Geology topics

Rima Dey

Publications and source records attributed to Rima Dey.

4 recordsLinked to original sources

USGS2016

A stochastic bioenergetics model based approach to translating large river flow and temperature in to fish population responses: The pallid sturgeon example

In managing fish populations, especially at-risk species, realistic mathematical models are needed to help predict population response to potential management actions in the context of environmental conditions and changing climate while effectively incorporating the stochastic nature of real world conditions. We provide a key component of such a model for the endangered pallid sturgeon ( Scaphirhynchus albus ) in the form of an individual-based bioenergetics model influenced not only by temperature but also by flow. This component is based on modification of a known individual-based bioenergetics model through incorporation of: the observed ontogenetic shift in pallid sturgeon diet from marcroinvertebrates to fish; the energetic costs of swimming under flowing-water conditions; and stochasticity. We provide an assessment of how differences in environmental conditions could potentially alter pallid sturgeon growth estimates, using observed temperature and velocity from channelized portions of the Lower Missouri River mainstem. We do this using separate relationships between the proportion of maximum consumption and fork length and swimming cost standard error estimates for fish captured above and below the Kansas River in the Lower Missouri River. Critical to our matching observed growth in the field with predicted growth based on observed environmental conditions was a two-step shift in diet from macroinvertebrates to fish.

Missouri River↗

USGS2015

Hierarchical stochastic modeling of large river ecosystems and fish growth across spatio-temporal scales and climate models: the Missouri River endangered pallid sturgeon example

We present a hierarchical series of spatially decreasing and temporally increasing models to evaluate the uncertainty in the atmosphere – ocean global climate model (AOGCM) and the regional climate model (RCM) relative to the uncertainty in the somatic growth of the endangered pallid sturgeon (Scaphirhynchus albus). For effects on fish populations of riverine ecosystems, cli- mate output simulated by coarse-resolution AOGCMs and RCMs must be downscaled to basins to river hydrology to population response. One needs to transfer the information from these climate simulations down to the individual scale in a way that minimizes extrapolation and can account for spatio-temporal variability in the intervening stages. The goal is a framework to determine whether, given uncertainties in the climate models and the biological response, meaningful inference can still be made. The non-linear downscaling of climate information to the river scale requires that one realistically account for spatial and temporal variability across scale. Our down- scaling procedure includes the use of fixed/calibrated hydrological flow and temperature models coupled with a stochastically parameterized sturgeon bioenergetics model. We show that, although there is a large amount of uncertainty associated with both the climate model output and the fish growth process, one can establish significant differences in fish growth distributions between models, and between future and current climates for a given model.

Missouri River basin↗

USGS2012

Modeling responses of large-river fish populations to global climate change through downscaling and incorporation of predictive uncertainty

Climate change operates over a broad range of spatial and temporal scales. Understanding its effects on ecosystems requires multi-scale models. For understanding effects on fish populations of riverine ecosystems, climate predicted by coarse-resolution Global Climate Models must be downscaled to Regional Climate Models to watersheds to river hydrology to population response. An additional challenge is quantifying sources of uncertainty given the highly nonlinear nature of interactions between climate variables and community level processes. We present a modeling approach for understanding and accomodating uncertainty by applying multi-scale climate models and a hierarchical Bayesian modeling framework to Midwest fish population dynamics and by linking models for system components together by formal rules of probability. The proposed hierarchical modeling approach will account for sources of uncertainty in forecasts of community or population response. The goal is to evaluate the potential distributional changes in an ecological system, given distributional changes implied by a series of linked climate and system models under various emissions/use scenarios. This understanding will aid evaluation of management options for coping with global climate change. In our initial analyses, we found that predicted pallid sturgeon population responses were dependent on the climate scenario considered.

Missouri River↗

USGS2010

Neosho madtom and other ictalurid populations in relation to hydrologic characteristics of an impounded Midwestern warmwater stream: Update

The Neosho madtom, Noturus placidus , is a small (less than 75 millimeters in total length) ictalurid that is native to the main stems of the Neosho and Cottonwood Rivers in Kansas and Oklahoma and the Spring River in Kansas and Missouri. The Neosho madtom was federally listed as threatened by the U.S. Fish and Wildlife Service in May 1990. The U.S. Fish and Wildlife Service has been monitoring Neosho madtoms since 1991, and questioned whether or not Neosho madtom densities were affected by other catfish species, reservoirs, and hydrologic characteristics. Using the first 8 years of U.S. Fish and Wildlife Service monitoring data, Wildhaber and others (2000) analyzed whether or not Neosho madtom densities were related to these environmental characteristics. The goal of this report is to update these results with data from 1999 to 2008. The trends of Neosho madtom densities in respect to John Redmond Reservoir and other catfish species remains consistent with the previous report. In both the Neosho and Spring Rivers, Neosho madtoms had a significant positive association with all catfish species. Of those species tested, only in the population of Neosho madtoms were significantly different in density above verses below the John Redmond Reservoir after accounting for the yearly variation. The average density of Neosho madtoms at the streamgage immediately below the reservoir had the second lowest density compared to the other streamgages. The positive associations with Neosho madtoms that remained consistent from the previous report included the 1-, 3-, and 7-day minima discharges and the annual minimum discharge from the previous water year (water year prior to when the fish were sampled) and the 1-, 3-, 7-, and 30-day minima discharges from the current water year (same water year fish were sampled).

Kansas, Missouri, Oklahoma↗