Charles Yackulic
Science and Products
Rainbow 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...
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
Construction of Glen Canyon Dam has led to large changes in environmental conditions of the downriver Colorado River. Whereas the pre-dam Colorado River experienced large seasonal variation in temperature and discharge and was highly turbid, the post-dam Colorado River is far less variable in terms of temperature and discharge and is frequently clear. Many nonnative fish species had already...
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...
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...
A need for speed in Bayesian population models: A practical guide to marginalizing and recovering discrete latent states
Bayesian population models can be exceedingly slow due, in part, to the choice to simulate discrete latent states. Here, we discuss an alternative approach to discrete latent states, marginalization, that forms the basis of maximum likelihood population models and is much faster. Our manuscript has two goals: 1) to introduce readers unfamiliar...
Yackulic, Charles B.; Dodrill, Michael J.; Dzul, Maria C.; Sanderlin, Jamie S.; Reid, Janice A. Is your ad hoc model selection strategy affecting your multimodel inference?
(Yackulic) 1. Ecologists routinely fit complex models with multiple parameters of interest, where hundreds or more competing models are plausible. To limit the number of fitted models, ecologists often define a model selection strategy composed of a series of stages in which certain features of a model are compared while other features are held...
Morin, Dana J.; Yackulic, Charles B.; Diffendorfer, James; Lesmeister, Damon B.; Nielsen, Clayton K.; Reid, Janice; Schauber, Eric M. Calcite precipitation in Lake Powell reduces alkalinity and total salt loading to the Lower Colorado River Basin
Reservoirs can retain and transform carbon, nitrogen, phosphorus, and silica, but less is known about their effects on other biogeochemically relevant solutes. The salinization of freshwater ecosystems is a growing concern in many regions, and the role of reservoirs in salinity transport is an important research frontier. Here, we examine how a...
Deemer, Bridget; Stets, Edward G.; Yackulic, Charles B.
Effects of water temperature, turbidity, and rainbow trout on humpback chub population dynamics
Humpback chub (Gila cypha Miller 1946), found only in the Colorado River Basin, was one of the first species to be given full protection under the Endangered Species Act of 1973. Habitat alterations, such as changes in flow and water temperature caused by dams, and the introduction of nonnative fish have contributed to population declines in...
Frederick, Phil; Yackulic, Charles; Hull, Julia B. Safety in numbers: Cost-effective endangered species management for viable populations
We develop a bioeconomic model to identify the cost-effective control of an invasive species (rain-bow trout) to achieve a population viability goal for an endangered species (humpback chub) in the Grand Canyon of the U.S. southwest. The population viability optimization problem is no-toriously difficult to solve due to a probabilistic restriction...
Donovan, Pierce; Bair, Lucas S.; Yackulic, Charles B.; Springborn, Michael R. Migration triggers in a large herbivore: Galapagos giant tortoises navigating resources gradients on volcanoes
To understand how migratory behavior evolved and to predict the future of migratory species in the face of global environmental change it is important to quantify intra- and inter-individual variation in migratory behavior. Intra-individual variation includes behavioral response to changing environmental conditions and hence behavioral plasticity...
Bastille-Rousseau, Guillaume; Yackulic, Charles B.; Gibbs, James P.; Friar, Jacqueline L.; Cabrera, Freddy; Blake, Stephen Incorporating social-ecological considerations into basin-wide responses to climate change in the Colorado River Basin
(Bair) During the last 50 years, construction of dams in the western United States declined. This is partly because of increasing recognition of varied and unintended social-ecological consequences of dams. Today, resource managers are recognizing the wide array of tradeoffs and are including a more diverse group of stakeholders in decision making...
Bair, Lucas; Yackulic, Charles B.; Schmidt, John C.; Perry, Denielle M.; Kirchhoff, Christine J.; Chief, Karletta; Colombi, Benedict J. Effects of high flow events (and other factors) on Salmonids
Spring and fall high flow events released by Glen Canyon Dam appear to affect rainbow and brown trout in different ways that also very geographically, however other environmental factors are likely to play as important, or more important. Teasing apart impacts is made difficult by the lack of experimental design and limited replication of spring...
Yackulic, Charles B. The past and future roles of competition and habitat in the range‐wide occupancy dynamics of Northern Spotted Owls
Slow ecological processes challenge conservation. Short‐term variability can obscure the importance of slower processes that may ultimately determine the state of a system. Furthermore, management actions with slow responses can be hard to justify. One response to slow processes is to explicitly concentrate analysis on state dynamics. Here, we...
Yackulic, Charles B.; Bailey, Larissa L.; Dugger, Catherine; Davis, Raymond J.; Franklin, Alan B.; Forsman, Eric D.; Ackers, Steven H.; Andrews, Lawrence S.; Diller, Lowell V.; Gremel, Scott A.; Hamm, Keith A.; Herter, Dale R.; Higley, J. Mark; Horn, Rob B.; McCafferty, Christopher; Reid, Janice A.; Rockweit, Jeremy T.; Sovern, Stan G. The metabolic regimes of 356 rivers in the United States
A national-scale quantification of metabolic energy flow in streams and rivers can improve understanding of the temporal dynamics of in-stream activity, links between energy cycling and ecosystem services, and the effects of human activities on aquatic metabolism. The two dominant terms in aquatic metabolism, gross primary production (GPP) and...
Appling, Alison P.; Read, Jordan S.; Winslow, Luke A.; Arroita, Maite; Bernhardt, Emily S.; Griffiths, Natalie A.; Hall, Robert O.; Harvey, Judson W.; Heffernan, James B.; Stanley, Emily H.; Stets, Edward G.; Yackulic, Charles B. Warm water temperatures and shifts in seasonality increase trout recruitment but only moderately decrease adult size in western North American tailwaters
Dams throughout western North America have altered thermal regimes in rivers, creating cold, clear “tailwaters” in which trout populations thrive. Ongoing drought in the region has led to highly publicized reductions in reservoir storage and raised concerns about potential reductions in downstream flows. Large changes in riverine thermal regimes...
Dibble, Kimberly L.; Yackulic, Charles B.; Kennedy, Theodore A. Spatial distribution of estuarine diamond-backed terrapins (Malaclemys terrapin) and risk analysis from commercial blue crab (Callinectes sapidus) trapping at the Savannah Coastal Refuges Complex, USA
The diamond-backed terrapin (Malaclemys terrapin) is a small estuarine turtle distributed along the Atlantic and Gulf Coasts of the USA. Terrapin populations are declining throughout their range and one of the main causes is mortality by drowning as bycatch in commercially-fished blue crab (Callinetes sapidus) traps (aka pots). We conducted head...
Lovich, Jeffrey E.; Thomas, Meagan; Ironside, Kirsten E.; Yackulic, Charles B.; Puffer, Shellie R.
SBSC Research on Barred and Spotted Owls Covered by Ecological Society of America
The Ecological Society of America put out a press release on a paper that investigated the relative importance of barred owl competition and habitat on northern spotted owls in an effort to assist managers. The lead author of the paper is Charles Yackulic of the USGS Southwest Biological Science Center.
Barred Owls Ousting Spotted Owls in the Pacific Northwest
An increase in the barred owl population is contributing to the decline of threatened Northern spotted owls, according to models developed by U.S. Geological Survey and U.S. Forest Service scientists.