard Island, Wassaw, and Wolf Island) that are a part of the greater Savannah Coastal Refuges Complex in southeast Georgia, USA; 2) to use occupancy modeling to determine detection prob - Publications
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Long-term monitoring in transition: Resolving spatial mismatch and integrating multistate occupancy data
The success of long-term wildlife monitoring programs can be influenced by many factors and study designs often represent compromises between spatial scales and costs. Adaptive monitoring programs can iteratively manage this tension by adopting new cost-efficient technologies, which can provide projects the opportunity to reallocate costs to address new hypotheses, adapt to changing ecological conImpeding access to tributary spawning habitat and releasing experimental fall-timed floods increases brown trout immigration into a dam's tailwater
River ecosystems have been altered by flow regulation and species introductions. Regulated flow regimes often include releases designed to benefit certain species or restore ecosystem processes, and invasive species suppression programs may include efforts to restrict access to spawning habitat. The impacts of these management interventions are often uncertain. Here, we assess hypotheses regardingDrought related changes in water quality surpass effects of experimental flows on trout growth downstream of Lake Powell reservoir
Flows released from reservoirs are often modified to mitigate the negative ecosystem effects of dams. We estimated the effects of two experimental flows, fall-timed floods and elimination of sub-daily variation in flows on weekends, on growth rates of rainbow trout (Oncorhynchus mykiss) in the Colorado River downstream from Glen Canyon Dam. Experimental flow effects were compared to effects of watThe hydroclimate niche: A tool for predicting and managing riparian plant community responses to streamflow seasonality
Habitat suitability is a consequence of interacting environmental factors. In riparian ecosystems, suitable plant habitat is influenced by interactions between stream hydrology and climate, hereafter referred to as “hydroclimate”. We tested the hypothesis that hydroclimate variables would improve the fit of ecological niche models for a suite of riparian species using occurrence data from the westThe Colorado River – The science-policy interface
No abstract available.Dry forest decline is driven by both declining recruitment and increasing mortality in response to warm, dry conditions
Aim: Anticipating when and where changes in species' demographic rates will lead to range shifts in response to changing climate remains a major challenge. Despite evidence of increasing mortality in dry forests across the globe in response to drought and warming temperatures, the overall impacts on the distribution of dry forests are largely unknown because we lack comparable large-scale data onQuantifying flow and nonflow management impacts on an endangered fish by integrating data, research, and expert opinion
Managers charged with recovering endangered species in regulated river segments often have limited flexibility to alter flow regimes and want estimates of the expected population benefits associated with both flow and nonflow management actions. Disentangling impacts on different life stages from concurrently applied actions is essential for determining the effectiveness of each action, but difficLittle bugs, big data, and Colorado River adaptive management: Preliminary findings from the ongoing bug flow experiment at Glen Canyon Dam
The undammed Colorado River in Grand Canyon was characterized by spring snow-melt floods that sometimes exceeded 100,000 cubic feet per second (cfs). These were followed by occasional flash floods during summer monsoons, then by low flows from fall through early spring (Figure 1; Topping and others, 2003). This seasonally variable flow regime carried huge loads of sediment and was an important driExploring metapopulation-scale suppression alternatives for a global invader in a river network experiencing climate change
Invasive species can dramatically alter ecosystems, but eradication is difficult, and suppression is expensive once they are established. Uncertainties in the potential for expansion and impacts by an invader can lead to delayed and inadequate suppression, allowing for establishment. Metapopulation viability models can aid in planning strategies to improve responses to invaders and lessen invasiveRange-wide sources of variation in reproductive rates of northern spotted owls
We conducted a range-wide investigation of the dynamics of site level reproductive rate of northern spotted owls using survey data from 11 study areas across the sub-species geographic range collected during 1993–2018. Our analytical approach accounted for imperfect detection of owl pairs and misclassification of successful reproduction (i.e., at least one young fledged) and contributed further inExperimental reductions in sub-daily flow fluctuations increased gross primary productivity for 425 river kilometers downstream
Aquatic primary production is the foundation of many river food webs. Dams change the physical template of rivers, often driving food webs toward greater reliance on aquatic primary production. Nonetheless, the effects of regulated flow regimes on primary production are poorly understood. Load following is a common dam flow management strategy that involves sub-daily changes in water releases propWater storage decisions and consumptive use may constrain ecosystem management under severe sustained drought
Drought has impacted the Colorado River basin for the past 20 years and is predicted to continue. In response, decisions about how much water should be stored in large reservoirs and how much water can be consumptively used will be necessary. These decisions have the potential to limit riverine ecosystem management options through the effect water-supply decisions have on reservoir elevations. We - Web Tools
Colorado River Basin Projects
The Colorado River Basin Actionable and Strategic Integrated Science and Technology Team has created an interactive map of USGS projects to highlight the integrated science currently conducted within the Colorado River Basin. These projects are not all inclusive of the work conducted by the USGS within the CRB, but highlight the broad range of integrated science currently conducted.
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