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Gao X.,Central Regional Office and Conservation Research Center | He C.,University of Missouri | Sun D.,University of Missouri
Spatial Statistics | Year: 2013

Nonresponse is a persistent problem in surveys because results from respondents only are subject to nonresponse bias. Many methods have been developed to deal with ignorable (missing at random) nonresponse data. In this paper, we provide a method to assess and adjust nonignorable (not missing at random) nonresponse bias in a small area estimation problem. We propose a bivariate Bayesian hierarchical linear mixed model to estimate both satisfaction rate and response rate. This model uses spatial dependencies among subdomains and auxiliary information from sample units to assess and adjust nonresponse bias. In addition, it explicitly includes a parameter that indicates whether the nonresponse is ignorable or not. The method is used to analyze the 2001 Missouri Deer Hunter Attitude Survey (MDHAS). The result shows that the nonresponse in MDHAS is nonignorable. Hunter age and the number of deer harvested have strong effects on satisfaction and response rates, and spatial dependencies are strong amongst counties of hunters' residences. The estimated satisfaction rates are lower after adjusting for nonresponse bias. © 2013 Elsevier Ltd. All rights reserved. Source

Randklev C.R.,Texas A&M University | Johnson M.S.,Texas A&M University | Tsakiris E.T.,Texas A&M University | Rogers-Oetker S.,U.S. Fish and Wildlife Service | And 6 more authors.
American Malacological Bulletin | Year: 2012

During a recent survey a small population of Quadrula mitchelli (Simpson, 1895), a species thought to have been extinct, was discovered in Texas. In total, 7 live individuals were collected from the Guadalupe River near Gonzales, Gonzales County, Texas. Our finding represents the only known population for this species in Texas and the first record of live specimens in over 30 y, which is significant because this species is currently under review for protection under the Endangered Species Act. Source

Allert A.L.,Columbia Environmental Research Center | DiStefano R.J.,Central Regional Office and Conservation Research Center | Schmitt C.J.,Columbia Environmental Research Center | Fairchild J.F.,Columbia Environmental Research Center | Brumbaugh W.G.,Columbia Environmental Research Center
Archives of Environmental Contamination and Toxicology | Year: 2012

Riffle-dwelling crayfish populations were sampled at 16 sites in 4 tributaries of the Spring River located within the Tri-State Mining District in southwest Missouri. Crayfish density, physical habitat quality, and water quality were examined at each site to assess the ecological effects of mining-derived metals on crayfish. Metals (lead, zinc, and cadmium) were analyzed in samples of surface water, sediment, detritus, and whole crayfish. Sites were classified a posteriori into reference, mining, and downstream sites primarily based on metal concentrations in the materials analyzed. Three species of crayfish (Orconectes neglectus neglectus, O. macrus, and O. virilis) were collected during the study; however, only O. n. neglectus was collected at all sites. Mean crayfish densities were significantly lower at mining sites than at reference sites. Mean concentrations of metals were significantly correlated among the materials analyzed and were significantly greater at mining and downstream sites than at reference sites. Principal component analyses showed a separation of sites due to an inverse relationship among crayfish density, metals concentrations, and physical habitat quality variables. Sediment probableeffects quotients and surface-water toxic unit scores were significantly correlated; both indicated risk of toxicity to aquatic biota at several sites. Metals concentrations in whole crayfish at several sites exceeded concentrations known to be toxic to carnivorous wildlife. Mining-derived metals have the potential to impair ecosystem function through decreased organic matter processing and nutrient cycling in streams due to decreased crayfish densities. © Springer Science+Business Media, LLC 2012. Source

Westhoff J.T.,University of Missouri | Westhoff J.T.,Central Regional Office and Conservation Research Center | Rosenberger A.E.,U.S. Geological Survey
Reviews in Fish Biology and Fisheries | Year: 2016

Conservation efforts, environmental planning, and management must account for ongoing ecosystem alteration due to a changing climate, introduced species, and shifting land use. This type of management can be facilitated by an understanding of the thermal ecology of aquatic organisms. However, information on thermal ecology for entire taxonomic groups is rarely compiled or summarized, and reviews of the science can facilitate its advancement. Crayfish are one of the most globally threatened taxa, and ongoing declines and extirpation could have serious consequences on aquatic ecosystem function due to their significant biomass and ecosystem roles. Our goal was to review the literature on thermal ecology for freshwater crayfish worldwide, with emphasis on studies that estimated temperature tolerance, temperature preference, or optimal growth. We also explored relationships between temperature metrics and species distributions. We located 56 studies containing information for at least one of those three metrics, which covered approximately 6 % of extant crayfish species worldwide. Information on one or more metrics existed for all 3 genera of Astacidae, 4 of the 12 genera of Cambaridae, and 3 of the 15 genera of Parastacidae. Investigations employed numerous methodological approaches for estimating these parameters, which restricts comparisons among and within species. The only statistically significant relationship we observed between a temperature metric and species range was a negative linear relationship between absolute latitude and optimal growth temperature. We recommend expansion of studies examining the thermal ecology of freshwater crayfish and identify and discuss methodological approaches that can improve standardization and comparability among studies. © 2016 Springer International Publishing Switzerland (outside the USA) Source

Hinck J.E.,U.S. Geological Survey | Mcmurray S.E.,Central Regional Office and Conservation Research Center | Roberts A.D.,U.S. Fish and Wildlife Service | Barnhart M.C.,Missouri State University | And 3 more authors.
Journal of Fish and Wildlife Management | Year: 2012

The Meramec River basin in east-central Missouri has one of the most diverse unionoid mussel faunas in the central United States with >40 species identified. Data were analyzed from historical surveys to test whether diversity and abundance of mussels in the Meramec River basin (Big, Bourbeuse, and Meramec rivers, representing >400 river miles) decreased between 1978 and 1997. We found that over 20 y, species richness and diversity decreased significantly in the Bourbeuse and Meramec rivers but not in the Big River. Most species were found at fewer sites and in lower numbers in 1997 than in 1978. Federally endangered species and Missouri Species of Conservation Concern with the most severe temporal declines were Alasmidonta viridis, Arcidens confragosus, Elliptio crassidens, Epioblasma triquetra, Fusconaia ebena, Lampsilis abrupta, Lampsilis brittsi, and Simpsonaias ambigua. Averaged across all species, mussels were generally being extirpated from historical sampling sites more rapidly than colonization was occurring. An exception was one reach of the Meramec River between river miles 28.4 and 59.5, where mussel abundance and diversity were greater than in other reaches and where colonization of Margaritiferidae, Lampsilini, and Quadrulini exceeded extirpation. The exact reasons mussel diversity and abundance have remained robust in this 30-mile reach is uncertain, but the reach is associated with increased gradients, few long pools, and vertical rock faces, all of which are preferable for mussels. Complete loss of mussel communities at eight sites (16%) with relatively diverse historical assemblages was attributed to physical habitat changes including bank erosion, unstable substrate, and sedimentation. Mussel conservation efforts, including restoring and protecting riparian habitats, limiting the effects of in-stream sand and gravel mining, monitoring and controlling invasive species, and protecting water quality, may be warranted in the Meramec River basin. Source

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